{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T02:33:48Z","timestamp":1791426828643,"version":"4.3.3"},"reference-count":39,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2023,8,20]],"date-time":"2023-08-20T00:00:00Z","timestamp":1692489600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Erasmus+ KA107 (EU) Program of the University of C\u00e1diz (Spain)","award":["MCIN\/AEI\/10.13039\/501100011033\/FEDER"],"award-info":[{"award-number":["MCIN\/AEI\/10.13039\/501100011033\/FEDER"]}]},{"name":"Erasmus+ KA107 (EU) Program of the University of C\u00e1diz (Spain)","award":["SC2022\u2013001"],"award-info":[{"award-number":["SC2022\u2013001"]}]},{"name":"Erasmus+ KA107 (EU) Program of the University of C\u00e1diz (Spain)","award":["PR2022-025, SENSPOT"],"award-info":[{"award-number":["PR2022-025, SENSPOT"]}]},{"name":"EU \u201cERDF: A way of making Europe\u201d","award":["MCIN\/AEI\/10.13039\/501100011033\/FEDER"],"award-info":[{"award-number":["MCIN\/AEI\/10.13039\/501100011033\/FEDER"]}]},{"name":"EU \u201cERDF: A way of making Europe\u201d","award":["SC2022\u2013001"],"award-info":[{"award-number":["SC2022\u2013001"]}]},{"name":"EU \u201cERDF: A way of making Europe\u201d","award":["PR2022-025, SENSPOT"],"award-info":[{"award-number":["PR2022-025, SENSPOT"]}]},{"name":"University of Cadiz","award":["MCIN\/AEI\/10.13039\/501100011033\/FEDER"],"award-info":[{"award-number":["MCIN\/AEI\/10.13039\/501100011033\/FEDER"]}]},{"name":"University of Cadiz","award":["SC2022\u2013001"],"award-info":[{"award-number":["SC2022\u2013001"]}]},{"name":"University of Cadiz","award":["PR2022-025, SENSPOT"],"award-info":[{"award-number":["PR2022-025, SENSPOT"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>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 \u00b5M, 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.<\/jats:p>","DOI":"10.3390\/bios13080830","type":"journal-article","created":{"date-parts":[[2023,8,21]],"date-time":"2023-08-21T01:49:34Z","timestamp":1692582574000},"page":"830","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Magnetic Molecularly Imprinted Chitosan Combined with a Paper-Based Analytical Device for the Smartphone Discrimination of Tryptophan Enantiomers"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3341-5232","authenticated-orcid":false,"given":"Abdelhafid","family":"Karrat","sequence":"first","affiliation":[{"name":"Department of Analytical Chemistry, Institute of Research on Electron Microscopy and Materials (IMEYMAT), Faculty of Sciences, Campus de Excelencia Internacional del Mar (CEIMAR), University of Cadiz, Campus Universitario de Puerto Real, Pol\u00edgono del R\u00edo San Pedro S\/N, 11510 Puerto Real, C\u00e1diz, Spain"},{"name":"Laboratory of Process Engineering & Environment, Faculty of Science and Technology, Hassan II University of Casablanca, B.P. 146, Mohammedia 28810, Morocco"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan Jos\u00e9","family":"Garc\u00eda-Guzm\u00e1n","sequence":"additional","affiliation":[{"name":"Department of Analytical Chemistry, Institute of Research on Electron Microscopy and Materials (IMEYMAT), Faculty of Sciences, Campus de Excelencia Internacional del Mar (CEIMAR), University of Cadiz, Campus Universitario de Puerto Real, Pol\u00edgono del R\u00edo San Pedro S\/N, 11510 Puerto Real, C\u00e1diz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5407-1208","authenticated-orcid":false,"given":"Jos\u00e9 Mar\u00eda","family":"Palacios-Santander","sequence":"additional","affiliation":[{"name":"Department of Analytical Chemistry, Institute of Research on Electron Microscopy and Materials (IMEYMAT), Faculty of Sciences, Campus de Excelencia Internacional del Mar (CEIMAR), University of Cadiz, Campus Universitario de Puerto Real, Pol\u00edgono del R\u00edo San Pedro S\/N, 11510 Puerto Real, C\u00e1diz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7909-2224","authenticated-orcid":false,"given":"Aziz","family":"Amine","sequence":"additional","affiliation":[{"name":"Laboratory of Process Engineering & Environment, Faculty of Science and