A Digital Colorimetric Analysis Method For Rapid Sulfonamides Detection Based On Aptamer/AuNPs Structure And Smartphone

With the development of the world,smartphone has been popularized rapidly.In the field of real-time online detection,smartphone has gradually attracted the attention of scholars.Antibiotics abuse leads to excessive antibiotic residue in water environment and food in the process of the prevention and treatment of diseases,which has a serious threat to human health.Therefore,it is very important to detect the residual antibiotic in water environment and food.In this paper,a digital colorimetric analysis method for rapid sulfonamides detection using smartphone was proposed.It was based on the color change from red to purple-blue which caused by AuNPs aggregation in high concentration of sodium chloride.Sequently,sulfonamides detection was carried out by color analysis and complementary wavelength analysis using smartphone.In this paper,sulfadimethoxine(SDM)detection was used as an example and the main research contents and conclusions were shown as follows.(1)Au NPs were prepared by reduction of chloroauric acid with sodium citrate.An AuNPs/aptamer analysis system was structured.Aptamers were bound on the surface of AuNPs by the electrostatic interaction.The complexation of AuNPs with aptamer protected the nanoparticles from aggregating in a high-salt solution.The solution kept a stable red.In the presence of sulfonamides,sulfonamides bound with aptamers which led to the separation of the aptamers from the surface of the nanoparticles.The nanoparticles aggregated,which resulted in a color changed from red to purple-blue.In this paper,the concentration of salt solution and aptamer was optimized.Under optimal experimental conditions,the quantitative detection of SDM was realized under the UV spectrophotometer,and the detection range from 0-5 ppm.(2)The complementary wavelength of images was captured by smartphone and analyzed by a smartphone App.SDM concentration can be determined by analyzing the correlation between SDM concentration and the complementary wavelength.The detection ranged from 0 ppm to 1 ppm.In order to improve the detection limit,a colorimetric method was proposed.SDM concentration can be determined by analyzing the correlation between SDM concentration and the R Value.The method showed high sensitivity for SDM with a detection range from 0 ppm to 0.6 ppm and the limit of detection is 0.023 ppm.(3)SDM can directly lead to the aggregation of AuNPs,this paper further discusses the reason that SDM can lead to the aggregation of AuNPs.Different antibiotics were detected by Au NPs with aggregation and this method had no specificity.According to the molecular structure of various antibiotics,some molecules with amino and carboxyl groups can cause the AuNPs aggregation because the reaction changes the charge balance in solution.