Formulation and characterization of gelatin methacrylamide-hydroxypropyl methacrylate based bioink for bioprinting applications.

Three-dimensional (3D) bioprinting has emerged as a revolutionary technology for constructing functional tissue equivalents/scaffolds for tissue engineering applications. Bioink design is a crucial element in 3D bioprinting, which typically comprises a mixture of biomaterials, biological molecules or cells followed by its printing and tissue maturation. An ideal bioink should possess suitable physicochemical, mechanical, rheological, and biological features of the target tissue. However, mimicking multifaceted compositions similar to native extracellular matrix (ECM) with bioactive milieu of soluble and non-soluble factors is challenging. Herein, we report the formulation and characterization of a bioink system, comprising methacrylamide modified gelatin (GelMA) and 2-hydroxylpropyl methacrylate (HPMA) with a cost-effective redox initiators based cross-linking. GelMA was synthesized by reacting gelatin with methacrylic anhydride (MA) and subsequently, copolymerized with HPMA at room temperature by redox mechanism. Various hydrogel formulations by varying GelMA: HPMA w/v% ratios (G:HP) were studied as 10:0 (G100HP0), 9.5:0.5 (G95HP05), 9:1 (G90HP10), 8:2 (G80HP20), and 6:4 (G60HP40), to identify the best bioink composition. The formulations were characterized for its opacity, chemical, rheological, mechanical, porosity and swelling properties and cytocompatibility as per ISO-10993 standards. Cell encapsulation studies using live/dead assay analyzed cell viability inside the handprinted and 3D printed constructs. The preliminary results indicate successful formulation of cytocompatible bioink for potential 3D bioprinting and biofabrication applications.

A highly sensitive wearable pressure sensor capsule based on PVA/Mxene composite gel.

Wearable sensors have drawn considerable interest in the recent research world. However, simultaneously realizing high sensitivity and wide detection limits under changing surrounding environment conditions remains challenging. In the present study, we report a wearable piezoresistive pressure sensor capsule that can detect pulse rate and human motion. The capsule includes a flexible silicon cover and is filled with different PVA/MXene (PVA-Mx) composites by varying the weight percentage of MXene in the polymer matrix. Different characterizations such as XRD, FTIR and TEM results confirm that the PVA-Mx silicon capsule was successfully fabricated. The PVA-Mx gel-based sensor capsule remarkably endows a low detection limit of 2 kPa, exhibited high sensitivity of 0.45 kPa-1 in the ranges of 2-10 kPa, and displayed a response time of ~ 500 ms, as well as good mechanical stability and non-attenuating durability over 500 cycles. The piezoresistive sensor capsule sensor apprehended great stability towards changes in humidity and temperature. These findings substantiate that the PVA/MXene sensor capsule is potentially suitable for wearable electronics and smart clothing.