A rotating paper-based microfluidic sensor array combining Michael acceptors and carbon quantum dots for discrimination of biothiols

Biothiols play critical roles in maintaining physiological and pathological processes. However, effective and affordable tools for rapid and simple identification of biothiols are currently lacking. This work constructed a paper-based fluorescence sensor-array platform for biothiol recognition by grafting three biothiol receptors (TRs) modified carbon quantum dots (CQDs) on paper substrates. A multi-channel rotating paper-based microfluidic device (μPAD) was constructed by inkjet printing technology. The three TRs are self-synthesized Michael receptors, and they can trigger photoinduced electron transfer (PET) effect to quench the fluorescence of CQDs. When biothiols were introduced onto the sensor array, they reacted with the CQDs-TRs hybrids at the sensor array due to their high nucleophilicity and disrupted the PET effect, resulting in partial recovery of the fluorescence. Six different biothiols produced their unique fluorescence response patterns as “fingerprints”, which can be quantitatively differentiated by linear discriminant analysis (LDA) and hierarchical clustering analysis (HCA) in concentration ranges of 5∼100 μM. Practicality of the platform was verified by fast, accurate and sensitive identification of the six biothiols in blind samples and fetal bovine serum. In all, the platform features mini size, easy preparation and high integration, showing great potential for clinical point-of-care and other on-site testing towards multiple analytes.