Publications
2024
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(2024) Nature Communications. 15, 6671. Abstract
Silk fibers\u2019 unique mechanical properties have made them desirable materials, yet their formation mechanism remains poorly understood. While ions are known to support silk fiber production, their exact role has thus far eluded discovery. Here, we use cryo-electron microscopy coupled with elemental analysis to elucidate the changes in the composition and spatial localization of metal ions during silk evolution inside the silk gland. During the initial protein secretion and storage stages, ions are homogeneously dispersed in the silk gland. Once the fibers are spun, the ions delocalize from the fibroin core to the sericin-coating layer, a process accompanied by protein chain alignment and increased feedstock viscosity. This change makes the protein more shear-sensitive and initiates the liquid-to-solid transition. Selective metal ion doping modifies silk fibers\u2019 mechanical performance. These findings enhance our understanding of the silk fiber formation mechanism, laying the foundations for developing new concepts in biomaterial design.
(2024) Proceedings of the National Academy of Sciences. 121, 34, e231551012. Abstract[All authors]Mechanical energy, specifically in the form of ultrasound, can induce pressure variations and temperature fluctuations when applied to an aqueous media. These conditions can both positively and negatively affect protein complexes, consequently altering their stability, folding patterns, and self-assembling behavior. Despite much scientific progress, our current understanding of the effects of ultrasound on the self-assembly of amyloidogenic proteins remains limited. In the present study, we demonstrate that when the amplitude of the delivered ultrasonic energy is sufficiently low, it can induce refolding of specific motifs in protein monomers, which is sufficient for primary nucleation; this has been revealed by MD. These ultrasound-induced structural changes are initiated by pressure perturbations and are accelerated by a temperature factor. Furthermore, the prolonged action of low-amplitude ultrasound enables the elongation of amyloid protein nanofibrils directly from natively folded monomeric lysozyme protein, in a controlled manner, until it reaches a critical length. Using solution X-ray scattering, we determined that nanofibrillar assemblies, formed either under the action of sound or from natively fibrillated lysozyme, share identical structural characteristics. Thus, these results provide insights into the effects of ultrasound on fibrillar protein self-assembly and lay the foundation for the potential use of sound energy in protein chemistry.
(2024) ACS Applied Materials and Interfaces. 16, 7, p. 9210-9223 Abstract[All authors]Biology resolves design requirements toward functional materials by creating nanostructured composites, where individual components are combined to maximize the macroscale material performance. A major challenge in utilizing such design principles is the trade-off between the preservation of individual component properties and emerging composite functionalities. Here, polysaccharide pectin and silk fibroin were investigated in their composite form with pectin as a thermal-responsive ion conductor and fibroin with exceptional mechanical strength. We show that segregative phase separation occurs upon mixing, and within a limited compositional range, domains ∼50 nm in size are formed and distributed homogeneously so that decent matrix collective properties are established. The composite is characterized by slight conformational changes in the silk domains, sequestering the hydrogen-bonded β-sheets as well as the emergence of randomized pectin orientations. However, most dominant in the composite’s properties is the introduction of dense domain interfaces, leading to increased hydration, surface hydrophilicity, and increased strain of the composite material. Using controlled surface charging in X-ray photoelectron spectroscopy, we further demonstrate Ca ions (Ca2+) diffusion in the pectin domains, with which the fingerprints of interactions at domain interfaces are revealed. Both the thermal response and the electrical conductance were found to be strongly dependent on the degree of composite hydration. Our results provide a fundamental understanding of the role of interfacial interactions and their potential applications in the design of material properties, polysaccharide-protein composites in particular.
(2024) Angewandte Chemie - International Edition. 63, 14, e202318365. AbstractProtein self-assembly is a fundamental biological process where proteins spontaneously organize into complex and functional structures without external direction. This process is crucial for the formation of various biological functionalities. However, when protein self-assembly fails, it can trigger the development of multiple disorders, thus making understanding this phenomenon extremely important. Up until recently, protein self-assembly has been solely linked either to biological function or malfunction; however, in the past decade or two it has also been found to hold promising potential as an alternative route for fabricating materials for biomedical applications. It is therefore necessary and timely to summarize the key aspects of protein self-assembly: how the protein structure and self-assembly conditions (chemical environments, kinetics, and the physicochemical characteristics of protein complexes) can be utilized to design biomaterials. This minireview focuses on the basic concepts of forming supramolecular structures, and the existing routes for modifications. We then compare the applicability of different approaches, including compartmentalization and self-assembly monitoring. Finally, based on the cutting-edge progress made during the last years, we summarize the current knowledge about tailoring a final function by introducing changes in self-assembly and link it to biomaterials' performance.This Minireview sums up cutting-edge concepts regarding the formation of protein-based supramolecular structures, compartmentalization, and self-assembly monitoring; it compares the routes of their modifications and applications in multifunctional biomaterial design. We summarize the current knowledge about machine learning/artificial intelligence applications for protein structure prediction/obtainment and link it to biomaterial performance.+image
2023
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(2023) Small. 20, 22, 2308069. Abstract
A notable feature of complex cellular environments is protein-rich compartments that are formed via liquid\u2013liquid phase separation. Recent studies have shown that these biomolecular condensates can play both promoting and inhibitory roles in fibrillar protein self-assembly, a process that is linked to Alzheimer's, Parkinson's, Huntington's, and various prion diseases. Yet, the exact regulatory role of these condensates in protein aggregation remains unknown. By employing microfluidics to create artificial protein compartments, the self-assembly behavior of the fibrillar protein lysozyme within them can be characterized. It is observed that the volumetric parameters of protein-rich compartments can change the kinetics of protein self-assembly. Depending on the change in compartment parameters, the lysozyme fibrillation process either accelerated or decelerated. Furthermore, the results confirm that the volumetric parameters govern not only the nucleation and growth phases of the fibrillar aggregates but also affect the crosstalk between the protein-rich and protein-poor phases. The appearance of phase-separated compartments in the vicinity of natively folded protein complexes triggers their abrupt percolation into the compartments' core and further accelerates protein aggregation. Overall, the results of the study shed more light on the complex behavior and functions of protein-rich phases and, importantly, on their interaction with the surrounding environment.
(2023) FEBS Letters. 597, 24, p. 3013-3037 AbstractMechanical energy in the form of ultrasound and protein complexes intuitively have been considered as two distinct unrelated topics. However, in the past few years, increasingly more attention has been paid to the ability of ultrasound to induce chemical modifications on protein molecules that further change protein-protein interaction and protein self-assembling behavior. Despite efforts to decipher the exact structure and the behavior-modifying effects of ultrasound on proteins, our current understanding of these aspects remains limited. The limitation arises from the complexity of both phenomena. Ultrasound produces multiple chemical, mechanical, and thermal effects in aqueous media. Proteins are dynamic molecules with diverse complexation mechanisms. This review provides an exhaustive analysis of the progress made in better understanding the role of ultrasound in protein complexation. It describes in detail how ultrasound affects an aqueous environment and the impact of each effect separately and when combined with the protein structure and fold, the protein-protein interaction, and finally the protein self-assembly. It specifically focuses on modifying role of ultrasound in amyloid self-assembly, where the latter is associated with multiple neurodegenerative disorders.
