A sensitive plasmonic copper(II) sensor based on gold nanoparticles deposited on ITO glass substrate

•The Au NPs onto ITO solid substrate was fabricated by self-assembly method and calcination.•The ITO/Au NPs/Cys probe can be used to plasmonic detection of Cu2+ ions.•The introduction of BSA can greatly improve the sensitivity of detection.•The plasmonic sensor was of high sensitivity and wide linear range.

Gold nanoparticles (Au NPs) based plasmonic probe was developed for sensitive and selective detection of Cu2+ ion. The Au NPs were self-assembled on transparent indium tin oxide (ITO) film coated glass substrate using poly dimethyl diallyl ammonium chloride (PDDA) as a linker and then calcined at 400 °C to obtain pure Au NPs on ITO surface (ITO/Au NPs). The probe was fabricated by functionalizing l-cysteine (Cys) on to gold surface (ITO/Au NPs/Cys). The strong chelation of Cu2+ with Cys formed a stable Cys-Cu complex, and resulted in the red-shift of localized surface plasmon resonance (LSPR) peak of the Au NPs. The introduction of bovine serum albumin (BSA) as the second complexant could form complex of Cys-Cu-BAS and further markedly enhanced the red-shift of the LSPR peak. This plasmonic probe provided a highly sensitive and selective detection towards Cu2+ ions, with a wide linear detection range (10−11–10−5 M) over 6 orders of magnitude. The simple and cost-effective probe was successfully applied to the determination of Cu2+ in real samples.