The vast domain of regenerative medicine comprises complex interactions between specific cells’ extracellular matrix (ECM) towards intracellular matrix formation, its secretion, and modulation of tissue as a whole. In this domain, engineering scaffold utilizing biomaterials along with cells towards formation of living tissues is of immense importance especially for bridging the existing gap of late; nanostructures are offering promising capability of mechano-biological response needed for tissue regeneration. Materials are selected for scaffold fabrication by considering both the mechanical integrity and bioactivity cues they offer. Herein, polycaprolactone (PCL) (biodegradable polyester) and ‘nature’s wonder’ biopolymer silk fibroin (SF) are explored in judicious combinations of emulsion electrospinning rather than conventional electrospinning of polymer blends. The water in oil (W/O) emulsions’ stability is found to be dependent upon the concentration of SF (aqueous phase) dispersed in the PCL solution (organic continuous phase). The spinnability of the emulsions is more dependent upon the viscosity of the solution, dominated by the molecular weight of PCL and its concentration than the conductivity. The nanofibers exhibited distinct core-shell structure with better cytocompatibility and cellular growth with the incorporation of the silk fibroin biopolymer.

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The lack of optimal physiological properties, bacterial colonization, and auto-osteoinduction, are the foremost issues of orthopedic implantations. In terms of bone healing, many researchers have reported the release of additional growth factors of the implanted biomaterials to accelerate the bone regeneration process. However, the additional growth factor may cause side effects such as contagion, nerve pain, and the formation of ectopic bone. Thus, the design of an osteoconductive scaffold having excellent biocompatibility, appropriate physicomechanical properties, and promoted auto osteoinductivity with antibacterial activity is greatly desired. In this study, 2D rodlike nanohydroxyapatite (nHA) adorned titanium phosphate (TP) with a flowerlike morphology was synthesized by a hydrothermal precipitation reaction. The nanohybrid material (nHA−TP) was incorporated into the synthesized polycaprolactone diol and spermine based thermoplastic polyurethane−urea (PUU) via in situ technique followed by salt leaching to fabricate the macroporous 3D polymer nanohybrid scaffold (PUU/ nHA−TP). Structure explication of PUU was performed by NMR spectroscopy. The synthesized nanohybrid scaffold with 1% nHA−TP showed 67% increase of tensile strength and 18% improved modulus compared to the pristine PUU via formation of H-bonding or dative bonds between the metal and the amide linkage of the polyurethane or polyurea. In vitro study showing improved cell viability and proliferation of the seeded cell revealed the superior osteoconductivity of the nanohybrid scaffold. Most importantly, the in vivo experiments revealed a significant amount of bone regeneration in the nanohybrid scaffold implanted tibial site compared to the pristine scaffold without any toxic effect. Introduction of the minute amount of titanium phosphate within the adorned nHA promotes the osteoconductivity significantly by the capability of forming coordinate bonds of the titanium ion. Depending on the mechanical, physicochemical, in vitro characteristics, and in vivo osteoconductivity, the PUU/nHA−TP nanohybrid scaffold has great potential as an alternative biomaterial in bone tissue regeneration application.

The reduction of the carbon black quantity in elastomeric composites is a massive requirement from environmental perspective and a huge challenge for industrial implementation. The present work consists of the replacement of half amount of carbon black with silica without compromising the basic properties along with ushering of superior characteristics of fluoroelastomer and silicone rubber blends. The comparative study of carbon black-silica hybrid filler (1:1 ratio) with carbon black and silica at different loadings shows much superior aging behavior and thermal stability compared with the other composites with unforeseen increment of tensile strength (56%). The fundamentals of rubber-filler interaction and reinforcement phenomenon of the hybrid filler composites have been determined by the correlation of the experimental findings with different models like Nicolais-Narkis, Nielsen, Guth, and Kerner model. Furthermore, enhanced compatibility between the two rubber phases has been observed in terms of T g shifting (3.8 C) and reduced FKM domain size (from 450 to 300 nm) in the silicone rubber matrix for hybrid filler composites. Morphological studies reflect the selected homogeneous dispersion of the carbon black in fluoroelastomer domain and silica in silicone rubber phase. These super specialty elastomeric composites can be used as oil and fuel resistant gaskets and O-rings for wide temperature range.

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