(2023) ACS Materials Au. 3, 6, p. 699-710 AbstractNoble metal nanoparticles (NPs) and particularly gold (Au) have become emerging materials in recent decades due to their exceptional optical properties, such as localized surface plasmons. Although multiple and relatively simple protocols have been developed for AuNP synthesis, the functionalization of solid surfaces composed of soft matter with AuNPs often requires complex and multistep processes. Here we developed a facile approach for functionalizing soft adhesive flexible films with plasmonic AuNPs. The synthetic route is based on preparing Au nanoislands (AuNI) (ca. 2-300 nm) on a glass substrate followed by hydrophobization of the functionalized surface, which in turn, allows efficient transfer of AuNIs to flexible adhesive films via soft-printing tape lithography. Here we show that the AuNI structure remained intact after the hydrophobization and soft-printing procedures. The AuNI-functionalized flexible films were characterized by various techniques, revealing unique characteristics such as tunable localized plasmon resonance and Raman enhancement factors beneficial for chemical and biological sensing applications.
(2023) Langmuir. 39, 26, p. 8984-8995 AbstractThe rheological characteristics of pre-spun native silk protein, which is stored as a viscous pulp inside the silk gland, are the key factors that determine the mechanical performance of the endpoint material: the spun silk fibers. In silkworms and arthropods, microcompartmentalization was shown to play an important regulatory role in storing and stabilizing the aggregation-prone silk and in initiating the fibrillar self-assembly process. However, our current understanding of the mechanism of stabilization of the highly unstable protein pulp in its soluble state inside the microcompartments and of the conditions required for initiating the structural transition in protein inside the microcompartments remains limited. Here, we exploited the power of droplet microfluidics to mimic the silk protein\u2019s microcompartmentalization event; we introduced changes in the chemical environment and analyzed the storage-to-spinning transition as well as the accompanying structural changes in silk fibroin protein, from its native fold into an aggregative β-sheet-rich structure. Through a combination of experimental and computational simulations, we established the conditions under which the structural transition in microcompartmentalized silk protein is initiated, which, in turn, is reflected in changes in the silk-rich fluid behavior. Overall, our study sheds light on the role of the independent parameters of a dynamically changing chemical environment, changes in fluid viscosity, and the shear forces that act to balance silk protein self-assembly, and thus, facilitate new exploratory avenues in the field of biomaterials.
(2023) Proceedings of the National Academy of Sciences - PNAS. 120, 3, e221284912. AbstractProtein folding is crucial for biological activity. Proteins’ failure to fold correctly underlies various pathological processes, including amyloidosis, the aggregation of insoluble proteins (e.g., lysozymes) in organs. The exact conditions that trigger the structural transition of amyloids into β-sheet-rich aggregates are poorly understood, as is the case for the amyloidogenic self-assembly pathway. Ultrasound is routinely used to destabilize a protein’s structure and enhance amyloid growth. Here, we report on an unexpected ultrasound effect on lysozyme amyloid species at different stages of aggregation: ultrasound-induced structural perturbation gives rise to nonamyloidogenic folds. Our infrared and X-ray analyses of the chemical, mechanical, and thermal effects of sound on lysozyme’s structure found, in addition to the expected ultrasound-induced damage, evidence of irreversible disruption of the β-sheet fold of fibrillar lysozyme resulting in their structural transformation into monomers with no β-sheets. This structural transition is reflected in changes in the kinetics of protein self-assembly, namely, either prolonged nucleation or accelerated fibril growth. Using solution X-ray scattering, we determined the structure, the mass fraction of lysozyme monomer, and the morphology of its filamentous assemblies formed under different sound parameters. A nanomechanical analysis of ultrasound-modified protein assemblies revealed a correlation between the β-sheet content and elastic modulus of the protein material. Suppressing one of the ultrasound-derived effects allowed us to control the structural transformations of lysozyme. Overall, our comprehensive investigation establishes the boundary conditions under which ultrasound damages protein structure and fold. This knowledge can be utilized to impose medically desirable structural modifications on amyloid β-sheet-rich proteins.
2022
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(2022) Nature Communications. 13, 1, 7856. Abstract[All authors]
Silk is a unique, remarkably strong biomaterial made of simple protein building blocks. To date, no synthetic method has come close to reproducing the properties of natural silk, due to the complexity and insufficient understanding of the mechanism of the silk fiber formation. Here, we use a combination of bulk analytical techniques and nanoscale analytical methods, including nano-infrared spectroscopy coupled with atomic force microscopy, to probe the structural characteristics directly, transitions, and evolution of the associated mechanical properties of silk protein species corresponding to the supramolecular phase states inside the silkworm's silk gland. We found that the key step in silk-fiber production is the formation of nanoscale compartments that guide the structural transition of proteins from their native fold into crystalline β-sheets. Remarkably, this process is reversible. Such reversibility enables the remodeling of the final mechanical characteristics of silk materials. These results open a new route for tailoring silk processing for a wide range of new material formats by controlling the structural transitions and self-assembly of the silk protein's supramolecular phases.
(2022) ACS Omega. 7, 51, p. 47747-47754 AbstractThe spontaneous gelation of poly(4-vinyl pyridine)/pyridine solution produces materials with conductive properties that are suitable for various energy conversion technologies. The gel is a thermoelectric material with a conductivity of 2.2–5.0 × 10–6 S m–1 and dielectric constant ε = 11.3. On the molecular scale, the gel contains various types of hydrogen bonding, which are formed via self-protonation of the pyridine side chains. Our measurements and calculations revealed that the gelation process produces bias-dependent polymer complexes: quasi-symmetric, strongly hydrogen-bonded species, and weakly bound protonated structures. Under an applied DC bias, the gelled complexes differ in their capacitance/conductive characteristics. In this work, we exploited the bias-responsive characteristics of poly(4-vinyl pyridine) gelled complexes to develop a prototype of a thermal energy harvesting device. The measured device efficiency is S = ΔV/ΔT = 0.18 mV/K within the temperature range of 296–360 K. Investigation of the mechanism underlying the conversion of thermal energy into electric charge showed that the heat-controlled proton diffusion (the Soret effect) produces thermogalvanic redox reactions of hydrogen ions on the anode. The charge can be stored in an external capacitor for heat energy harvesting. These results advance our understanding of the molecular mechanisms underlying thermal energy conversion in the poly(4-vinyl pyridine)/pyridine gel. A device prototype, enabling thermal energy harvesting, successfully demonstrates a simple path toward the development of inexpensive, low-energy thermoelectric generators.
(2022) Colloids and surfaces, B, Biointerfaces. 216, p. - 112532. AbstractBODIPY dyes possess favorable optical properties for a variety of applications including in vivo and in vitro diagnostics. However, their utilization might be limited by their water insolubility and incompatibility with chemical modifications, resulting in low aggregation stability. Here, we outline the route for addressing this issue. We have demonstrated two approaches, based on dye entrapment in micellar coordination clusters (MCCs); this provides a general solution for water solubility as well as aggregation stability of the seven BODIPY derivatives. These derivatives have various bulky aromatic substituents in the 2,3,5,6- and meso-positions and can rotate relative to a dipyrrin core, which also provides molecular rotor properties. The molecular structural features and the presence of aromatic groups allows BODIPY dyes to be used as "supporting molecules", thus promoting micelle-micelle interaction and micellar network stabilization. In the second approach, self-micellization, following BODIPY use, leads to MCC formation without the use of any mediators, including chelators and/or metal ions. In both approaches, BODIPY exhibits an excellent optical response, at a concentration beyond its solubilization limit in aqueous media and without undesired crystallization. The suggested approaches represent systems used to encapsulate BODIPY in a capsule-based surfactant environment, enabling one to track the aggregation of BODIPY; these approaches represent an alternative system to study and apply BODIPY's molecular rotor properties. The stabilized compounds, i.e., the BODIPY-loaded MCCs, provide a unique feature of permeability to hydrophilic ligand-switching proteins such as BSA; they exhibit a bright "turn-on" fluorescence signal within the clusters via macromolecular complexation, thus expanding the possibilities of water-soluble BODIPY-loaded MCCs utilization for functional indicators.
