Smartphone-assisted on-site detection of ciprofloxacin hydrochloride in coastal zone water using a one-pot...

Coastal zones, characterized by intensive human activities, face dynamic contamination from emerging pollutants such as antibiotics. Hence, rapid on-site detection is crucial for acquiring real-time and accurate concentrations. Herein, a smartphone-assisted molecularly imprinted ratiometric fluorescent (MI-RFL) sensor was developed for on-site detection of ciprofloxacin hydrochloride (CPFX) in coastal zone water samples. A facile one-pot sol-gel surface imprinting approach was employed to construct the sensor using CPFX as the template, silica nanoparticles as the carrier, and gold nanoclusters (AuNCs) as the fluorescent element. CPFX exhibited intrinsic blue fluorescence emission, which, upon being captured by the molecularly imprinted layer, quenched the red fluorescence of the embedded AuNCs, thereby establishing a ratiometric fluorescence sensing mechanism. Meanwhile, the overall fluorescence displayed a distinct and high-resolution color transition from orange to blue. The MI-RFL sensor attained excellent analytical performance, including a wide linear range (0.1-20 ppm), low detection limit (0.028 ppm), and high selectivity toward CPFX. Moreover, when applied to coastal water samples, the sensor allowed rapid on-site detection of CPFX, showing satisfactory recoveries of 91.28-108.23% with relative standard deviations (RSDs) below 3.35%. Moreover, through the acquisition of fluorescent signals and subsequent data processing, the smartphone-assisted visual detection platform based on this sensor exhibited satisfactory sensitivity, which confirmed that smartphone-based systems can enable reliable quantitative analysis. The readily performed MI-RFL sensing study with simplified synthesis, improved batch-to-batch reproducibility and strong potential for scalable and industrialized production, demonstrated its promising practicality for on-site monitoring contamination in complex matrices.