Rapid quantitative electrochemical detection of SARS-CoV-2 antibodies in plasma and dried blood spot samples

Coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is a highly contagious disease with several variants, continues to spread as part of the global pandemic. With the roll-out of vaccines and development of new therapeutics that may be targeted to distinct viral molecules, there is a need to screen populations for viral antigen-specific SARS-CoV-2 antibodies. Here, we describe a rapid, multiplexed, electrochemical (EC) platform with on-chip control that enables detection of SARS-CoV-2 antibodies in less than 10 min using 1.5 {micro}L of a patient sample. The EC biosensor demonstrated 100% sensitivity and specificity, and an area under the receiver operating characteristic curve of 1, when evaluated using 93 clinical samples, including plasma and dried blood spot samples from 54 SARS-CoV-2 positive and 39 negative patients. This EC biosensor platform enables simple, cost-effective, sensitive, and rapid detection of anti-SARS-CoV-2 antibodies in complex clinical samples, which is convenient for monitoring host humoral responses to vaccination or viral infection in broad population testing, including applications in low-resource settings. We also demonstrate the feasibility of using dried blood spot samples that can be collected locally and transported to distant clinical laboratories at ambient temperature for detection of anti-SARS-CoV-2 antibodies which can be used for serological surveillance and demonstrate the utility of remote sampling.

Low-cost bioanalysis on paper-based and its hybrid microfluidic platforms.

Low-cost assays have broad applications ranging from human health diagnostics and food safety inspection to environmental analysis. Hence, low-cost assays are especially attractive for rural areas and developing countries, where financial resources are limited. Recently, paper-based microfluidic devices have emerged as a low-cost platform which greatly accelerates the point of care (POC) analysis in low-resource settings. This paper reviews recent advances of low-cost bioanalysis on paper-based microfluidic platforms, including fully paper-based and paper hybrid microfluidic platforms. In this review paper, we first summarized the fabrication techniques of fully paper-based microfluidic platforms, followed with their applications in human health diagnostics and food safety analysis. Then we highlighted paper hybrid microfluidic platforms and their applications, because hybrid platforms could draw benefits from multiple device substrates. Finally, we discussed the current limitations and perspective trends of paper-based microfluidic platforms for low-cost assays.