Technology, Hassan II University of Casablanca, B.P. 146, Mohammedia 28810, Morocco"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3559-2697","authenticated-orcid":false,"given":"Laura","family":"Cubillana-Aguilera","sequence":"additional","affiliation":[{"name":"Department of Analytical Chemistry, Institute of Research on Electron Microscopy and Materials (IMEYMAT), Faculty of Sciences, Campus de Excelencia Internacional del Mar (CEIMAR), University of Cadiz, Campus Universitario de Puerto Real, Pol\u00edgono del R\u00edo San Pedro S\/N, 11510 Puerto Real, C\u00e1diz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,8,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"115640","DOI":"10.1016\/j.trac.2019.115640","article-title":"Enantiomers Separation by Capillary Electrochromatography","volume":"120","author":"Fanali","year":"2019","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1002\/chir.22139","article-title":"Differential Pharmacologic Properties of the Two C75 Enantiomers: (+)-C75 Is a Strong Anorectic Drug; (\u2212)-C75 Has Antitumor Activity: Stereoselectivity of c75 enantiomers","volume":"25","author":"Makowski","year":"2013","journal-title":"Chirality"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1294","DOI":"10.1038\/s41598-018-19202-7","article-title":"Structural Basis of Thalidomide Enantiomer Binding to Cereblon","volume":"8","author":"Mori","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"140409","DOI":"10.1016\/j.electacta.2022.140409","article-title":"Fusiform-like Metal-Organic Framework for Enantioselective Discrimination of Tryptophan Enantiomers","volume":"419","author":"Li","year":"2022","journal-title":"Electrochim. Acta"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"870","DOI":"10.1016\/j.talanta.2017.10.005","article-title":"Chiral Recognition of Tryptophan Enantiomers Using Chitosan-Capped Silver Nanoparticles: Scanometry and Spectrophotometry Approaches","volume":"178","author":"Jafari","year":"2018","journal-title":"Talanta"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"461147","DOI":"10.1016\/j.chroma.2020.461147","article-title":"Synthesis of Molecularly Imprinted Polymer Modified Magnetic Particles for Chiral Separation of Tryptophan Enantiomers in Aqueous Medium","volume":"1622","author":"Liu","year":"2020","journal-title":"J. Chromatogr. A"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1195","DOI":"10.1007\/s00726-010-0752-7","article-title":"Tryptophan Metabolism, from Nutrition to Potential Therapeutic Applications","volume":"41","author":"Otten","year":"2011","journal-title":"Amino Acids"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1038\/s41573-019-0016-5","article-title":"Tryptophan Metabolism as a Common Therapeutic Target in Cancer, Neurodegeneration and Beyond","volume":"18","author":"Platten","year":"2019","journal-title":"Nat. Rev. Drug Discov."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1007\/s00216-007-1427-4","article-title":"Chiral Recognition Applications of Molecularly Imprinted Polymers: A Critical Review","volume":"389","author":"Maier","year":"2007","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"133751","DOI":"10.1016\/j.snb.2023.133751","article-title":"New Strategies for the Removal of Template from the Ion and Molecularly Imprinted Polymers: Application to the Fast and on-Site Cr(VI) Detection with a Smartphone","volume":"386","author":"Karrat","year":"2023","journal-title":"Sens. Actuators B Chem."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"D\u00edaz-\u00c1lvarez, M., and Mart\u00edn-Esteban, A. (2021). Molecularly Imprinted Polymer-Quantum Dot Materials in Optical Sensors: An Overview of Their Synthesis and Applications. Biosensors, 11.","DOI":"10.3390\/bios11030079"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1016\/j.trac.2018.01.011","article-title":"Application of Molecularly Imprinted Polymers in Analytical Chiral Separations and Analysis","volume":"102","author":"Rutkowska","year":"2018","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"108157","DOI":"10.1016\/j.microc.2022.108157","article-title":"Advanced Molecularly Imprinted Polymer-Based Paper Analytical Device for Selective and Sensitive Detection of Bisphenol-A in Water Samples","volume":"184","author":"Karrat","year":"2023","journal-title":"Microchem. J."