Papers by Author: Shula Radin

Abstract: Controlled release silica sol-gels are room temperature processed, porous, resorbable, and biocompatible materials. Many molecules including drugs, proteins, and growth factors can be released from sol-gels, and the quantity and duration of the release can vary widely. Processing parameters render these release properties exquisitely versatile [1]. The synthesis of controlled release sol-gels involves several steps: an acid-catalyzed hydrolysis to form a sol with the molecules included, followed by casting, aging, and drying. Additional steps such as grinding and sieving are required to produce sol-gel granules of a desirable size. In this study, we focus on the synthesis of controlled release sol-gel microspheres by using a novel process, which involves only two steps:sol formation followed by emulsification. Sol-gel microspheres containing either vancomycin (antibiotic) or bupivacaine (analgesic) were successfully synthesized via this synthesis route. Both drugs showed controlled, load-dependent and time-dependent release from the microspheres. The in vitro release properties of sol-gel microspheres were different from those of sol-gel granules produced by grinding and sieving. In comparison to a fast, short-term release from the granules, the release from the microspheres was slower and of longer duration. In addition, the degradation rate of microspheres was significantly slower than that of the granules. These data enable the use of sol-gel powders for controlled long-term release.

Abstract: Beneficial properties of room temperature processed silica sol-gels as resorbable and biocompatible materials for the controlled release of drugs and macromolecules have been described before. Recently, it was shown that a thin sol-gel film can be used for the controlled delivery of antibiotics such as vancomycin. It was also demonstrated that the release and degradation properties of the sol-gel films can be tailored via processing parameters. In this work, we evaluated the in vitro and in vivo bactericidal effects of vancomycin-containing thin sol-gel films applied on Ti-alloy intramedullary nails. Both the in vitro and the in vivo results demonstrate a pronounced bactericidal effect of the sol-gel/antibiotic films. This study suggests that thin antibiotic-containing sol-gel film holds great promise for the prevention and treatment of bone infections.

Abstract: Previously, the properties of room temperature processed silica sol gel (also called xerogels) as resorbable and biocompatible controlled release systems were described. It was demonstrated that drugs and macromolecules with a variety of properties and characteristics could be released in a controlled manner. In this study, we focus on the synthesis of antibacterial thin solgel films on intramedullary nails and fracture fixation materials. We determine the effect of processing parameters on the in vitro properties and demonstrated a time- and load- dependent release of vancomycin from the film. This study suggests that thin sol-gel films hold great promise for the prevention and treatment of bone infections.

Abstract: A previous study demonstrated that the incorporation of bioactive glass (BG) into poly (lactic-co-glycolic acid) (PLGA) can promote the osteoblastic differentiation of marrow stromal cells (MSC) on PLGA by forming a calcium phosphate rich layer on its surface. To further understand the mechanisms underlying the osteogenic effect of PLGA-BG composite scaffolds, we tested whether solution-mediated factors derived from composite scaffolds/hybrids can promote osteogenesis of marrow stromal cells. The dissolution product from PLGA-30%BG scaffold stimulated osteogenesis of MSC, as was confirmed by increased mRNA expression of osteoblastic markers such as osteocalcin (OCN), alkaline phosphatase (ALP), and bone sialoprotein (BSP). The three-dimensional structure of the scaffolds may contribute to the production of cell derived factors which promoted distant MSC differentiation. Thus PLGA-BG composites demonstrates significant potential as a bone replacement material.