Organic chemistry and tests for high school chemistry experiments.
Many substances are used in the production of biomaterials: metals (titanium), ceramics (alumina), synthetic polymers (polyurethanes, silicones, polyglycolic acid (PGA), polylactic acid (PLA), copolymers of lactic and glycolic acids (PLGA), polyanhydrides, polyorthoesters) and natural polymers (chitosan, glycosaminoglycans, collagen). With the rapid development in tissue engineering, these different biomaterials have been used as three-dimensional scaffolds and cell transplant devices. The principal biochemical and biological characteristics of the collagen-based biomaterials are presented, including their interactions with cells (fibroblasts), distinct from those of synthetic polymers, and their potential use in gene therapy through the formation of neo-organs or organoids.
Program | 6th World Congress and Expo on …
Polylactic acid (PLA) is a biodegradable, environmental friendly, biocompatible, easily processable and transparent polymer. Although PLA has these advantages, its applications are limited due to its high cost, thermal and structural properties. The physical, thermal or mechanical properties of PLA can be improved by several methods, such as modification, addition of additives or polymer blends. The one of the most effective methods is seen as composite materials. The composite films based on PLA could be improved for package and medical applications. The goal of this study was to evaluate behavior of PLA/hydroxyapatite, PLA/montmorillonite and PLA/hydroxyapatite/montmorillonite composites. Films were prepared by using solvent-casting procedure and characterized by FTIR (Fourier Transform Infrared Spectroscopy), TGA (Thermogravimetric Analysis) and Water Absorption Capacity. Factorial design of experiments was employed to study the effect of montmorillonite amounts (5% and 20%), hydroxyapatite amounts (5% and 20%).Main and interaction effects of three factors were analyzed using statistical techniques. A regression model suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student’s t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage PLA amounts. After optimization studies, the most effective parameters were determined using the full factorial design method of experimental statistics.
This work compares the biodegradability of polyesters produced by an esterification reaction between glycerol and oleic di-acid (D 18:1) issued from green chemical pathways, via either classical thermo-chemical methods, or an enzymatic method using the immobilized lipase of Candida antartica B (Novozym 435). An elastomeric polymer synthesized by enzymatic catalysis is more biodegradable than an elastomeric thermo-chemical polyester synthesized by a standard chemical procedure. This difference lies in percentage of the dendritic motifs, in values of the degree of substitution, and certainly in cross-links inducing an hyper-branched structure less accessible to the lipolytic enzymes in a waste treatment plant. However, when the elastomeric polymer synthesized by enzymatic catalysis is processed at high temperature as required for certain industrial applications, it presents an identical rate of biodegradation than the chemical polyester. The advantages of the thermo-chemical methods are greater speed and lower cost. Enzymatic synthesis appears be suited to producing polyesters, devoid of metallic catalysts, which must be used without processing at high temperature to keep a high biodegradability.