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"642","DOI":"10.1016\/j.tifs.2021.03.003","article-title":"Molecularly Imprinted Polymers for Food Applications: A Review","volume":"111","author":"Villa","year":"2021","journal-title":"Trends Food Sci. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Li, R., Feng, Y., Pan, G., and Liu, L. (2019). Advances in Molecularly Imprinting Technology for Bioanalytical Applications. Sensors, 19.","DOI":"10.3390\/s19010177"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Kadhem, A.J., Gentile, G.J., and Fidalgo de Cortalezzi, M.M. (2021). Molecularly Imprinted Polymers (MIPs) in Sensors for Environmental and Biomedical Applications: A Review. Molecules, 26.","DOI":"10.3390\/molecules26206233"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.teac.2018.01.001","article-title":"Green Aspects in Molecular Imprinting Technology: From Design to Environmental Applications","volume":"17","author":"Madikizela","year":"2018","journal-title":"Trends Environ. Anal. Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"128787","DOI":"10.1016\/j.snb.2020.128787","article-title":"Surface Molecularly-Imprinted Magnetic Nanoparticles Coupled with SERS Sensing Platform for Selective Detection of Malachite Green","volume":"325","author":"Ekmen","year":"2020","journal-title":"Sens. Actuators B Chem."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Moya Betancourt, S.N., C\u00e1mara, C.I., and Riva, J.S. (2023). Interaction between Pharmaceutical Drugs and Polymer-Coated Fe3O4 Magnetic Nanoparticles with Langmuir Monolayers as Cellular Membrane Models. Pharmaceutics, 15.","DOI":"10.3390\/pharmaceutics15020311"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"105055","DOI":"10.1016\/j.reactfunctpolym.2021.105055","article-title":"Preparation and Evaluation of Magnetic Graphene Oxide Molecularly Imprinted Polymers (MIPs-GO-Fe3O4@SiO2) for the Analysis and Separation of Tripterine","volume":"169","author":"Chen","year":"2021","journal-title":"React. Funct. Polym."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2821","DOI":"10.1002\/adfm.201202397","article-title":"Solid-Phase Synthesis of Molecularly Imprinted Polymer Nanoparticles with a Reusable Template\u2014\u201cPlastic Antibodies\u201d","volume":"23","author":"Poma","year":"2013","journal-title":"Adv. Funct. Mater."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1841","DOI":"10.1007\/s11356-011-0703-1","article-title":"Removal of Cyanotoxins from Surface Water Resources Using Reusable Molecularly Imprinted Polymer Adsorbents","volume":"19","author":"Krupadam","year":"2012","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"115982","DOI":"10.1016\/j.trac.2020.115982","article-title":"Electrochemical Sensors Based on Molecularly Imprinted Chitosan: A Review","volume":"130","author":"Zouaoui","year":"2020","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Mulyasuryani, A., Prananto, Y.P., Fardiyah, Q., Widwiastuti, H., and Darjito, D. (2023). Application of Chitosan-Based Molecularly Imprinted Polymer in Development of Electrochemical Sensor for p-Aminophenol Determination. Polymers, 15.","DOI":"10.3390\/polym15081818"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"754","DOI":"10.3934\/publichealth.2021059","article-title":"Preparation of Teucrium polium extract-loaded chitosan-sodium lauryl sulfate beads and chitosan-alginate films for wound dressing application","volume":"8","author":"Kharroubi","year":"2021","journal-title":"AIMS Public Health"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1757","DOI":"10.1007\/s11433-011-4486-7","article-title":"Utilization of Unmodified Gold Nanoparticles in Colorimetric Detection","volume":"54","author":"He","year":"2011","journal-title":"Sci. China Phys. Mech. Astron."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Chang, C.