Synthesis of nanosized hydroxyapatite/agarose powders for bone filler and drug delivery application

•Calcium-deficient HAp/agarose powder with reduced crystallite size (∼ 40%) was produced by microwave heating.•Microwave heating retain the organic agarose phase in the composite compared to conventional heating.•Controlled drug release was observed from microwave sintered composites.•Negative zeta potential may enhance cell attachment and proliferation.•HAp/agarose composite powder could be used as bone filler and for drug delivery applications.

Drug-loaded bioactive composite powders are used for the treatment of orthopedic diseases and prevention of infection or inflammatory reaction after surgical implantation. Nanosized (80 × 23 nm2) and porous (17 ± 1 nm) hydroxyapatite (HAp)/agarose composite rods were prepared by sol-gel synthesis and subjected to microwave and conventional heating. Microwave heating increased the degree of crystallinity and the thermal stability and produced calcium-deficient HAp/agarose composite powders. There was a considerable reduction (by 39%) in the size of rods on microwave heating whereas the conventional heating at 700 °C rendered the samples porous and agglomerated with a significant decrease in the specific surface area. The agarose contents in as-synthesized and microwave heated samples were ∼14% and 4%, respectively. The samples were partially degradable upon immersion in SBF, and later exhibited calcium phosphate deposition which was confirmed by gravimetry. An antibiotic (amoxicillin) and anticancer (5-fluorouracil) drug-loaded microwave-heated nanosized HAp/agarose composite powder gave an extended drug release when compared to the as-synthesized and the conventionally heated samples. The composite powders showed a negative zeta potential, hemocompatibility and better antimicrobial efficacy than pure HAp (conventional heated sample). The microwave heating retained the organic phase (agarose) along with a reduction in particle size. In addition, this technique is simple, fast and cost-effective to produce mesoporous, bioactive and resorbable nanocomposite (HAp/agarose) powders which could find application as bone filling materials and drug delivery systems.

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