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The cellular niche provides combination of biomolecular and biophysical cues to control stem cell fate. Three-dimensional (3D) aligned nanofibrous scaffolds can effectively augment stem cell cardiomyogenesis. This work aims to understand the role of biomolecular signals from extracellular matrix (ECM) proteins and leverage them to further promote cardiomyogenesis on nanofibrous scaffolds. Human mesenchymal stem cells (hMSCs) were cultured on 3D aligned polycaprolactone scaffolds coated with different ECM proteins. Among multiple coatings tested, collagen coated fibers were most effective in promoting cardiomyogenesis as determined from increased expression of cardiac biomarkers and intracellular calcium flux. At molecular level, enhanced differentiation on collagen coated fibers was associated with an increased level of sirtuin 6 (SIRT6). Depletion of SIRT6 using siRNA attenuated the differentiation process through activation of Wnt signaling pathway. This study, thus, demonstrates that protein coated scaffolds can augment cardiomyogenic differentiation of stem cells through a combination of topographical and biomolecular signals.

A low modulus beta Ti-Nb-Ta-O alloy was subjected to heat treatment to investigate its phase stability upon aging. The resultant effect on the mechanical and functional properties was systematically evaluated. The aging of the beta-only microstructure, obtained by solutionizing and quenching, resulted in the formation of ultrafine alpha-precipitates with increasing order of size as the aging temperature increased from 400 degrees C to 600 degrees C. The variation in the size of alpha-precipitates effected the mechanical properties at the three different aging temperature. The highest hardening observed at 400 degrees C was associated with macroscopic embrittlement, whereas age softening was observed in samples aged at 600 degrees C due to coarsening of precipitates and softening of the beta-matrix. In contrast, aging at 500 degrees C resulted in about 32% increase in tensile strength from the beta-solutionized condition. As the samples aged at 500 degrees C showed optimum combination of mechanical properties among the aged samples, these were further characterized for their electrochemical, tribological and biological responses. The fretting wear studies showed that the wear rate of the solution-treated samples increased after aging due to the higher corrosion rate leading to a higher rate of tribocorrosive dissolution and formation of a transfer layer harder than that of solution treated sample. The Ti-Nb-Ta-O alloy supported the attachment and proliferation of osteoblasts similar to that on commercially pure Ti. Taken together, this work provides new insights into the preparation of next-generation Ti alloys for biomedical applications with high strength and low modulus through microstructural control induced by heat treatment.

Keratin has been attracting interest due to its stability against enzymatic degradation thereby allowing more predictable degradation profile for tissue regeneration applications. While the efficacy of keratin has been demonstrated in different tissue models, there has been no systematic study to investigate and compare the different routes of keratin extraction from human hair. Here, we compared the four commonly used extraction methods and highlighted both physical and chemical differences in the extracted keratin. Keratin was extracted from human hair using one of four common agents, namely, sodium sulfide, peracetic acid, urea and thioglycolic add. Whereas no specific trend was observed, the keratin extracted through peracetic acid method had significantly different properties. It resulted in lowest yield of 52 mu g/mL and low crystallinity but the protein formed aggregates with highest hydrodynamic average size of around 283 nm compared to the other three methods. However, despite greater aggregation, keratin extracted from peracetic acid method exhibited secondary structural conformation similar to thioglycolic acid method. All the four extracted keratin promoted cellular proliferation of osteoblasts compared to the uncoated surface. These results provide new insight into the extraction of keratin from human hair with implications for its use as a biomaterial.

In Ti-Nb-Ta-Zr based beta-titaniumalloys intended for orthopedic applications, Zr does not affect the stability of low modulus beta-phase, unlike Nb and Ta. The present study attempts to investigate the influence of Zr on the overall mechanical and functional responses of a Ti-Nb-Ta-Zr-O alloy in contrast to a new Ti-Nb-Ta-O alloy. In each material, different crystallographic textures were produced by varying the processing route. While both alloys were found to show low elastic modulus values due to their beta-only microstructures, Ti-Nb-Ta-O alloy had lower elastic modulus because of its favorable crystallographic orientation caused by absence of Zr. The tensile strength values were remarkably high for both due to the presence of interstitial oxygen. The hardening effect of Zr was also evident from the higher strength of Ti-Nb-Ta-Zr-O as compared to Ti-Nb-Ta-O alloy. Although the corrosion resistance and in vitro biological behavior of the two alloys were satisfactory, the Ti-Nb-Ta-Zr-O alloy showed lower corrosion rate and improved osteoblast attachment than the Ti-Nb-Ta-Oalloy. Thus, whereas the two alloys show promising performance in terms of their mechanical and functional response, presence of Zr marginally improves the performance in the Ti-Nb-Ta-Zr-O for orthopedic applications. (C) 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.

Surface mechanical attrition treatment (SMAT) is recognized as a surface severe plastic deformation (SPD) method that is effective in improving the surface-dependent mechanical and functional properties of conventional metallic biomaterials. In this study, we aimed to systemically investigate the effect of SMAT on the physical, electrochemical, tribological and biological performances of a newly developed low modulus β Ti-Nb-Ta-O alloy with two different microstructures, namely, single phase β-treated and dual phase β + α aged. The microhardness results showed considerable hardening for the β-treated condition due to formation of deformation substructures; that was associated with increased corrosion resistance resulting from a stronger and denser passive layer on the surface, as revealed by Tafel polarization, impedance studies and Mott-Scottky plots. The wear volume loss during fretting in serum solution was found to decrease by 46% while friction coefficient decreased only marginally, due to presence of a harder and more brittle surface. In the β + α condition of the alloy, minimal hardening was observed due to coarsening of the precipitates during SMAT. However, this also reduced the number of α-β interfaces, which in turn minimized the tendency for galvanic corrosion resulting in lower corrosion rate after SMAT. Wear resistance was enhanced after SMAT, with 32% decrease in wear volume loss and 21% decrease in friction coefficient resulted due to improved ductility on the surface. The attachment and growth of osteoblasts on the alloys in vitro were not affected by SMAT and was comparable to that on commercially pure Ti. Taken together, these results provide new insights into the effects of surface SPD of low modulus β- Ti alloys for orthopedic applications and underscore the importance of the initial microstructure in determining the performance of the alloy.