Study On Detection Methods Of Bisphenol A Based On Fe₃O₄ Magnetic Nanomaterials

In recent years,food safety incidents related to bisphenol A have been frequent,which have a certain impact on people's physical and mental health.At present,the common detection methods of bisphenol A include liquid chromatography?Liquid Chromatography,LC?and gas chromatography?Gas Chromatography,GC?.These methods are relatively mature,high sensitivity,but there are several disadvantage of high cost of equipment,tedious operating procedures,time consuming,poor selectivity and other defects.In this study,on the basis of the target enrichment and the food safety detection application by sensitized effect of magnetic nanoparticles,using nanomaterial as a carrier and make it functional,construct a rapid pretreatment enrichment platform with magnetic separation and specificity for the recognition of the target by high performance liquid chromatography with fluorescence spectra,shorten the pretreatment time from more than ten hours to two hours,simplifies the pretreatment process.In addition,combine the amplification characteristics of horseradish peroxidase and acetylcholinesterase,established a high sensitivity and high selectivity in situ analysis detection method for bisphenol A,this method has simple operation process and portable equipment,detection limit of the method reduced by 3 orders of magnitude.Mainly carried out the following two aspects of the research works:First,the Fe₃O₄ magnetic nanoparticles were synthesized by hydrothermal method,and the silica coated magnetic nanoparticles?Fe₃O₄@SiO₂?with core-shell structure were synthesized by the sol gel method.Subsequently,the functional silica coated magnetic nanoparticles?Fe₃O₄@SiO₂-Apt?were prepared by EDC/NHS method through modified the BPA aptamer on the surface of Fe₃O₄@SiO₂ nanoparticles.A rapid pretreatment analysis method for BPA based on functional silica coated magnetic nanoparticles is established,and determined by high performance liquid chromatography with fluorescence spectroscopy?HPLC-FLD?.The morphological and polymeric characteristics of the Fe₃O₄@SiO₂ was characterized by transmission electron microscopy?Transmission electron microscope,TEM?and dynamic light scattering?Dynamic Light Scattering,DLS?.Various of parameters such as the adsorption buffer,adsorption time and the elution agent were investigated and optimized.The results showed that with methanol-water as mobile phase by waters C18 column analysis,and set the detection excitation wavelength and emission wavelength at 227 nm and 313 nm respectively,bulid the standard curve of BPA concentration versus HPLC peak area,the linear range was 0.1¹00 ng/mL with a detection limit of 0.05 ng/mL.The recovery rate of BPA added in tap water was 78.62%⁸9.94%.On the basis of the above research,combined with the enzyme linked amplification effect,establish a enzyme linked sensitized platform detection of bisphenol A.The functional magnetic?Fe₃O₄-DNA1?and gold nanoparticles?AuNPs-DNA2?were prepared by the chemical bond of bisphenol A aptamer and it's complementary chains on the surface of bare magnetic and gold nanoparticles.And the enzyme horseradish peroxidase?HRP?,acetylcholinesterase?AchE?were modified on the surface of the gold nanoparticles through electrostatic interactions,two kinds of rapid and in situ analysis detection methods for BPA were established by enzyme linked amplification effect using two detection terminal of visible spectrophotometer and two kinds of pH method?pH meter/pH test paper?.The structure characteristics of functional magnetic nanoparticles?Fe₃O₄-DNA1?and functionalized gold nanoparticles?AuNPs-DNA2?were characterized by transmission electron microscopy?TEM?and dynamic light scattering?DLS?.The results showed that under the two kinds of enzyme system,the standard curve in the range of 0.001⁵0 ng/mL and 0.01¹000 ng/mL had good linear relation?R²=0.972 and 0.993?,the recoveries were 98.75¹01.37%and 97.83¹04.96%respectively in tap-water sample.The limit of detection?LOD?for BPA of the UV-Vis method is 0.5pg/mL,pH meter and pH test paper method is 5 pg/mL and 10 pg/mL,respectively,and all had good specificity.The method can be applied to the determination of trace BPA in tap water with high sensitivity.Therefore,the method established in this study is expected to be widely used in the establishment of a new method of rapid detection.