RT journal article T1 Magnetic Molecularly Imprinted Chitosan Combined with a Paper-Based Analytical Device for the Smartphone Discrimination of Tryptophan Enantiomers A1 Karrat, Abdelhafid A1 García Guzmán, Juan José A1 Palacios Santander, José María A1 Amine, Aziz A1 Cubillana Aguilera, Laura A2 Química Analítica K1 chitosan K1 discrimination of enantiomers K1 magnetic molecularly imprinted polymer K1 paper-based analytical device K1 smartphone K1 tryptophan AB The separation of enantiomers plays a critical role in pharmaceutical development, ensuring therapeutic efficacy, safety, and patent protection. It enables the production of enantiopure drugs and enhances our understanding of the properties of chiral compounds. In this study, a straightforward and effective chiral detection strategy was developed for distinguishing between tryptophan (TRP) enantiomers. The approach involved the preparation of a magnetic molecularly imprinted chitosan (MMIC) for preparation of the sample, which was combined with a nitrocellulose membrane (a paper-based analytical device, PAD) integrated with D-TRP covalently grafted with polymethacrylic acid (PAD-PMA_D-TRP). Discriminating between the TRP enantiomers was achieved using AuNPs as a colorimetric probe. Indeed, the presence of D-TRP rapidly induced the aggregation of AuNPs due to its strong affinity to PAD-PMA_D-TRP, resulting in a noticeable change in the color of the AuNPs from red to purple. On the other hand, L-TRP did not induce any color changes. The chiral analysis could be easily performed with the naked eye and/or a smartphone. The developed method exhibited a detection limit of 3.3 µM, and it was successfully applied to detect TRP in serum samples, demonstrating good recovery rates. The proposed procedure is characterized by its simplicity, cost-effectiveness, rapidity, and ease of operation PB Multidisciplinary Digital Publishing Institute (MDPI) SN 2079-6374 YR 2023 FD 2023 LK http://hdl.handle.net/10498/31783 UL http://hdl.handle.net/10498/31783 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 10-nov-2026