The influence of supercritical foaming conditions on properties of polymer scaffolds for tissue engineering

Abstract

The results of experimental investigations into foaming process of poly(ε-caprolactone) using supercritical CO2 are presented. The objective of the study was to explore the aspects of fabrication of biodegradable and biocompatible scaffolds that can be applied as a temporary three-dimensional extracellular matrix analog for cells to grow into a new tissue. The influence of foaming process parameters, which have been proven previously to affect significantly scaffold bioactivity, such as pressure (8-18 MPa), temperature (323-373 K) and time of saturation (1-6 h) on microstructure and mechanical properties of produced polymer porous structures is presented. The morphology and mechanical properties of considered materials were analyzed using a scanning electron microscope (SEM), x-ray microtomography (µ-CT) and a static compression test. A precise control over porosity and morphology of obtained polymer porous structures by adjusting the foaming process parameters has been proved. The obtained poly(ε-caprolactone) solid foams prepared using scCO2 have demonstrated sufficient mechanical strength to be applied as scaffolds in tissue engineering.

Foaming of PCL-Based Composites Using scCO2—Biocompatibility and Evaluation for Biomedical Applications

“…The process of foaming the materials was carried out in a specially designed and built high-pressure system. A detailed description and diagram of the system is presented in previous papers [ 19 , 20 ], especially the first part of this study [ 4 ]. The foaming process itself was carried out in a three-step batch process.…”

“…The essence of the problem under consideration is the assessment of relationship between the conditions of the foaming process with the use of supercritical fluids, such as temperature, pressure, and saturation time, as well as the relationship between the polymer–gas or polymer composite–gas interface and the properties of the produced solid foams [ 19 , 20 ]. On the basis of a critical review of the literature and the results of independent experimental research, a significant role of the commonly used biodegradable polymer, namely poly(ε-caprolactone) (PCL), in the field of tissue engineering was demonstrated [ 11 , 15 , 20 , 21 ].…”

Engineering bioactive synthetic polymers for biomedical applications: a review with emphasis on tissue engineering and controlled release

“…133 Despite the disordered nature of the method, an accurate control of the pore size distribution, porosity, open-cell features, and tortuosity, as well as the surface roughness, can be achieved by carefully controlling the processing parameters. 134,135 The lack of any requirement for cytotoxic solvents, the possibility of operating at mild conditions (for example, with PCL, at temperatures below 37 1C), and the potential to process a wide variety of polymers for biomedical use are the main advantages of the technique. 136 The use of CO 2 or N 2 as a blowing agent represents another important advantage of supercritical foaming in tissue engineering applications, since these gases rapidly leave the porous matrix during foaming and have negligible residual cytotoxicity.…”

Foaming of PCL-Based Composites Using scCO2: Structure and Physical Properties

“…Given the above limitations on production methods, special attention was paid to the foaming process using media in the supercritical state [ 9 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. It is worth mentioning that it is possible to modify the characteristics of the produced porous structures by combining different manufacturing methods and using composite materials [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Additionally, the morphology of the polymer foam is modeled by the properties of the polymer and its structure, crystallinity and degree of hardening [ 42 ].…”

“…Generally, the process of foaming polymers using supercritical carbon dioxide is based on three basic steps [ 27 , 29 , 35 , 36 , 46 , 47 ]. The first step consists in saturating the polymer material with CO 2 at an elevated pressure and temperature.…”