Laser-induced breakdown spectroscopy mediated amplification sensor for copper (Ⅱ) ions detection using click chemistry

New strategies for super-sensitive detection of toxic heavy-metal-ion pollutants are urgently needed. Here, we outline a simple and highly sensitive assay for copper(II) ions. The method is based on click chemistry and uses laser-induced breakdown spectroscopy (LIBS) as the readout method. Copper(I) ions formed in situ by the reduction of copper(II) ions in the presence of sodium ascorbate (AA) can catalyze the cycloaddition reaction between an alkyne and an azide (CuAAC). In the presence of copper(II) ions and AA, the AgNPs-BSA-Azide can be clicked with the BSA-Alkyne via a cycloaddition reaction to form a BSA-triazole-BSA-AgNPs sandwich conjugate based on this CuAAC&LIBS system. The intensity of the LIBS signal from the residual AgNPs-BSA-Azide in the supernatant is inversely proportional to the concentration of copper(II) ions. The sensor shows a good detection limit of 0.045 nM and a linear relationship between copper ions concentration and the LIBS signal. This click-based method will broaden the potential applications of LIBS for metal detection in drinking water and environment.