Enabling Multiplexed Electrochemical Detection of Biomarkers with High Sensitivity in Complex Biological Samples

Conspectus The ability to perform multiplexed detection of various biomarkers within complex biological fluids in a robust, rapid, sensitive, and cost-effective manner could transform clinical diagnostics and enable personalized healthcare. Electrochemical (EC) sensor technology has been explored as a way to address this challenge because it does not require optical instrumentation and it is readily compatible with both integrated circuit and microfluidic technologies; yet this approach has had little impact as a viable commercial bioanalytical tool to date. The most critical limitation hindering their clinical application is the fact that EC sensors undergo rapid biofouling when exposed to complex biological samples (e.g., blood, plasma, saliva, urine), leading to the loss of sensitivity and selectivity. Thus, to break through this barrier, we must solve this biofouling problem. In response to this challenge, our group has developed a rapid, robust, and low-cost nanocomposite-based antifouling coating for multiplexed EC sensors that enables unprecedented performance in terms of biomarker signal detection compared to reported literature. The bioinspired antifouling coating that we developed is a nanoporous composite that contains various conductive nanomaterials, including gold nanowires (AuNWs), carbon nanotubes (CNTs), or reduced graphene oxide nanoflakes (rGOx). Each study has progressively evolved this technology to provide increasing performance while simplifying process flow, reducing time, and decreasing cost. For example, after successfully developing a semipermeable nanocomposite coating containing AuNWs cross-linked to bovine serum albumin (BSA) using glutaraldehyde, we replaced the nanomaterials with reduced graphene oxide, reducing the cost by 100-fold while maintaining similar signal transduction and antifouling properties. We, subsequently, developed a localized heat-induced coating method that significantly improved the efficiency of the drop-casting coating process and occurs within the unprecedented time of