There is an increasing acceptance of the importance of tailoring biomaterial surface properties. This study aimed to introduce and characterise amine functionalities onto the hydrophobic bacterial polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Gamma irradiation induced simultaneous grafting of 2-aminoethyl methacrylate (AEMA) onto PHBV films was carried out using various concentrations of AEMA (2.5 or 4.5 w/v%) in either water or methanol and at two irradiation doses (4.5 or 9 kGy). Successful grafting was verified from XPS analysis, water contact angle and ATR-FTIR spectroscopy. Characterisation using DSC indicated that grafting had occurred predominantly in the amorphous region of the PHBV substrate. H-1 NMR of the grafting solution post grafting showed that monomer conversion is incomplete in methanol. The use of gold nano-particles (AuNPs) as a simple tool to probe the presence of these functional groups was evaluated using a suspension of citrate functionalized AuNPs prepared by reduction of Au(III) with citric acid. These particles were found to be polydisperse (0.8-2 nm and 7-70 nm) and negatively charged (zeta potential of -33 +/- 9 mV) and capable of interacting electrostatically with the amine groups on the PHBV surface and imaged using SEM. (C) 2011 Elsevier Ltd. All rights reserved.