(2017). Silk micrococoons for protein stabilisation and molecular encapsulation. NATURE COMMUNICATIONS. 8. Abstract
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 beta-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.
(2017). Sequential Release of Proteins from Structured Multishell Microcapsules. BIOMACROMOLECULES. 18:3052-3059. 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
(2016). Fabrication of fibrillosomes from droplets stabilized by protein nanofibrils at all-aqueous interfaces. NATURE COMMUNICATIONS. 7. 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.
(2015). Protein microgels from amyloid fibril networks. ACS Nano. 9:43-51. Abstract
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.
(2013). Proteinaceous microspheres for targeted RNA delivery prepared by an ultrasonic emulsification method. J. Mater. Chem. B,. 1:82-90. Abstract
In 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). Graphene oxide microspheres prepared by a simple, one-step ultrasonication method. New J. Chem. 36:36-39. Abstract
We 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 μm. 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). Releasing Dye Encapsulated in Proteinaceous Microspheres on Conductive Fabrics by Electric Current. ACS Appl. Mater. Interfaces. 4:2926-30. Abstract
The 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 O), 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.
(2011). Stabilizing RNA by the Sonochemical Formation of RNA Nanospheres. Small. 7:(8)1068-74. Abstract
Biological 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.
(2011). Sonochemical Synthesis of DNA Nanospheres. Chembiochem. 12:1678-81. Abstract
Ultrasonic 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). Encapsulation of RNA Molecules in BSA Microspheres and Internalization into Trypanosoma Brucei Parasites and Human U2OS Cancer Cells. Advanced Functional Materials. 21:3659-66. Abstract
RNA 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 μm. 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.
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