Microfluidic sensor integrated with selenite-enriched lanthanum hydroxide and in situ filtration for the on-site detection of the antibiotic trimethoprim in environmental samples
The improper disposal of antibiotics in water bodies and using contaminated wastewater in irrigation severely damage the environment. Despite efforts to monitor these contaminants, effective detection methods are limited. Here, we design and develop a novel microfluidic electrochemical (EC) sensor for on-site detection of trimethoprim (TMP) using a selenite-enriched lanthanum hydroxide (La(OH)(3):SeOx) working electrode and a polyimide (PI)-filter integrated microfluidic channel (MFC), thus termed a mu TMP-chip. For the first time, we introduced a new two-pronged strategy for enhancing TMP detection: i) incorporating selenite into the La(OH)(3) lattice to improve charge transfer properties and ii) using a laser-processed PI filter in the MFC to trap and isolate complex biomasses. Material characterizations confirmed that incorporating selenite into the La(OH)(3) lattice initiated La-O-Se bond formation and enhanced hybridization between the La 4f and O 2p orbitals. This process created holes in the O 2p valence band and improved the charge transfer properties, thus enhancing both sensitivity and selectivity. EC studies confirmed that when the PI filter is not used in the MFC, the mu TMP-chip experiences a 15-45 % drop in efficiency. The scalable mu TMP-chip offers cost-effective, highly reproducible TMP detection in soil and water.
