Development of Porous Polyvinyl Acetate/Polypyrrole/Gallic Acid Scaffolds Using Supercritical CO2 as Tissue Regenerative Agents.

Diego Valor,Clara Pereyra,Antonio Cózar,Enrique Martínez De La Ossa,Antonio Montes

doi:10.3390/polym14040672

Abstract

Scaffolds are advanced devices employed in tissue engineering, as they are intended to mimic the characteristics of extracellular matrices. In this respect, conjugated materials are gaining relevance in the manufacturing of the foams used for therapeutic scaffolds, since they can provide certain properties that are missing in the other polymers used to form the scaffolds. This work has, therefore, focused on the development of functional scaffolds formed by conjugated-non-conjugated polymers such as polyvinyl acetate and polypyrrole, impregnated with gallic acid as the model drug and produced by means of a supercritical CO2 foaming/impregnation process. The effects from a series of parameters such as pressure, temperature, depressurization rate, and contact time of the scaffold production process have been determined. The impregnated foams have been characterized according to their morphology, including their porosity and expansion factor, their drug loading and delivering capabilities, and their mechanical and electrical properties. The characterization of the experiments was carried out using scanning electron microscopy, liquid displacement, in vitro release, electrochemical impedance spectroscopy, and compression techniques. The results from our tests have revealed a considerable influence of all the input variables studied, as well as relevant interactions between them. Values close to 35% porosity were obtained, with a drug release of up to 10 h with a fast initial release. The best operating conditions were 353 K, 30 MPa, 0.5 MPa/min depressurization rate, and 1 h contact time. By means of the supercritical foaming/impregnation technique, scaffolds with potential in tissue engineering due to their studied properties were obtained.

Highlights

Publisher’s Note: MDPI stays neutralTissue engineering is a currently emerging scientific discipline
It can be clearly observed that part of the PPy and the Gallic acid (GA) were impregnated both inside and outside the porous nuclei of the scaffolds produced by runs 1, 3, 8, and 12
Foam structures based on the non-conductive polymer were produced while a conductive polymer was impregnated to provide the said structures with the required electrical conductive properties for medical usage

Summary

Introduction

Tissue engineering is a currently emerging scientific discipline It focuses on the regeneration of damaged or destroyed tissues/organs in living organisms, and substantial improvements have been achieved over the last decade [1,2]. Given this state of things, the biomaterials that are being used for wound healing and tissue regeneration have attracted the interest of the scientific community. One of the key properties of human tissues is its conductivity, since human cells produce an electric field as part of the self-healing process [5] It is, essential to use conductive biomaterials that support the activity of the electrically responsive cells so that the healing process can be accelerated [6]

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