Development of a Highly Specific Fluoroimmunoassay for the Detection of Doxycycline Residues in Water Environmental and Animal Tissue Samples

Advances on chalcogenide quantum dots-based sensors for environmental pollutants monitoring

Water contamination represents a significant ecological impact with global consequences, contributing to water scarcity worldwide. The presence of several pollutants, including heavy metals, pharmaceuticals, pesticides, and pathogens, in water resources underscores a pressing global concern, prompting the European Union (EU) to establish a Water Watch List to monitor the level of these substances. Nowadays, the standard methods used to detect and quantify these contaminants are mainly liquid or gas chromatography coupled with mass spectrometry (LC/GC-MS). While these methodologies offer precision and accuracy, they require expensive equipment and experienced technicians, and cannot be used on the field. In this context, chalcogenide quantum dots (QDs)-based sensors have emerged as promising, user-friendly, practical, and portable tools for environmental monitoring. QDs are semiconductor nanocrystals that possess excellent properties, and have demonstrated versatility across various sensor types, such as fluorescent, electrochemical, plasmonic, and colorimetric ones. This review summarizes recent advances (2019-2023) in the use of chalcogenide QDs for environmental sensing, highlighting the development of sensors capable of detect efficiently heavy metals, anions, pharmaceuticals, pesticides, endocrine disrupting compounds, organic dyes, toxic gases, nitroaromatics, and pathogens.

A ratiometric dual-fluorescent paper-based synthetic biosensor for visual detection of tetracycline on-site

The excessive use of tetracycline poses a threat to human health, making it essential to monitor and regulate its usage. While whole-cell biosensors offer a simple and cost-effective method, their utility is constrained by limitations in sensitivity, portability, and robustness, hindering real-time measurements within complex environmental contexts. In this study, a ratiometric i/cTetR synthetic biosensing test strip with an engineered modified dual-fluorescence reporting was developed for detecting Tet antibiotics in water and food. First, the standardized unidirectional promoter PtetR by tailoring and screening TetR transcription factor binding sites and verified by molecular docking, shortening the detection time. Secondly, decoupling the sensing and reporting modules enhances the biosensor's performance, eliminating genetic background leakage and tripling the output signal. Thirdly, a ratiometric dual fluorescence signal i/cTetR biosensing test strip was designed. Under the light box LED/UV light source, the dual signal output method significantly reduced false negative results and enhanced the anti-interference capability of the biosensor. The i/cTetR strips can detect Tet in tap water (5-1280 μg/mL) and milk (50-3200 μg/kg) within 45 min in high volume on-site without separation and purification. This study provides a standardized and universal sensing method for the field detection of antibiotic contaminants.

Detection of doxycycline by using a tapered droplet structure fiber sensor

The abuse of doxycycline (DC) can lead to residues in animals and water environments, which severely threaten human health; however, currently accepted detection methods are generally complicated and cannot be used for real-time detection. Therefore, developing a method for rapid real-time detection of DC microcontent residues is highly important. Herein, based on the Mach-Zehnder interference, we propose a simple tapered droplet structure fiber sensor with a high detection sensitivity. By modifying the sensing region with a molecularly imprinted polymer film of DC, this sensor realizes the specific detection of DC and has a detection sensitivity of 58.81 pm/ppm for DC in a large concentration range of 0-300 ppm. This sensor can be used to detect DC microcontent in aqueous solutions in real time.

Editorial for the Special Issue on Quantum Dots Frontiers

Thanks to state-of-the-art chemical and device engineering in past decades, we have witnessed more and more novel applications based on semiconductor nanocrystals: quantum dots (QDs) [...].