Jugal Kishore Sahoo

Biocatalytic amide condensation and gelation controlled by light

We report on a supramolecular self-assembly system that displays coupled light switching, biocatalytic condensation/hydrolysis and gelation. The equilibrium state of this system can be regulated by light, favouring in situ formation, by protease catalysed peptide synthesis, of self-assembling trans- in ambient light; however, irradiation with UV light gives rise to the cis-isomer, which readily hydrolyzes to its amino acid derivatives (cis- + ) with consequent gel dissolution.

Mesenchymal Stem Cell Fate: Applying Biomaterials for Control of Stem Cell Behavior

The materials pipeline for biomaterials and tissue engineering applications is under continuous development. Specifically, there is great interest in the use of designed materials in the stem cell arena as materials can be used to manipulate the cells providing control of behavior. This is important as the ability to “engineer” complexity and subsequent in vitro growth of tissues and organs is a key objective for tissue engineers. This review will describe the nature of the materials strategies, both static and dynamic, and their influence specifically on mesenchymal stem cell fate.

Biocatalytic Self-Assembly Cascades

The properties of supramolecular materials are dictated by both kinetic and thermodynamic aspects, providing opportunities to dynamically regulate morphology and function. Herein, we demonstrate time-dependent regulation of supramolecular self-assembly by connected, kinetically competing enzymatic reactions. Starting from Fmoc-tyrosine phosphate and phenylalanine amide in the presence of an amidase and phosphatase, four distinct self-assembling molecules may be formed which each give rise to distinct morphologies (spheres, fibers, tubes/tapes and sheets). By varying the sequence or ratio in which the enzymes are added to mixtures of precursors, these structures can be (transiently) accessed and interconverted. The approach provides insights into dynamic self-assembly using competing pathways that may aid the design of soft nanostructures with tunable dynamic properties and life times.

Dynamic Surfaces for the Study of Mesenchymal Stem Cell Growth through Adhesion Regulation

Out of their niche environment, adult stem cells, such as mesenchymal stem cells (MSCs), spontaneously differentiate. This makes both studying these important regenerative cells and growing large numbers of stem cells for clinical use challenging. Traditional cell culture techniques have fallen short of meeting this challenge, but materials science offers hope. In this study, we have used emerging rules of managing adhesion/cytoskeletal balance to prolong MSC cultures by fabricating controllable nanoscale cell interfaces using immobilized peptides that may be enzymatically activated to change their function. The surfaces can be altered (activated) at will to tip adhesion/cytoskeletal balance and initiate differentiation, hence better informing biological mechanisms of stem cell growth. Tools that are able to investigate the stem cell phenotype are important. While large phenotypical differences, such as the difference between an adipocyte and an osteoblast, are now better understood, the far more subtle differences between fibroblasts and MSCs are much harder to dissect. The development of technologies able to dynamically navigate small differences in adhesion are critical in the race to provide regenerative strategies using stem cells.

Biocatalytic self-assembly on magnetic nanoparticles

Combining (bio)catalysis and molecular self-assembly provides an effective approach for the production and processing of self-assembled materials by exploiting catalysis to direct the assembly kinetics and hence controlling the formation of ordered nanostructures. Applications of (bio)catalytic self-assembly in biologically interfacing systems and in nanofabrication have recently been reported. Inspired by self-assembly in biological cells, efforts to confine catalysts on flat or patterned surfaces to exert spatial control over molecular gelator generation and nanostructure self-assembly have also emerged. Building on our previous work in the area, we demonstrate in this report the use of enzymes immobilized onto magnetic nanoparticles (NPs) to spatially localize the initiation of peptide self-assembly into nanofibers around NPs. The concept is generalized for both an equilibrium biocatalytic system that forms stable hydrogels and a nonequilibrium system that normally has a preset lifetime. Characterization of the hydrogels shows that self-assembly occurs at the site of enzyme immobilization on the NPs to give rise to gels with a hub-and-spoke morphology, where the nanofibers are linked through the enzyme-NP conjugates. This NP-controlled arrangement of self-assembled nanofibers enables both remarkable enhancements in the shear strength of hydrogel systems and a dramatic extension of the hydrogel stability in the nonequilibrium system. We are also able to show that the use of magnetic NPs enables the external control of both the formation of the hydrogel and its overall structure by application of an external magnetic field. We anticipate that the enhanced properties and stimuli-responsiveness of our NP-enzyme system will have applications ranging from nanomaterial fabrication to biomaterials and biosensing.

Injectable network biomaterials via molecular or colloidal self-assembly

&NA; Self‐assembly is a powerful tool to create functional materials. A specific application for which self‐assembled materials are ideally suited is in creating injectable biomaterials. Contrasting with traditional biomaterials that are implanted through surgical means, injecting biomaterials through the skin offers numerous advantages, expanding the scope and impact for biomaterials in medicine. In particular, self‐assembled biomaterials prepared from molecular or colloidal interactions have been frequently explored. The strategies to create these materials are varied, taking advantage of engineered oligopeptides, proteins, and nanoparticles as well as affinity‐mediated crosslinking of synthetic precursors. Self‐assembled materials typically facilitate injectability through two different mechanisms: i) in situ self‐assembly, whereby materials would be administered in a monomeric or oligomeric form and self‐assemble in response to some physiologic stimulus, or ii) self‐assembled materials that, by virtue of their dynamic, non‐covalent interactions, shear‐thin to facilitate flow within a syringe and subsequently self‐heal into its reassembled material form at the injection site. Indeed, many classes of materials are capable of being injected using a combination of these two mechanisms. Particular utility has been noted for self‐assembled biomaterials in the context of tissue engineering, regenerative medicine, drug delivery, and immunoengineering. Given the controlled and multifunctional nature of many self‐assembled materials demonstrated to date, we project a future where injectable self‐assembled biomaterials afford improved practice in advancing healthcare. Graphical abstract Figure. No caption available.

Immunoengineering with Supramolecular Peptide Biomaterials

AbstractThe versatility of supramolecular design in creating biomaterials and drug delivery devices for applications in medicine has gained considerable traction in recent years. The design of peptide-based self-assembling materials is one example of a highly useful and biomimetic approach to the generation of supramolecular biomaterials. One exciting area where designed supramolecular biomaterials created from peptides have demonstrated promise is in the field of immunoengineering. nSpecifically, peptide-based biomaterials have been used in several different contexts to modify the host immune system through the controlled release of active signaling proteins, pharmaceutical agents, or gasotransmitters. In a separate approach, this class of materials has emerged as a powerful immune-modulating strategy that can enlist the adaptive immune system in mounting a cellular or humoral immune response to a presented epitope or antigen. The ease with which these materials are synthesized, their alignment with injection-based procedures, their low toxicity, and their rapid biodegradation make these useful materials for application in immunoengineering.

Data for: "Biocatalytic Self-Assembly on Magnetic Nanoparticles"

This dataset comprises of 8 Microsoft Excel xlsx files. The files contain the raw data for CD, HPLC and FRET analytical measurements. The titles of the file indicate to which measurements the data belong.nnData embargo until 31/01/18