(2022) Data in Brief. 43, 108464. AbstractThe data presented here refer to the research article by Aleksei V. Solomonov, Yuriy S. Marfin, Alexander B. Tesler, Dmitry A. Merkushev, Elizaveta A. Bogatyreva, Elena V. Antina, Evgeniy V. Rumyantsev, and Ulyana Shimanovich \u201cSpanning BODIPY fluorescence with self-assembled micellar clusters\u201d, Colloids and Surfaces B: Biointerfaces, 216, 2022, 112532. The present article provides details on optical characterization for a set of meso- and tetra-substituted boron-dipyrrin (BODIPY) complexes encapsulated inside of self-assembled Triton-X-based micellar coordination clusters (MCCs), based on Triton-X family surfactants. Changes in the optical properties of the BODIPY complexes upon interaction with bovine serum albumin, in a binary mixture of THF:H2O and titrated with Triton TX-114, were evaluated. The optical properties and the formation kinetics of the BODIPY-based MCCs and the BODIPY-supported micelle chelator aggregates (MCAs) are presented as well. The presented data provide additional insights into the structural and formation aspects of both the traditional and newly obtained micellar coordination clusters for their future optimization, control, and application. The synthetic procedures for the synthesis of a set of meso- and tetra-substituted BODIPY complexes and their optical properties in different media are also presented. The research is related to the paper (Solomonov et al., 2022).
2021
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(2021) Molecules. 26, 22, 6925. Abstract
Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals. We show that this light-induced process is only partially reversible, and that the photogenerated aminoaldehyde and aminoaldehyde-pending groups undergo self-condensation to produce cross-linked, conjugated oligomers that absorb light in the visible spectrum up to the near-infrared range. Such a sequence of chemical reactions results in the formation of gel with two distinct morphologies: spheres and fiber-like matrices. To gain deeper insight into this process, we prepared poly(4-vinyl pyridine) with low molecular weight (about 2000 g/mol) and monitored the respective changes in absorption, fluorescence,1H-NMR spectra, and electrical conductivity. The conductivity of the polymer gel upon irradiation changes from ionic to electronic, indicative of a conjugated molecular wire behavior. Quantum mechanical calculations confirmed the feasibility of the proposed polycondensation process. This new polyacetylene analog has potential in thermal energy-harvesting and sensor applications.
(2021) Small (Weinheim an der Bergstrasse, Germany). e2007188. Abstract[All authors]Peptides and proteins have evolved to self-assemble into supramolecular entities through a set of non-covalent interactions. Such structures and materials provide the functional basis of life. Crucially, biomolecular assembly processes can be highly sensitive to and modulated by environmental conditions, including temperature, light, ionic strength and pH, providing the inspiration for the development of new classes of responsive functional materials based on peptide building blocks. Here, it is shown that the stimuli-responsive assembly of amyloidogenic peptide can be used as the basis of environmentally responsive microcapsules which exhibit release characteristics triggered by a change in pH. The microcapsules are biocompatible and biodegradable and may act as vehicles for controlled release of a wide range of biomolecules. Cryo-SEM images reveal the formation of a fibrillar network of the capsule interior with discrete compartments in which cargo molecules can be stored. In addition, the reversible formation of these microcapsules by modulating the solution pH is investigated and their potential application for the controlled release of encapsulated cargo molecules, including antibodies, is shown. These results suggest that the approach described here represents a promising venue for generating pH-responsive functional peptide-based materials for a wide range of potential applications for molecular encapsulation, storage, and release.
(2021) Communications Chemistry. 4, 1, 62. AbstractThe process of amyloid nanofibril formation has broad implications including the generation of the strongest natural materials, namely silk fibers, and their major contribution to the progression of many degenerative diseases. The key question that remains unanswered is whether the amyloidogenic nature, which includes the characteristic H-bonded β-sheet structure and physical characteristics of protein assemblies, can be modified via controlled intervention of the molecular interactions. Here we show that tailored changes in molecular interactions, specifically in the H-bonded network, do not affect the nature of amyloidogenic fibrillation, and even have minimal effect on the initial nucleation events of self-assembly. However, they do trigger changes in networks at a higher hierarchical level, namely enhanced 2D packaging which is rationalized by the 3D hierarchy of β-sheet assembly, leading to variations in fibril morphology, structural composition and, remarkably, nanomechanical properties. These results pave the way to a better understanding of the role of molecular interactions in sculpting the structural and physical properties of protein supramolecular constructs.
2019
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(2019) Biological and Bio-Inspired Natanomaterials: Properties and assembly mechanisms. Buell AK., Perrett S. & Knowles T.(eds.). p. 223-263 Abstract
Nanofibrillar forms of amyloidogenic proteins were initially discovered in the context of protein misfolding and disease but have more recently been found at the origin of key biological functionality in many naturally occurring functional materials, such as adhesives and biofilm coatings. Their physiological roles in nature reflect their great strength and stability, which has led to the exploration of their use as the basis of artificial protein-based functional materials. Particularly for biomedical applications, they represent attractive building blocks for the development of, for instance, drug carrier agents due to their inherent biocompatibility and biodegradability. Furthermore, the propensity of proteins to self-assemble into amyloid fibrils can be exploited under microconfinement, afforded by droplet microfluidic techniques. This approach allows the generation of multi-scale functional microgels that can host biological additives and can be designed to incorporate additional functionality, such as to aid targeted drug delivery.
(2019) Israel Journal of Chemistry. 12, p. 1152-1170 AbstractSupramolecular self-assembled structures, based on protein-protein interactions, have garnered widespread interest as prospective functional bionanomaterials. Possessing unique properties, proteins have been widely investigated in the last years, due to their capability to form a diversity of natural and artificially designed zero-, one-, two- and three-dimensional assemblies. These structures laid the basis for bionanomaterials design, including films, foams, gels, and others, with widespread applications in electronics, biomedicine, and environmental sciences. In this context, the present review is devoted to revealing the diversity of protein assemblies and related bionanomaterials. Special interest is paid to recent advances and new trends in functional amyloids and fibrillar silk-based self-assembling architectures, as well as their current and potential applications. We emphasize the protein nanostructures' diversity for the future design of functional protein-based materials.
(2019) Macromolecular Rapid Communications. 40, 8, 1800898. Abstract[All authors]Silk fibroin is a natural protein obtained from the Bombyx mori silkworm. In addition to being the key structural component in silkworm cocoons, it also has the propensity to self-assemble in vitro into hierarchical structures with desirable properties such as high levels of mechanical strength and robustness. Furthermore, it is an appealing biopolymer due to its biocompatability, low immunogenicity, and lack of toxicity, making it a prime candidate for biomedical material applications. Here, it is demonstrated that nanofibrils formed by reconstituted silk fibroin can be engineered into supramolecular microgels using a soft lithography-based microfluidic approach. Building on these results, a potential application for these protein microgels to encapsulate and release small molecules in a controlled manner is illustrated. Taken together, these results suggest that the tailored self-assembly of biocompatible and biodegradable silk nanofibrils can be used to generate functional micromaterials for a range of potential applications in the biomedical and pharmaceutical fields.
