Molecular Dynamics Study of the Biodegradation Process of the Biopolymer Poly (LACTIC)/Poly (VINYL) Scaffold for Bone Tissue Engineering

Abstract

The biomaterial chosen for the design of the scaffold is poly (lactic) acid (PLA), this type of polyester together with poly(glycolic) acid (PGA) and Poly(lactic-co-glycolic) acid (PLGA) are widely used in tissue engineering because of their ability to tailor mechanical properties, degradation kinetics and also because its morphology and shape that can be easily manipulated in order to improve osteoconduction and osteoinduction. It is important to emphasize that this biopolymer can be found as a racemic mixture. In vitro degradation experiments showed that stereochemical composition has an important role on the rate of degradation, concluding that L(+)-PLA degrades much better that D(-)-PLA.The common process of biodegradation of this type of synthetic polymers is hydrolysis of its ester bonds producing lactic acid. Then this product enters the tricarboxylic acid cycle generating water and carbon dioxide which are non-toxic products present in human body. It is important to highlight that the scaffold degradation process should occur at the same rate of new bone tissue proliferation and the scaffold should keep its mechanical functionality during all the procedure. Previous experiments showed that the width of the biopolymer is directly proportional to the rate of hydrolysis. This is because water molecules can spread quicker throw all the scaffold if it has a wide surface instead of a folded one. Another aspect to consider is the molecular weight and the Young module of the material which determines the degree of elasticity of the bone-scaffold system. Here we report the use of molecular dynamics simulation to estimate several of these parameters from the data generated from these simulations. For instance, we address the solvent accessibility of the polymer and how it changes during the degradation process.