Optical & electrochemical fiber-optic sensor: in situ detection of antibiotics with fM detection limit

Abstract

The ultrasensitive and rapid detection of antibiotics is crucial for environmental monitoring and risk management. However, achieving ultrasensitive and in situ detection of antibiotics remains a formidable challenge. Here, we present the development of optical & electrochemical fiber sensors for the ultrasensitive, rapid, and in situ detection of antibiotic ciprofloxacin (CIP). In this study, the fiber sensor can act as an electrochemical working electrode while exciting surface plasmon resonance to monitor the entire electrochemical kinetic process in real-time. During the electrochemical detection process, Cu²⁺ exhibits a prominent stripping peak current response, which can be effectively suppressed by CIP due to the formation of complexes between Cu²⁺ and CIP. The relative change in Cu²⁺ response serves as the basis for CIP detection. The experiment demonstrates exceptional sensitivity at the femtomolar (fM) level, rapid detection within 255 s, and high specificity in CIP detection. In addition, the recovery rate of CIP is successfully assessed using a spiked test method in a seawater sample. The proposed optical & electrochemical fiber sensors open new avenues for in situ biochemical detection in diverse fields, particularly in hazardous and confined aquatic environments.