Electrochemically assisted SERS sensing of adenosine triphosphate using a carbon microelectrode with composite plasmonic nanostructures

The detection of adenosine triphosphate (ATP) is crucial in several biomedical applications. Here, we propose an electro-optical sensor for ATP that functions without optical labels or recognition unit based on the electrochemistry-assisted formation of ATP-Ag+ complexes and subsequent plasmon-supported generation of the intrinsic surface-enhanced Raman scattering (SERS) spectrum of ATP. Using bimetal-functionalized carbon fiber microelectrodes (CFME), the analysis of ATP with the sensor can be carried out in cellular microenvironments. Bimetallic nanostructures composed of gold nanoparticles and silver nanoparticles were electrochemically deposited on CFME as SERS substrates. Both, fabrication and sensing mainly rely on the execution of redox reactions of silver nanoparticles on the microelectrode, where silver ions released from the oxidation reaction are used as a mediator for the formation of complexes with ATP, which are then anchored to the surface of the microelectrode by the reduction reaction. The SERS spectrum collected from this plasmonic substrate can be used to recognize ATP at low concentrations in the nM range. The miniaturized SERS sensor was applied to cell culture medium and human serum as complex biological microenvironments.