Engineering of a ratiometric upconversion luminescence nanoprobe based on competition effect for precisely monitoring L-arginine in red wines

L-arginine (L-Arg) is a conditionally essential amino acid with multiple physiological functions, and also serves as a key factor in the quality control of red wine. However, selective detection of L-Arg in red wine still remains challenge due to red wine containing a variety of amino acids. Therefore, developing methods with high selectivity for L-Arg quantitative detection is crucial for red wine quality control. Herein, a ratiometric L-Arg upconversion luminescence nanoprobe was designed by assembling cresyl violet (CV) onto the surface of citrate-functionalized upconversion nanoparticles (Cit-UCNPs) through electrostatic interaction to form UCNPs@CV. In which, the UCNPs and CV was employed as energy donor and acceptor, respectively. Under 980 nm excitation, luminescence resonance energy transfer (LRET) occurred, quenching the UCNPs emission at 540 nm and activating the CV emission at 620 nm. In the presence of L-Arg, CV on the surface of Cit-UCNPs could be displaced by L-Arg via the specific interaction between the guanidine group of L-Arg and the carboxyl group of Cit, which interrupted the LRET. As a result, the emission of UCNPs at 540 nm was recovered, and the emission of CV at 620 nm was weakened. Moreover, the ratio of I₅₄₀/I₆₂₀ exhibited a good linear relationship with L-Arg concentration, and allowing for high selectively and sensitively detecting L-Arg with a limit of detection (LOD) 0.079 μM (S/N= 3). More importantly, the proposed nanoprobe could successfully detect L-Arg in different types of red wines, holding potential application in the field of red wine quality control.