Nanomaterial‐Based Sensor Arrays With Deep Learning for Screening of Illicit Drugs

Abstract

UNODC) states the seized amounts in decreasing order of cocaine (1131 tons), MA (228 tons), heroin and morphine (139 tons), synthetic cathinone (19 tons), and ketamine (11 tons) in 2018. [2] Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-MS (LC-MS) have been commonly applied to identify illicit drugs, [3] but they are expensive and require experienced operators to conduct the analysis. In addition, the laboratory usually cannot provide results quickly to law enforcement officers, mainly because of tedious analysis procedures needed and large number of suspected samples provided. Thus, before sending suspected samples to the laboratory, screening of illicit drugs at crime sites is required. [4] Several commercial colorimetric test kits have been employed for screening of illicit drugs. [5] Most of the assays are convenient, but poor selectivity toward the analyte, limits to small groups of analytes, and interference from colorful matrix are sometimes problematic. Although sensitive and selective immunoassay kits are available for screening of few common drugs like cocaine in urine, [6] their high cost and short shelf life are concerns. Immunoassay kits for new psychoactive substances (NPSs) like synthetic cathinones with various analogs are unavailable. It usually takes a long period of time to develop a specific immunoassay for a new NPS, limiting its immediate use to meet the market need. A handhold Raman analyzer has been rolled out, but it is expensive and limited to the analysis of high-purity samples. [7] Although metal and carbon based nanomaterials have been well applied for sensing of various analytes, [8] only few nanomaterials-based sensing systems have been used for screening of illicit drugs. [9] For example, an aptamer specific to cocaine was used to functionalize gold nanoparticles (Au NPs) for colorimetric screening of cocaine. [9a] Citrate-capped Au NPs conjugated with melamine were used for the detection of clonazepam through hydrogen bonding. Aptamer-modified CdSe/ZnS quantum dots (QDs) were employed for fluorescent sensing of cocaine through fluorescence resonance energy transfer. DNA (sequence: 5′-TGGGGATGGAGAACT) templated silver nanoclusters (DNA-Ag NCs) represent another case of using fluorescent probes for the detection of ketamine, Rapid and accurate screening techniques are demanded for illicit drugs that have raised international tensions. Bovine serum albumin-stabilized gold nanoclusters (BSA-Au NCs), carbon dots (C dots), thiosalicylic acid-stabilized silver nanoclusters (TA-Ag NCs), and Marquis reagent as photoluminescent sensing probes for five common illicit drugs are demonstrated in this study. Cocaine, 4-chloroethcathinone (4-CEC), and ketamine induce different degrees of photoluminescence changes of BSA-Au NCs, C dots, and TA-Ag NCs. Detection of heroin and methamphetamine (MA) is based on their formation of fluorescence polymer particles with Marquis reagent. To provide a unique pattern for each analyte, 2 × 4 sensor arrays are prepared. A deep lear...

Advances in the application of novel carbon nanomaterials in illicit drug detection

“…The need to overcome the lack of specificity of this sensor probe makes it difficult to identify the presence of illicit drugs in suspected samples with the naked eye. 68 In addition, the use of electrochemical sensing for illicit drug identification has not yet moved away from the use of large instruments, increasing the threshold and cost of drug detection, but its advantages of no sample pre-treatment and fast and accurate analysis are still undeniable. Therefore, the idea of using electrochemical sensors based on different carriers such as wearable gloves to detect illicit drugs provides a new research direction to address the major challenges of field screening, and also takes into account the evaluation of medical facilities and the safety of first responders.…”

Recent advances in aggregation-induced emission (AIE)-based chemosensors for the detection of organic small molecules

“…For example, Chang et al prepared a sensor array ( B38 ) using an orange-red emissive thiosalicyclic acid-stabilized Ag NC (TA-Ag NCs), a red-magenta -emissive BSA-stabilized Au NC (BSA-Au NCs), a blue-emissive carbon dot (C-dots), and Marquis reagent. 215 B38 is able to sense and differentiate 4-chloroethcathinone (4-CEC), cocaine, ketamine, meth, and heroin, based on their interactions and reactions with the different components of the array: 4-CEC quenches the fluorescence of BSA-Au NCs and C-dots via electron transfer while cocaine only quenches that of C-dots; emission of TA-Ag NCs was enhanced by varying extent of the different drugs due to aggregate formation; meth and heroin induced the formation of light-blue and green -emissive fluorescent polymer particles (FPPs), respectively, with Marquis reagent. Putting these together, a multi-colour array could then be achieved.…”

Luminescence-based detection and identification of illicit drugs

“…Recently, the same group developed a nanomaterialbased sensor array comprising bovine serum albumin-stabilized gold nanoclusters (BSA-Au NCs), carbon dots (C dots), thiosalicylic acid-stabilized silver nanoclusters (TA-Ag NCs), and Marquis reagent (an established colorimetric sensor) to identify five illicit drugs. 86 Each of the drugs caused different luminescence responses (turn-on: ''1'', turn-off: ''À1'', and no response: ''0'') when exposed to the four materials. Using this approach, a specific response pattern (e.g., ''0, À1, 1, 0'' for cocaine) could be established for each drug.…”