A GO-MoS₂/Au nanohybrid aptasensor for trace level monitoring of ciprofloxacin in water, food, environmental and pharmaceutical samples

Ciprofloxacin (CIP) is a broad-spectrum fluoroquinolone widely used in human and veterinary medicine; its largely unregulated use in low and middle incomed countries (LMICs) contributes to antimicrobial resistance (AMR). It enters the environment through human and animal excreta, effluents from pharmaceutical industries and hospitals, making it a potential contaminant in various environmental and biological matrices, necessitating a need for sensitive and specific detection technologies. To address this problem, a screen-printed carbon electrode modified with graphene oxide-MoS₂ (GO-MoS₂), gold nanoparticles and aptamer was used to detect CIP in real-world samples. The developed sensor utilizes a unique 2D/2D-3D material architecture, where the layered graphene oxide and MoS₂ nanosheets provide a high surface area, conductivity and electrocatalytic activity, while the electrodeposited 3D- gold nanoparticles enable increased electrocatalytic activity and aptamer binding. The sensor was calibrated for a range of 0.0001 µg/mL to 1 µg/mL in the buffer, 0.001 µg/mL to 1 µg/mL in milk and 0.001 µg/mL to 0.1 µg/mL hospital effluent water. The developed sensor showed a detection limit of 0.0001 µg/mL in the buffer and 0.001 µg/mL in milk and hospital effluent water samples. The sensor demonstrated a good recovery percentage in milk, hospital effluent wastewater and ophthalmic formulation with an overall RSD of <10 %. Hence, this sensor can be potentially used in screening of milk samples to check the presence of CIP; in wastewater treatment plant to monitor the presence of CIP after the treatment, and also can be used in pharmaceutical industries in qualitative and quantitative analysis of CIP.