Affinity-Based Capturing, Release, and Glycoprofiling of PSA Cancer Biomarker Using Miniaturized Micropillar-Based Platform

The work presents affinity-based biomolecular capturing and release employing a PDMS micropillar-based microfluidic chip. The microfluidic chip has been equipped with a micropillar-based capture chamber specifically optimized to provide enhanced surface area for biomolecular capturing without having any fluid and material clogging. A novel multi-step surface functionalization immunoassay protocol to optimize on-the-flow surface functionalization and capturing efficiency of the biomolecules has been developed and demonstrated. The novel immunoassay protocol involved conjugation of the anti-PSA IgG antibodies with a photo-cleavable (PC)-biotin-PEG3-NHS-ester, capturing of free-PSA (f-PSA) cancer biomarker, the capability of multiplexed glycoprofiling for elucidating the PTMs of the f-PSA using the Sambucus Nigra Lectin (SNA) and Maackia Amurensis Lectin II (MAA-II) lectins, and on-demand release of the captured f-PSA biomarkers. The work provides a proof-of-concept demonstration of affinity-based capturing, multiplexing, glycoprofiling, and release of f-PSA biomarkers with a minimum limit of detection of ~10 pg/ml and a limit of quantification of ~20 pg/ml using a low-cost, disposable microfluidic chip.