SERS-assisted toxicity profiling of nitrofurantoin photodegradation towards sustainable water treatment

Abstract Nitrofurantoin, a broad-spectrum nitrofuran-class antibiotic, persists in food and aquatic environments, posing risks of hepatotoxicity and contributing to antibiotic resistance. Although LC-MS/MS and HPLC-based provide exceptional sensitivity, they are incompatible for rapid and on-site analysis. Beyond trace on-site detection, effective management of antibiotic load requires scalable and efficient remediation strategies to prevent indirect entry and minimize secondary toxicity. While conventional UV-photodegradation is extensively studied for antibiotic removal, it often leads to formation of toxic intermediates raising concerns about environmental safety. Thus, exists a need for alternate photodegradation approach with less toxic intermediates. This study comprehensively investigates the Near-infrared (NIR) light-based degradation of nitrofurantoin (NFT) coupled with surface-enhanced Raman spectroscopy (SERS)-based toxicity profiling. To ensure rigorous comparison, identical power of 37 W was used with UV and NIR irradiations for constant exposure duration. To investigate the field deployability of this strategy, we developed a low-cost paper-based microfluidic platform integrated with silver nanorods for simultaneous degradation and SERS-based detection of the non-toxic intermediates. SERS fingerprint of the UV degraded samples corresponded to 1-aminohydantoin (AHD), a toxic and carcinogenic metabolite, while NIR irradiation favours the formation of a less toxic 5-nitro-2-furaldehyde (NFA). Time-resolved Raman analysis demonstrated systematic degradation of NFT with R 2 > 0.95 upon NIR irradiation. These results establish NIR-assisted degradation as a safer alternative to UV degradation and signify the potential of SERS-based paper microfluidics as a field-deployable device for Sustainable Development Goals 3 and 6 through sustainable water management and improved public health safety.