Wang, Yiwei, Chang, Hsin-I, Wertheim, David F., Jones, Allan S., Jackson, Chris and Coombes, Allan G.A. (2007) Characterisation of the macroporosity of polycaprolactone-based biocomposites and release kinetics for drug delivery. Biomaterials, 28(31), pp. 4619-4627. ISSN (print) 0142-9612

Abstract

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.

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