A new dual-mode SERS and RRS aptasensor for detecting trace organic molecules based on gold nanocluster-doped covalent-organic framework catalyst

A new Au nanocluster-doped covalent organic framework (AuCOF) was prepared and characterized by electron microscopy and molecular spectroscopy. Based on aptamer-mediated COF nanocatalytic amplification signal strategy, a dual-mode analytical platform of surface-enhanced Raman scattering/resonance Rayleigh scattering (SERS/RRS) was established to detect ultatrace small molecules. The catalysis of AuCOFs on AgNO3-citrate nanoreaction was investigated. The formed yellow silver nanoparticles (AgNPs) exhibit strong RRS and SERS effect. The aptamer (Apt) suppressed the catalysis of AuCOFs to cause the RRS and SERS signals decreasing. Upon addition of target organic molecule such as adenosine triphosphate (ATP), the specific aptamer reaction occurred to restore the catalysis of AuCOFs, which will generate more AgNPs, and resulting in a linear increase in the signals of RRS and SERS. On this basis, inelastic scattering SERS, elastic scattering RRS and SERS/RRS dual-mode biosensors were established for small organic molecules such as ATP, urea, and estradiol, which is of high sensitivity and good accuracy compared to the single mode scattering method.