Gold Triangular Nanoplates Based Single-Particle Dark-Field Microscopy Assay of Pyrophosphate

Owing to the sharp edge-enhanced electric field, gold triangular nanoplates (AuNPLs) exhibit strong localized surface plasmon resonance (LSPR) scattering and display as red spots with high intensity and narrow distribution under dark-field microscopy (DFM), based on which sensitive sensing applications could be developed. As a concept of proof, the inhibition effects of pyrophosphate (PPi) against the etching of AuNPLs based on Cu²⁺ and I^- mediated is dynamically monitored. The etching proceeding of AuNPLs by copper ions and iodide ions leads to the gradually blue-shifted LSPR scattering color of AuNPLs under DFM from the original red to green, accompanied by the reduced LSPR scattering intensity. As a result of the strong affinity of PPi to copper ions, the presence of PPi makes the etching process greatly suppressed, thereby achieving sensitive detection of the PPi.