Synthesis, physicochemical, rheological and in-vitro characterization of double-crosslinked hyaluronic acid hydrogels containing dexamethasone and PLGA/dexamethasone nanoparticles as hybrid systems for specific medical applications.

Injectable hydrogels and biodegradable nanoparticles are using in tissue engineering applications and drug delivery systems. To improve physiochemical properties of biomaterials and to develop their applications, hybrid systems consist of hydrogels, and biodegradable nanoparticles were synthesized. In this study, hybrid systems based on double crosslinked hyaluronic acid and PLGA/Dexamethasone sodium phosphate (PLGADEX) nanoparticles are designed and synthesized in several steps. At the first step, poly(l-lactide-co-glycolide) (PLGA) in a ratio of LLA:GA = 85:15 mol% was synthesized via ring-opening polymerization. Then, PLGADEX nanoparticles were synthesized in different ratios using the partially modified emulsification-diffusion method and fully characterized, and desirable nanoparticle was selected (PLGADEX20). At the second step, a double cross-linked hyaluronic acid (XHA) was prepared by mixing various ratios of amino-hyaluronic acid and aldehyde-hyaluronic acid in the presence of genipin. Finally, by mixing of various ratios of PLGADEX20 and Dexamethasone sodium phosphate (DEX) with different ratios of XHA, hybrid systems were prepared. Based on the characterization of hybrid samples and the release studies, hydrogels containing nanoparticles showed a controlled drug release, while the best sample with 3% of optimized nanoparticle was chosen. According to physiochemical and biological properties, these hybrid systems can be good candidates for anti-adhesion barriers, wound dressings, and novel drug delivery systems.

Investigating composite systems based on poly L-lactide and poly L-lactide/triclosan nanoparticles for tissue engineering and medical applications.

In this study, the encapsulated triclosan with a low molecular weight PLLA (LATC30) is dispersed into a PLLA having higher molecular weight via melt blending to increase the overall properties and particularly antibacterial activity of the system. The proposed method results in a completely homogenous composite as 5% LATC30 improved mechanical properties. For instance, the elongation at break was increased ca. 3%. The mechanical properties of the fabricated composites were also affected by the plasticizing role of LATC30. The kinetics of hydrolytic degradation in an accelerated condition was obtained using a novel method by the Beer-Lambert equation. It was found that the incorporation of LATC30 into the composite increases the rate of hydrolytic degradation. The calorimetry showed a reduction in crystallinity upon addition of LATC30. Moreover, the degradation of the composites was studied and fully described the kinetic analysis by the Flynn-Wall-Ozawa (FWO) method. From which, it was found that the activation energy of the system was decreased. As the LATC30 content of the composite was increased, the hydrophilicity of the composite was increased. The fabricated scaffolds with 5% LATC30 demonstrated a good osteoblast cell attachment and mineralization on the composite scaffolds. This composite is a suitable antibacterial candidate for the bone tissue engineering and medical applications since the real dosage of triclosan stays at ca. 1.5%.