Abstract
Herein, we report novel “off–on” fluorescent sensing of organophosphate pesticides using a carbon dot (CD)–Au(iii) complex/acetylcholinesterase (AChE) system. The above sensor utilizes the quenching of CD fluorescence by Au(iii) and its subsequent recovery by thiocholine, which is generated by AChE-catalyzed hydrolysis of acetylthiocholine (ATCh) and effectively scavenges Au(iii). In the presence of organophosphates, the catalytic activity of AChE is inhibited, allowing these species to be quantified based on the decreased recovery of CD fluorescence intensity. The developed sensor was used to analyze a real pesticide-spiked sample (4.48 μM), achieving a recovery of 99.85% and exhibiting a linear response range of 0.45–44.80 μM.
Highlights
We report a novel “off–on” uorescent biosensor for organophosphate pesticides, in which the carbon dot (CD) uorescence initially quenched by Au(III)[20] is recovered by thiocholine (TCh, an effective Au(III) scavenger) generated by AChE-catalyzed hydrolysis of acetylthiocholine (ATCh) that is structurally similar to ACh
AChE catalyzes the hydrolysis of S-acetylthiocholine iodide to TCh,[22] which can effectively capture Au(III) and recover the CD uorescence quenched by the same.[20]
Scheme 1 Mechanism of organophosphate pesticide sensing by the developed CD/Au(III) sensor
Summary
Organophosphate pesticides nd extensive applications worldwide, exhibiting acute toxicity upon ingestion and posing a serious risk to human health.[1,2] The above pesticides mainly target acetylcholinesterase (AChE),[3] inhibiting its catalytic activity and hindering the hydrolysis of acetylcholine (ACh, a neurotransmitter), with the accumulation of excess ACh leading to lethal overexcitation.[4,5] the above activity inhibition can be successfully utilized in organophosphate pesticide sensing. Carbon dots (CDs) have recently found numerous applications due to exhibiting excellent uorescence, good biocompatibility, and low toxicity and cost.[6,7] Recently, much effort has been directed at utilizing CD uorescence or electrochemiluminescence to fabricate “off–on” or “on–off” sensors,[8,9,10] which exhibit the advantages of fast response, easy operation, and clear signal recognition.[11] Notably, metal ions such as Cu2+, Fe3+, Hg2+, K+, and Ag+ Metal ions such as Cu2+, Fe3+, Hg2+, K+, and Ag+ (ref. 11–15) are able to quench the uorescence of CDs,[16] allowing the sensing of heavy metals, organic pollutants in water, sugar in blood, and biomarkers in living cells.[17,18,19,20]
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