Characterization of poly (L-co-D,L Lactic Acid) and a study of polymer-tissue interaction in subcutaneous implants in wistar rats

Abstract

Poly (L-co-D,L lactic acid) (PLDLA) is an important biomaterial because of its biocompatibility properties that promote cellular regeneration and growth. The aim of this study was to evaluate the polymer-tissue interaction of PLDLA implants in the dorsal subcutaneous tissue of male Wistar rats at various intervals (2, 7, 15, 30, 60 and 90 days) after implantation. Physical properties such as the glass transition point (Tg), degradation behavior and other mechanical properties were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), scanning electron microscopy (SEM) and tension tests. Analysis of the degradation of PLDLA membranes in vitro showed that the polymer became crystalline as a function of the degradation time. Mechanical tension tests showed that the polymer behaved like a ductile material: when subjected to constant tension it initially suffered deformation, then elongation and finally ruptured. TGA/MEV provided evidence of PLDLA membrane degradation. For histological analysis, samples from each group were processed in xylol/paraffin, except for the 60 -and 90 -day samples. Each of the latter samples was divided in two: one half was treated with xylol/paraffin and the other with historesin. Light microscopy showed the adhesion of cells to the biomaterial, the formation of a conjunctive capsule around the implant, the presence of epithelioid cells, the formation of foreign body giant cells and angiogenesis. During degradation, the polymer showed a 'lace' -like appearance when processed in xylol/paraffin compared to the formation of "centripetal cracks in the form of glove fingers" when embedded in historesin.

Synthesis and characterization of a novel terpolymer based on L-lactide, D,L-lactide and trimethylene carbonate

“…Among bioresorbable polymers of interest is the copolymer poly (L,co-D,L-lactic acid; PLDLA) that is widely used in the proportion 70:30 because of its good mechanical properties and excellent biocompatibility. This polymer has been the subject of study of this research group and its synthesis is already consolidated so that the polymer has high molecular weight [7][8][9][10][11][12][13][14] . Though PLA is limited by its inherent brittleness, its properties can be significantly enhanced and broadened by modification via copolymerization, which provides a number of advantages because the architecture and composition of the biomaterials can be tailored to control and composition of the biomaterials can be tailored to control the material properties (by anionic or coordinated polymerization) 15 .…”

Biological Evaluation of PLDLA Polymer Synthesized as Construct on Bone Tissue Engineering Application

“…These reactions occurred primarily in the center of the defects, around the particle-polymer interface within the scaffold. The inflammatory response observed in the implants was not considered to be indicative of a toxic effect of the PLDLA constructs but was most likely related to the rapid degradation of the PLDLA polymer at this stage, which can result in a high concentration of polymer fragments and local acidification of the implanted area 8,11,28,29 .…”

“…We have reported the synthesis and development of a number of bioreabsorbable polylactide-based polymers obtained by ring-opening polymerization of lactide and glycolide monomers [7][8][9][10] . Their potential use as biomedical devices and their biocompatibility with skin, bone, cartilage and neuronal tissue also have been explored [11][12][13][14][15] . Among the polymers synthesized by the group, we highlight the amorphous copolymer poly(L-co-D,L lactide)-PLDLA which has molecular weight range of 10 5 g/mol and glass transition temperature of 55-60 o C 8,16 .…”

Characteristics of Biodegradable Implants

“…A non-crystalline polymer composed of 70% poly-L-lactide and 30% poly-D,L-lactide (70:30 PLDLLA), having a degradation time of 12 -18 months, has been chosen by MAST Biosurgery [26] to be adequate as tissue implants. This adopted by Ciambelli, et al [27], resulted in PDLLA 70:30 usage with improved biocompatibility. A scaffold made of 50% PLA and 50% PCL (PLCL 50:50) has been found to be efficient for vascular tissue engineering as it gives perfect tissue compatibility [28].…”