Multifunctional biodegradable polymer nanocomposite incorporating graphene-silver hybrid for biomedical applications

Toward preparing a biodegradable multifunctional material, hybrid graphene-silver particles were used to reinforce poly(epsilon-caprolactone) (PCL). Composites of reduced graphene oxide (RGO) sheets decorated with silver (RGO_Ag) were compared with PCL/RGO and PCL/Ag composites containing RGO and silver nanoparticles (AgNPs), respectively. RGO_Ag particles were well dispersed in PCL unlike RGO and AgNPs due to enhanced exfoliation. Uniformly dispersed RGO_Ag led to 77% increase in the modulus of PCL and electrical conductivity increased four orders of magnitude to 10(-7) S/cm at 5 wt% filler greatly exceeding the improvements with RGO or AgNP alone in PCL. RGO_Ag particles reinforced in PCL showed sustained release of silver ions from the PCL matrix unlike the burst release from PCL/Ag. PCL/RGO_Ag and PCL/RGO were non-toxic to human mesenchymal stem cells unlike the highly toxic PCL/Ag composites. PCL/RGO_Ag also supported stem cell differentiation. The PCL/RGO_Ag composites exhibited good antibacterial effect due to a combination of silver ion release from the AgNPs and the mechanical rupture induced by the RGO in the hybrid nanoparticles. Thus, the synergistic effect of Ag and RGO in the hybrid particles in the PCL matrix uniquely resulted in a multifunctional material for potential use in fracture fixation devices and tissue engineering. (C) 2016 Elsevier Ltd. All rights reserved.