2018
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(2018) Advanced Materials. 30, 41, 1706462. Abstract
Protein self-assembly processes, by which polypeptides interact and independently form multimeric structures, lead to a wide array of different endpoints. Structures formed range from highly ordered molecular crystals to amorphous aggregates. Order arises in the system from a balance between many low-energy processes occurring due to a set of interactions between residues in a chain, between residues in different chains, and between solute and solvent. In Nature, self-assembling protein systems have evolved over millions of years to organize into supramolecular structures, optimized for specific functions, with this propensity determined by the sequence of their constituent amino acids, of which only 20 are encoded in DNA. The structural materials that arise from biological self-assembly can display remarkable mechanical properties, often as a result of hierarchical structure on the nano- and microscales, and much research has been devoted to mimicking and exploiting these properties for a variety of end uses. This work presents a review of a range of studies in which biological functions are effectively reproduced through the design of self-assembling fibrous protein systems.
(2018) Macromolecular Bioscience. 18, 4, 1700295. Abstract[All authors]Native silk fibroin (NSF) is a unique biomaterial with extraordinary mechanical and biochemical properties. These key characteristics are directly associated with the physical transformation of unstructured, soluble NSF into highly organized nano-and microscale fibrils rich in beta-sheet content. Here, it is shown that this NSF fibrillation process is accompanied by the development of intrinsic fluorescence in the visible range, upon near-UV excitation, a phenomenon that has not been investigated in detail to date. Here, the optical and fluorescence characteristics of NSF fibrils are probed and a route for potential applications in the field of self-assembled optically active biomaterials and systems is explored. In particular, it is demonstrated that NSF can be structured into autofluorescent microcapsules with a controllable level of beta-sheet content and fluorescence properties. Furthermore, a facile and efficient fabrication route that permits arbitrary patterns of NSF microcapsules to be deposited on substrates under ambient conditions is shown. The resulting fluorescent NSF patterns display a high level of photostability. These results demonstrate the potential of using native silk as a new class of biocompatible photonic material.
2017
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(2017) Biomacromolecules. 18, 10, p. 3052-3059 Abstract
In nature, a wide range of functional materials is based on proteins. Increasing attention is also turning to the use of proteins as artificial biomaterials in the form of films, gels, particles, and fibrils that offer great potential for applications in areas ranging from molecular medicine to materials science. To date, however, most such applications have been limited to single component materials despite the fact that their natural analogues are composed of multiple types of proteins with a variety of functionalities that are coassembled in a highly organized manner on the micrometer scale, a process that is currently challenging to achieve in the laboratory. Here, we demonstrate the fabrication of multicomponent protein microcapsules where the different components are positioned in a controlled manner. We use molecular self-assembly to generate multicomponent structures on the nanometer scale and droplet microfluidics to bring together the different components on the micrometer scale. Using this approach, we synthesize a wide range of multiprotein microcapsules containing three well-characterized proteins: glucagon, insulin, and lysozyme. The localization of each protein component in multishell microcapsules has been detected by labeling protein molecules with different fluorophores, and the final three-dimensional microcapsule structure has been resolved by using confocal microscopy together with image analysis techniques. In addition, we show that these structures can be used to tailor the release of such functional proteins in a sequential manner. Moreover, our observations demonstrate that the protein release mechanism from multishell capsules is driven by the kinetic control of mass transport of the cargo and by the dissolution of the shells. The ability to generate artificial materials that incorporate a variety of different proteins with distinct functionalities increases the breadth of the potential applications of artificial protein-based materials
(2017) Patent No. US20170202779A1, 04 Sep 2014, Priority No. GB201415681A AbstractThe present invention provides capsules having a shell of material that comprises an assembly of a protein, and the capsule is optionally provided with a network of material within the shell that is an assembly of the protein. The assembly of the protein is obtained or obtainable by the aggregation of the protein, optionally together with another protein. The assembly is a non-covalent assembly of a protein.
(2017) Israel Journal of Chemistry. 57, 7, p. 724-728 AbstractProtein aggregation is commonly associated with the onset and development of neurodegenerative disorders, including Alzheimer's, Parkinson's and other forms of pathological disorders. While this phenomenon has historically been studied in the context of its relevance to human health, over the past decade significant research effort has focused on utilizing amyloid-like protein assemblies as building blocks for the development of functional biomaterials and a number of protein-based functional materials have been demonstrated. Here we extend this concept by synthesizing hybrid organic/inorganic microcapsules containing metal-based NPs and protein nanofibrils as a nanocomposite. To this effect, we exploit the propensity of lysozyme to self-assemble into amyloid nanofibrils and their functionalization by carboxyl-modified Fe3O4 NPs. We use a microfluidics-based approach to control the micron scale moprhology of the newly formed nanocomposites. Our results illustrate the potential ofthis strategy as a platform for fabricating microcapsules from nanofibril-inorganic NPs hybrid materials.
(2017) Nature Communications. 8, 15902. Abstract[All authors]Naturally spun silks generate fibres with unique properties, including strength, elasticity and biocompatibility. Here we describe a microfluidics-based strategy to spin liquid native silk, obtained directly from the silk gland of Bombyx mori silkworms, into micron-scale capsules with controllable geometry and variable levels of intermolecular β-sheet content in their protein shells. We demonstrate that such micrococoons can store internally the otherwise highly unstable liquid native silk for several months and without apparent effect on its functionality. We further demonstrate that these native silk micrococoons enable the effective encapsulation, storage and release of other aggregation-prone proteins, such as functional antibodies. These results show that native silk micrococoons are capable of preserving the full activity of sensitive cargo proteins that can aggregate and lose function under conditions of bulk storage, and thus represent an attractive class of materials for the storage and release of active biomolecules.
2016
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(2016) Nature Communications. 7, 12934. Abstract
All-aqueous emulsions exploit spontaneous liquid-liquid separation and due to their water-based nature are particular advantageous for the biocompatible storage and processing of biomacromolecules. However, the ultralow interfacial tensions characteristic of all-aqueous interfaces represent an inherent limitation to the use of thermally adsorbed particles to achieve emulsion stability. Here, we use protein nanofibrils to generate colloidosome-like two-dimensional crosslinked networks of nanostructures templated by all-aqueous emulsions, which we term fibrillosomes. We show that this approach not only allows us to operate below the thermal limit at ultra-low surface tensions but also yields structures that are stable even in the complete absence of an interface. Moreover, we show that the growth and multilayer deposition of fibrils allows us to control the thickness of the capsule shells. These results open up the possibility of stabilizing aqueous two-phase systems using natural proteins, and creating self-standing protein capsules without the requirement for three-phase emulsions or water/oil interfaces.
