The aim of the study was to prepare bioactive and bioabsorbable composites of polylactide/wollastonite (PDLLA/W) and evaluate their mechanical properties and biocompatibility in vitro. PDLLA and wollastonite were physically mixed and the mechanical properties of the composition showed the influence of wollastonite, and that a partial composite, e.g., a PDLLA/wollastonite composition with 15 wt% wollastonite (PW-15) has similar mechanical properties compared to pure PDLLA. However, an in vitro biocompatibility testing showed that the composite has no deleterious effects on the osteoblast cells and facilitates both adhesion and proliferation of the osteoblast cells on the PDLLA/wollastonite film surface. The introduction of wollastonite could also induce the deposition of hydroxyapatite (HA) on the surface of the composite in simulated body fluids (SBF) which has important implications on bone regeneration. These mechanical and biocompatibility properties represent PDLLA/wollastonite composites as potential biomaterials.

Biodegradable polymers have been extensively investigated as nano-carrier delivery systems in anti-cancer therapy. The anti-cancer drugs generally suffer from low aqueous solubility, short in vivo half-life and haphazard side effects. In this work, biodegradable poly(d,l-lactide-co-glycolide) nanoparticles (PLGA) containing tamoxifen citrate as a model anti-cancer drug were prepared using an o/w emulsification- solvent evaporation method. Dynamic light scattering (DLS), scanning electron microscopy (SEM) and analytical HPLC procedures were used to characterize the nanoparticles in terms of particle size, morphology and drug content. The characteristics of the nanoparticles including size, drug loading, and the efficiency of encapsulation were optimized by means of a full factorial experimental design over the influence of four different independent variables. Analyses of variance (ANOVA) were used to evaluate the optimized conditions for the preparation of nanoparticles. Based on the results, the most significant variables were homogenization speed and concentration of PLGA in organic phase with known total volume. Also, the interactions between the percentage of PVA and the amount of PLGA and organic phase volume were the most important cross-factor parameters. The optimum formulation condition with 192 nm mean size and 33 w/w% loading capacity was established by using 3 mg.mL-1 PLGA/dichloromethane in 7 w/v% PVA solution and 40% oil/water solvent ratio for emulsification at 24000 rpm homogenization rate. The results of this work facilitate the development of nano-carriers for tamoxifen delivery through optimization studies to control nanoparticles with specific properties and establish correlations between optimum production conditions and the required nano-carrier desired characteristics.

Aliphatic polyesters are the source of the attractive polymeric matrices that are currently investigated for making controlled drug delivery devices. In spite of the large number of investigations dealing with LA/GA polymers which have been reported in the literature, only little is known about the degradation mechanism of these polyesters in solid state. In this study poly (L,D-lactide-co-glycolide) 50:50 (PLGA) was hydrolyzed at 37oC for periods up to 56 days. PLGA discs were prepared in 60oC and the results of their in vitro biodegradation behaviour are reported. We observed that hydrolysis of PLGA proceeds in 7 stages: surface hydrolysis ,outer layers hydrolysis, outer layers water soluble oligomers formation, exiting water soluble oligomers, bulk hydrolysis and exiting degradation products, bulk catalyzed hydrolysis, and at the last step fragile porous structure formation. The remained porous structure is crystallized and shows more resistance to further degradation.

In this study, porous scaffolds from poly (D,L-lactic acid) have been prepared via liquid- liquid phase separation method in ternary system of polymer-1,4-dioxane-water. Polymer dissolved in dioxane in 1.5, 2.5 and 5 % wt/v and the solvent/non-solvent ratios were 13/87, 15/85 and 17/83. Cloud point curves prepared by visual turbidometry. In order to obtain porous scaffolds with inter-connected pores structure, each system cooled below its cloud point temperature to achieve phase separation then promptly freezed. Furthermore, sublimation in freeze-dryer took place. Scanning electron microscopy have been used to study the morphologies of the scaffold and average pore sizes from 10 to 37 mm were obtained with variation in systems concentrations. Porosity density and of the scaffolds were measured by volumetric method and 85.5% was achieved. The results show that variation in concentration of ternary system has great effect on morphology, pore size and porosity density of the scaffolds.