Hand-powered centrifugal microfluidic disc with magnetic chitosan bead-based ELISA for antibody quantitation

Extreme point-of-care testing (POCT) is a medical test performed at or near patients at a resource-limited condition. POCT technology has advantages over traditional medical lab tests for molecular detection and infection diagnosis, such as being simple, portable, low-cost, and user-friendly. However, some POCT devices might rely on bulky equipment, and some might be easily influenced by components in biofluid, which might result in higher prices and lower accuracy. In this paper, we demonstrated a low-cost method for detecting bacterial infection in the early stage. We designed a hand-powered centrifugal microfluidic (CMF) disc with magnetic chitosan beads (MCBs) to detect specific circulating antibodies in human whole blood. Nine identical units was used for calibration curve plotting and sample testing. The MCBs, generated with another microfluidic chip and coated with MBL proteins (biomarker of drug-resistant Streptococcus pneumoniae, DRSP, taken as an example for bacterial infection), were served as the substrate of sandwich-structured enzyme-linked immunosorbent assays (ELISA) and as the micro stirring sphere at the same time. The limit of detection (LOD) in PBS and human whole blood were 22.67 ng/mL and 24.83 ng/mL, respectively. The comparison between calibration curves from the antibody spiked in human whole blood and that in PBS was shown to prove the high compatibility and low interference of biofluid, and the recovery rate was 92 %. In conclusion, since our low-cost, time-saving, and user-friendly hand-powered CMF device with minimally consumed electricity detected the target antibody precisely, we believe that other similar assays would be feasible as well. Therefore, we are firmly convinced that this alternative POCT device may lead to the development of next-generation healthcare diagnoses.