Prerak Gupta

Silk-microfluidics for advanced biotechnological applications: A progressive review.

Silk based biomaterials have not only carved a unique niche in the domain of regenerative medicine but new avenues are also being explored for lab-on-a-chip applications. It is pertinent to note that biospinning of silk represents natures signature microfluidic-maneuver. Elucidation of non-Newtonian flow of silk in the glands of spiders and silkworms has inspired researchers to fabricate devices for continuous extrusion and concentration of silk. Microfluidic channel networks within porous silk scaffolds ensure optimal nutrient and oxygen supply apart from serving as precursors for vascularization in tissue engineering applications. On the other hand, unique topographical features and surface wettability of natural silk fibers have inspired development of a number of simple and cost-effective devices for applications like blood typing and chemical sensing. This review mirrors the recent progress and challenges in the domain of silk-microfluidics for prospective avant-garde applications in the realm of biotechnology.

Native honeybee silk membrane: a potential matrix for tissue engineering and regenerative medicine

Biomimetic natural origin biomaterials are noteworthy targets for further innovation in biomedical and tissue engineering. In this study, honeybee silk membranes (HBSM) are investigated in their native form to explore their applicability for tissue engineering. HBSMs extracted from honeybee combs were physico-chemically characterized for their surface topography, stability followed by evaluation of the biodegradation, mechanical and biological properties. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) studies revealed a uniform sheet-like morphology with sub-micron pores and the presence of evenly knitted fibers in a specific pattern/alignment. Fourier transform infrared (FTIR) spectroscopy suggested the presence of a native coiled coil structural conformation. HBSMs were found to be cytocompatible and supported the proliferation of murine L929 fibroblasts, human osteosarcoma MG-63 cells and primary porcine knee chondrocytes. Cells cultured on HBSMs maintained osteogenic and chondrogenic potential as indicated by mineralization and accumulation of sulphated glycosaminoglycans (GAGs), respectively. In vitro analysis of the immune response (in terms of TNF-α release) and blood compatibility (in terms of LDH activity) further attests its possible applicability. Moreover, an in vivo subcutaneous implantation study in mice showed minimal inflammation. Taken together, this study demonstrates the potential of natural, biocompatible HBSMs as a suitable biomaterial for tissue engineering and regenerative medicine.

Silk-based matrices for bone tissue engineering applications

Abstract A growing world population with rapidly rising fractions of elderly and traumatic bone fracture cases makes bone tissue engineering (BTE) a necessity of the current times. Developing low-cost and biocompatible scaffolds using bioderived materials could be the logical choice for bone tissue repair. Silk is a biopolymer with several characteristics, including excellent biocompatibility and mechanical strength that makes it a potential candidate for various tissue engineering applications. There exists a vast body of literature regarding the use of silk in BTE. Several successful works have reported use of silk scaffolds for bone repair and regeneration. These works involve trials both in vitro and in vivo. A growing trend is observed towards designing mineralized nanofibrous and composite scaffolds. This chapter presents an overview of the field, from the perspective of materials and fabrication.

Immunomodulatory injectable silk hydrogels maintaining functional islets and promoting anti-inflammatory M2 macrophage polarization

Islet transplantation is considered the most promising treatment for type 1 diabetes. However, the clinical success is limited by islet dysfunction in long-term culture. In this study, we have utilized the rapid self-gelation and injectability offered by blending of mulberry silk (Bombyx mori) with non-mulberry (Antheraea assama) silk, resulting in a biomimetic hydrogel. Unlike the previously reported silk gelation techniques, the differences in amino acid sequences of the two silk varieties result in accelerated gelation without requiring any external stimulus. Gelation study and rheological assessment depicts tuneable gelation as a function of protein concentration and blending ratio with minimum gelation time. In vitro biological results reveal that the blended hydrogels provide an ideal 3D matrix for primary rat islets. Also, A. assama fibroin with inherent Arg-Gly-Asp (RGD) shows significant influence on islet viability, insulin secretion and endothelial cell maintenance. Furthermore, utility of these hydrogels demonstrate sustained release of Interleukin-4 (IL-4) and Dexamethasone with effective M2 macrophage polarization while preserving islet physiology. The immuno-informed hydrogel demonstrates local modulation of inflammatory responses in vivo. Altogether, the results exhibit promising attributes of injectable silk hydrogel and the utility of non-mulberry silk fibroin as an alternative biomaterial for islet encapsulation.