Thangaraj S. T. Balamurugan

The rapid expansion of electroanalytical platforms offers promising routes for simultaneous monitoring of nitrate, phosphate, and cyanotoxins, the principal causes and consequences of harmful algal blooms (HAB), respectively. This review summarizes research progress from the past five years under three interrelated objectives. Our mapping of research progression unveils significant disparities across the three target analytes, with cyanotoxins being the most studied target while phosphates are the least. A sequential critical assessment of research progress for reliable electrochemical detection of nitrate, phosphate, and cyanotoxins in environmental waters reveals immense variations in electrochemical transducing techniques across the three targets. For instance, Potentiometric ion-selective electrodes (ISE) and Cu-catalyst enhanced voltammetric sensors dominate nitrate analysis, while phosphate, as an electrochemically inert probe, is most effectively addressed via indirect detection relying on, e.g., molybdate and copper phthalocyanine complexation. Cyanotoxin sensing encompasses immunoassays and label-free aptameric and genomic/CRISPR-based platforms. Finally, we highlight significant milestones, challenges, and opportunities for the future design of electrochemical sensors targeting this group of analytes. In doing so, we summarize the current state of the art, highlight most promising sensing solutions, and underline a sound knowledge gap that is especially prominent in the electroanalysis of cyanotoxins. There is also a need for the integration of machine learning (ML), LoRa (Long Range), and Internet of Things (IoT) tools to develop comprehensive electroanalytical solutions for remote monitoring of water quality.

Harmful algal blooms and cyanotoxins pose a global threat to water sanitation and public health. Microcystin-LR (MC-LR) is an eminent cyanotoxin produced by freshwater cyanobacteria species, including Microcystis aeruginosa. This work presents an efficient sampling and label-free electroanalytical solution based on the electrified liquid–liquid interface (eLLI) for monitoring MC-LR release from M. aeruginosa cultures over 35-days. The key innovation of this study lies in the direct, label-free detection of MC-LR at eLLI which in contrast to other established electrochemical MC-LR sensors. A standardized sampling and analytical protocol are established for an alternative electrochemical detection of MC-LR and for periodic monitoring of cyanotoxin release from algal cultures under controlled laboratory conditions, with clear potential for real-world adoption. The sensing platform exploits a voltammetric signal originating from the toxin-induced interfacial charge-transfer processes, involving a combination of interfacial adsorption and ion transfer. Analytical sensitivity and limit of quantification of the eLLI sensor were observed to be 14.28 A·M-1 and 500 nM, respectively. While the detection limit was calculated to be 55 nM. Electroanalytical findings of the eLLI-MC-LR sensor are well correlated with chromatographic observations, demonstrating the platform’s sensitivity, reliability, and capability for rapid monitoring of cyanotoxin dynamics in complex biological matrices using a low-cost sensing strategy. This study lays the foundation for the future design of low-cost soft sensing solutions that can be tuned to monitor cyanotoxin release in environmental waters, with the potential to significantly reduce the time and cost associated with cyanotoxin screening.

Clozapine (CZ) is a prescribed benzodiazepine psychiatric drug, that is often possessed as an illicit drug associated with drug-facilitated sexual assaults (DFSA) due to its strong seductive capabilities. Hence, we propose an electrified liquid-liquid interface (eLLI) based transducing element as an alternative electroanalytical platform for rapid screening of CZ in soft and hard drinks which habitually associated with DFSA crimes. First, molecular partitioning and the effect of chemical composition, pH, and the presence of ethanol in the biphasic configuration of the aqueous phase on the interfacial behaviour and analytical performance of the CZ at the eLLI have been investigated with voltammetry. Next, the electrochemical profiles of various soft and hard drinks were studied at eLLI. The eLLI-based CZ sensor has shown a broad dynamic range (15-150 M), lower detection limits (1M), and adequate reliability towards rapid CZ screening in spiked soft and hard drink samples in reference to the standard chromatographic analysis.

Clozapine (CZ) is a benzodiazepine psychiatric drug and also an illicit drug associated with drug-facilitated sexual assaults (DFSA). In this work CZ detection method was developed using electrifed liquid–liquid interface.

We present a promising strategy to enhance the performance and stability of flexible all-polymer TENGs via rational surface engineering, yielding stable output characteristics together with record high specific power for a TENG.

Designing and engineering nanocomposites with tailored physiochemical properties through teaming distinct components is a straightforward strategy to yield multifunctional materials. Here, we describe a rapid, economical, and green one-pot microwave synthetic procedure for the preparation of ternary nanocomposites carbon/polydopamine/Au nanoparticles (C/PDA/AuNPs; C = carbon nanotubes (CNTs), reduced graphene oxide (rGO)). No harsh reaction conditions were used in the method, as are used in conventional hydrothermal or high-temperature methods. The PDA unit acts as a non-covalent functionalizing agent for carbon, through π stacking interactions, and also as a stabilizing agent for the formation of AuNPs. The CNTs/PDA/AuNPs modified electrode exhibited excellent electrocatalytic activity to oxidize chloramphenicol and the resulting sensor exhibited a low detection limit (36 nM), wide linear range (0.1–534 μM), good selectivity (against 5-fold excess levels of interferences), appreciable reproducibility (3.47%), good stability (94.7%), and practicality (recoveries 95.0%–98.4%). Likewise, rGO/PDA/AuNPs was used to fabricate a sensitive folic acid sensor, which exhibits excellent analytical parameters, including wide linear range (0.1–905 μM) and low detection limit (25 nM). The described synthetic route includes fast reaction time (5 min) and a readily available household microwave heating device, which has the potential to significantly contribute to the current state of the field.