Colorimetric/fluorescent/SERS triple-channel sensing of Cu2+ in real systems based on chelation-triggered self-aggregation

[Display omitted] •The GNRs@BAMH can be used as colorimetric and fluorescent probes for Cu2+.•The GNRs@BAMH can be served as a high active SERS substrate.•The Cu2+-triggered GNRs self-aggregation enables visualization of Cu2+.•The GNRs@BAMH facilitates accurate and selective analysis of Cu2+. Multi-modal detection of analytes using plasmonic nanoprobes has inspired intensive interests due to its remarkable structure features and optical functions. In this study, we have developed a robust and trimodal sensing strategy capable of visual colorimetric and fluorescence discrimination and accurate surface-enhanced Raman spectroscopy (SERS) detection of Cu2+ by stimuli-responsive binaphthalene (BAMH)-functionalized Au nanorods (GNRs@BAMH). The phenolic hydroxyl group and Schiff-base of BAMH act as scaffolds and reporters for Cu2+ due to their preferential affinity with Cu2+, which enables visualization of Cu2+ from complex matrices by the decreased fluorescent signals accompanied with a simultaneous increase in a colorimetric response of GNRs@BAMH. The detection limits of colorimetric and fluorescent assays are 3.0 nM and 0.42 nM, respectively. Importantly, the GNRs@BAMH is capable of highly sensitive SERS analysis of Cu2+ in environmental and biological specimens with detection limit of 0.38 pM due to the chelation-triggered GNRs self-aggregation. Considering merits of this multifunctional platform such as flexibility, simplicity of the detection procedures, without any additional pre-treatment, it is a promising technique for point-of-care screening or in-field monitoring.