Portable electrochemical sensing methodologies for on-site detection of pesticide residues in fruits and vegetables

The quality analysis of water, pharmaceutical and environmental compounds is a basic subject for human health. The presence of low-quality drugs, biological toxins and chemical compounds in water or forbidden additives in the nourishments lead to irreversible problems in human health. Hence, multiple analytical approaches have been presented for investigating the quality of environmental, pharmaceutical, and food compounds and monitoring the detection of toxic compounds and pollutants in water. Sensing tools based on analytical strategies are required for identifying and quantifying the different pollutants including biological and chemical contaminants in water samples. Among different biosensing and sensing tools, portable sensing assays are of special importance because of their great advantages such as simplicity, affordability, portability and ability to on-site detection. Therefore, during the last decades, designing and fabricating portable assays with great sensitivity and selectivity have been considered by many researchers and scientists for detection of various water pollutants. In this paper, the latest improvements in portable biosensors and sensors in the monitoring of biological and chemical pollutants in different samples of water are extensively explained. Initially, different portable sensing assays and novel technologies in their development are addressed. Then, by introducing various biological (bacteria, algae, toxins) and chemical pollutants (heavy metals, aromatic compounds, pesticides and insecticides), different portable sensors which have been developed for the detection of the pollutants are presented. Finally, upcoming perspectives and future challenges are thoroughly described.

Recent advances on portable sensing and biosensing assays applied for detection of main chemical and biological pollutant agents in water samples: A critical review

Key Laboratory of Vegetation Ecology, Ministry of Education, Institute of Grassland Science, Northeast Normal University, Changchun, Jilin 130024, China Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan 650500, China State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China Northwest Land and Resources Research Center, Shaanxi Normal Northwest University, China State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun, Jilin 130024, China Ecology and Environment Department of Jilin Province, Changchun, Jilin 130024, China Heilongjiang Provincial Key Laboratory of Ecological Restoration and Resource Utilization for Cold Region, Heilongjiang University, Harbin 150080, China School of Life Science and Geology, Yili Normal University, Yili, Xinjiang 835000, China

https://downloads.hindawi.com/journals/js/2020/8503491.pdf

Sensors Applied for the Detection of Pesticides and Heavy Metals in Freshwaters

Micropillar array electrodes (μAEs) have been widely applied in electrochemical detection owing to their advantages of increased mass transport, lower detection limit, and potential to be miniaturized. This paper reports the fabrication, simulation, surface modification, and characterization of PDMS-based μAEs coated with gold films. The μAEs consist of 9 × 10 micropillars with a height of either 100 μm, 300 μm, or 500 μm in a 0.09 cm2 region. Numerical simulation was employed to study the influence of geometrical parameters on the current density. The μAEs were fabricated by soft lithography and characterized using both SEM and cyclic voltammetry. Experiments revealed that high pillars enabled enhanced voltammetric current density regardless of the scan rates. The platinum–palladium/multi-walled carbon nanotubes (Pt–Pd/MWCNTs) were coated on the μAEs to improve their electrochemical detection capability. The μAEs demonstrated 1.5 times larger sensitivity compared with the planar electrode when hydrogen peroxide was detected. Furthermore, μAE500 with Pt–Pd/MWCNTs was employed to detect sarcosine, a potential biomarker for prostate cancer. The linear range and limit of detection for sarcosine were from 5 to 60 μM and 1.28 μM, respectively. This detection range covers the concentration of sarcosine in human tissues (0–60 μM). These results suggest that the μAEs have better detection performance in comparison to planar electrodes due to their large surface area and pillar height. This paper provides essential guidelines for the application of μAEs in high sensitivity electrochemical detection of low abundance analytes.

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Development of micropillar array electrodes for highly sensitive detection of biomarkers

A compact, durable, low-reagent-usage, portable miniaturized electrochemical sensor is successfully developed for the high sensitivity detection of trace lead. We fabricated micropillars array working electrodes on the chip and established ultra-low concentration sodium acetate-acetate (NaAC-HAC) buffers (pH≈4.5) system to enhance the detection sensitivity of the sensor. The ultra-low concentration buffer possesses unique features of low baseline current and high peak current difference height. The analytical performance of the fabricated electrochemical sensor with three-dimensional gold (Au) working electrodes modified by Bismuth-film was comprehensively studied. The microsensor exhibited a high sensitivity of 0.0412μAppb−1 and a satisfactory detection limit of 0.15ppb when detecting lead ions under optimized conditions. Moreover, good linearity (correlation coefficient: 0.9993) with lead ions measurement in the concentration range of 1 to 120ppb and excellent repeatability (RSD: 1.79%) was obtained. the chip has satisfactory selectivity for common Interference ion. Besides, a low consumption of 350 μL of reagents per test was acquired. Finally, the proposed microsensor was applied to detect trace metal ions in tap and lake samples with satisfactory results.

Xiangyi Hu

Papers

Miniaturized electrochemical sensor with micropillar array working electrode for trace lead online measurement in tap water