-C., Chen, C.-P., Wu, T.-H., Yang, C.-H., Lin, C.-W., and Chen, C.-Y. (2019). Gold Nanoparticle-Based Colorimetric Strategies for Chemical and Biological Sensing Applications. Nanomaterials, 9.","DOI":"10.3390\/nano9060861"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Chahri, I., Karrat, A., Mohammadi, H., and Amine, A. (2023). Development of a New Route for the Immobilization of Unmodified Single-Stranded DNA on Chitosan Beads and Detection of Released Guanine after Hydrolysis. Molecules, 28.","DOI":"10.3390\/molecules28052088"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"11835","DOI":"10.1021\/acs.chemrev.0c01335","article-title":"Microfluidic Paper-Based Analytical Devices: From Design to Applications","volume":"121","author":"Noviana","year":"2021","journal-title":"Chem. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1021\/ac9013989","article-title":"Diagnostics for the Developing World: Microfluidic Paper-Based Analytical Devices","volume":"82","author":"Martinez","year":"2010","journal-title":"Anal. Chem."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1016\/j.trac.2018.08.018","article-title":"Detection Methods and Applications of Microfluidic Paper-Based Analytical Devices","volume":"107","author":"Fu","year":"2018","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"6626","DOI":"10.1016\/j.arabjc.2020.06.018","article-title":"A Novel Electrochemical Sensor Based on Magnetic Core@shell Molecularly Imprinted Nanocomposite (Fe3O4@graphene Oxide@MIP) for Sensitive and Selective Determination of Anticancer Drug Capecitabine","volume":"13","author":"Afzali","year":"2020","journal-title":"Arab. J. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"789","DOI":"10.1016\/j.ultsonch.2010.10.009","article-title":"New, Fast and Green Procedure for the Synthesis of Gold Nanoparticles Based on Sonocatalysis","volume":"18","author":"Gil","year":"2011","journal-title":"Ultrason. Sonochemistry"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1016\/j.jallcom.2007.11.100","article-title":"Preparation and Properties of Magnetic Fe3O4\u2013Chitosan Nanoparticles","volume":"466","author":"Li","year":"2008","journal-title":"J. Alloy. Compd."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"6892","DOI":"10.1002\/slct.201801289","article-title":"Smartphone-Assisted Colorimetric Detection of Cr3+ Using Vitamin B6 Cofactor Functionalized Gold Nanoparticles and Its Applications in Real Sample Analyses","volume":"3","author":"Upadhyay","year":"2018","journal-title":"ChemistrySelect"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Karrat, A., and Amine, A. (2022). Paper-Based Analytical Device for One-Step Detection of Bisphenol-A Using Functionalized Chitosan. Chemosensors, 10.","DOI":"10.3390\/chemosensors10110450"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"548","DOI":"10.1016\/j.trac.2019.06.019","article-title":"The Modern Role of Smartphones in Analytical Chemistry","volume":"118","author":"Rezazadeh","year":"2019","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"136376","DOI":"10.1016\/j.foodchem.2023.136376","article-title":"A Wearable Gloved Sensor Based on Fluorescent Ag Nanoparticles and Europium Complexes for Visualized Assessment of Tetracycline in Food Samples","volume":"424","author":"Xu","year":"2023","journal-title":"Food Chem."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"127741","DOI":"10.1016\/j.cej.2020.127741","article-title":"A Smartphone-Integrated Method for Visual Detection of Tetracycline","volume":"416","author":"Xu","year":"2021","journal-title":"Chem. Eng. J."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/13\/8\/830\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:37:48Z","timestamp":1760128668000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/13\/8\/830"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,8,20]]},"references-count":39,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2023,8]]}},"alternative-id":["bios13080830"],"URL":"https:\/\/doi.org\/10.3390\/bios13080830","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,8,20]]}}}