Dual-functional Cu2-xSe nanoparticles enabled photothermal SDA-LFA for sensitive miRNA-146a on-site detection in dairy safety

Bovine Mastitis (BM) adversely impacts the health of dairy cows and the quality of milk. Rapid and precise detection to miRNA-146a, a biomarker of BM for early diagnosis, is therefore crucial for the safety of dairy products. Herein, a high-efficiency method for the detection of miRNA-146a was developed, integrating photothermal Cu 2-x Se nanoparticles (CS NPs), strand displacement amplification (SDA) and lateral flow assay (LFA). The core innovation utilizes photothermal materials for dual functionality: (1) CS NPs as a photothermal nanomaterial enables rapid photocontrolled SDA (pSDA) under 808 nm laser irradiation, achieving target amplification within 20 min−2.3 times faster than conventional water-bathed SDA; and (2) Au coated Cu 2-x Se nanoparticles (CSA NPs) facilitates quantitative detection within a specifically designed photothermal LFA (pLFA). This pLFA measures temperature changes (ΔT) in the test zone via infrared thermal imaging to quantify the single-labeled amplicons. The integrated pSDA-pLFA method achieves an excellent balance of speed and sensitivity, featuring a detection limit of 28.6 fM and a wide linear range of 1.0 × 10 2  fM to 1.0 × 10 8  fM (R 2  = 0.9907). Validation using spiked milk samples demonstrated strong consistency with quantitative PCR (qPCR) results, confirming the establishment of a novel, rapid, and quantitative pSDA-pLFA platform for miR-146a detection. This approach holds significant promise for enhancing dairy industry bio-surveillance and ensuring food safety.