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A Hg2+‐related quenching photoluminescence (PL) sensor was fabricated based on nitrogen‐doped graphene quantum dots (N‐GQDs) as the luminescent agent and glutathione as the masking agent to detect Hg2+ in tap water. The addition of Hg2+ significantly reduced the PL intensity of N‐GQDs, which was attributed to coordination reaction inducing the aggregation of N‐GQDs. The Hg2+‐related quenching PL sensor with glutathione as the masking agent has good selectivity and accuracy. The sensor showed a linear relationship ranging from 0.5 to 110 nM with the detection limit 0.08 nM (S/N = 3). The proposed method was applied to the determination of Hg2+ in tap water, and the results were consistent with atomic absorption spectroscopy (AAS). [ABSTRACT FROM AUTHOR]

AbstractAn electrochemiluminescent (ECL) aptasensor for lysozyme (Lyz) based on a graphene quantum dot (GQD)-ruthenium bipyridine (Ru(bpy)32+)-silica (GQDs-Ru(bpy)32+@SiO2) nanocomposite were prepared by encapsulating GQDs and the luminophore Ru(bpy)32+ in silica nanospheres (SiO2). The nanocomposite GQDs-Ru(bpy)32+@SiO2 with uniform size exhibited a strong and reproducible ECL response. The nanoprobe (DNA-GQDs-Ru(bpy)32+@SiO2) was obtained via amidation between GQDs-Ru(bpy)32+@SiO2 and the complementary DNA sequence. The ECL platform was constructed by hybridization between the aptamer and the complementary strand DNA. The specific recognition between aptamer and the target lysozyme maintained the nanoprobe DNA-GQDs-Ru(bpy)32+@SiO2 away from the electrode, which led to the decreasing ECL response. The aptasensor exhibited a linear relationship from 0.1 to 100 pg/mL with a detection limit of 1.7 × 10−11 mg/mL. This study provided a simple and sensitive analytical approach for lysozyme. [ABSTRACT FROM AUTHOR]