Bio-mimetic mineralization potential of collagen hydrolysate obtained from chromium tanned leather waste

A novel peptide isolated from Catla skin collagen acts as a self-assembling scaffold promoting nucleation of calcium-deficient hydroxyapatite nanocrystals

Catla collagen hydrolysate (CH) was fractionated by chromatography and each fraction was subjected to HA nucleation, with the resultant HA-fraction composites being scored based on the structural and functional group of the HA formed. The process was repeated till a single peptide with augmented HA nucleation capacity was obtained. The peptide (4.6 kDa), exhibited high solubility, existed in polyproline-II conformation and displayed a dynamic yet stable hierarchical self-assembling property. The 3D modelling of the peptide revealed multiple calcium and phosphate binding sites and a high propensity to self-assemble. Structural analysis of the peptide-HA crystals revealed characteristic diffraction planes of HA with mineralization following the (002) plane, retention of the self-assembled hierarchy of the peptide and intense ionic interactions between carboxyl groups and calcium. The peptide-HA composite crystals were mostly of 25-40 nm dimensions and displayed 79% mineralization, 92% crystallinity, 39.25% porosity, 12GPa Young's modulus and enhanced stability in physiological pH. Cells grown on peptide-HA depicted faster proliferation rates and higher levels of osteogenic markers. It was concluded that the prerequisite for HA nucleation by a peptide included: a conserved sequence with a unique charge topology allowing calcium chelation and its ability to form a dynamic self-assembled hierarchy for crystal propagation.

The Significance and Utilisation of Biomimetic and Bioinspired Strategies in the Field of Biomedical Material Engineering: The Case of Calcium Phosphat-Protein Template Constructs

This review provides a summary of recent research on biomimetic and bioinspired strategies applied in the field of biomedical material engineering and focusing particularly on calcium phosphate-protein template constructs inspired by biomineralisation. A description of and discussion on the biomineralisation process is followed by a general summary of the application of the biomimetic and bioinspired strategies in the fields of biomedical material engineering and regenerative medicine. Particular attention is devoted to the description of individual peptides and proteins that serve as templates for the biomimetic mineralisation of calcium phosphate. Moreover, the review also presents a description of smart devices including delivery systems and constructs with specific functions. The paper concludes with a summary of and discussion on potential future developments in this field.

Biomimetic synthesis of nanocrystalline hydroxyapatite from sharkskin collagen

Hydroxyapatite (HA) ceramics have gained popularity as bone-grafting materials due to their excellent biocompatibility. However, chemically synthesized HA lacks a strong load-bearing capacity as required by bones. An alternative solution is to grow HA crystals by biomimetic mineralization of collagen under laboratory conditions. Marine industry wastes such as skin and bones, generally dumped in landfill, provide an alternative cheap source of collagen. This study was undertaken to utilize the recovered collagen from sharkskin, generally discarded as waste, as a substrate for growing nanocrystalline HA. Hammerhead sharkskin collagen was isolated, characterized and identified as type I. The biomimetic growth of HA was induced by subjecting the purified collagen to optimal mineralization condition with an in vitro nucleation solution. Fourier transform infrared spectroscopy and X-ray diffraction studies revealed the formation of HA after 21 d of incubation. The dimensions of the crystals were determined to be in the nanoscale range by scanning electron microscopy and atomic force microscopy. Osteoblasts displayed significantly higher adhesion and differentiation compared to Vero cells on dishes coated with HA crystals. The size, crystallinity and cellular interaction of biomimetically grown HA indicated that sharkskin could offer an ideal alternative substrate for nucleating bone growth in vivo.