(2016) Patent No. WO2016034730A1, 09 Sep 2014, Priority No. GB201415679A AbstractThe present invention provides a capsule having a shell of material that comprises an assembly of a silk protein, such as an assembly that is a non-aggregated assembly of the silk protein, such as an assembly where the a-helix, β-sheet (native) and random coil content is at least 55%. Also provided are methods for preparing the capsule, which comprises the step of contacting a flow of a first phase and a flow of a second phase in a channel, thereby to generate in the channel a dispersion of discrete regions, preferably droplets, of the second phase in the first phase, wherein the second phase comprises a silk protein suitable for forming an assembly of a protein, thereby to form a capsule shell at the boundary of the discrete region, wherein the first and second phases are immiscible.
(2016) Journal of Materials Chemistry B. 4, 5, p. 824-833 AbstractThis review focuses on the development of nanoparticle systems that enables to enhance and restore the antibiotic activity for drug-resistant organisms. New and more aggressive antibiotic resistant bacteria and parasites calls for the development of new therapeutic strategies to overcome the inefficiency of conventional antibiotics and bypass treatment limitations related to these pathologies. Nanostructured biomaterials, nanoparticles in particular, have unique physicochemical properties such as ultra-small and controllable size, large surface area to mass ratio, high reactivity, and functionalizable structure. These properties can be applied to facilitate the administration of antimicrobial drugs, thereby overcoming some of the limitations in traditional antimicrobial therapeutics. Here the current progress and challenges in synthesizing nanoparticle platforms for restoring activity of various antimicrobial drugs are reviewed with an emphasis on antibiotics. We also call attention to the need to unite the shared interest between nanoengineers and microbiologists in developing nanotechnology for the treatment of microbial diseases.
(2016) Journal of Materials Chemistry B. 4, 48, p. 7989-7999 Abstract[All authors]Protein nanofibrils were first discovered in the context of misfolding and neurodegenerative diseases but have recently been found in naturally occurring functional materials including algal adhesives, bacterial coatings, and even mammalian melanosomes. These physiologically beneficial roles have led to the exploration of their use as the basis for artificial protein-based functional materials for a range of applications as bioscaffolds and carrier agents. In this work, we fabricate core-shell protein microgels stabilized by protein fibrillation with hierarchical structuring on scales ranging from a few nanometers to tens of microns. With the aid of droplet microfluidics, we exploit fibrillar protein self-assembly together with the aqueous phase separation of a polysaccharide and polyethylene glycol to control the internal structure of the microgels on the micro- and nanoscales. We further elucidate the local composition, morphology, and structural characteristics of the microgels and demonstrate a potential application of core-shell protein microgels for controlling the storage and sequential release of small drug-like molecules. The controlled self-assembly of protein nanofibrils into hierarchical structures can be used in this manner to generate a class of nanomaterials with a range of potential functions and applications.
2015
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(2015) Colloids And Surfaces B-Biointerfaces. 135, p. 90-98 Abstract[All authors]
Bovine serum albumin (BSA) nanoemulsions were produced by high pressure homogenization with a tri-block copolymer (Poloxamer 407), which presents a central hydrophobic chain of polyoxypropylene (PPO) and two identical lateral hydrophilic chains of polyethylene glycol (PEG). We observed a linear correlation between tri-block copolymer concentration and size - the use of 5 mg/mL of Poloxamer 407 yields nanoemulsions smaller than 100 nm. Molecular dynamics and fluorescent tagging of the tri-block copolymer highlight their mechanistic role on the size of emulsions. This novel method enables the fabrication of highly stable albumin emulsions in the nano-size range, highly desirable for controlled drug delivery. Folic Acid (FA)-tagged protein nanoemulsions were shown to promote specific folate receptor (FR)-mediated targeting in FR positive cells. The novel strategy presented here enables the construction of size controlled, functionalized protein-based nanoemulsions with excellent characteristics for active targeting in cancer therapy. (C) 2015 Elsevier B.V. All rights reserved.
(2015) Biomacromolecules. 16, 9, p. 2904-2910 Abstract[All authors]Specific folate receptors are abundantly overexpressed in chronically activated macrophages and in most cancer cells. Directed folate receptor targeting using liposomes is usually achieved using folate linked to a phospholipid or cholesterol anchor. This link is formed using a large spacer like polyethylene glycol. Here, we report an innovative strategy for targeted liposome delivery that uses a hydrophobic fragment of surfactant protein D linked to folate. Our proposed spacer is a small 4 amino acid residue linker. The peptide conjugate inserts deeply into the lipid bilayer without affecting liposomal integrity, with high stability and specificity. To compare the drug delivery potential of both liposomal targeting systems, we encapsulated the nuclear dye Hoechst 34580. The eventual increase in blue fluorescence would only be detectable upon liposome disruption, leading to specific binding of this dye to DNA. Our delivery system was proven to be more efficient (2-fold) in Caco-2 cells than classic systems where the folate moiety is linked to liposomes by polyethylene glycol.
(2015) Proceedings of the National Academy of Sciences of the United States of America. 112, 31, p. 9524-9529 Abstract[All authors]The generation of mechanical forces are central to a wide range of vital biological processes, including the function of the cytoskeleton. Although the forces emerging from the polymerization of native proteins have been studied in detail, the potential for force generation by aberrant protein polymerization has not yet been explored. Here, we show that the growth of amyloid fibrils, archetypical aberrant protein polymers, is capable of unleashing mechanical forces on the piconewton scale for individual filaments. We apply microfluidic techniques to measure the forces released by amyloid growth for two systems: insulin and lysozyme. The level of force measured for amyloid growth in both systems is comparable to that observed for actin and tubulin, systems that have evolved to generate force during their native functions and, unlike amyloid growth, rely on the input of external energy in the form of nucleotide hydrolysis for maximum force generation. Furthermore, we find that the power density released from growing amyloid fibrils is comparable to that of high-performance synthetic polymer actuators. These findings highlight the potential of amyloid structures as active materials and shed light on the criteria for regulation and reversibility that guide molecular evolution of functional polymers.
(2015) Nanomedicine: Nanotechnology, Biology, and Medicine. 11, 5, p. 1077-1083 AbstractFolic Acid (FA)-tagged protein nanoemulsions were found to be preferentially internalized on B-cell lymphoma cell line (A20 cell line), which, for the first time, is reported to express folate receptor (FR)-alpha. Carbon monoxide releasing molecule-2 (CORM-2) was incorporated in the oil phase of the initial formulation. FA-functionalized nanoemulsions loaded with CORM-2 exhibited a considerable antitumor effect and an increased survival of BALB/c mice bearing subcutaneous A20 lymphoma tumors. The developed nanoemulsions also demonstrated to be well tolerated by these immunocompetent mice. Thus, the results obtained in this study demonstrate that FA-tagged protein nanoemulsions can be successfully used in cancer therapy, with the important ability to delivery drugs intracellularly.From the Clinical Editor: In this research, the authors developed folic acid tagged nanoemulsions containing a carbon monoxide releasing protein molecule for targeted cancer cell treatment. In-vitro and in-vivo experiments showed efficacy against B-cell lymphoma cells. The same nanocarrier platform could be applied to other tumor cells expressing folate receptors on the cell surface. (C) 2015 Elsevier Inc. All rights reserved.
