A novel, porous triphasic calcium phosphate composed of nonresorbable hydroxyapatite (HAp) and resorbable tricalcium phosphate (alpha- and beta-TCP) has been synthesized hydrothermally at a relatively low temperature. The calcium phosphate precursor for hydrothermal treatment was prepared by gel method in the presence of ascorbic acid. XRD, FT-IR, Raman analyses confirmed the presence of HAp/TCP. The surface area and average pore size of the samples were found to be 28 m2/g and 20 nm, respectively. The samples were found to be bioactive in simulated body fluid (SBF).

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Mesoporous nanocrystalline hydroxyapatite (nHAp) rods of size 40-75 nm long and 25 nm wide (resembling bone mineral) were synthesized under microwave irradiation without using any surfactants or modifiers. The surface area and average pore size of the nHAp were found to be 32 m(2) g(-1) and 4 nm, respectively. Rifampicin (RIF) and ciprofloxacin (CPF) loaded nHAp displayed an initial burst followed by controlled release (zero order kinetics). Combination of CPF and RIF loaded nHAp showed enhanced bacterial growth inhibition against Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli) compared to individual agent loaded nHAp and pure nHAp. In addition, decreased bacterial adhesion (90%) was observed on the surface of CPF plus RIF loaded nHAp. The biocompatibility test toward MG63 cells infected with micro-organisms showed better cell viability and alkaline phosphatase activity (ALP) for the combination of CPF and RIF loaded nHAp. The influence on cell viability of infected MG63 cells was attributed to the simultaneous and controlled release of CPF and RIF from nHAp, which prevented the emergence of subpopulations that were resistant to each other. Hence, apart from the issue of the rapid synthesis of nHAp without surfactants or modifiers, the simultaneous and controlled release of dual drugs from nHAp would be a simple, non-toxic and cost-effective method to treat bone infections.

The effect of swift heavy ion irradiation on the surface modification and bioactivity of microwave sintered hydroxyapatite (HAp) pellets has been studied. The irradiated surface of the pellets was completely covered by tightly packed rectangular platy crystals. The pellets subjected to 300°C conventional sintering (after microwave sintering) before irradiation showed a plain surface. XRD studies confirmed the surface to be HAp but decrease in crystallinity and crystal size was observed. In vitro bioactivity study had revealed the formation of unique three dimensional macroporous apatite layer on irradiated surfaces. The irradiation with swift heavy oxygen ions enhanced the bioactivity of the HAp bioceramics.

Development of low-cost membranes with enhanced mechanical strength and minimal sensitivity to variation in humidity, for PEMFC applications.