A ratiometric fluorescent “off-on” sensor for acrylamide detection in toast based on red-emitting copper nanoclusters stabilized by bovine serum albumin

[Display omitted] •Red-emitting copper nanoclusters (CuNCs) stabilized by bovine serum albumin were synthesized by green hydrothermal method.•The prepared CuNCs exhibited bimodal emission at 395 nm and 650 nm (strong).•The detection strategy of acrylamide was based on thiol-ene Michael addition reaction between acrylamide and glutathione.•A ratiometric fluorescent “turn-on” sensor was applied successfully for the assay of acrylamide in toast. Acrylamide, as a Class 2A carcinogen, poses serious threats to human health. To achieve rapid and accurate determination of acrylamide in food, a ratiometric fluorescent “off-on” sensor was designed by incorporating red-emitting copper nanoclusters and glutathione. Copper nanoclusters with bimodal emission at 395 nm and 650 nm (excited at 310 nm) were synthesized by using bovine serum albumin as the ligand and ascorbic acid as the reductant. With glutathione addition, the fluorescence intensity at 650 nm gradually decreased, while the case at 395 nm slightly increased. The quenched fluorescence at 650 nm was subsequently restored by acrylamide through thiol-ene Michael addition reaction between acrylamide and glutathione. The constructed sensor showed excellent performance towards acrylamide detection in the range of 5-300 μM with a detection limit of 1.48 μM, and was further applied to real-sample detection of acrylamide in toast and exhibited good recoveries (90.29-101.30%), indicating potential applications of this sensor.