A novel difunctional COF-loaded peptide Au nanocluster probe and its application to molecular spectral determination of trace Cd2+

Abstract

Nanoclusters (NCs) have extremely strong catalytic activity, but their stability is poor. Loading them on covalent-organic framework (COF) not only increase their stability but also hold strong catalysis. Furthermore, COF-loaded peptide nanoclusters have attracted wide spread attention due to specific recognition, strong catalytic amplification and good stability. Cd2+ was one of important metal of pollution, and it is of great significance to explore new peptide assay for Cd2+. This study was synthesized COF-loaded peptide AuNC (COF-PTAuNC) nanoprobes with recognition and catalysis functions using the peptide Csy-Pro-Pro-Cys-Trp-NH2 (PT) as a template. The experiment found that COF-PTAuNC not only recognize Cd2+ but also had a strong catalytic effect on the indicator reaction of HAuCl4-sodium formate (Fo) to produce gold nanoparticles (AuNPs) to amplify the signal. The AuNPs has an absorption (Abs), resonance Rayleigh scattering (RRS) and surface enhanced Raman scattering (SERS) peak at 533 nm, 370 nm and 1618 cm−1 respectively. Using this new strategy, the concentration of Cd2+ in the range of 0.4–50 nmol/L had a linear relationship with the SERS intensity, and the detection limit (DL) was 0.16 nmol/L. This method has been used to detect Cd2+ content in water and rice samples, with recovery and relative standard deviation(RSD) of 91.8–109.8% and 1.2–8.7%, respectively.