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A ratiometric nanosensor based on fluorescent carbon dots for label-free and highly selective recognition of DNA.

Herein we report a quantum dots (QDs)-based “OFF–ON” fluorescent biosensor for the sensitive and specific determination ofl-ascorbic acid.

The interaction between Ru anticancer drug and HSA was investigated systematically under physiological conditions.

Stereoselective recognition of amino acids is extremely important due to its high chirality-dependent interactions and physiological activities in life activities. We herein report a novel functionalized chiral fluorescent nanosensor prepared from surface modification of CdSe/ZnS quantum dots (QDs) with pyroglutamic acid derivatives, which could serve as a chiral recognition module for fluorescence detection of chiral molecules. The sensor exhibited a unique stereoselective fluorescence response to histidine (His), glutamate (Glu), and dihydroxyphenylalanine (Dopa) and had preferable response performance to l-enantiomers. The enantiomeric fluorescence difference ratios of His, Glu, and Dopa enantiomers were 3.90, 3.40, and 2.49, respectively. The mechanism for the enantiomeric fluorescence recognition was systematically studied through a fluorescence spectrum, fluorescence life, and density functional theory (DFT) calculation. Presumably, the different hydrogen bonding capacity of the chiral recognition module with two enantiomers mainly contributed to the difference in fluorescence signals. As a result, a broader application of the pyroglutamic acid derivative-coated QDs as a fluorescence-responsive chiral sensing platform for enantiomeric detection would be expected.