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.
The study represents a promising venue for generating pH‐responsive functional peptide‐based materials, which are biodegradable and biocompatible, for a wide range of potential applications. The authors have utilized a stimuli‐responsive assembly of amyloidogenic peptide building blocks as the basis of environmentally responsive microcapsules which exhibit release characteristics triggered by a change in pH.
Nanoparticles are widely studied as carrier vehicles in biological systems because their size readily allows access through cellular membranes. Moreover, they have the potential to carry cargo ...molecules and as such, these factors make them especially attractive for intravenous drug delivery purposes. Interest in protein‐based nanoparticles has recently gained attraction due to particle biocompatibility and lack of toxicity. However, the production of homogeneous protein nanoparticles with high encapsulation efficiencies, without the need for additional cross‐linking or further engineering of the molecule, remains challenging. Herein, we present a microfluidic 3D co‐flow device to generate human serum albumin/celastrol nanoparticles by co‐flowing an aqueous protein solution with celastrol in ethanol. This microscale co‐flow method resulted in the formation of nanoparticles with a homogeneous size distribution and an average size, which could be tuned from ≈100 nm to 1 μm by modulating the flow rates used. We show that the high stability of the particles stems from the covalent cross‐linking of the naturally present cysteine residues within the particles formed during the assembly step. By choosing optimal flow rates during synthesis an encapsulation efficiency of 75±24 % was achieved. Finally, we show that this approach achieves significantly enhanced solubility of celastrol in the aqueous phase and, crucially, reduced cellular toxicity.
Nanotechnology: We demonstrate a microfluidic co‐flow device to produce drug‐loaded albumin nanoparticles without additional cross‐linking steps. This method showed high loading efficiency of the lipophilic drug celastrol, which created spherical nanoparticles with considerable reduced drug cytotoxicity (see figure).
Biomimetics is a design principle within chemistry, biology, and engineering, but chemistry biomimetic approaches have been generally limited to emulating nature’s chemical toolkit while emulation of ...nature’s physical toolkit has remained largely unexplored. To begin to explore this, we designed biophysically mimetic microfluidic reactors with characteristic length scales and shear stresses observed within capillaries. We modeled the effect of shear with molecular dynamics studies and showed that this induces specific normally buried residues to become solvent accessible. We then showed using kinetics experiments that rates of reaction of these specific residues in fact increase in a shear-dependent fashion. We applied our results in the creation of a new microfluidic approach for the multidimensional study of cysteine biomarkers. Finally, we used our approach to establish dissociation of the therapeutic antibody trastuzumab in a reducing environment. Our results have implications for the efficacy of existing therapeutic antibodies in blood plasma as well as suggesting in general that biophysically mimetic chemistry is exploited in biology and should be explored as a research area.
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.
Reconstituted silk fibroin nanofibrils are used to generate supramolecular microgels by a soft‐lithography‐based microfluidic approach. The kinetic process of microgel formation has been explored in detail and has been applied to encapsulate small molecules within these microgels. The molecular release‐kinetics for drug‐delivery applications are further evaluated, and it is shown that they are dependent on microgel morphology.
In nature, intracellular microcompartments have evolved to allow the simultaneous execution of tightly regulated complex processes within a controlled environment. This architecture serves as the ...blueprint for the construction of a wide array of artificial cells. However, such systems are inadequate in their ability to confine and sequentially control multiple central dogma activities (transcription, translation, and post‐translational modifications) resulting in a limited production of complex biomolecules. Here, an artificial cell‐on‐a‐chip comprising hierarchical compartments allowing the processing and transport of products from transcription, translation, and post‐translational modifications through connecting channels is designed and fabricated. This platform generates a tightly controlled system, yielding directly a purified modified protein, with the potential to produce proteoform of choice. Using this platform, the full ubiquitinated form of the Parkinson's disease‐associated α‐synuclein is generated starting from DNA, in a single device. By bringing together all central dogma activities in a single controllable platform, this approach will open up new possibilities for the synthesis of complex targets, will allow to decipher diverse molecular mechanisms in health and disease and to engineer protein‐based materials and pharmaceutical agents.
