Rapid and sensitive on-site detection of clothianidin in surface waters with a reusable fiber-embedded optofluidic biochip.

There is an increasing demand for rapid and high-frequency on-site detection of clothianidin (CLO) in water and food sources due to its high toxicity to non-target organisms. To address this, we introduce an innovative and decentralized testing method for CLO employing a reusable fiber-embedded optofluidic biochip. This biochip leverages evanescent wave fluorescence, indirect competitive immunoassay, and optofluidic technology to provide reliable, rapid, straightforward, and cost-effective CLO measurements. The integration of an all-fiber optical structure with a tapered fiber nano-biosensor significantly enhances fluorescence excitation and collection efficiency, bolstering the biochip's on-site detection capabilities and scalability. This biochip demonstrated high sensitivity and specificity in detecting CLO, achieving a satisfactory limit of detection of 1.0 µg/L within 12 min. It was successfully applied to  rapid on-site screening of CLO in surface waters and food in the Beijing-Tianjin region, offering timely and decentralized feedback. The biochip detected spiked surface waters and food with satisfactory recoveries . These confirms the biochip's potential as a robust tool for rapid and high-frequency on-site CLO screening in water and food, particularly in settings with limited resources. This biochip is highly adaptable and can be easily expanded to detect other trace pollutants by utilizing the appropriate functionalized fiber biosensors and antibodies.