Electrochemical detection of vancomycin using aptamer - screen - printed carbon surfaces

Measuring vancomycin concentration in vivo is a crucial component of the standard of care for administering this drug. To this end, several examples of aptasensors based on gold macroelectrodes or wire electrodes have been successfully applied for the analysis of vancomycin, both in vitro in blood and in vivo in rat animal models. However, the use of gold as the interrogating electrode in these sensors has limitations, including the potential detachment of thiolated aptamers from the gold surface in biological fluids and the risk of unwanted electrochemical reactions occurring at imperfections in the monolayer. In search for alternative strategies, here we applied screen-printed carbon electrodes modified using aptamers containing an anthracene group at the 5' end, using the detection of vancomycin as our test bed. With soluble redox indicator sodium anthraquinone-2-sulfonic acid we succeeded in measuring vancomycin in the range from 0.01 to 0.5 mM. This was achieved by using a receptor layer composed of an aptamer and a 2-phenoxyethanol blocking agent. As a second sensor architecture, we explored carbon electrodes functionalized with a methylene blue-modified aptamer. The signal response of this aptasensor, however, was significantly lower than that of a similar electrochemical aptamer-based (EAB) sensor fabricated on gold electrodes.