(2015) ACS Nano. 9, 6, p. 5772-5781 AbstractAmyloid fibrils represent a generic class of protein structure associated with both pathological states and with naturally occurring functional materials. This class of protein nanostructure has recently also emerged as an excellent foundation for sophisticated functional biocompatible materials including scaffolds and carriers for biologically active molecules. Protein-based materials offer the potential advantage that additional functions can be directly incorporated via gene fusion producing a single chimeric polypeptide that will both self-assemble and display the desired activity. To succeed, a chimeric protein system must self-assemble without the need for harsh triggering conditions which would damage the appended functional protein molecule. However, the micrometer to nanoscale patterning and morphological control of protein-based nanomaterials has remained challenging. This study demonstrates a general approach for overcoming these limitations through the microfluidic generation of enzymatically active microgels that are stabilized by amyloid nanofibrils. The use of scaffolds formed from biomaterials that self-assemble under mild conditions enables the formation of catalytic microgels while maintaining the integrity of the encapsulated enzyme. The enzymatically active microgel particles show robust material properties and their porous architecture allows diffusion in and out of reactants and products. In combination with microfluidic droplet trapping approaches, enzymatically active microgels illustrate the potential of self-assembling materials for enzyme immobilization and recycling, and for biological flow-chemistry. These design principles can be adopted to create countless other bioactive amyloid-based materials with diverse functions.
(2015) Advanced healthcare materials. 4, 5, p. 723-728 AbstractThe spread of antibiotic-resistant bacteria and parasites calls for the development of new therapeutic strategies with could potentially reverse this trend. Here, a proposal is presented to exploit a sonochemical method to restore the antibiotic activity of tetracycline (TTCL) against resistant bacteria by converting the antibiotic into a nanoparticulate form. The demonstrated sonochemical method allows nanoscale TTCL assembly to be driven by supramolecular hydrogen bond formation, with no further modification to the antibiotic's chemical structure. It is shown that tetracycline nanoparticles (TTCL NPs) can act as antibacterial agents, both against TTCL sensitive and against resistant bacterial strains. Moreover, the synthesized antibiotic nanoparticles (NPs) can act as effective gene-silencing agents through the use of a TTCL repressor in Trypanosome brucei parasites. It is demonstrated that the NPs are nontoxic to human cells and T. brucei parasites and are able to release their monomer components in an active form in a manner that results in enhanced antimicrobial activity relative to a homogeneous solution of the precursor monomer. As the TTCL NPs are biocompatible and biodegradable, sonochemical formation of TTCL NPs represents a new promising approach for generation of pharmaceutically active nanomaterials.
(2015) Macromolecular Bioscience. 15, 4, p. 501-508 AbstractPeptides and proteins represent attractive building blocks for the development of new functional materials due to the biocompatibility and biodegradability of many naturally abundant proteins. In nature, sophisticated material functionality is commonly achieved through spatial control of protein localisation and structure on both the nano and micro scales. We approached this requirement in an artificial setting by exploiting the propensity of proteins to self-assemble into amyloid fibrils to achieve nano scale order, and utilised aqueous liquid/liquid phase separation to control the micron scale localization of the proteinaceous component under microconfinement. We show that in combination with droplet microfluidics, this strategy allows the synthesis of core-shell microgel particles composed of protein nanofibrils.
(2015) ACS Nano. 9, 1, p. 43-51 Abstract[All authors]Nanofibrillar forms of proteins were initially recognized in the context of pathology, but more recently have been discovered in a range of functional roles in nature, including as active catalytic scaffolds and bacterial coatings. Here we show that protein nanofibrils can be used to form the basis of monodisperse microgels and gel shells composed of naturally occurring proteins. We explore the potential of these protein microgels to act as drug carrier agents, and demonstrate the controlled release of four different encapsulated drug-like small molecules, as well as the component proteins themselves. Furthermore, we show that protein nanofibril self-assembly can continue after the initial formation of the microgel particles, and that this process results in active materials with network densities that can be modulated in situ. We demonstrate that these materials are nontoxic to human cells and that they can be used to enhance the efficacy of antibiotics relative to delivery in homogeneous solution. Because of the biocompatibility and biodegradability of natural proteins used in the fabrication of the microgels, as well as their ability to control the release of small molecules and biopolymers, protein nanofibril microgels represent a promising class of functional artificial multiscale materials generated from natural building blocks.
2014
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(2014) ChemCatChem. 6, 7, p. 1961-1968 Abstract[All authors]
Enzyme immobilization is an important strategy to enhance the stability and recoverability of enzymes and to facilitate the separation of enzymes from reaction products. However, enzyme purification followed by separate chemical steps to allow immobilization on a solid support reduces the efficiency and yield of the active enzyme. Here we describe polypeptide constructs that self-assemble spontaneously into nanofibrils with fused active enzyme subunits displayed on the amyloid fibril surface. We measured the steady-state kinetic parameters for the appended enzymes in situ within fibrils and compare these with the identical protein constructs in solution. Finally, we demonstrated that the fibrils can be recycled and reused in functional assays both in conventional batch processes and in a continuous-flow microreactor.
(2014) Journal of Nanomedicine and Nanotechnology. 5, 3, 1000204. AbstractThe knowledge that small RNAs can affect gene expression has had a tremendous impact on basic and applied research, and gene silencing is currently one of the most promising new approaches for disease therapy. However, RNAs cannot easily penetrate cell membranes, therefore RNA delivery become one of the major challenges for gene silencing technology. In the current paper we discuss a general approach for converting siRNA molecules into a dense siRNA nanoparticles using environmentally friendly sonochemical method. The RNA nanoparticulation enhance its gene-silencing activity in vascular bovine endothelial as well as in cancer 293T/GFP-Puro cell lines without causing any toxic effect. We show that ultrasonic waves do not lead to RNA degradation or any changes in its chemical structure. Moreover, sonochemically produced siRNA nanoparticles have been shown to be resistant to a variety of environmental stresses including pH levels, enzymes and temperatures, hence solving problem of the short half-life of the RNA molecules. As the siRNA nanoparticles are biocompatibile and biodegradabile, and their RNA release properties may be controlled within limits, sonochemical formation of siRNA nanoparticles represent a new promising approach for generation of functional bionano materials.
(2014) Molecular Pharmaceutics. 11, 5, p. 1479-1488 AbstractA novel transdermal hyaluronic acid (HA) conjugated with bovine serum albumin (BSA) was developed in the form of solid-in-oil (S/O) nanodispersion (129.7 nm mean diameter). Ex vivo skin penetration analysis by fluorescence and confocal observation of histological skin sections revealed the ability of BSA/HA nanodispersions to cross the stratum corneum and penetrate into the dermis. Furthermore, no significant toxicity was found in fibroblast and keratinocyte cells in vitro. These results proved the potential of the developed nanodispersion for transdermal delivery of hyaluronic acid constituting a high value to biopharmaceutical and cosmetics industries.
(2014) MedChemComm. 5, 4, p. 459-462 AbstractThe preparation of Au NP complexes of the premiRNA-145/GFP expressing plasmid is reported; the latter is successfully delivered to glioma cells and the transcripted miRNA-145 efficiently decreases the expression of its target gene, connective tissue growth factor (CTGF).
(2014) Lab on a Chip. 14, 7, p. 1315-1319 AbstractDroplet microfluidics has emerged as a powerful platform allowing a large number of individual reactions to be carried out in spatially distinct microcompartments. Due to their small size, however, the spectroscopic characterisation of species encapsulated in such systems remains challenging. In this paper, we demonstrate the acquisition of infrared spectra from single microdroplets containing aggregation-prone proteins. To this effect, droplets are generated in a microfluidic flow-focussing device and subsequently deposited in a square array onto a ZnSe prism using a micro stamp. After drying, the solutes present in the droplets are illuminated locally by an infrared laser through the prism, and their thermal expansion upon absorption of infrared radiation is measured with an atomic force microscopy tip, granting nanoscale resolution. Using this approach, we resolve structural differences in the amide bands of the spectra of monomeric and aggregated lysozyme from single microdroplets with picolitre volume.
