(334e) Controlled ZnO Nanostructures Alignment and Electrode Spacing – an Approach Towards Multiplexed Biomarker Detection

We demonstrate a methodology to tailor the morphology of zinc oxide (ZnO) nanostructures growth in aqueous chemical bath which in turn dictates the multiplexing capabilities of nanostructured microelectrode sensor platform. A key challenge in multiplexed biomarker quantification is to detect low concentrations of target analytes with high specificity and sensitivity from physiological fluids. Technological advancements provide capabilities to synthesize and integrate nanomaterials into high density arrays leading to development of miniaturized, portable electrical biosensor platforms that meets these requirements. In this work, we demonstrate the multiplexed electrical detection of cardiac biomarkers, troponin-T (cTnT) and troponin-I (cTnI) using one dimensional (1D) ZnO nanostructures as our sensing platform. Electrode characteristics such as material, dimensions and its surface modifications dictate the performance of electrochemical biosensors. In this regard, we demonstrate the methodology to design ultra-small electrodes using 1D ZnO nanostructures via hydrothermal synthesis. We have studied and identified the influence of various aqueous chemical bath parameters on morphology of ZnO nanostructure formation and characterized using SEM and AFM. We have established previously that the density of ZnO nanostructure on microelectrode platform can be effectively controlled by varying precursor concentration, which in turn modulates the electrode behavior (micro/ nanoelectrode). Nanoelectrode behavior enables biomolecule detection under steady state condition due to improved electrochemical reaction rates and increased signal to noise ratio. Here, we discuss the various electrode configurations that enables detection of multiple analytes simultaneously in physiological buffer. Electrode spacing and dimensions that offer minimum interconnect issues and no signal crosstalk were identified through COMSOL simulation and verified experimentally. The charge perturbations due to biomolecular binding events on nanostructured sensing sites were recorded using electrochemical impedance spectroscopy (EIS). Results demonstrate amplified signal response and larger dynamic range for cTnT and cTnI detection with limit at femtogram/mL. Multiplexed detection of these two biomarkers yield about 90% sensitivity and selectivity that individual detection of cTnT and cTnI on separate microelectrode platform. Concurrent detection of these cardiac biomarkers have greater significance in improving quality of life for those suffering from acute myocardial infarction.