Water‐soluble luminescent copper nanoclusters as a fluorescent quenching probe for the detection of rutin and quercetin based on the inner filter effect

Abstract

In the present study, we proposed a simple, sensitive and selective fluorescence method for the detection of rutin (Rut) and quercetin (Que) based on the inner filter effect (IFE) utilizing water‐ soluble cysteine‐stabilized copper nanoclusters (Cys‐CuNCs) as a fluorescent probe. The Cys‐CuNCs were successfully synthesized and characterized using UV–visible absorption, emission, Fourier‐transform infrared (FT‐IR) spectroscopy, fluorescence lifetime, high resolution transmission electron microscopy (HR‐TEM) and zeta potential measurements. Cys‐CuNCs exhibited bluish‐green luminescence under UV light with characteristic emission maxima at 486 nm. Cys‐CuNCs was successfully exploited as fluorescent probes for the detection of Rut/Que. The addition of increasing concentrations of Rut/Que led to a gradual decrease in the emission intensity of Cys‐CuNCs. The decrease in Cys‐CuNC emission intensities were attributed to the strong IFE and static quenching mechanism. The calculated limit of detection values for Rut and Que were as low as 0.021 μM and 0.035 μM, respectively. The Cys‐CuNCs sensing probe exhibited excellent selectivity in the presence of other potential interfering compounds. Furthermore, the present method was successfully applied to the analysis of both Rut and Que in biological samples.

Construction of a Near-Infrared Luminescent 48-Metal Rectangular Zn(II)–Yb(III) Nanocluster with Carbonate Templates for the Dual-Emissive Detection of Rutin as a Medicinal Ingredient

“…UV–vis absorption spectra show that the bands of Rut and 1 overlap effectively, and the molar absorption coefficient (ε) of Rut at λ ex (395 nm) is more than twice that of 1 (0.048 × 10 5 vs 0.019 × 10 5 M –1 cm –1 ; Figure S4). Thus, Rut is able to compete with the Schiff base in 1 to absorb the light energy, resulting in a decrease of the ligand-centered emission (“inner filter effect”) . Meanwhile, the emission of Rut at 510 nm is weak upon excitation at 395 nm (Figure S13).…”

“…Thus, a possible mechanism of the energy transfer is long-range photoinduced electron transfer (PET), where the electron moves from the Schiff base ligand (or Rut) to Yb 3+ (Scheme S2). 34 The LUMO energy level of Rut is reported to be −1.42 eV, 13 which is higher than that of the Schiff base ligand (−2.62 eV; Figure 8) in 1. This indicates that the driving force in the PET process of Rut is greater than that of the Schiff base ligand.…”

“…Thus, Rut is able to compete with the Schiff base in 1 to absorb the light energy, resulting in a decrease of the ligand-centered emission ("inner filter effect"). 13 Meanwhile, the emission of Rut at 510 nm is weak upon excitation at 395 nm (Figure S13).…”

“…10 For example, the luminescence of lanthanide complexes can be in the visible and near-infrared (NIR) ranges and is characterized by narrow emission bands, long decay times, and large effective antennagenerated shifts. 11 Currently, some visible fluorescent copper nanoclusters 12,13 and luminescent lanthanide metal−organic frameworks (Ln-MOFs; Ln = Eu and Tb) 14 have been designed to detect Rut, but so far the use of luminescent highnuclearity lanthanide-based complexes as probes in the Rut detection has not been reported.…”

Surface-Defect-Involved and Eye-Visible Electrochemiluminescence of Unary Copper Nanoclusters for Immunoassay

“…Ascorbic acid (AA)-capped CuNCs (AA-CuNCs), bovine serum albumin (BSA)-capped CuNCs (BSA-CuNCs), d -penicillamine (DP)-capped CuNCs (DP-CuNCs), mercaptopropionic acid (MPA)-capped CuNCs (MPA-CuNCs), thiomalic acid (TA)-capped CuNCs (TA-CuNCs), and 11-mercaptoundecanoic acid (MUA)-capped CuNCs (MUA-CuNCs) were synthesized as controls. Specific procedures on the preparation of AA-CuNCs, BSA-CuNCs, DP-CuNCs, MPA-CuNCs, TA-CuNCs, and MUA-CuNCs were, respectively, described in the Supporting Information. ,− …”