(2014) Chemical Society Reviews. 43, 5, p. 1361-1371 AbstractMicro- and nano-scale systems have emerged as important tools for developing clinically useful drug delivery systems. In this tutorial review, we discuss the exploitation of biomacromolecules for this purpose, focusing on proteins, polypeptides, nucleic acids and polysaccharides and mixtures thereof as potential building blocks for novel drug delivery systems. We focus on the mechanisms of formation of micro-and nano-scale protein-based capsules and shells, as well as on the functionalization of such structures for use in targeted delivery of bioactive materials. We summarise existing methods for protein-based capsule synthesis and functionalization and highlight future challenges and opportunities for delivery strategies based on biomacromolecules.
(2014) RSC Advances. 4, 20, p. 10303-10309 AbstractEncapsulation in the form of micro and nanocapsules is an attractive route for controlling the delivery and release of active proteins and peptides. Many approaches exist to probe the morphology of such capsules as well as their mechanisms of formation. By contrast, the release of proteins from such components in a complex biological environment has been challenging to probe directly. In this paper we show that the spectral differences between green fluorescent protein (GFP) in capsules and in its free form can be used to monitor in situ the release of the protein from the confinement of capsules. These findings represent a new route towards engineering the spectral characteristics of GFP through physical rather than chemical means. We demonstrate the use of GFP protein capsules for monitoring in real time the release of protein in live cells by exposing rat L6 myotubes to protein capsules. The GFP spheres with a blue fluorescent signal dissociate inside the L6 myotubes to individual GFP molecules with a change in fluorescent signal from blue to green. These sensitive spectral characteristics enabled us to resolve the dissociation of capsules inside the cells in both time and space. We discuss the implications of our results for quantifying parameters crucial for the delivery of proteins in biological environments.
2013
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(2013) International Journal of Applied Ceramic Technology. 10, s1, p. E267-E273 Abstract
The present article describes the creation and immobilization of Polyethylene imine (PEI) capsules on a glass surface. The synthesis and deposition were accomplished by short-time (3min) one-step reaction. The preparation and immobilization of PEI spheres, was carried out using an environmental friendly method, the ultrasonic emulsification. The ultrasonic technique enables to control size and fulfillment of the internal part of the immobilized PEI spheres. Moreover, the ultrasonic emulsification method showed 100% efficiency in PEI spheres creation, which means no residues of aqueous PEI and oil solvents remained in the reaction flask after the nanosphere's creation. The immobilized PEI spheres have sizes varied from 50 to 500nm. The PEI spheres were successfully filled either with organic solvent (hydrophobic) or with water (hydrophilic). This method provides us the perspective for future encapsulation of varies molecules which have hydrophobic or hydrophilic nature.
(2013) Colloids And Surfaces B-Biointerfaces. 108, p. 271-278 AbstractTransdermal perfusion of a large protein is reported for the first time, using a nanoemulsion of bovine serum albumin (66 kDa) of 160 nm prepared by a solid-in-oil (S/O) process. Molecular dynamics simulations confirmed skin permeation by these formulations, with integration of the protein into the lipid bilayers. These results demonstrate the real possibility of delivering large proteins transdermally for a range of medical and cosmetic applications. (C) 2013 Elsevier B.V. All rights reserved.
(2013) International Journal of Cosmetic Science. 35, 3, p. 244-249 Abstract[All authors]Human hair has an important and undeniable relevance in society due to its important role in visual appearance and social communication. Hair is mainly composed of structural proteins, mainly keratin and keratin associated proteins and lipids. Herein, we report a comprehensive study of the content and distribution of the lipids among ethnic hair, African, Asian and Caucasian hair. More interestingly, we also report the study of the interaction between those two main components of hair, specifically, the influence of the hair internal lipids in the structure of the hair keratin. This was achieved by the use of a complete set of analytical tools, such as thin layer chromatography-flame ionization detector, X-ray analysis, molecular dynamics simulation and confocal microscopy. The experimental results indicated different amounts of lipids on ethnic hair compositions and higher percentage of hair internal lipids in African hair. In this type of hair, the axial diffraction of keratin was not observed in X-ray analysis, but after hair lipids removal, the keratin returned to its typical packing arrangement. In molecular dynamic simulation, lipids were shown to intercalate dimers of keratin, changing its structure. From those results, we assume that keratin structure may be influenced by higher concentration of lipids in African hair. Resume Les cheveux humains ont une pertinence importante et indeniable dans la societe en raison de leur importantrole dans l'aspect visuel et la communication sociale. Les cheveux sont principalement composes de proteines de structure, surtoutdes keratines et des proteines keratiniques et des lipides. Nous rapportons une etude approfondie du contenu et de la distribution des lipides dans les cheveux ethniques, Africains, Asiatiques et Caucasiens. Plus interessant, nous presentons egalement l'etude de l'interaction entre ces deux composantes principales des cheveux, en particulier l'influence des lipides internes du cheveusur la structure de la keratine des cheveux. Ceci a ete realise par l'utilisation d'unensemble complet d'outils d'analyse tels que la chromatographie sur couche mince-au detecteur d'ionisation de flamme (FID), l'analyse aux rayons X, la simulation de dynamique moleculaire et de la microscopie confocale. Les resultats experimentaux indiquent des quantites differentes de lipides dans des compositions capillaires ethniques et des pourcentages plus eleves de lipides internes dans les cheveux africains. Dans ce type de cheveux, la diffraction axiale de la keratine n'a pas ete observee dans l'analyse aux rayons X, mais apres l'enlevement des lipides, la keratine revient a sa disposition de compactage typique. La simulation dynamiquemoleculaire montre que les lipides s'intercalent entre les dimeres de keratine, changeant ainsi sa structure. A partir de ces resultats, noussupposons que la structure de la keratine peut etre influencee par l'augmentation de la concentration de lipides dans les cheveux de type africain.
(2013) Journal of Materials Chemistry B. 1, 5, p. 595-605 AbstractBy the early 90s, K. S. Suslick had developed a method using high-intensity ultrasound to make aqueous suspensions of proteinaceous microcapsules filled with water-insoluble liquids. This method was extended on the one hand to include (instead of proteins) starch, chitosan, DNA, RNA, PEG, and more. The second direction was the encapsulation of drugs, dyes, magnetic and other materials in various micro-and nanocapsules. The current paper will review the materials that were encapsulated in various spheres using high-intensity ultrasound. The amount encapsulated, its release from the sphere, bioactivity, and application aspects will be discussed.
