From mineral to sensing: Colorimetric determination of ciprofloxacin from water and food samples using natural chalcopyrite as nanozyme

A simple and efficient method for detecting the widely used antibiotic Ciprofloxacin (CIP) in different media is crucial. In this study, we employed a colorimetric method using natural chalcopyrite (CuFeS₂) with enzyme-mimic activity to detect CIP. The natural CuFeS₂ which shows peroxidase-like activity using 3,3′,5,5′-tetramethylbenzidine (TMB) was used as a chromogenic substrate. The absorption intensities of oxidized TMB (oxTMB) that show the peroxidase-like activity of CuFeS₂, increased proportionally with increasing CIP concentration. The increment linearly regressed over a concentration range of 0.5–15 μM. The limit of detection (LOD) was found to be 0.21 μM. The method is more responsive to CIP showing higher absorption intensity for the oxTMB than other tested molecules and metal ions. It further proved to be feasible in determining CIP concentration in tap water and beef with recovery rates of 88–101 % and 91–101 %, respectively. Our results indicate that this method could be applicable in measuring CIP in environmental and food samples. This study opens an avenue for exploring similar readily available minerals as nanozymes for sensing and other applications.