A facile and selective resonance Rayleigh scattering method for trace nitrite using gold nanocluster surface molecularly imprinted polyisopropylacrylamide probe

A novel gold nanocluster surface molecularly imprinted polyisopropylacrylamide probe (AuNC@MIP) was synthesized for the specific detection of NO₂⁻, using N-isopropylacrylamide (NIPAM) as the functional monomer, gold nanoclusters (AuNC) as the substrate, ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent, and nitrosophenol (NPN) produced from sodium nitrite (NaNO₂) and phenol (PN) as the template molecule, N,N-dimethylformamide (DMF) as the solvent, and azobisisobutyronitrile (AIBN) as the initiator. The nanoprobe was characterized using molecular spectroscopy, XPS, TEM, TGA, and zeta potential analysis. The probes revealed a prominent resonance Rayleigh scattering (RRS) peak at 370 nm. Upon addition of NO₂⁻, the RRS intensity at 370 nm decreased due to the RRS energy transfer enhancing. The linear determination range is 0.125–1.50 nmol/L NO₂⁻, with a limit of detection (LOD) of 0.085 nmol/L. The new RRS method was applied to determine NO₂⁻ in meat, dairy products, and water samples, with recovery of 96–107% also relative standard deviations (RSDs) of 1.1–8.0%.