Specific biofunctional performances of the hydroxyapatite-sodium maleate copolymer hybrid coating nanostructures evaluated by in vitro studies

The nanohybrid structures consisting of hydroxyapatite (HA) and sodium maleate-vinyl acetate copolymer (MP) deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique on Ti surfaces were investigated for specific biological qualities required in bone implantology. The data from in vitro studies demonstrated that human primary osteoblasts (OBs) firmly adhered to Ti coated with HA-MP as indicated by cytoskeleton and vinculin dynamics. OBs spread onto biomaterial surface and formed groups of cells which during their biosynthetic activity expressed OB phenotype specific markers (collagen and non-collagenous proteins) and underwent controlled proliferation.

The inhibition of calcium oxalate monohydrate crystal growth by maleic acid copolymers

The crystallization of calcium oxalate monohydrate (COM) was investigated at conditions of constant supersaturation both in the absence and in the presence of synthetic maleic acid copolymers at 37C, 0.15 M NaCl. The dependence of the rates of COM crystallization in the absence of inhibitors was found to be second order at low and first order at higher supersaturations suggesting a surface diffusion controlled mechanism. The presence of all copolymers tested at concentration levels up to 5 ppm retarded the rates of COM crystal growth up to 90%. The decrease of the COM crystal growth rates by the polymers depended on the nature of the comonomer polymerized with maleic acid and the order of inhibition was found to be vinyl acetate > N-vinylpyrrolidone > styrene. Taking into consideration kinetics data published in the literature concerning the inhibition of COM crystal growth, it is suggested that molecular weight also plays a role, with more inhibition at higher molecular weights. The morphology of the COM crystals grown was unaffected yet the crystals growing at lower rates in the presence of the copolymers were larger and their size more uniform. It is concluded that maleic acid copolymers are strong inhibitors of the crystallization of COM, the inhibitory activity being more pronounced in the case of the linear copolymers.