title: Control of pore size and structure of tissue engineering scaffolds produced by supercritical fluid processing.
abstract: Tissue engineering scaffolds require a controlled pore size and structure to host tissue formation. Supercritical carbon dioxide (scCO2) processing may be used to form foamed scaffolds in which the escape of CO2 from a plasticized polymer melt generates gas bubbles that shape the developing pores. The process of forming these scaffolds involves a simultaneous change in phase in the CO2 and the polymer, resulting in rapid expansion of a surface area and changes in polymer rheological properties. Hence, the process is difficult to control with respect to the desired final pore size and structure. In this paper, we describe a detailed study of the effect of polymer chemical composition, molecular weight and processing parameters on final scaffold characteristics. The study focuses on poly(DL-lactic acid) (PDLLA) and poly(DL-lactic acid-co-glycolic acid) (PLGA) as polymer classes with potential application as controlled release scaffolds for growth factor delivery. Processing parameters under investigation were temperature (from 5 to 55 degrees C) and pressure (from 60 to 230 bar). A series of amorphous PDLLA and PLGA polymers with various molecular weights (from 13 KD to 96 KD) and/or chemical compositions (the mole percentage of glycolic acid in the polymers was 0, 15, 25, 35 and 50 respectively) were employed. The resulting scaffolds were characterised by optical microscopy, scanning electron microscopy (SEM), and micro X-ray computed tomography (microCT). This is the first detailed study on using these series polymers for scaffold formation by supercritical technique. This study has demonstrated that the pore size and structure of the supercritical PDLLA and PLGA scaffolds can be tailored by careful control of processing conditions.
authors: School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors: Hongyun
authors: H
authors: Tai
authors: Melissa L
authors: ML
authors: Mather
authors: Daniel
authors: D
authors: Howard
authors: Wenxin
authors: W
authors: Wang
authors: Lisa J
authors: LJ
authors: White
authors: John A
authors: JA
authors: Crowe
authors: Steve P
authors: SP
authors: Morgan
authors: Amit
authors: A
authors: Chandra
authors: David J
authors: DJ
authors: Williams
authors: Steven M
authors: SM
authors: Howdle
authors: Kevin M
authors: KM
authors: Shakesheff
mesh_terms: D020341:Absorbable Implants; D001672:Biocompatible Materials; D002625:Chemistry, Organic / Q000379:methods; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems / Q000295:instrumentation / Q000379:methods*; D048091:Guided Tissue Regeneration; D036341:Intercellular Signaling Peptides and Proteins / Q000008:administration & dosage; D019344:Lactic Acid / Q000737:chemistry* / Q000627:therapeutic use; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011091:Polyesters; D011100:Polyglycolic Acid / Q000737:chemistry* / Q000627:therapeutic use; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry* / Q000627:therapeutic use; D016062:Porosity; D013499:Surface Properties; D013718:Tensile Strength; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D036341:Intercellular Signaling Peptides and Proteins; D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)