Automated Immunoassay Performed on a 3D Microfluidic Paper-Based Device for Malaria Detection by Ambient Mass Spectrometry.

Microfluidic paper-based analytical devices (µPADs) are emerging as a prominent platform for disease detection, specifically in developing countries. This paper device offer simplicity and affordability not typically seen in centralized laboratory settings. However, detection limits in µPADs are inadequate and often require test results to be read within a specific time interval to ensure accuracy. To overcome these challenges, we are developing an on-chip mass spectrometry (MS) detection strategy for immunoassays performed on paper substrates. Herein, we present our initial results from a proof-of-concept study toward the development of µPADs capable of storing immunoassay reagents within the confinements of the 3D device, automatic splitting of biofluid into four individual test zones, immuno-capture of the disease biomarker, and on-chip MS detection of the captured species. The reported study encourages the development of point-of-care and direct-to-customer testing using disposable µPADs to collect samples, followed by sensitive analysis using portable MSs. We demonstrate this capability using malaria Plasmodium falciparum histidine-rich protein 2 (PfHRP2) antigen detection.