Manishekhar Kumar

Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds.

Composite nanofibrous membranes based on sol-gel derived 45SiO2 24.5CaO 24.5 Na2O 6 P2O5 (bioglass, BG) and 43SiO2 24.5CaO 24.5 Na2O 6 P2O5 2Fe2O3 (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application.

A renewable resource based carbon dot decorated hydroxyapatite nanohybrid and its fabrication with waterborne hyperbranched polyurethane for bone tissue engineering

Use of renewable resources in material science creates new opportunities for fabricating novel biomaterials. In this context, a carbon dot (CD) decorated hydroxyapatite (HAp) nanohybrid (CD@HAp) was synthesized by a simple one pot hydrothermal process. Different bio-based and waste materials were used in the synthesis of the nanohybrid. The aqueous extract of corms of Colocasia esculenta was used as the CD precursor, whereas egg shell was used to obtain CaO, which served as the precursor for HAp. The synthesized nanohybrid was characterized by using different analytical and spectroscopic techniques viz. FTIR, XRD, TEM, SEM/EDX and Raman spectroscopy. TEM and HRTEM images confirmed the formation of needle shaped HAp (length 60–80 nm, average diameter 20–30 nm) with decorated CDs over its surface. Elemental analysis showed a Ca/P ratio of 1.69, which is close to the Ca/P ratio (1.67) found in natural bone. Biological assessment of the nanohybrid demonstrated excellent cytocompatibility, cell proliferation and alkaline phosphatase activity against MG 63 osteoblast cell line. Synthesized CD@HAp was fabricated in situ with a tannic acid based waterborne hyperbranched polyurethane. Substantial improvement in the mechanical properties of the nanocomposite was perceived. These nanocomposite films were tested for osteogenic activities and the results confirmed its utility as a bone regenerating material. The overall results thus endorse development of a sustainable nanocomposite with high load bearing ability and profound bioactivity which can be employed for bone tissue engineering application.

Electrospun polyvinyl alcohol-polyvinyl pyrrolidone nanofibrous membranes for interactive wound dressing application

Abstract Cross-linked polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) composite nanofibrous membranes have been prepared by electrospinning. Mechanical properties of the membranes improved significantly with PVP addition. PVP improved hydrophilicity and sustainable degradation of the membranes. Biocompatibility of the membranes was assessed by in vitro culture of native skin cells (L929 fibroblast and HaCaT keratinocytes). Tests showed sustained release of the antibiotic ciprofloxacin hydrochloride monohydrate by the membranes. Further, zone of inhibition study against Staphylococcus aureus growth demonstrated protective action against external pathogenic microbes. These studies show these simple PVA–PVP nanofibrous membranes are promising interactive antibiotic-eluting wound dressing materials.

An in situ prepared photo-luminescent transparent biocompatible hyperbranched epoxy/carbon dot nanocomposite

A photo-luminescent transparent biocompatible hyperbranched epoxy/carbon dot nanocomposite was prepared by incorporation of carbon dots during formation of hyperbranched epoxy resin. The prepared nanocomposite was characterized by FTIR, NMR and TEM analyses. The poly(amido-amine) cured nanocomposite exhibited high tensile strength (62.5 MPa), high elongation at break (45%), good thermal stability (291 °C), high transparency and excellent wavelength dependent photoluminescence behavior along with biocompatibility with skin cells. The performance of this nanocomposite was also compared with the pristine hyperbranched epoxy as well as hyperbranched epoxy/carbon dot nanocomposite obtained through an ex situ solution technique. The study revealed that the in situ prepared nanocomposite possessed superior mechanical, optical and biocompatible properties compared to pristine epoxy as well as the ex situ prepared nanocomposite. Thus, the study will significantly contribute to the field of high performance transparent fluorescent polymeric materials used in optoelectronics. Good viability, spreading and proliferation of skin fibroblasts and keratinocyte cells on the nanocomposite suggest it is also a highly potential material for bio-sealant application.

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.

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.