ABSTRACT
Electrochemical biosensing has evolved as a diverse and potent method for detecting and analyzing biological entities ranging from tiny molecules to large macromolecules. Electrochemical biosensors are a desirable option in a variety of industries, including healthcare, environmental monitoring, and food safety, due to significant advancements in sensitivity, selectivity, and portability brought about by the integration of electrochemical techniques with nanomaterials, bio-recognition components, and microfluidics. In this review, we discussed the realm of electrochemical sensors, investigating and contrasting the diverse strategies that have been harnessed to push the boundaries of the limit of detection and achieve miniaturization. Furthermore, we assessed distinct electrochemical sensing methods employed in detection such as potentiometers, amperometers, conductometers, colorimeters, transistors, and electrical impedance spectroscopy to gauge their performance in various contexts. This article offers a panoramic view of strategies aimed at augmenting the limit of detection (LOD) of electrochemical sensors. The role of nanomaterials in shaping the capabilities of these sensors is examined in detail, accompanied by insights into the chemical modifications that enhance their functionality. Furthermore, our work not only offers a comprehensive strategic framework but also delineates the advanced methodologies employed in the development of electrochemical biosensors. This equips researchers with the knowledge required to develop more accurate and efficient detection technologies.
ABSTRACT
Both the environment and human health have suffered as a result of excessive and irrational pesticide use. The human body is vulnerable to a wide range of illnesses brought on by prolonged exposure to or intake of food contaminated with pesticide residues, including immunological and hormonal abnormalities and the development of certain tumors. Sensors based on nanoparticles stand out from more conventional spectrophotometry analytical methods due to their low detection limits, high sensitivity, and ease of use; that is why the demand for simple, fast, and less expensive sensing methods increases daily and presents myriad uses. Such demands are fulfilled by employing paper-based analytical devices having intrinsic properties. The presented work reports an on-site, easy-to-handle, and disposable paper-based sensing device for performing fast screening along with readout from a smartphone. The fabricated device utilizes luminescent silica quantum dots, immobilized into a paper cellulose matrix, and the resonance energy transfer phenomenon is employed. The silica quantum dots probes were fabricated from citric acid and, by undergoing physical adsorption, were confined on the nitrocellulose substrate in small wax-traced spots. The silica quantum dots were excited by smartphone ultraviolet LED, acting as an energy source and for capturing the image. The obtained LOD is 0.054 µM, and the coefficient of variation is less than 6.1%, comparable to the result obtained by UV-Visible and fluorometric analysis under similar experimental conditions. In addition, high reproducibility (≥9.8%) and high recovery ≥90% were obtained in spiked blood samples. The fabricated sensor sensitively detected pesticides giving a LOD of 2.5 ppm along with the development of yellow color within a short period of 5 min. The sensor functions well when sophisticated instrumentation is not accessible. The presented work shows the potential of the paper strip for the on-site detection of pesticides in biological and environmental samples.
