The Rapid Visualization Detection Of Ochratoxin A And The Studies On The Interaction Between Aptamers And Toxin Molecules

In this study,a simple and sensitive aptamer-based colorimetric method for the detection of Ochratoxin A by using gold nanoparticles(AuNPs)has been developed.In this assay,unmodified gold nanoparticles(AuNPs)were used as probes with a 36-mer aptamer as recognition element.In the absence of Ochratoxin A,free aptamer could be adsorbed onto the surface of AuNPs and protect AuNPs from aggregation even with high concentrations of salt.The salt-induced aggregation of AuNPs was caused by the specific recognition of aptamers with OTA.Under optimum conditions,calibration modeling showed that the analytical linear range covered from 32 ng·mML-1 to 1024 ng·mL-1 and the detection limit of 20 ng·mL-1 was realized successfully.This proposed colorimetric bio-assay also showed high selectivity over other antibody based methods.Meanwhile,this strategy was further used to determine the concentrations of Ochratoxin A in white wine sample with satisfying recovery rates.Experiments have shown that the aptamers have good specificity,but the combination of aptamers and OTA is not yet accurate.In the experiment,we used SYBYL software to explore the interaction between aptamers and small molecules.First,SYBYL software is used to simulate the combination of small molecules and aptamers,and we use the scoring function in the software to score each docking.Select the structure of the scoring function,recording the active center of these structures,and then we use GeneDoc software to analyze the base sequence of the active center.According to the results of the analysis,we can design a series of base sequences.For each base sequence,SYBYL software was used to simulate the base sequence.Each of the selected base chains was labeled with fluorescence,and the ability of each base chain binding to OTA was determined by Microscale Thermophoresis after fluorescent labeled.By determining the Kd value of the base chain,the binding capacity of the base chain can be compared.In the experiment,we found that one of the three base chains synthesized had the ability to bind OTA.