(2013) DNA and RNA Nanobiotechnologies in Medicine. Erdmann V. A.(eds.). p. 373-394 AbstractThe advanced science behind DNA/RNA-based discovery is to provide new therapeutic tools for disease treatment. DNA/RNA-based therapeutics hold the promise of tremendously expanding the number of “druggable” targets by overcoming the major limitation of existing medicines, which are able to deliver only a limited amount of nucleic acid molecules to the cells involved in disease pathways. The transfer of RNA and DNA molecules into cells is often helped by nanoparticles. The use of the nanoparticles (NPs) is limited due to the presence of polymeric, metal, or cross-linker molecules which react with the NPs, thereby avoiding the transfer of DNA and RNA into the cells. Thus the delivery agents of RNA/DNA are impaired. This chapter presents and discusses the results of integrating the fields of nanotechnology and biochemistry to overcome the problems of introducing nucleic acids into cells. This report is focused on the discovery of a new method for the fabrication of RNA and DNA nanospheres from nucleic acid chains.
Proteinaceous microspheres for targeted RNA delivery prepared by an ultrasonic emulsification method(2013) Journal of Materials Chemistry B. 1, 1, p. 82-90 AbstractIn the present work we used sonochemically prepared proteinaceous BSA spheres as a novel RNA-delivery system. The preparation of RNA-loaded BSA spheres was accomplished using an environmental friendly method termed the "ultrasonic emulsification method". It was demonstrated that ultrasonic waves do not cause the RNA chains to degrade and the RNA molecules remain untouched. The BSA-RNA complex was successfully introduced into mammalian (human) U2OS osteosarcoma cells and Trypanosoma brucei parasites. Using PVA coating of the RNA-BSA spheres we have achieved a significant increase in the number of microspheres penetrating mammalian cells. The mechanism of RNA encapsulation and the structure of the RNA-BSA complex are reported.
2012
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(2012) Molecular Pharmaceutics. 9, 11, p. 3079-3088 Abstract
Microspheres of bovine serum albumin (BSA) and silk fibroin are produced by applying ultrasound in a biphasic system consisting of an aqueous protein solution and an organic solvent. The protein microspheres are dispersed in an aqueous media where the protein remains at the interface covering the organic solvent. This only occurs when high shear forces are applied that induce changes to force the protein to the interface. Fourier transform infrared results indicate a large increase in the content of the beta-sheet during the formation of silk fibroin microspheres. Molecular dynamics simulations show a clear adaption on the 3D structure of BSA when stabilized at the interface, without major changes in secondary structure. Further studies demonstrate that high water content, oil solvents, and larger peptides with separated and clear hydrophobic and hydrophilic areas lead to more stable and smaller spheres. This is the first time that these results are presented. We also present herein the rationale to produce tailored protein microspheres with a controlled size, controlled charge, and increased stability.
(2012) ACS applied materials & interfaces. 4, 6, p. 2926-2930 AbstractThe current paper reports on the relase properties of conductive fabrics coated with proteinaceous microspheres containing a dye. The release of the dye was achieved by passing an electric current through the fabric. The conductivity of the polyester fibers resulted from nanosilver (Ag NPs) coated on the surface of these fibers. Both types of coatings (nanosilver coating and the coating of the proteinaceous microspheres) were performed using high-intensity ultrasonic waves. Two different types of dyes, hydrophilic RBBR (Remazol Brilliant Blue R) and hydrophobic ORO (Oil Red 0), were encapsulated inside the microspheres (attached to the surface of polyester) and then released by applying an electric current. The Proteinaceous Microsphere (PM)-coated conductive fabrics could be used in medicine for drug release. The encapsulated dye can be replaced with a drug that could be released from the surface of fabrics by applying a low voltage.
(2012) New Journal of Chemistry. 36, 1, p. 36-39 AbstractWe demonstrate herein a simple, one-step method for preparing stabilized microspheres of graphene oxide (GO), by applying ultra-sonic power to a biphasic system. The microsphere's size was affected by the pH of the aqueous solution, ranging from a few mm to mu m. Further characterization indicated that the microsphere's inner content is composed mainly of organic solvents, though water and GO molecules may be also present at the microsphere's core. The microspheres were stable for several months without a significant conformation change. We predict that the stability arises from hydrophobic and hydrophilic interactions between the GO sheets and the solvents. Changing the organic solvent resulted in changes in the microsphere's morphology.
(2012) Chemistry-A European Journal. 18, 1, p. 365-369 AbstractA novel antibacterial coating for cotton and polyester fabrics has been developed by using drug-loaded proteinaceous microspheres made of bovine serum albumin and casein proteins. The microbubbles were created and anchored onto the fabrics (see figure) in a one-step reaction that lasts 3 min. The sonochemically produced antibacterial fabrics have been characterized. The efficiency of the sonochemical process in converting the native proteins into microspheres, encapsulating the drug, and coating the fabric has also been studied.
2011
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(2011) Patent No. US20110300767A1, 08 Jun 2010, Priority No. 13/154,855 Abstract
The present invention discloses a novel system for preparing fabrics with antibacterial properties by sonochemically impregnating the fabrics with proteinaceous microspheres loaded with antibiotic. Antibacterial fabrics are widely used for production of outdoor clothes, under-wear, bed-linen, bandages, etc.
(2011) Advanced Functional Materials. 21, 19, p. 3659-3666 AbstractRNA was encapsulated in bovine serum albumin (BSA) microspheres using a one-step sonochemical process from an water-oil solvent biphasic system. Confocal microcoscopy and fluorescence-activated cell sorting indicate that a CY3-RNA (RNA labeled with red fluorescent indocarbocyanine Cy3 dye) sphere is encapsulated in the BSA outer sphere. The diameter of the sphere depends on the number of nucleotides of the RNA, ranging from 0.63 to 2.74 mu m. Total RNA (t-RNA) was used as a prototype for the future small interfering RNA (siRNA) delivery. A very broad size distribution characterizes the RNA spheres and therefore, among the loaded BSA spheres, there were sufficiently small spheres to be successfully introduced into trypanosoma brucei parasites and human osteosarcoma U2OS cancer cells.
(2011) ChemBioChem. 12, 11, p. 1678-1681 AbstractUltrasonic waves can be used to convert native DNA molecules into DNA nanospheres. This sonochemical nanospherization could be used as a method of protecting DNA from degradation in harsh environments. Due to its as a carrier of genetic information, DNA spheres could be used as a biocompatible material for the delivery of the genetic information to the cells.
(2011) Small. 7, 8, p. 1068-1074 AbstractBiological macromolecules, including DNA, RNA, and proteins, have intrinsic features that make them potential building blocks for the bottom-up fabrication of nanodevices. Unlike DNA, RNA is a more versatile molecule whose range in the cell is from 21 to thousands of nucleotides and is usually folded into stem and loop structures. RNA is unique in nanoscale fabrication due to its diversity in size, function, and structure. Because gene expression analysis is becoming a clinical reality and there is a need to collect RNA in minute amounts from clinical samples, keeping the RNA intact is a growing challenge. RNA samples are notoriously difficult to handle because of their highly labile nature and tendency to degrade even under controlled RNase-free conditions and maintenance in the cold. Silencing the RNA that induces the RNA interference is viewed as the next generation of therapeutics. The stabilization and delivery of RNA to cells are the major concerns in making siRNAs usable drugs. For the first time, ultrasonic waves are shown to convert native RNA molecules to RNA nanospheres. The creation of the nanobubbles is performed by a one-step reaction. The RNA nanospheres are stable at room temperature for at least one month. Additionally, the nanospheres can be inserted into mammalian cancer cells (U2OS). This research achieves: 1) a solution to RNA storage; and 2) a way to convert RNA molecules to RNA particles. RNA nanosphere formation is a reversible process, and by using denaturing conditions, the RNA can be refolded into intact molecules.