SERS-based molecularly imprinted polymer sensor for highly sensitive norfloxacin detection

The overuse and misuse of antibiotics in the environment and food animals have created worsening issues against bacteria exposure to the antibiotics. Due to the high resistance of antibiotics in living beings, the fast and effective sensing of antibiotics and their residue in real samples is a requirement of the time. This article describes an ultra-detection of norfloxacin (NOR) antibiotic in milk and water samples using SERS (surface-enhanced Raman scattering) based molecularly imprinted polymer (MIP) coupled by gold nanoparticle (AuNP). To facilitate the collection of SERS spectra, AuNPs were reduced by chitosan and combined with MIP, denoted as CS/AuMIP, for the adsorption of NOR with high sensitivity and selectivity, i.e. down to the nanomolar level. The linear regression model in water and milk samples show peaks at Raman shifts 1418 cm−1 and 1400 cm−1, respectively. A satisfactory linear fit was seen with R2 = 0.95 and R2 = 0.97, respectively. The limit of detection (LOD) was calculated as 2.5 × 10−11 M based on band intensity. In various types of foods, the LOD recorded by CS/AuMIP fabricated film for NOR is lower than that stipulated by European Union regulation (8.0 ×10−9 – 4.0 ×10−8 M). The binding constant of CS/AuMIP for NOR in milk and tap water sample is 4 × 104 M−1, and 8.5 × 103 M−1, respectively. The CS/AuMIP film was optimised, characterised, and tested on spiked water and milk samples. The results of this study displayed that synthesized MIP has a lot of potential for separating and applicable for detecting trace amounts of antibiotics and their residues in environmental samples such as tap water and milk.