{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,5]],"date-time":"2026-09-05T05:17:31Z","timestamp":1788585451860,"version":"build-2803163510"},"reference-count":44,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T00:00:00Z","timestamp":1788393600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["52305606"],"award-info":[{"award-number":["52305606"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["U25A20273"],"award-info":[{"award-number":["U25A20273"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"award":["52305606"],"award-info":[{"award-number":["52305606"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"award":["U25A20273"],"award-info":[{"award-number":["U25A20273"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Key R&D Program of Shandong Province Shandong","award":["2025JMRH0304"],"award-info":[{"award-number":["2025JMRH0304"]}]},{"DOI":"10.13039\/501100007129","name":"Shandong Provincial Natural Science Foundation","doi-asserted-by":"crossref","award":["ZR2023QE187"],"award-info":[{"award-number":["ZR2023QE187"]}],"id":[{"id":"10.13039\/501100007129","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Basic Research Program of Jiangsu","award":["BK20230254"],"award-info":[{"award-number":["BK20230254"]}]},{"name":"Qilu Young Scholars Program of Shandong University"},{"id":[{"id":"https:\/\/ror.org\/0207yh398","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Saxitoxin (STX) is a highly potent marine biotoxin, and trace contamination in aquatic environments can pose serious risks to human health. Therefore, reliable detection of low-concentration STX is crucial for water safety monitoring. Here, we developed a robust electrochemical aptasensor based on a gold nanoparticle\/chitosan (AuNP\/CS) conductive network for STX detection in freshwater samples. The chitosan matrix provides a three-dimensional scaffold for aptamer immobilization, while interconnected AuNPs create efficient electron-transfer pathways across the sensing interface. This integrated architecture improves interfacial conductivity and supports stable target-induced aptamer recognition. The aptasensor exhibits a linear response from 1 to 1000 nM and a limit of detection of 0.74 nM, with an apparent dissociation constant Kd = 70.29 \u00b1 29.2 nM, together with high batch-to-batch consistency and long-term stability, retaining 93% of its initial response after 25 days. In spiked freshwater samples, the aptasensor achieved recoveries ranging from 99.10% to 111.33%, demonstrating the practical potential of this platform for monitoring STX contamination in aquatic environments.<\/jats:p>","DOI":"10.3390\/bios16090489","type":"journal-article","created":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T10:10:33Z","timestamp":1788430233000},"page":"489","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Robust Electrochemical Aptasensor Based on a AuNP\/Chitosan Conductive Network for Saxitoxin Detection in Freshwater Samples"],"prefix":"10.3390","volume":"16","author":[{"given":"Luyang","family":"Zhang","sequence":"first","affiliation":[{"name":"Key Laboratory of High Efficiency and Clean Mechanical Manufacture, School of Mechanical Engineering, Shandong University, Ministry of Education, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zongyu","family":"Yan","sequence":"additional","affiliation":[{"name":"Key Laboratory of High Efficiency and Clean Mechanical Manufacture, School of Mechanical Engineering, Shandong University, Ministry of Education, Jinan 250100, China"},{"name":"State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zaiyu","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of High Efficiency and Clean Mechanical Manufacture, School of Mechanical Engineering, Shandong University, Ministry of Education, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-7693-1390","authenticated-orcid":false,"given":"Ziran","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of High Efficiency and Clean Mechanical Manufacture, School of Mechanical Engineering, Shandong University, Ministry of Education, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-8776-7958","authenticated-orcid":false,"given":"Guorui","family":"Zhao","sequence":"additional","affiliation":[{"name":"Key Laboratory of High Efficiency and Clean Mechanical Manufacture, School of Mechanical Engineering, Shandong University, Ministry of Education, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.toxicon.2009.12.013","article-title":"Paralytic Shellfish Poisoning: