Microbubbling Digital Assay

P. Wang
University of Pennsylvania,
United States

Keywords: microbubbling, high sensitivity, biomarker, diagnostics, COVID


Quantitating ultra-low concentrations of protein biomarkers is critical for early disease diagnosis and treatment. However, most current point-of-care (POC) assays are limited in sensitivity. Herein, we introduce an ultra-sensitive and facile microbubbling assay for the quantification of protein biomarkers with a digital-readout method that requires only a smartphone camera. We used machine learning to develop a smartphone application for automated image analysis to facilitate accurate and robust counting. Using this method, post-prostatectomy surveillance of prostate specific antigen (PSA) can be achieved with a detection limit (LOD) of 2.1 fm (0.060 pg/mL), and early pregnancy detection using betahCG can be achieved with a of 0.034 mIUmL1 (2.84 pg/mL). This work provides the proof-of-principle of the microbubbling assay with a digital readout as an ultra-sensitive technology with minimal requirement for power and accessories, facilitating future POC applications. In a recent project, we have successfully applied the micro bubbling digital assay to the high sensitivity detection of femtomolar (0.5 pg/mL) concentration of SARS-CoV-2 antigen, and demonstrated 97% positive percent agreement with PCR in detecting acute infections in clinical samples. This demonstrates the excellent performance and high potential for the microbubbling digital assay as a diagnostic technology.