Assembling PVP-Au NPs as portable chip for sensitive detection of cyanide with surface-enhanced Raman spectroscopy.

Cyanide (C≡N) can lead to blood, cardiovascular system, and nervous system disorders owing to the acute and chronic toxicity; thus, aiming at the group or individual poisoning incidents, it is necessary to develop the sensitive and credible method for rapid on-site detection of poisons cyanide. Surface-enhanced Raman spectroscopy (SERS) with the advantages of providing fingerprint information of target molecules and single-molecules sensitivity has been widely used in on-site analysis; however, the SERS measurements always suffer from the problem of the stability of substrates. Here, the polyvinylpyrrolidone (PVP)-stabilized Au NPs (PVP-Au NPs) have been assembled through the simple, convenient evaporation-induced strategy with the large-scale hotspots substrates. The presence of PVP can not only facilitate the assembly of Au NPs but also prevent the corrosion of CN towards the Au NPs with the formation of [Au (CN)], providing high stable and reproducible SERS signals. Moreover, the PVP-Au NPs have been assembled on the Si wafer to fabricate the portable SERS chip for rapid on-site detection of CN with an RSD of 5.8% and limitation of 100 ppb. Furthermore, by coupling a portable Raman spectrometer, the SERS spectra of CN spiked into different specimens to simulate the poison samples have been collected and analyzed on SERS chips with the recovery of 89-103% and RSD not higher than 11.3%. Consequently, the fabricated SERS chip with assembled PVP-Au NPs can provide sensitive and credible detection for CN in different specimens, and then would satisfy the rapid on-site evaluation of CN in poisoning incidents with the portable Raman spectrometer. Graphical Abstract.