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Building a Fluorescent Aptasensor Based on Exonuclease-Assisted Target Recycling Strategy for One-Step Detection of T-2 Toxin
摘要： In this work, a rapid and accurate assay was successfully developed for T-2 toxin detection based on exonuclease-catalyzed target recycling strategy. Upconversion nanoparticles (UCNPs) were conjugated with T-2 aptamer and used as signal probes, while magnetic nanoparticles (MNPs) were conjugated with the complementary DNA of T-2 aptamer (cDNA) and used as capture probes. The results reveled that good linear correlation (R2 = 0.9988) was achieved for T-2 toxin detection over the concentration range of 0.1–100 ng/mL with a detection limit as low as 0.035 ng/mL (S/N = 3). In addition, the reliability of the proposed method was also applied to the determination of T-2 toxin contents in real food samples and the average recoveries ranged from 95.97 to 104.00%. The sensing platform developed in our study demonstrated great potential for simple and sensitive detection of T-2 toxin contents in food samples.
关键词： T-2 toxin,Food safety,Fluorescence,Aptasensor,Target recycling strategy
更新于2025-09-23 15:23:52
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G-quadruplex specific dye-based ratiometric FRET aptasensor for robust and ultrafast detection of toxin
摘要： G-quadruplex specific dyes are powerful tools for probing nucleic acid structures. Among nucleic acids, aptamers are of great interest, and widely exploited to construct versatile bioassays. Herein, based on G-quadruplex selective dye, thioflavin T (ThT), for probing the intrinsic structure of aptamers, we proposed a ratiometric fluorescence resonance energy transfer (FRET) aptasensor enabling robust and ultrafast detection of toxin. The binding of target ochratoxin A (OTA) would destruct the G-quadruplex structure of aptamer. It would lead to the detachment of ThT dye from aptamer which diminished the FRET effect between ThT and terminal-labeled dye, thus allowing quantification of OTA via FRET signals. The FRET aptasensor would confer an enhancement of 76.9% of signal to background ratio compared to the ThT-based non-FRET aptasensor. Remarkably, the FRET mechanism would eliminate the signal fluctuation resulted from varied probe concentration, thus benefiting the robustness of the assay. The aptasensor could achieve a detection of limit of 0.38 ng/mL for OTA detection. And the detection of OTA could be finished within 30 s. Besides, the assay was successful in analyzing OTA in coffee and oat samples with recoveries rate of 93.93%–107.59%. Therefore, G-quadruplex specific dye-based probing and FRET method would be a compelling design strategy for aptasensor, and may facilitate their practical application in food safety and environmental screening.
关键词： Fluorescence resonance energy transfer,G-quadruplex specific dyes,Homogeneous analysis,Toxin,Thioflavin T,Aptamer
更新于2025-09-23 15:23:52
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Determination of Saxitoxin by Aptamer-Based Surface-Enhanced Raman Scattering
摘要： Saxitoxin is one of the most harmful paralytic shellfish toxins due to its high toxicity and adverse effects on the environment and human health. Aptasensors provide simple detection procedures because they have the advantages of chemical stability, easy synthesis and modification, and high convenience in signal transformation. Surface-enhanced Raman scattering (SERS) is an analytical technique that amplifies the analytical signals of molecules at extremely low concentrations, or even at the single molecule level, when the analyte is very close to rough metal surfaces or nanostructures. In this study, an SERS aptasensor is reported for the determination of saxitoxin for the first time. The optimized saxitoxin aptamer (M-30f) was modified on gold nanoparticles and served as the recognition element. Crystal violet was used as the Raman reporter without chemical bounding. The analytical principles of the aptasensor are that saxitoxin destabilized the conformations of the aptamer at high temperature conditions and altered the binding of crystal violet on the gold nanoparticles. In the presence of saxitoxin, the conformation of aptamer containing the G-quadruplex that selectively bound crystal violet unfolded to a large extent and hence the crystal violet molecules were released from gold nanoparticles with a reduced SERS signal. The effects of the gold nanoparticle size, the amount of DNA, aptamer density, sodium chloride concentration, and operation temperature upon the SERS determination were optimized. The resulting simple SERS aptasensor was developed with a satisfactory limit of detection (11.7 nM) and selectivity. The application for the analysis of real shellfish samples with simple procedures demonstrates that this SERS aptasensor is promising for on-site applications.
关键词： saxitoxin,paralytic shellfish toxin,surface-enhanced Raman scattering (SERS),Aptamer
更新于2025-09-23 15:23:52
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Immunochromatographic assay for T-2 toxin based on luminescent quantum dot beads
摘要： A quantum dot bead based immunochromatographic assay (QB-ICA) system was established for T-2 toxin (T-2), which widely occurs in agriculture and could be used as a potential biological warfare agent. After optimization, the dynamic linear detection range of T-2 calculated from a calibration curve was from 0.12 to 0.67 ng mL(cid:1)1 and the limit of detection (LOD) was 0.08 ng mL(cid:1)1, which is lower than those of the ICA based on colloidal gold nanoparticles or a ?uorescent material or an antibody-based biochip in other reports. The performance and practicability of the established ICA system were validated with a commercial ELISA kit and the two methods were comparable. The proposed QB-ICA for T-2 could be an alternative for rapid, sensitive, and quantitative on-site detection of this toxin in biosafety monitoring in agriculture and for susceptibility testing of the potential release of this biological warfare agent.
关键词： Biological warfare agent,Quantum dot beads,T-2 toxin,Biosafety monitoring,Immunochromatographic assay
更新于2025-09-16 10:30:52
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Visualizing the Pharmacologic Preconditioning Effect of Botulinum Toxin Type A by Infrared Thermography in a Rat Pedicled Perforator Island Flap Model
摘要： Background: Surgical delay can improve flap viability, leading to vasodilation, neovascularization, and vessel reorganization. Experiments suggest a similar positive effect of botulinum toxin type A on pedicled flap viability. However, whether it may convert choke anastomoses into true anastomoses and how to identify the optimal timing for flap transfer remain unclear. Methods: One hundred fifty-four Sprague-Dawley rats were divided into a control group, three saline injection groups, and three botulinum toxin type A injection groups defined by time of injection (2, 3, and 4 weeks before flap harvest). A pedicled 11 × 3-cm flap was marked on the unilateral dorsum of each rat. Before flap harvest, the flap donors were assessed by infrared thermal imaging, postmortem arteriography, immunohistochemical staining of CD31, and enzyme-linked immunosorbent assay. Flap survival area percentage was measured on postoperative day 7. Results: In the control and saline groups, infrared thermography showed three independent white hotspots interspaced by red zones over flaps, whereas it presented a continuous white band in the botulinum toxin type A groups. There was a significant increase in flap survival area, flap surface temperatures, numbers of identifiable vessels in the choke zones, microvascular density, and vascular endothelial growth factor concentration in the botulinum toxin type A groups. Conclusions: Botulinum toxin type A can convert choke anastomoses into true anastomoses, and its preconditioning effect cannot increase over time; it is appropriate to choose the timing point when the infrared thermal images show a continuous white band existing over flaps for flap transfer.
关键词： pedicled perforator island flap,flap viability,surgical delay,botulinum toxin type A,infrared thermography
更新于2025-09-12 10:27:22