A highly selective and sensitive electrochemical biosensor was developed for the detection of Brucella abortus bacteria using a molecularly imprinted polymer (MIP) synthesized via electropolymerization of dopamine onto screen-printed gold electrodes. The fabrication process is simple, cost-effective, and suitable for scalable production. Morphological and structural characterization using Raman spectroscopy, field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM) confirmed a successful imprinting and uniform film formation. Electrochemical impedance spectroscopy (EIS) enabled sensitive detection, achieving a wide linear range from 10 to 106 CFU/mL, with a correlation coefficient (R2) of 0.9925, and a maximum ΔRct of 37.56 kΩ. Selectivity tests against closely related and non-target bacterial species, including Brucella melitensis, Brucella suis, Escherichia coli, and Salmonella spp., showed negligible cross-reactivity, confirming high molecular recognition for Brucella abortus species. The use of MIP-based sensor with other electroactive monomers [e.g., polyaniline, poly(pyrrole propionic acid), poly(pyrrole-2-carboxylic acid), and poly(2-aminophenol)] displayed significantly lower response compared to the suggested polydopamine-based MIP, probably due to their low conductivity, weak compatibility, and less favorable film properties. The developed technique has many advantages over methods based on bacterial culture, PCR, and ELISA, which are often expensive, time-consuming, and require specialized facilities. The developed sensor offered a high selectivity, rapid response, high stability, extended durability, robustness, universal applicability and design flexibility. These results highlight the potential of dopamine-based MIP/impedimetric sensor for practical Brucella abortus bacteria detection and supported their future integration into a portable diagnostic device for continuous real-sample analysis.

Persistent organic pesticides (POPs), particularly chlorinated pesticides, represent a critical environmental threat due to their chemical stability, bioaccumulation potential, and resistance to conventional water-treatment methods. Herein, a rapid and cost-effective photocatalytic strategy is developed for the degradation of seventeen structurally diverse POPs in water under ultraviolet (UV) irradiation at ambient temperature. A magnetic heterostructured nanocomposite consisting of activated carbon, derived from sugarcane bagasse, and bentonite, coupled with a magnetite/cerium oxide (Fe3O4/CeO2) nanocomposite, is fabricated via a facile ball-milling approach and tested. The material exhibits a strong light absorption, high adsorption capability, high surface activity, and excellent magnetic recoverability. Comprehensive characterization is performed using ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) surface analysis. Under optimized conditions (0.1 g L−1 catalyst, 20 °C, UV 365 nm, 20 min), removal efficiencies exceeding 90% are achieved for δ-benzene hexachloride (δ-BHC), heptachlor, dichlorodiphenyl trichloroethane (DDT), endrine aldehyde, and methoxychlor, while 73.9–86.6% degradation is recorded for α-BHC, β-BHC, γ-BHC, aldrin, heptachlor epoxide, dichlorodiphenyldichloroethylene (DDE), endrin, dieldrin, dichlorodiphenyldichloroethane (DDD), and endosulfan sulfate. The developed AC/Bentonite/Fe3O4/CeO2 nanocomposite demonstrates some key advantages including high adsorption affinity, fast reaction kinetics, broad pollutant applicability, magnetic separability, and significantly shorter treatment time compared with many of those previously reported using cerium-based photocatalysts. These results highlight the potential of this sustainable catalyst system for efficient remediation of POP-contaminated water.