Long-Lasting Chemiluminescence-Based POCT for Portable and Visual Pathogenic Detection and In Situ Inactivation.

Bacterial infections seriously threaten human health and also bring huge financial burden. It is critical to construct multifunctional platforms for effectively inactivating bacteria right after point-of-care testing (POCT). Chemiluminescence (CL) bioassays are considered as powerful candidates for POCT as they are free from using an excitation light source, while the flash-type emission limits their further application. Herein, a CL system with long, persistent, and intensive intensity was constructed based on the peroxidase-like property of 4-mercaptophenylboronic acid (MPBA)-functionalized CuSe nanoprobes (CuSeNPs@MPBA), which improved the detection accuracy and sensitivity. By further integrating a smartphone as an analyzer, quantitative POCT of bacteria was realized with high sensitivity. The limit of detection was as low as 1.25 and 1.01 cfu mL-1 for Staphylococcus aureus and Escherichia coli detection, respectively. Specifically, bacteria can be eliminated with high efficiency due to excellent photothermal property of CuSeNPs@MPBA. The developed multifunctional platform also has advantages of simple operation with low cost, suggesting its high potential for use in food safety, environment monitoring, and clinical applications.

A smartphone integrated ratiometric fluorescent sensor for point-of-care testing of fluoride ions.

In view of the high toxicity and widespread availability, it is of great importance to develop accurate, sensitive, and convenient assays for fluoride ion (F-) detection. Herein, a ratiometric fluorescent system is established for point-of-care testing (POCT) of F- with a smartphone as analyzer. The sensing system of calcein-QDs-Eu3+ contains two fluorescent probes of calcein (green emission) and ZnCdSe/ZnS QDs (red emission). The sensing system only presents red emission in that the calcein emission is quenched due to the combination between calcein and Eu3+. When F- is introduced, the fluorescence of calcein is recovered due to the stronger interaction between F- and Eu3+, which changes the emission from red to green. The ratiometric strategy offers an obvious fluorescence color change of the system, which eliminates interference and improves the detection accuracy. Specifically, the sensing system has excellent selectivity in that Eu3+ is more inclined to bind with F- rather than other anions. The developed assay was further used to prepare a test paper and hydrogel for POCT. To further improve the detection sensitivity and realize quantitative analysis, a smartphone installed with a color scan app is integrated as signal reader and analyzer, which is used for POCT of F- in real samples, showing great application potential in environmental protection and food safety evaluation.