Abstract:
A sustained-release carrier system for the drug cephalexin (CEF) using functionalized graphene oxide is
reported. PEGylation of GO (GO-PEG) and successful loading of CEF into PEGylated graphene oxide (GOPEG-CEF) nanoconjugate are confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy,
and thermogravimetric analysis. Encapsulation efficiency of 69% and a loading capacity of 19% are obtained
with the optimized formulation of GO-PEG-CEF. In vitro CEF release profiles show an initial burst release
followed by a more sustained release over a 96 h period with cumulative release of 80%. The half maximal
inhibitory concentration (IC50) values have both dose- and time-dependent antibacterial activity for GOPEG-CEF against both gram-positive and gram-negative bacteria while pure CEF showed only dosedependent antibacterial activity. The minimum inhibitory concentration values of GO-PEG-CEF are 7.8
and 3.9 mg/mL against S. aureus and B. cereus, respectively, while it is 10 mg/mL with pure CEF against both
gram-positive bacteria. This confirms the enhanced antibacterial activity of GO-PEG-CEF over pure CEF
against gram-positive bacteria. These findings therefore show GO-PEG-CEF is promising as a sustainedrelease nanoantibiotic system for effective treatment against S. aureus and B. cereus infections
