Exploration of Calcium Rich Marine Benthos Bio-Waste to Develop Bio-Genic Hydroxyapatite for Bone Regeneration and UV Protection

Abstract

In this study, a scalable biogenic synthesis of phase-pure hydroxyapatite (Ca10(PO4)6(OH)2, HA) (Ca/P = 1.66) scaffold from the marine-resource-derived HA together with different pore formers were conventionally sintered to produce physiologically relevant scaffolds with porous architecture. A combination of moderate compressive strength (12−15 MPa) with elastic modulus up to 1.6 GPa was achieved with ∼98% interconnected porosity using wheat flour as the pore former. More importantly, the faster nucleation and growth of the biomineralized apatite layer with full coverage within 3 days of incubation in a simulated body fluid, together with a combination of mechanical properties, establish the potential of marine-resource-derived biomimetic HA scaffold as a new generation of cancellous bone analogue. MTT assay and cell morphological analysis established the good cytocompatibility of naturally derived HA porous scaffolds, as evident from the good cellular adhesion, proliferation, and phenotypical features of osteoblast cells. The effect of Fe3+ ionic substitution in HA was studied using structural modification, such as lattice parameter, crystallite size, and particle size resulting into a drastic improvement in UV absorption through a tailored optical band structure. Ca2+ of HA being larger (0.99 Å) compared to Fe3+ (0.64 Å) contributes to the shrinkage of the lattice. Hence, hexagonal lattice parameters, a and c of HA are reduced successively as the concentration of Fe3+ increases, is observed via XRD. UV absorption of Fe-HA in the entire UVA and UVB range with an increase in Fe content because of the remarkable decrease in band gap with undoped and doped HA. Also, present work explores the use of marine resourced prawn exoskeleton/shell as a new class of naturally occurring composite containing UV absorbing proteins. Mycosporine-like amino acids with a central aromatic ring in the exoskeleton/shell of naturally occurring prawns (Fenneropenaeus Indicus) offer excellent UV protection. The presence of tryptophan, phenylalanine, and tyrosine, forming the basic building blocks of mycosporines, is confirmed by structural, compositional, and microscopic studies on prawn shells. The UV spectroscopic signatures at 290 and 320 nm provides strong evidence for the highest UV absorption. UV absorption attributes to the presence of mycosporine-like amino acids.