Magnetic Layered Double Hydroxides Intercalated with Polydopamine-Modified Carbon Dots for the Detection of Nonsteroidal Anti-Inflammatory Drugs by Spectrofluorometric Analysis

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the often identified pharmaceutical residue pollutants due to their common use and persistence. In this study, a magnetic nanocomposite comprising layered double hydroxides intercalated with polydopamine-modified carbon dots ( m –Mg-Al LDH_PDA@CDs) was developed for the recognition of trace levels of NSAIDs in environmental water samples. The polydopamine functionalization enhanced the surface activity and stability of the carbon dots, while intercalation into the layered double hydroxide’s structure suppressed aggregation and improved photoluminescence and adsorption efficiency. The synthesized materials were thoroughly characterized using FTIR, XRD, HR-TEM-EDS, FESEM, XPS, BET, VSM, and photoluminescence spectroscopy, confirming their structural integrity, high surface area, and magnetic and sensing properties. The m –Mg-Al LDH_PDA@CDs were further utilized for the detection of commonly detected NSAIDs (diclofenac, aspirin, mefenamic acid, naproxen, and ibuprofen) by spectrofluorometric analysis. The sensor showed dynamic quenching in the presence of NSAIDs. The developed sensor demonstrated excellent analytical performance, with a wide linear detection range of 1.2–16 nM, low limits of detection ranging from 0.42–0.63 nM, and high recovery rates between 94.23–100.51% across different matrices (aqueous and pharmaceutical samples). The material showed high selectivity toward NSAIDs, along with good repeatability and reusability over five cycles. Moreover, the current approach exhibits a BAGI score of 77.5. This work presents a green, efficient, and magnetically retrievable sensing platform, offering significant potential for the environmental monitoring of pharmaceutical contaminants.