Photoelectrochemical sensor based on polymeric composite filled with cerium(III) molybdate to monitor pyriproxyfen releases in natural waters

Abstract

Arboviruses transmitted by the Aedes Aegypti mosquito represent a global public health concern and, given the lack of vaccines and effective drugs against such viral infections, the use of pyriproxyfen (PYR) as larvicide and growth inhibitor has become the most common sanitary control strategy. However, environmental diagnostic studies have shown that the complete hydrolysis or degradation of this insecticide in treated water is questionable, allowing uncontrolled and unintentional disposal in waste-receiving bodies and endangering non-target organisms. Aware that continuous PYR monitoring in environments vulnerable to contamination must be prioritized, an innovative photoelectrochemical sensor for this purpose is presented in this report. The platform has a multifunctional composite based on cerium(III) molybdate (Ce2(MoO4)3; photoactivity and electrocatalysis), nanocellulose (NC; molybdate aggregation inhibition), and polypyrrole (Ppy; electrode modification and charge-transfer resistance enhancement), immobilized on glassy-carbon electrode (GCE), which works as a highly reactive interface to monitor PYR oxidation in acid medium from sub-micromolar levels. Operating Ce2(MoO4)3–NC–PPy/GCE by square-wave voltammetry under visible light incidence, remarkable values of linear dynamic range (4.53 × 10−2–1.40 µM), detection limit (2.03 × 10−8 M) and sensitivity (73.2 µA/µM cm−2) were obtained, through highly stable and accurate measurements. The Ce2(MoO4)3–NC–PPy/GCE photoelectrochemical sensor still demonstrated suitable analytical performance to analyze PYR in river waters with different levels of organic matter, being attractive for examining environmental samples in which the presence of this pesticide deserves greater attention.