Seafood Safety and Human Health Perspectives","volume":"56","author":"Etheridge","year":"2010","journal-title":"Toxicon"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"101271","DOI":"10.1016\/j.lanplh.2025.05.001","article-title":"Global Epidemiology of Paralytic Shellfish Poisoning: A Systematic Search Literature Review","volume":"9","author":"Gribble","year":"2025","journal-title":"Lancet Planet. Health"},{"key":"ref_3","first-page":"245","article-title":"Cause of Death in Experimental Paralytic Shellfish Poisoning (PSP)","volume":"46","author":"Evans","year":"1965","journal-title":"Br. J. Exp. Pathol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"91","DOI":"10.3109\/15569543.2011.640743","article-title":"Paralytic Shellfish Poisoning (PSP) Toxin- and\/or Tetrodotoxin-Contaminated Crabs and Food Poisoning by Them","volume":"30","author":"Noguchi","year":"2011","journal-title":"Toxin Rev."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"139515","DOI":"10.1016\/j.scitotenv.2020.139515","article-title":"Freshwater Neurotoxins and Concerns for Human, Animal, and Ecosystem Health: A Review of Anatoxin-a and Saxitoxin","volume":"736","author":"Christensen","year":"2020","journal-title":"Sci. Total Environ."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1039\/b501296c","article-title":"Saxitoxin, a Toxic Marine Natural Product That Targets a Multitude of Receptors","volume":"23","author":"Llewellyn","year":"2006","journal-title":"Nat. Prod. Rep."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1016\/j.etap.2016.09.020","article-title":"Low Dose Extended Exposure to Saxitoxin and Its Potential Neurodevelopmental Effects: A Review","volume":"48","author":"Musgrave","year":"2016","journal-title":"Environ. Toxicol. Pharmacol."},{"key":"ref_8","unstructured":"Office of Inspections and Investigations (2026, June 25). CPG Sec 540.250 Clams, Mussels, Oysters, Fresh, Frozen or Canned\u2014Paralytic Shellfish Poison, Available online: https:\/\/www.fda.gov\/regulatory-information\/search-fda-guidance-documents\/cpg-sec-540250-clams-mussels-oysters-fresh-frozen-or-canned-paralytic-shellfish-poison."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1007\/s10337-023-04251-6","article-title":"Research Progress on Extraction and Analytical Methods for Saxitoxin and Its Congeners","volume":"86","author":"Ishak","year":"2023","journal-title":"Chromatographia"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"146","DOI":"10.1007\/s13206-022-00054-3","article-title":"Recent Trends in Biosensors Based on Electrochemical and Optical Techniques for Cyanobacterial Neurotoxin Detection","volume":"16","author":"Park","year":"2022","journal-title":"BioChip J."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Jiao, Y., Yang, L., Hao, J., Wen, Y., Wang, J., E, H., Zhao, Z., Chen, Y., and Yang, X. (2025). Rapid Detection of Saxitoxin Using a Nucleic Acid Aptamer Biosensor Based on Graphene Oxide as a Fluorescence Quencher. Toxins, 17.","DOI":"10.3390\/toxins17090430"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"106190","DOI":"10.1016\/j.jfca.2024.106190","article-title":"A Dual-Mode Optical Sensor for Sensitive Detection of Saxitoxin in Shellfish Based on Three-in-One Functional Nanozymes","volume":"130","author":"Wu","year":"2024","journal-title":"J. Food Compos. Anal."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5433","DOI":"10.1039\/D4AY00932K","article-title":"Nanopillar Array-Based Electrochemical Aptamer Sensor for STX Sensitivity Detection","volume":"16","author":"Li","year":"2024","journal-title":"Anal. Methods"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1128\/JCM.40.1.271-274.2002","article-title":"Direct Detection and Characterization of Shiga Toxigenic Escherichia Coli by Multiplex PCR for Stx1, Stx2, Eae, ehxA, and Saa","volume":"40","author":"Paton","year":"2002","journal-title":"J. Clin. Microbiol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.chroma.2003.11.083","article-title":"Analysis of Cyanobacterial Toxins by Hydrophilic Interaction Liquid Chromatography\u2013Mass Spectrometry","volume":"1028","author":"Eaglesham","year":"2004","journal-title":"J. Chromatogr. A"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.chroma.2019.03.066","article-title":"Determination of Microcystins, Nodularin, Anatoxin-a, Cylindrospermopsin, and Saxitoxin in Water and Fish Tissue Using Isotope Dilution Liquid Chromatography Tandem Mass Spectrometry","volume":"1599","author":"Haddad","year":"2019","journal-title":"J. Chromatogr. A"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1016\/j.toxicon.2015.03.017","article-title":"Detection of Human Exposure to Saxitoxin and Neosaxitoxin in Urine by Online-Solid Phase Extraction-Liquid Chromatography\u2013Tandem Mass Spectrometry","volume":"99","author":"Bragg","year":"2015","journal-title":"Toxicon"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"110432","DOI":"10.1016\/j.microc.2024.110432","article-title":"A Novel Screening on the Specific Peptides by Molecular Simulation and Development of the Highly-Sensitive Electrochemical Sensor for Saxitoxin","volume":"200","author":"Liu","year":"2024","journal-title":"Microchem. J."