title: A highly sensitive fluorescence resonance energy transfer aptasensor for staphylococcal enterotoxin B detection based on exonuclease-catalyzed target recycling strategy.
abstract: An ultrasensitive fluorescence resonance energy transfer (FRET) bioassay was developed to detect staphylococcal enterotoxin B (SEB), a low molecular exotoxin, using an aptamer-affinity method coupled with upconversion nanoparticles (UCNPs)-sensing, and the fluorescence intensity was prominently enhanced using an exonuclease-catalyzed target recycling strategy. To construct this aptasensor, both fluorescence donor probes (complementary DNA1-UCNPs) and fluorescence quencher probes (complementary DNA2-Black Hole Quencher3 (BHQ3)) were hybridized to an SEB aptamer, and double-strand oligonucleotides were fabricated, which quenched the fluorescence of the UCNPs via FRET. The formation of an aptamer-SEB complex in the presence of the SEB analyte resulted in not only the dissociation of aptamer from the double-strand DNA but also both the disruption of the FRET system and the restoration of the UCNPs fluorescence. In addition, the SEB was liberated from the aptamer-SEB complex using exonuclease I, an exonuclease specific to single-stranded DNA, for analyte recycling by selectively digesting a particular DNA (SEB aptamer). Based on this exonuclease-catalyzed target recycling strategy, an amplified fluorescence intensity could be produced using different SEB concentrations. Using optimized experimental conditions produced an ultrasensitive aptasensor for the detection of SEB, with a wide linear range of 0.001-1 ng mL(-1) and a lower detection limit (LOD) of 0.3 pg mL(-1) SEB (at 3σ). The fabricated aptasensor was used to measure SEB in a real milk samples and validated using the ELISA method. Furthermore, a novel aptasensor FRET assay was established for the first time using 30 mol% Mn(2+) ions doped NaYF4:Yb/Er (20/2 mol%) UCNPs as the donor probes, which suggests that UCNPs are superior fluorescence labeling materials for food safety analysis.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors.forename: Shijia
authors.initials: S
authors.lastname: Wu
authors.forename: Nuo
authors.initials: N
authors.lastname: Duan
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Ma
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.forename: Hongxin
authors.initials: H
authors.lastname: Wang
authors.forename: Zhouping
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide; D004768:Enterotoxins / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D005090:Exodeoxyribonucleases / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination; D008892:Milk / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D009829:Oleic Acids / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D052157:Aptamers, Nucleotide; D004768:Enterotoxins; D009829:Oleic Acids; C031818:enterotoxin B, staphylococcal; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I