Silicon oxycarbide particles were subjected to chemical oxidation processes to incorporate carbonyl and carboxylic functionalities on their surfaces. These materials were subjected to in vitro tests to determine their adsorption and release capabilities of the antiretroviral drug molecule acyclovir. The spectroscopic characterization revealed the distribution of the functionalities in the different nanophases contained within the silicon oxycarbide structure. This selective distribution in either the carbon or the silicon oxycarbide phase leads to a differential charge availability that in fact is responsible for the adsorption of the drug molecule on the surface of the particles. This adsorption occurs via donor-acceptor interactions with no chemical bonds involved in the drug delivery system.