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e20270","DOI":"10.1002\/adfm.202520270","article-title":"A Multiplexed and In Situ Self-Calibration Biosensor Integrated System for Metabolic Health Analysis in Human Urine","volume":"36","author":"Zhang","year":"2026","journal-title":"Adv. Funct. Mater."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1655","DOI":"10.1007\/s00216-010-3459-4","article-title":"Comparison of Analytical Tools and Biological Assays for Detection of Paralytic Shellfish Poisoning Toxins","volume":"397","author":"Humpage","year":"2010","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"405","DOI":"10.1111\/j.1745-4514.1991.tb00425.x","article-title":"Paralytic Shellfish Toxins: Their Origin, Characteristics and Methods of Detection: A Review","volume":"15","author":"Levin","year":"1991","journal-title":"J. Food Biochem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"114300","DOI":"10.1016\/j.bios.2022.114300","article-title":"Electrochemical Biosensor with Aptamer\/Porous Platinum Nanoparticle on Round-Type Micro-Gap Electrode for Saxitoxin Detection in Fresh Water","volume":"210","author":"Park","year":"2022","journal-title":"Biosens. Bioelectron."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"117033","DOI":"10.1016\/j.bios.2024.117033","article-title":"Electric Field-Induced Alignment of Ag\/Au Nanowires for Ultrasensitive in Situ Detection of Interleukin-6","volume":"271","author":"Li","year":"2025","journal-title":"Biosens. Bioelectron."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"990","DOI":"10.1002\/elan.201600652","article-title":"Development of an Electrochemical Biosensor for the Rapid Detection of Saxitoxin Based on Air Stable Lipid Films with Incorporated Anti-STX Using Graphene Electrodes","volume":"29","author":"Bratakou","year":"2017","journal-title":"Electroanalysis"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6393","DOI":"10.1007\/s00216-021-03603-1","article-title":"Electrochemical Impedance Biosensor for Detection of Saxitoxin in Aqueous Solution","volume":"413","author":"Serrano","year":"2021","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"46495","DOI":"10.1021\/acsami.4c11419","article-title":"Nanoflower Microreactor Based Versatile Enhancer for Recognition Cofactor-Dependent Enzyme Biocatalysis toward Saxitoxin Detection","volume":"16","author":"Wei","year":"2024","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"136811","DOI":"10.1016\/j.foodchem.2023.136811","article-title":"Highly Sensitive Electrochemical Peptide-Based Biosensor for Marine Biotoxin Detection Using a Bimetallic Platinum and Ruthenium Nanoparticle-Tethered Metal\u2013Organic Framework Modified Electrode","volume":"428","author":"Raju","year":"2023","journal-title":"Food Chem."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"122215","DOI":"10.1016\/j.talanta.2021.122215","article-title":"Highly Sensitive Electrochemical Detection of the Marine Toxins Okadaic Acid and Domoic Acid with Carbon Black Modified Screen Printed Electrodes","volume":"228","author":"Nelis","year":"2021","journal-title":"Talanta"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"143114","DOI":"10.1016\/j.chemosphere.2024.143114","article-title":"Enhancing Early Warning: A DNA Biosensor with Polyaniline\/Graphene Nanocomposite for Label-Free Voltammetric Detection of Saxitoxin-Producing Harmful Algae","volume":"364","author":"Akbar","year":"2024","journal-title":"Chemosphere"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"342134","DOI":"10.1016\/j.aca.2023.342134","article-title":"Development of a Highly Sensitive Aptamer-Based Electrochemical Sensor for Detecting Saxitoxin Based on K3Fe(CN)6 Regulated Silver Nanoparticles","volume":"1287","author":"Zeng","year":"2024","journal-title":"Anal. Chim. Acta"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Ullah, N., Chen, W., Noureen, B., Tian, Y., Du, L., Wu, C., and