Polypeptide@AuNC probe catalytic amplification-tetramode molecular spectral biosensor for trace Al3+

Abstract

Nanoclusters have strong catalytic effect, but their stability was poor. Biomolecule functionalized gold nanoclusters (AuNC) have attracted extensive attention due to their good biocompatibility, stable physicochemical properties and strong catalytic activity. In this study, the peptide (PT) was used as a template to synthesize the PTAuNC nanoprobe with recognition and catalysis. The results show that PTAuNC has a strong catalytic effect on the indicator reaction of 3,3′,5,5′-tetramethylbenzidine (TMB)–H2O2 to produce the oxidized TMB (TMBox). The TMBox had a strongest fluorescence (FL) peak at 410 nm and an absorption peak at 650 nm. Addition of nanosilver (AgNPs), it produced a strong surface enhanced Raman scattering (SERS) peak at 1616 cm−1 and a resonance Rayleigh scattering (RRS) peak at 370 nm. The new nanocatalytic indicator reaction was organically coupled with the PTAuNC-Al3+ recognition reaction, and a PTAuNC catalytic amplification SERS/RRS/FL/Abs tetramode biosensor platform for Al3+ was constructed. The Al3+ concentration in the range of 0.5–60 nmol/L had a good linear relationship with SERS intensity, with detection limit of 0.21 nmol/L. The method has been applied to the determination of Al3+ in water and food samples. The recovery and relative standard deviation (RSD) were 92.4–109.8% and 1.2–9.8%, respectively.