Sensitive Fluorescence Aptasensor Based on Hybridization Chain Reaction with Upconversion Nanoparticles by Triplex DNA Formation for Bisphenol A Detection

Application of nanotechnology to detection can effectively increase the biocompatibility of detection sensors. However, since the traditional signal output element has a high background value, the detection sensitivity is often limited. Here, we designed a fluorescence aptasensor based on hybridization chain reaction (HCR) and triplex structure (TS). The aptamer was competitively bound by bisphenol A (BPA) and complementary DNA (cDNA). Unbound cDNA was obtained by magnetic separation. HCR could be triggered by cDNA to form long double-stranded DNA (dsDNA) products. The upconversion nanoparticle (UCNP)-modified ssDNA can form a TS with the HCR product. Thereby, the distance between the UCNPs and Dabcyl on the hairpin was brought closer, and fluorescence was quenched to generate a signal change. HCR and the low background value of UCNPs could improve the sensitivity of detection. The aptasensor has a detection limit as low as 0.057 ng/mL and has been successfully applied to actual sample detection. Its high sensitivity, strong specificity, and excellent biocompatibility make it promising for other target detection and clinical diagnosis.