Ma, J. (2021). An Electrochemical Ti3C2Tx Aptasensor for Sensitive and Label-Free Detection of Marine Biological Toxins. Sensors, 21.","DOI":"10.3390\/s21144938"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"123185","DOI":"10.1016\/j.talanta.2021.123185","article-title":"An Electrochemical PAH-Modified Aptasensor for the Label-Free and Highly-Sensitive Detection of Saxitoxin","volume":"240","author":"Noureen","year":"2022","journal-title":"Talanta"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1971","DOI":"10.1007\/s00604-016-1836-1","article-title":"Amperometric Aptasensor for Saxitoxin Using a Gold Electrode Modified with Carbon Nanotubes on a Self-Assembled Monolayer, and Methylene Blue as an Electrochemical Indicator Probe","volume":"183","author":"Hou","year":"2016","journal-title":"Microchim. Acta"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1016\/j.toxicon.2012.10.015","article-title":"First Report of the Use of a Saxitoxin\u2013Protein Conjugate to Develop a DNA Aptamer to a Small Molecule Toxin","volume":"61","author":"Handy","year":"2013","journal-title":"Toxicon"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1016\/j.toxicon.2015.04.017","article-title":"A Saxitoxin-Binding Aptamer with Higher Affinity and Inhibitory Activity Optimized by Rational Site-Directed Mutagenesis and Truncation","volume":"101","author":"Zheng","year":"2015","journal-title":"Toxicon"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"902","DOI":"10.1080\/00032719.2018.1505900","article-title":"Determination of Saxitoxin by Aptamer-Based Surface-Enhanced Raman Scattering","volume":"52","author":"Cheng","year":"2019","journal-title":"Anal. Lett."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"23801","DOI":"10.1039\/D2RA03690H","article-title":"A Simple Electrochemical Aptasensor for Saxitoxin Detection","volume":"12","author":"Zheng","year":"2022","journal-title":"RSC Adv."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1016\/j.saa.2018.06.036","article-title":"Study of the Binding Way between Saxitoxin and Its Aptamer and a Fluorescent Aptasensor for Detection of Saxitoxin","volume":"204","author":"Cheng","year":"2018","journal-title":"Spectrochim. Acta Part A Mol. Biomol. Spectrosc."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"4690","DOI":"10.1039\/c4cc01290a","article-title":"Use of Thiolated Oligonucleotides as Anti-Fouling Diluents in Electrochemical Peptide-Based Sensors","volume":"50","author":"McQuistan","year":"2014","journal-title":"Chem. Commun."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"8888","DOI":"10.1021\/ac5027226","article-title":"Effects of DNA Probe and Target Flexibility on the Performance of a \u201cSignal-on\u201d Electrochemical DNA Sensor","volume":"86","author":"Wu","year":"2014","journal-title":"Anal. Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3422","DOI":"10.1039\/c3cc41281d","article-title":"Development of a \u201cSignal-on\u201d Electrochemical DNA Sensor with an Oligo-Thymine Spacer for Point Mutation Detection","volume":"49","author":"Wu","year":"2013","journal-title":"Chem. Commun."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"117152","DOI":"10.1016\/j.bios.2025.117152","article-title":"An aptamer-based electrochemical sensor for the quantification of the malaria biomarker lactate dehydrogenase","volume":"274","author":"Yang","year":"2025","journal-title":"Biosens. Bioelectron."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/j.snb.2017.02.078","article-title":"A Biolayer Interferometry-Based Competitive Biosensor for Rapid and Sensitive Detection of Saxitoxin","volume":"246","author":"Gao","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"130320","DOI":"10.1016\/j.snb.2021.130320","article-title":"Development of a Terminal-Fixed Aptamer and a Label-Free Colorimetric Aptasensor for Highly Sensitive Detection of Saxitoxin","volume":"344","author":"Li","year":"2021","journal-title":"Sens. Actuators B Chem."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/9\/489\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,5]],"date-time":"2026-09-05T04:51:40Z","timestamp":1788583900000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/9\/489"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,3]]},"references-count":44,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["bios16090489"],"URL":"https:\/\/doi.org\/10.3390\/bios16090489","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,3]]}}}