Artificial cell‐on‐a‐chip, which allows the production of modified proteins by programming transcription, translation and post‐translational modifications (PTMs) in a discrete and highly precise manner has been developed. The modular nature of microfluidics grants significant advantages to control a wide range of cell‐free processes and to study the effect of individual steps in protein expression and modifications.
Compartmentalization and selective transport of molecular species are key aspects of chemical transformations inside the cell. In an artificial setting, the immobilization of a wide range of enzymes ...onto surfaces is commonly used for controlling their functionality but such approaches can restrict their efficacy and expose them to degrading environmental conditions, thus reducing their activity. Here, we employ an approach based on droplet microfluidics to generate enzyme-containing microparticles that feature an inorganic silica shell that forms a semipermeable barrier. We show that this porous shell permits selective diffusion of the substrate and product while protecting the enzymes from degradation by proteinases and maintaining their functionality over multiple reaction cycles. We illustrate the power of this approach by synthesizing microparticles that can be employed to detect glucose levels through simultaneous encapsulation of two distinct enzymes that form a controlled reaction cascade. These results demonstrate a robust, accessible, and modular approach for the formation of microparticles containing active but protected enzymes for molecular sensing applications and potential novel diagnostic platforms.
Controlling the surface area, pore size and pore volume of microcapsules is crucial for modulating their activity in applications including catalytic reactions, delivery strategies or even cell ...culture assays, yet remains challenging to achieve using conventional bulk techniques. Here we describe a microfluidics-based approach for the formation of monodisperse silica-coated micron-scale porous capsules of controllable sizes. Our method involves the generation of gas-in water-in oil emulsions, and the subsequent rapid precipitation of silica which forms around the encapsulated gas bubbles resulting in hollow silica capsules with tunable pore sizes. We demonstrate that by varying the gas phase pressure, we can control both the diameter of the bubbles formed and the number of internal bubbles enclosed within the silica microcapsule. Moreover, we further demonstrate, using optical and electron microscopy, that these silica capsules remain stable under particle drying. Such a systematic manner of producing silica-coated microbubbles and porous microparticles thus represents an attractive class of biocompatible material for biomedical and pharmaceutical related applications.
Controlling surface area and pore size of microcapsules are key parameters for modulating their activity in various applications. Here we describe a microfluidics-based approach for the formation of monodisperse silica-coated micron-scale porous capsules of controllable sizes.
Antimicrobial resistance is a leading threat to global health. Alternative therapeutics to combat the rise in drug-resistant strains of bacteria and fungi are thus needed, but the development of new ...classes of small molecule therapeutics has remained challenging. Here, we explore an orthogonal approach and address this issue by synthesising micro-scale, protein colloidal particles that possess potent antimicrobial properties. We describe an approach for forming silk-based microgels that contain selenium nanoparticles embedded within the protein scaffold. We demonstrate that these materials have both antibacterial and antifungal properties while, crucially, also remaining highly biocompatible with mammalian cell lines. By combing the nanoparticles with silk, the protein microgel is able to fulfill two critical functions; it protects the mammalian cells from the cytotoxic effects of the bare nanoparticles, while simultaneously serving as a carrier for microbial eradication. Furthermore, since the antimicrobial activity originates from physical contact, bacteria and fungi are unlikely to develop resistance to our hybrid biomaterials, which remains a critical issue with current antibiotic and antifungal treatments. Therefore, taken together, these results provide the basis for innovative antimicrobial materials that can target drug-resistant microbial infections.
Silk-based microgels that contain selenium nanoparticles embedded within the protein scaffold, that display potent antibacterial and antifungal properties, while importantly remain highly biocompatible with mammalian cells.
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