Abstract
Dual-emission nanosensor for Hg2+ detection was prepared by coupling CA-AEAPMS on the surface of RBS-doped modified silica microspheres. The CA-AEAPMS was synthesized by using N-(β-aminoethyl)-γ-aminopropyl methyldimethoxysilane (AEAPMS) and citric acid as the main raw material. The obtained nanosensor showed characteristic fluorescence emissions of Rhodamine B (red) and CA-AEAPMS (blue) under a single excitation wavelength (360 nm). Upon binding to Hg2+, only the fluorescence of CA-AEAPMS was quenched, resulting in the ratiometric fluorescence response of the dual-emission silica microspheres. This ratiometric nanosensor exhibited good selectivity to Hg2+ over other metal ions, because of the amide groups on the surface of CA-AEAPMS serving as the Hg2+ recognition sites. The ratio of F450/F580 linearly decreased with the increasing of Hg2+ concentration in the range of 0 to 3 × 10−6 M, and a detection limit was as low as 97 nM was achieved. Then, the addition of three thiol-containing amino acids (Cys, Hcy, GSH) to the quenched fluorescence solution with Hg2+ can restore the fluorescence, and the detection limits of the three biothiols (Cys, Hcy, GSH) are 0.133 μM, 0.086 μM, and 0.123 μM, respectively.
Highlights
Mercury is a kind of cumulative harmful metal element known for its excessive toxicity it derives from its high affinity for thiol groups in enzymes and proteins, leading to cell dysfunction and subsequent physical illness
A thin layer of silica was coated over the red silica core
We investigated the response response of the the prepared preparedof dual-emission fluorescent microspheres toward the of dual-emission microspheres toward rangeWe of investigated μM, indicating that the fluorescence
Summary
Mercury is a kind of cumulative harmful metal element known for its excessive toxicity it derives from its high affinity for thiol groups in enzymes and proteins, leading to cell dysfunction and subsequent physical illness. It usually enters the body through the atmosphere and water. Cysteine (Cys), homocysteine (Hcy), reduced glutathione (GSH), and other biothiols, as the most small bio-thiol molecules in the cell, play important roles in human physiological activities [6,7,8], including intracellular redox reactions, foreign body metabolism, signal transduction, and gene regulation, etc. Abnormal cystine concentrations often lead to diseases such as cancer, Alzheimer’s disease, and cardiovascular disease [9,10,11]
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