Signal amplification and dual recognition strategy for small-molecule detection by surface plasmon resonance based on calix[4]arene crown ether-modified gold nanoparticles

A signal-amplification and dual-recognition strategy was designed to construct a signal-enhanced surface plasmon resonance (SPR) platform for the highly sensitive detection of dopamine. This strategy was based on the specific recognition of boronic acid to diol and that of calix[4]arene crown ether-modified gold nanoparticles (CAL[4]-AuNPs) to amine groups. A 3-aminophenyl boronic acid monohydrate probe was immobilized onto a gold chip surface as capture probes via covalent bonds with 11-mercaptoundecanoic acid. CAL[4]-AuNPs were designed as signal probes and characterized by transmission electron microscopy and spectroscopic techniques. Upon the binding of dopamine with boronic acid followed by CAL[4]-AuNPs, the AuNPs were captured on the chip surface to enhance the SPR signal, thereby producing an ultra-low background signal. Signal amplification and dual recognition were used to quantify dopamine concentration from 0.1 nM to 1 μM, with a detection limit of 1.17 pM. This strategy is a new concept for the design of highly selective analytical methods to detect small biomolecules.