Carbon dots functionalized papers for high-throughput sensing of 4-chloroethcathinone and its analogues in crime sites

Abstract

Sensitive and selective assays are demanded for quantitation of new psychoactive substances such as 4-chloroethcathinone that is a π-conjugated keto compound. Carbon dots (C-dots) prepared from L-arginine through a hydrothermal route have been used for quantitation of 4-chloroethcathinone in aqueous solution and on C-dot-functionalized papers (CDFPs). To prepare CDFPs, chromatography papers, each with a pattern of 8 × 12 circles (wells), are first fabricated through a solid-ink printing method and then the C-dots are coated into the wells. π-Conjugated keto or ester compounds induce photoluminescence quenching of C-dots through an electron transfer process. At pH 7.0, the CDFPs allow screening of abused drugs such as cocaine, heroin and cathinones. Because of poor solubility of heroin and cocaine at pH 11.0, the C-dot probe is selective for cathinones. The C-dots in aqueous solution and CDFPs at pH 11.0 allow quantitation of 4-chloroethcathinone down to 1.73 mM and 0.14 mM, respectively. Our sensing system consisting of a portable UV-lamp, a smartphone and a low-cost CDFP has been used to detect cathinones, cocaine and heroin at pH 7.0, showing its potential for screening of these drugs in crime sites.

Grand Challenges in Analytical Science

“…Alternatively, Ag nanoclusters, carbon dots, upconversion nanoparticles, and quantum dots have been used to develop fluorescent probes for the detection of illicit drugs, including codeine, cocaine, and ketamine, based on analyte induced changes in their fluorescence. Carbon dots that are easily prepared from carbon precursors have been used for screening of cathinones and date rape drugs (Yen et al, 2019;Yen et al, 2020). Interference from colorful sample matrix is usually less serious when applying fluorescence over colorimetric approaches.…”

An Overview of the Recent Developments in Carbon Quantum Dots—Promising Nanomaterials for Metal Ion Detection and (Bio)Molecule Sensing

“…It is well known that surface functionalization and heteroatom doping of CQDs could enhance properties of obtained nanomaterials, mainly electronic, optical, and chemical properties, and it could also affect the selectivity and affinity toward ion and (bio)molecule detection and sensing. Usually, the most commonly used precursors for obtaining CQDs using "bottom-up" approaches are citric acid [42][43][44], glucose [45], amino acids [46,47], and natural products. The addition of the different molecules with distinct functional groups attached onto the CQDs surface could enhance quantum yield (QY), optical properties in general, and also surface reactivity.…”

Carbon Dots for Forensic Applications: A Critical Review

“…Yen et al [79] developed a system for selectively detecting and quantifying cathinones, with C-dots either in aqueous suspension or coated onto paper. The graphitic C-dots, with an average diameter of 4.4 nm, were derived hydrothermally from L-arginine and bore a range of O-and N-containing surface functional groups.…”

“… Fluorescence quenching of C-dots in aqueous suspension: ( a ) variation in fluorescence quenching at pH 11 by 4-chloroethcathinone concentration; ( b ) fluorescence quenching by a range of compounds at pH 11; ( c ) florescence quenching by the same compounds at pH 7; in ( b ) and ( c ), concentrations of glucose, sucrose, fructose, ephedrine, methamphetamine and 4-chloroethcathinone are 25.0 mM and the others are saturated; ( d ) fluorescence quenching by a range of ketones (all concentrations 25.0 mM), showing significant quenching only by those which are π-conjugated. Reproduced with permission from reference [ 79 ], Royal Society Open Science; published by The Royal Society Publishing, 2019. …”

“… Quenching of fluorescence of C-dot-impregnated paper at pH 11, under a 254 nm portable light: ( a ) by varying concentrations of 4-chloroethcathinone; ( b ) by a range of related compounds and common diluents (cocaine, heroin and ketamine are at saturation, other compounds at 25 mM), showing clear selectivity for 4-chloroethcathinone; ( c ) at different w / w % in the presence of glucose. Reproduced with permission from reference [ 79 ], Royal Society Open Science; published by The Royal Society Publishing, 2019. …”