Although hydroxyapatite (HA)-based porous scaffolds have been widely researched in the last three decades, the development of naturally derived biomimetic HA with a tunable elastic modulus and strength together with faster biomineralization properties has not yet been achieved. To address this specific issue, we report here a scalable biogenic synthesis approach to obtain submicron HA powders from cuttlefish bone. The marine-resource-derived HA together with different pore formers can be conventionally sintered to produce physiologically relevant scaffolds with porous architecture. Depending on pore formers, the scaffolds with a range of porosity of up to 51% with a larger range of pore sizes up to 50 μm were fabricated. An empirical relationship between the compression strength and the elastic modulus with fractional porosity was established. A combination of moderate compressive strength (12−15 MPa) with an elastic modulus up to 1.6 GPa was obtained from cuttlefish-bone-derived HA with wheat flour as the pore former. Most importantly, the specific HA scaffold supports the faster nucleation and growth of the biomineralized apatite layer with full coverage within 3 days of incubation in simulated body fluid. More importantly, the marine-species-derived HA supported better adhesion and proliferation of murine osteoblast cells than HA sintered using powders from nonbiogenic resources. The spectrum of physical and biomineralization properties makes cuttlefish-bone-derived porous HA a new generation of implantable biomaterial for potential application in cancellous bone regeneration.

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The effect of Fe3+ ionic substitution in hydroxyapatite (Ca10‐xFex(PO4)6(OH)2) was studied using structural modifications, resulting in an improvement in UV absorption through a tailored optical band structure. Ca2+ of HA being larger compared to Fe3+ contributes to the shrinkage of the lattice. Undoped HA has a peak at 1085 cm−1 (ʋ3 PO43−) which is shifted to 1033 cm−1 for Fe‐HA, because of the perturbation in HA structure. An improvement of UV absorption in the entire UVA and UVB range with an increase in Fe content because of a decrease in bandgap from 5.9 eV to 2.1 eV with undoped and doped HA. Theoretically obtained band gap and optical behaviour of the systems are well correlated with the experimental findings. Moreover, the use of marine biowaste from cuttlefish bone, as the source of HA; low cost and promising UV absorption can have a potential application as UV protective sunscreen filters.

The recognition of hydroxyapatite (HAp) as the major bone mineral triggered significant research in bone tissue engineering applications. Although laboratoryscale development involves the synthesis of HAp in different routes, scalability with uncompromised quality remains a major challenge. This article reports a large-scale wet precipitation-based synthesis of phase-pure HAp using indigenously customized stirred tank reactors. The different synthesis parameters, like pH, reaction time, stirring rate, precursor addition, were tailored, together with the post-synthesis mechano-chemical treatment (aging induced Ostwald ripening) and calcinations, as the technology is matured to manufacture HAp powders in large volume. At least three batches of HAp were produced in the pilotscale reactor with reproducible values of phase purity, compositional fingerprint, particle size distribution, flowability, etc. The post-calcination bluish tint was strategically addressed by adopting a proprietary calcination protocol. This batch process can produce around 200 kg/month of phase-pure and highly crystalline (91-94%) HAp using stirred tank reactors of different working volumes. Extensive scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses reveal the particle size of as-synthesized HAp powders with hexagonal crystal structure in the range of 20.47 ± 4.95 nm , while individual crystallite size in range of 22.3 ± 3.2 nm (XRD based Debye-Scherrer analysis). TEM-based SADP analysis confirms the highly crystalline hexagonal structure of as-synthesized HAp. The spray-dried powders with spherical shape having narrow size distribution (35-40 μm) could also be manufactured in large batches. The spray-dried HAp powders could be coated on clinically used stainless steel femoral stem implants using atmospheric plasma spray coating technique.