Integrated Biosensing and Biodegradation for Sustainable Remediation of Ciprofloxacin from Hospital Wastewater.

Pharmaceutical residues such as ciprofloxacin (CPRO) remain in aquatic ecosystems and contribute to antimicrobial resistance. This study reports a liquid crystal (LC)-based aptasensor integrated with a portable optical setup and biodegradation monitoring for in situ CPRO recognition and remediation in hospital wastewater. The optical sensing method leverages the stabilization of a CPRO-specific aptamer at the LC-aqueous interface, resulting in the reorientation of the LC directors and producing a distinct label-free optical response under crossed polarizers. The aptamer-CPRO binding interactions and the resulting changes to the LC birefringence were correlated using molecular dynamics simulations in conjunction with spectroscopic validation, providing insight into the biomolecule-mediated interfacial ordering. The sensor achieves a detection limit of 8 nM (>3 ppb) and was implemented in a portable, 3D-printed, smartphone-enabled polarizing optical microscope (POM) for decentralized monitoring. Toward remediation, a CPRO-degrading microbe, Klebsiella sp. SG01, was used to degrade the drug as an exclusive carbon source, achieving ≈81% removal within 30 days. This integrated detection-degradation platform demonstrates the amalgamation of interfacial sensing with microbial remediation for recalcitrant pharmaceutical pollutants.