Enhanced Enzymatically Amplified Metallization on Nanostructured Surfaces for Multiplexed Point‐of‐Care Electrical Detection of COVID‐19 Biomarkers
Neda Rafat, Hanhao Zhang, Josiah Rudge, Yoo Na Kim, Sai Preetham Peddireddy, Nabojeet Das, Aniruddh Sarkar
Abstract
Inexpensive yet sensitive and specific biomarker detection is a critical bottleneck in diagnostics, monitoring, and surveillance of infectious diseases such as COVID-19. Multiplexed detection of several biomarkers can achieve wider diagnostic applicability, accuracy, and ease-of-use, while reducing cost. Current biomarker detection methods often use enzyme-linked immunosorbent assays (ELISA) with optical detection which offers high sensitivity and specificity. However, this is complex, expensive, and limited to detecting only a single analyte at a time. Here, it is found that biomarker-bound enzyme-labeled probes act synergistically with nanostructured catalytic surfaces and can be used to selectively reduce a soluble silver substrate to generate highly dense and conductive, localized surface silver metallization on microelectrode arrays. This enables a sensitive and quantitative, simple, direct electronic readout of biomarker binding without the use of any intermediate optics. Furthermore, the localized and dry-phase stable nature of the metallization enables multiplexed electronic measurement of several biomarkers from a single drop (<10 µL) of sample on a microchip.This method is applied for the multiplexed point-of-care (POC) quantitative detection of multiple COVID-19 antigen-specific antibodies. Combining a simple microchip and an inexpensive, cellphone-interfaced, portable reader, the detection and discrimination of biomarkers of prior infection versus vaccination is demonstrated.