Myriads of electrode materials with interesting nanostructures have been fabricated for a range of electrochemical applications. Beyond the increases in their surface area, unconventional properties have been observed along with the development of new approach and methodologies to analyze and utilize such properties. For instance, once a redox-active molecule diffuses into the nanoscale cavity of the electrode, it frequently collides with the inner electrode surface before it escapes the cavity, which is termed nano-confinement effect. This effect can specifically amplify the signals of slow electron transfer reactions (e.g., glucose oxidation) and has been established as a new mechanism for sensing the target materials that have slow electron transfer kinetics.
In this study, we fabricated a Au nanopillar electrode and devised a new electrochemical platform using redox cycling reaction to utilize the nano-confinement effect of the Au nanopillar electrode, which is applicable even to the fast electron transfer reactions as demonstrated by facilitating the electrochemical reaction of a specific biomarker (i.e., pyocyanin which has fast electron transfer kinetics) of bacterial infection (i.e., Pseudomonas aeruginosa). The Au nanopillar electrode was fabricated by first treating a polymer substrate with plasma to render an array of polymer nanopillars on the substrate and then depositing Au onto the plasma-treated substrate to the appropriate thickness to form nanoscale inter-pillar space. The Au nanopillar surface was modified with the redox cycling counterpart of pyocyanin so that the pyocyanin confined in the inter-pillar space underwent repetitive cycles of reduction (by the electrode) and oxidation (by the redox cycling counterpart tethered to electrode surface) reactions resulting in the amplification of the pyocyanin signal. This redox cycling-assisted signal amplification was clearly observed with the Au nanopillar electrode with higher amplification by taller Au nanopillars while the amplification was insignificant for the flat Au electrode, demonstrating the nano-confinement effect of Au nanopillar electrodes. As a result, the sensitivity in measuring pyocyanin was improved by the Au nanopillar electrode compared with the flat Au electrode. We believe that this new platform based on the surface-bound redox cycling reaction could overcome the limit in applicability of the nano-confinement effect.
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E