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Updated: Feb 3, 2026

Development of an Electrochemical DNA Biosensor to Detect a Foodborne Pathogen
Published on: June 3, 2018
Development of LMW chitosan-stabilized gold nanoparticle DNA biosensors functionalized with thiolated probe for
Jessa D Alonzo1, Kristopher Ray S Pamintuan2, Khyle Glainmer N Quiton2
1School of Graduate Studies, Mapúa University, Muralla Street, Intramuros, Manila, 1002, Philippines; School of Chemical, Biological, and Materials Engineering and Sciences, Mapúa University, Muralla Street, Intramuros, Manila, 1002, Philippines; Department of Chemical Engineering, College of Engineering, Mariano Marcos State University, City of Batac, 2906, Ilocos Norte, Philippines.
Abstract:
Acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio parahaemolyticus (Vp) carrying pirvpA/pirvpB, continues to threaten shrimp aquaculture across Asia. This study demonstrates a laboratory proof-of-concept gold nanoparticle-based (AuNPs) colorimetric biosensor targeting the pirvpA gene of Vp. Citrate-reduced AuNPs (∼15.54 nm; SPR ≈ 520 nm) were functionalized with thiolated ssDNA probes (AuNP-Probe) using a deoxyadenosine triphosphate-assisted immobilization strategy and subsequently stabilized with low molecular weight (LMW) chitosan (AuNP-Probe-Chit). Loop-mediated isothermal amplification (LAMP) generated the target DNA, while detection relied on salt-induced aggregation assessed by visual color/precipitate formation and UV-Vis spectral shifts (A650/Aλmax, λmax ≈ 532 nm for AuNP-Probe-Chit). Optimization identified 1.0 μM probe and 0.01% (v/v) chitosan as the optimal conditions for forming stable conjugates. Upon hybridization, an 8:2 (v/v) AuNP-Probe-Chit:LAMP mixture, combined with 0.5 M NaCl, enabled clear discrimination between positive and negative samples. Positives retained a pink-red supernatant with minimal aggregation, whereas negatives formed precipitates and exhibited higher aggregation indices. The biosensor demonstrated strong specificity for pirvpA-positive DNA, without cross-reacting with Vibrio vulnificus or Vibrio alginolyticus, and exhibited sensitivity approaching the LAMP amplification threshold, with reliable discrimination observed at ≥10-1 ng of target DNA. These findings establish a robust, equipment-lean diagnostic platform that integrates sequence-specific hybridization with polymer-mediated colloidal stabilization. The AuNP-Probe-Chit system offers rapid, visible discrimination, highlighting its potential for future AHPND surveillance in resource-limited settings. Compared with previous works, the incorporation of thiolated ssDNA probe functionalization with chitosan stabilization within a single AuNPs-based platform tailored for aquaculture pathogens, such as Vp, is currently underexplored, highlighting a significant need that this study aims to address.
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