title: Design and synthesis of target-responsive aptamer-cross-linked hydrogel for visual quantitative detection of ochratoxin A.
abstract: A target-responsive aptamer-cross-linked hydrogel was designed and synthesized for portable and visual quantitative detection of the toxin Ochratoxin A (OTA), which occurs in food and beverages. The hydrogel network forms by hybridization between one designed DNA strand containing the OTA aptamer and two complementary DNA strands grafting on linear polyacrylamide chains. Upon the introduction of OTA, the aptamer binds with OTA, leading to the dissociation of the hydrogel, followed by release of the preloaded gold nanoparticles (AuNPs), which can be observed by the naked eye. To enable sensitive visual and quantitative detection, we encapsulated Au@Pt core-shell nanoparticles (Au@PtNPs) in the hydrogel to generate quantitative readout in a volumetric bar-chart chip (V-Chip). In the V-Chip, Au@PtNPs catalyzes the oxidation of H2O2 to generate O2, which induces movement of an ink bar to a concentration-dependent distance for visual quantitative readout. Furthermore, to improve the detection limit in complex real samples, we introduced an immunoaffinity column (IAC) of OTA to enrich OTA from beer. After the enrichment, as low as 1.27 nM (0.51 ppb) OTA can be detected by the V-Chip, which satisfies the test requirement (2.0 ppb) by the European Commission. The integration of a target-responsive hydrogel with portable enrichment by IAC, as well as signal amplification and quantitative readout by a simple microfluidic device, offers a new method for portable detection of food safety hazard toxin OTA.
authors.forename: Rudi
authors.initials: R
authors.lastname: Liu
authors.forename: Yishun
authors.initials: Y
authors.lastname: Huang
authors.forename: Yanli
authors.initials: Y
authors.lastname: Ma
authors.forename: Shasha
authors.initials: S
authors.lastname: Jia
authors.forename: Mingxuan
authors.initials: M
authors.lastname: Gao
authors.forename: Jiuxing
authors.initials: J
authors.lastname: Li
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: ‡Xiamen Entry-Exit Inspection and Quarantine Bureau, Xiamen 361026, China.
authors.forename: Dunming
authors.initials: D
authors.lastname: Xu
authors.affiliation: ‡Xiamen Entry-Exit Inspection and Quarantine Bureau, Xiamen 361026, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.affiliation: ‡Xiamen Entry-Exit Inspection and Quarantine Bureau, Xiamen 361026, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhu
authors.forename: Chaoyong
authors.initials: C
authors.lastname: Yang
mesh_terms: D052157:Aptamers, Nucleotide / Q000138:chemical synthesis / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000138:chemical synthesis / Q000737:chemistry*; D009183:Mycotoxins / Q000032:analysis*; D009793:Ochratoxins / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D009183:Mycotoxins; D009793:Ochratoxins; C025589:ochratoxin A; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate
keywords: DNA hydrogel; Ochratoxin A; microfluidics; visual detection