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Asparagusroot-like and scattered needle-like formation of hydroxyapatite nanoparticles under microwave irradiation.

In the present investigation, crab shells as seafood wastes were successfully recycled into an extremely useful biomaterial by the thermal treatment method. Thermogravimetric-differential thermal analysis studies concluded that the calcination temperature must be beyond ∼570 °C to get a fine and crystalline apatite powder from the crab shells. Thus, the calcination temperature is taken to be 700 °C. Powder X-ray diffraction analysis of the calcined crab shells revealed hydroxyapatite (HAp)/carbonated HAp (CHAp) with an average crystallite size of 24.4 nm. Scanning electron microscopy revealed the surface morphology of the crab shells-derived apatite powder as needle-like nanorods of HAp of diameter ≈ 100–300 nm and nanospheres of CHAp of diameter ≈ 100–500. Energy-dispersive X-ray spectroscopy showed the presence of calcium, phosphorous, magnesium, and oxygen as major elements in the apatite constituents. Fourier transform infrared as well as Raman spectroscopies confirmed the formation of apatite powder. X-ray photoelectron spectroscopy results indicated the electronic environment and oxidation states of the constituent elements, Ca, C, and P. On the basis of the results obtained from various characterization techniques, the overall study emphasized an environment-friendly and cost-effective approach for recycling of the bio-pollutant and synthesis of ultra-fine, ultra-crystalline apatite-based excellent biomaterial derived from crab shells as seafood wastes with its application as a futuristic biomaterial in bone/teeth implants.

Hydroxyapatite Ca10(PO4)6(OH)2: (HAp) with stoichiometric composition and Ca/P (ratio) = 1.67 has attracted much attention in the context of bone transplant due to its similarity with the mineral constituent of mammals bone and teeth. It is frequently used as a filler to replace amputated bone or as a coating to promote bone ingrowth into prosthetic implants. Biomimetics or biomimicry is the imitation of the models, systems, and elements of nature for the purpose of solving complex human problems. Living organisms have evolved well-adapted structures and materials over geological time through natural selection. Biomimetics has given rise to new technologies inspired by biological solutions at macro and nanoscales. Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features.In the present investigation hydroxyapatite and metals (scandium, magnesium and neodymium) doped hydroxyapatite were successfully synthesized in laboratory by chemical precipitation using hydrothermal route and also by taking ethylene diamine tetra-acetic acid as a complexing reagent. The crystal, grain, and bonding structures of resulting HAp were characterized structurally using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques and spectroscopically using Fourier transform infrared (FT-IR) techniques. From SEM analysis it was found that the irregular structure of HAp changes to nanorods with EDTA HAp which further gets converted to dandelium structure with scandium doping, plate structure with magnesium doping and whiskers structure on doping with neodymium.

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