AptaStick: A 3D-printed aptamer-functionalized stir-stick for selective extraction of bisphenol A from soft drinks

This work presents AptaStick, a stereolithography 3D-printed stir-stick device functionalized with a bisphenol A (BPA)-specific aptamer for selective extraction from soft drinks. For this purpose, several geometries were evaluated to optimize extraction performance, with a star-shaped design providing the highest extraction efficiency and reproducibility. Under optimized conditions, BPA retention reached 99%, and quantitative elution was achieved within 15 min using acetonitrile/phosphate-buffered saline containing adenosine triphosphate. The method provided a linear response between 2.5 and 2000 μg L^-1 (r² = 0.996), with limits of detection and quantification of 94 and 313 ng L^-1, respectively. Intra- and inter-device precision were 1.1% and 10.7% (relative standard deviation), and the device was reusable for at least four times. Application to commercial soft drinks yielded BPA recoveries from 87.8 to 99.5%. The proposed platform combines additive manufacturing versatility with aptamer selectivity, offering a simple, reusable, and sustainable alternative for selective extraction of BPA, a relevant endocrine-disrupting compound, in beverage analysis.