Characterisation of the macroporosity of polycaprolactone-based biocomposites and release kinetics for drug delivery.
Microporous, biocomposite matrices comprising a continuous phase of poly(epsilon-caprolactone) (PCL) and a dispersed phase of lactose or gelatin particles with defined size range (45-90, 90-125 and 125-250 microm) were produced by precipitation casting from solutions of PCL in acetone. Scanning electron microscopy (SEM) analysis revealed a characteristic surface morphology of particulates interspersed amongst crystalline lamellae of the polymer phase. Rapid release of around 80% of the lactose content occurred in PBS at 37 degrees C in 3 days, whereas biocomposites containing gelatin particles of size range 90-125 and 125-250 microm, respectively, displayed gradual and highly efficient release of around 90% of the protein phase over 21 days. A highly porous structure was obtained on extraction of the water-soluble phase. Micro-computed tomography (Micro-CT) and image analysis enabled 3-D visualisation and quantification of the internal pore size distribution. A maximum fractional pore area of 10.5% was estimated for gelatin-loaded matrices. Micro-CT analysis confirmed the presence of an extensive system of macropores, sufficiently connected to permit protein diffusion, but an absence of high volume, inter-pore channels. Thus tissue integration would be confined to the matrix surface initially if the designs investigated were used as tissue-engineering scaffolds, with the core potentially providing a depot system for controlled delivery of growth factors.
Wang
Yiwei
Y
Faculty of Pharmacy, Australian Key Centre for Microscopy and Microanalysis, Sutton Arthritis Research Laboratories, Royal North Shore Hospital, University of Sydney, NSW 2006, Australia.
Chang
Hsin-I
HI
Wertheim
David F
DF
Jones
Allan S
AS
Jackson
Chris
C
Coombes
Allan G A
AG
D001672:Biocompatible Materials / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004058:Diffusion; D004337:Drug Carriers / Q000737:chemistry*; D007700:Kinetics; D007785:Lactose / Q000737:chemistry*; D008422:Materials Testing; D011091:Polyesters / Q000737:chemistry*; D016062:Porosity
D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D011091:Polyesters; C016240:polycaprolactone; D007785:Lactose