Simultaneous Detection of Glucose and Lactate using Self-Powered design of Multiplexed Biosensor

It is generally accepted that glucose and lactate are the primary energy sources for brain function. Additionally, the brain uses about 20% of the body's energy to maintain optimal function. It is, therefore, important to have effective methods for simultaneous monitoring of glucose and lactate as their levels are critical evaluators of an individual's metabolic status and overall health. Here, we report on a novel design of a multiplexed biosensing platform capable of sensitive detection of glucose and lactate simultaneously. The platform employs DNA-templated silver nanoclusters (AgNCs@DNA), which exhibit advantageous characteristics such as fluorophores due to their small size as well as significant redox activity. Dual signal readout strategies can, therefore, be employed: 1) electrochemical and 2) optical. We proposed AgNCs–PCA/Glucose Oxidase (GOx) or Lactate Oxidase (LOx) composite for Electrochemical readout using modified screen-printed electrodes (SPE) and AgNCs–GOx(LOx) for Optical readout via fluorescence. Both electrochemical and optical readouts show excellent sensitivity of 250 µM and 23 µM when fitted using empirical models with 0.99 and 0.97 regression coefficients. The immobilized GOx and LOx enzymes, while oxidizing their substrates, generate electrons and pass them onto polymer-embedded AgNCs, which in turn pass them onto the surface of the working electrode, creating a charge-transmitting chain, which results in the self-powered operation of the device.