Triple-signal strategy utilizing a colorimetric, fluorescence, and chromogenic paper-based sensor for rapid detection of ATP at neutral pH.

This study presents a novel triple signal amplification strategy for paper-based colorimetric/fluorescence/chromogenic detection of adenosine triphosphate (ATP). Fluorescent gold nanoclusters (BSA-AuNCs) induce a redshift in the absorbance of quercetin (QCT), and the paper substrate displays a yellow color. Simultaneously, BSA-AuNCs activated QCT to emit fluorescence through the surface plasmon resonance (SPR) effect, producing a strong fluorescence signal at 541 nm, while the red fluorescence of BSA-AuNCs at 636 nm remained stable, resulting in a yellowish-green fluorescence of the paper. Upon the addition of ATP, the absorbance appeared to blue shift, and the paper substrate transitioned from yellow to colorless within 30 s. Concurrently, the fluorescence intensity of QCT decreased significantly, while the fluorescence intensity of BSA-AuNCs at 636 nm was almost unchanged, leading the fluorescence of the paper substrate to gradually shift to red. The QCT/BSA-AuNC paper-based system functions as a dual-signal sensor, enabling rapid ATP detection through both colorimetric and fluorescence modes with limits of detection (LOD) of 0.72 μM and 0.68 μM, respectively. Additionally, ATP enhances the peroxidase-like catalytic activity of BSA-AuNCs, promoting the chromogenic reaction of TMB and turning the paper sensor dark blue, with a LOD of 0.43 μM. This triple signal amplification method enables sensitive ATP screening using paper-based test strips, providing high sensitivity, selectivity, and reliable quantitative results. Notably, this three-mode sensing strategy holds significant potential for development into a quantitative method for ATP detection in normal and tumor cell samples, aiding in cell identification.