The nucleation and growth of hydroxyapatite is closely associated with the extracellular matrix environment. Bovine Serum Albumin, Collagen and poly vinyl alcohol were used to mimic the extracellular matrix. An attempt to understand the role of these matrices on the synthesis and function of Hydroxyapatite has been made. XRD, FT-IR, XPS, TG-DTA, SEM and TEM confirmed the formation of hydroxyapatite synthesized by the biomimetic route. Further the role of organic matrix in controlling the nucleation and growth of hydroxyapatite particles in the nano level is understood by the in-depth analysis of the XPS spectra. The in vitro release of the anti-cancer drug methotrexate, in aqueous solution was studied and the in vitro release profile was assayed by elution in phosphate buffered saline with pH 7.4 and pH 5 at 37 º C. The percentage of loading and release profiles of drug were evaluated. The results show that the use of matrix increased the drug release efficiency from 44.5% to 66% at pH 7.4 and 78% to 98.92% at pH 5. These results suggest that the synthesized hydroxyapatite can be used as a pH responsive vehicle for delivering drugs. Further the release profile was predicted by Higuchi and Peppas model. The results suggested that the release mechanism was governed by the Fickian diffusion for initial 8 hrs followed by anomalous transport for longer time. The cytocompatibility of the materials was evaluated by in vitro cytotoxicity test. Both MTT and live/dead assay observations indicated that the material had no adverse impact on the cell proliferation. The results imply these composites to be bioactive having a good cytocompatibility. Although all the matrices showed good results, the one with poly vinyl alcohol exhibited higher biocompatibility and drug release efficiency. A plausible explanation was proposed for the enhanced drug delivery efficiency of these materials.

For the first time, the heat dried biomass of a newly isolated fungus Arthrinium malaysianum was studied for the toxic Cr(VI) adsorption, involving more than one mechanism like physisorption, chemisorption, oxidation-reduction and chelation. The process was best explained by the pseudo-second order kinetic model and Redlich-Peterson isotherm with maximum predicted biosorption capacity (Q m) of 100.69 mg g−1. Film-diffusion was the rate-controlling step and the adsorption was spontaneous, endothermic and entropy-driven. The mode of interactions between Cr(VI) ions and fungal biomass were investigated by several methods [Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD) and Energy-Dispersive X-ray spectroscopy (EDX)]. X-ray Photoelectron Spectroscopy (XPS) studies confirmed significant reduction of Cr(VI) into non-toxic Cr(III) species. Further, a modified methodology of Atomic Force Microscopy was successfully attempted to visualize the mycelial ultra-structure change after chromium adsorption. The influence of pH, biomass dose and contact time on Cr(VI) depletion were evaluated by Response Surface Model (RSM). FESEM-EDX analysis also exhibited arsenic (As) and lead (Pb) peaks on fungus surface upon treating with synthetic solutions of NaAsO2 and Pb(NO3)2 respectively. Additionally, the biomass could also remove chromium from industrial effluents, suggesting the fungal biomass as a promising adsorbent for toxic metals removal.

Controlled size, shape and dispersibility of superparamagnetic iron oxide nanoparticles (SPIONs), has been achieved in a protein-polymer colloidal dispersion. Stable ferrofluid (FF) is synthesized in an aqueous medium of collagen, bovine serum albumin and poly(vinyl) alcohol that equilibrates with time, at ambient conditions, into an organized matrix with iron oxide particles sterically caged at defined sites. It mimics a biomineralization system; hence the process is termed biomimetics. Though the exact mechanism is not understood at this stage, we have established, with serial dilution of the protein-polymer solution that the SPIONs are formed inside the self-contained clusters of the two proteins and the polymer, which show a tendency to self assemble. More than the interparticle dipolar attractions of magnetic particles, electrostatic interactions play a role in cluster formation and collagen is responsible for the overall stability, supported by systematic dynamic light scattering data. The basic aim of this study was to increase magnetization of a previously synthesized ferrofluid without hampering stability, by reducing the total macromolecular concentration. Thrice the magnetization was achieved and in addition, the synthesized FFs exhibited very high transverse relaxivity and showed good contrast in mice liver, in the in vivo studies.