Hybrid light/acoustic-powered microbowl motors, composed of gold (Au) and titanium dioxide (TiO 2 ) with a structure-dependent optical modulation of both their movement and collective behavior are reported by reversing the inner and outer positions of Au and TiO 2 . The microbowl propels in an acoustic field toward its exterior side. UV light activates the photochemical reaction on the TiO 2 surface in the presence of hydrogen peroxide and the Au/TiO 2 system moves toward its TiO 2 side by self-electrophoresis. Controlling the light intensity allows switching of the dominant propulsion mode and provides braking or reversal of motion direction when TiO 2 is on the interior, or accelerated motion when the TiO 2 is on its exterior. Theoretical simulations offer an understanding of the acoustic streaming flow and self-electrophoretic fluid flow induced by the asymmetric distribution of ions around the microbowl. The light-modulation behavior along with the tunable structure also leads to the control of the swarm behaviors under the acoustic field, including expansion or compaction of ensembles of microbowls with interior and exterior TiO 2 , respectively. Such structure-dependent motion control thus paves the way for a variety of complex microscale operations, ranging from cargo transport to drug delivery in biomedical and environmental applications.
Over recent years there has been a progressive increase in the adulteration of common illicit street drugs, such as heroin and cocaine, with fentanyl and its derivatives (fentalogues) being the cause of over doses ending with fatal repercussions. Consequently, there is a need for the development of sensitive, selective and reliable analytical protocols for their separation and quantification. Herein, we report for the first time, a combination of high-performance liquid chromatography with a dual-diode array and electrochemical (amperometric) detector achieved for the simultaneous detection and quantification of heroin (HRN), fentanyl and ten fentalogues; the amperometric detection is achieved using a commercially available impinging jet flow-cell that incorporates in-house screen-printed graphite macroelectrodes (SPEs). Both protocols are analytically compared and contrasted in terms of their experimental parameters and chromatographic conditions with the separation and quantification being optimized, with these protocols demonstrating a high sensitivity and reproducibility. The proposed methods were successfully applied for the analysis of the investigated drugs of abuse, in the presence of common adulterants (e.g. caffeine, paracetamol and benzocaine), co-formulated excipients (starch, lactose, aerosil 200, etc.) and simultaneously within seized street samples. Scheme 1 Chemical synthesis and structures of fentanyl (2c), fentalogues (2a, 2b, 2d-2k), heroin (HRN) and cocaine (COC). a Mean AE SD of obtained % w/w of three determinations of each detected drug in each street sample. b Percentage relative standard deviation of obtained % w/w of three determinations of each detected drug in each street sample. c n.d. ¼ not detected.This journal is
The constant and persistent synthesis and abuse of new psychoactive substances have sparked the requirement for rapid, on-site, sensitive analytical protocols for their sensing and quantification. Mephedrone (4-MMC) is currently one of the most popular legal highs among recreational drug abusers and imposes a serious public health problem. In this paper, the electrochemical sensing of two metabolites of 4-MMC, namely, nor-mephedrone (4-methylcathinone, 4-MC) and dihydromephedrone (4-methylephedrine, 4-MMC-R), utilizing screen-printed graphite electrodes is performed. The accessible linear ranges by cyclic voltammetry were found to correspond to 40–300 μg mL–1 for 4-MC in both phosphate buffer solution (PBS, pH 7.0) and spiked diluted human urine, whereas in the case of 4-MMC-R, the linearity ranges are 15–300 μg mL–1 (PBS, pH 3.0) and 25–300 μg mL–1 (spiked diluted human urine). To maximize the assay sensitivity, differential pulse voltammetry (DPV) was performed toward the sensing of 4-MC, which exhibited a linear response over the range 10–250 and 10–300 μg mL–1 in PBS pH 7.0 and spiked diluted human urine, respectively. However, 4-MMC-R demonstrated slightly higher sensitivity over the range 5–300 μg mL–1 in both PBS pH 3.0 and spiked diluted human urine. Using DPV, the limits of detection (3σ) were calculated and found to correspond to ca. 3.97 and 3.64 μg mL–1 for 4-MC and 4-MMC-R (PBS, pH 7.0 and 3.0), respectively, and ca. 6.34 and 3.87 μg mL–1 for 4-MC and 4-MMC-R (spiked diluted human urine), respectively. The potential interference of adulterants’ metabolites commonly found in NPS street samples was also explored (at both pH 7.0 and 3.0). The electrochemical approach reported herein provides a novel laboratory tool for the identification and quantification of synthetic cathinone metabolites and has potential for the basis of a portable analytical sensor for their fast, cheap, reliable, and accessible determination in the field.
The emergence of a new class of novel psychoactive substances, N-benzyl-substituted phenethylamine derivatives so-called “NBOMes” or “Smiles”, in the recreational drug market has forced the development of new sensitive analytical methodologies for their detection and quantitation. NBOMes’ hallucinogenic effects mimic those of the illegal psychedelic drug lysergic acid diethylamide (LSD) and are typically sold as LSD on blotter papers, resulting in a remarkable number of fatalities worldwide. In this article, four halide derivatives of NBOMe, namely, 2-(4-fluoro-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, 2-(4-chloro-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, 2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, and 2-(4-iodo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, were detected and quantified simultaneously using a high-performance liquid chromatographic method, and two detection systems were compared: photodiode array detection (detection system I) and amperometric detection via a commercially available impinging jet flow-cell system incorporating embedded graphite screen-printed macroelectrodes (detection system II). Under optimized experimental conditions, linear calibration plots were obtained in the concentration range of 10–300 and 20–300 μg mL–1, for detection systems I and II, respectively. Detection limit (limit of detection) values were between 4.6–6.7 and 9.7–18 μg mL–1, for detection systems I and II, respectively. Both detectors were employed for the analysis of the four NBOMe derivatives in the bulk form, in the presence of LSD and adulterants commonly found in street samples (e.g. paracetamol, caffeine, and benzocaine). Furthermore, the method was applied for the analysis of simulated blotter papers, and the obtained percentage recoveries were satisfactory, emphasizing its advantageous applicability for the routine analysis of NBOMes in forensic laboratories.
Additive manufacturing is an emerging technology of vast applicability, receiving significant interest in a plethora of industrial and research domains as it allows the translation of designs produced via computer software, into 3D printed objects.
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