Semi-solid Extrusion 3D Printing of Chitosan/Carbon Nanotube Nanocomposite Films for Microextraction of Pesticides in Water

In this work, a novel thin-film microextraction (TF-SPME) device was developed using semi-solid extrusion 3D printing, aiming to provide a sustainable and customizable tool for the environmental monitoring of pesticides in water. The device was fabricated from a nanocomposite of chitosan (CS) and multi-walled carbon nanotubes (MWCNT) and the printing approach enabled direct shaping of the extraction films under mild conditions. Rheological evaluation confirmed that the CS-based hydrogels, with and without MWCNT, possess pseudoplastic and thixotropic behavior, suitable characteristics for extrusion-based printing. Films measuring 20 mm × 5 mm × 1 mm were designed in a geometry compatible with TF-SPME strips, and after printing, they were evaluated for the hydrolytic stability of chitosan. Both CS and CS/MWCNT films exhibited similar swelling index in water (287 ± 7 % and 244 ± 7 %, respectively) and maintained structural integrity without disintegration in either water or acetonitrile throughout the evaluation period, regardless of the presence of MWCNT. The printed devices were successfully applied to the thin-film solid-phase microextraction of organochlorine and organophosphorus pesticides in water followed by analysis using gas chromatography coupled to mass spectrometry (GC-MS). Better extraction efficiency and linear response were observed for the MWCNT-containing 3D-printed films for seven evaluated pesticides (alpha-BHC, aldrin, endosulfan I (alpha), dieldrin, 4,4-DDE, 4,4-DDD, and phorate). Molecular dynamics simulations suggest that the presence of CNT is associated with microstructural and hydration effects within the chitosan matrix, which favor interactions between the analytes and the sorbent phase. The limits of quantification were in the range 50–200 μg L-1. This study highlights the potential of semi-solid extrusion 3D printing in the development of green, functional, and versatile analytical platforms for monitoring of organic pollutants in environmental samples.