Visual and fluorescence dual mode platform for sensitive and accurate screening of breast carcinoma.

Compared to single-mode detection, dual-mode sensing strategies have garnered increasing attention from researchers due to their superior detection accuracy and reliability. Exosomes, as non-invasive biomarkers, hold significant potential for disease diagnosis. However, sensitive and precise detection of exosomes still presents considerable technical challenges. Inspired by the advantages of dual-mode detection, we developed a visual and fluorescence dual-mode platform (VFDMP) based on an aptamer strategy for exosome detection using enzyme-free nucleic acid amplification and nanomaterial-assisted cation exchange reactions (CERs). The Aptamer-ssDNA complexes capture tumor-derived exosomes, releasing abundant single-stranded DNA (ssDNAs), which then triggers the catalytic hairpin assembly (CHA) cycle, leading to the release of Ag. The introduced CdTe quantum dots (QDs) act as signal reporters, interacting with Ag through CERs, and switching both fluorescence and visual signals from "on" to "off" to achieve exosome detection. Based on this innovative sensing principle, the developed FL/visual dual-mode aptasensor demonstrated excellent sensitivity and accuracy, achieving a low detection limit of 1.1 particles/μL by fluorometer, while exosome concentrations as low as 300 particles/mL could be visually distinguished by naked eye. Furthermore, this dual-mode platform can directly detect exosomes in clinical human serum samples, with only a small volume (10 μL) required. It can accurately differentiate between healthy individuals and breast cancer patients, as well as identify cancer stages (Stage II and Stage III) and subtypes (triple-negative, luminal B, and HER2+). These results suggest that the developed dual-mode detection strategy holds great promise as a sensitive, accurate method for biomarker analysis in clinical samples.