Study On Detection Of Bisphenol A And Mercury In Water By Highly Sensitive Fluorescence Biosensing

With the development of human production and life,the environmental pollutants are becoming more dangerous to human being.People put higher requirements for the level of pollutant detection,and it is very important to establish new and sensitive detection methods.This paper mainly focuses on improving the sensitivity of the analytical method from the aspects of enhancing the detection signal and improving the selectivity.Based on different nanomaterials,several new biological sensing methods are constructed and applied for detect BPA and Hg2+.The detailed contains are as follows:(1)A magnetic separation fluorescence aptasensor with high sensitivity for detecting BPA was established.First,NH2-Fe3O4 was prepared,and then combined with a carboxyl-containing capture probe to obtain a DNA-nanoparticle complex.The AHN-labeled aptamer was added,and the aptamer can hybridize with the capture probe through the base complementary pairing.In the presence of BPA,the AHN-labeled aptamer is specifically bind to BPA,resulting in the BPA aptamer released from the double helix structure and wrapped the BPA.After magnetic separation,the fluorescence signal of the supernatant can be monitored.In the absence of BPA,the AHN-labeled aptamer was still hybridized with the capture probe and no fluorescence signal can be detected in the supernatant after magnetic separation.Under the optimal conditions,a detection limit of 0.047 ng/mL was obtained.In this method,NH2-Fe3O4 is used as a reaction platform and separation medium,which effectively reducing the interference of other substances,making the method have a good selectivity,and can be better applied to the actual sample detection.(2)Two pyrene molecules are respecti-vely labeled at the 3' and 5' ends of the competition chain(an oligonucleotide with a hairpin structure designed according to the BPA aptamer).In the absence of BPA,the competition strand hybridizes with the BPA aptamer so that the two pyrene molecules at both ends of the chain are far away from each other and the fluorene molecules emit monomer fluorescence.In the presence of BPA,the aptamer is separated from the competing strand because the aptamer is more likely to specifically bind to BPA.As a result,the competition chain is released and restored the original hairpin structure,so that the two pyrene molecules approach each other to form an excimer and the excimer fluorescence detected.The detection limit of this method is 0.094 ng/mL,the operation is simple,and the selectivity is good.It can be used to detect BPA in real water samples.(3)A sensor for detecting Hg2+ in water was designed based on two important principles:1)the adsorption of single-stranded DNA by MGO which has a strong quenching effect on organic fluorescent dyes;2)two thymine-enriched probes can form a T-Hg2+-T structure that is more stable than the Watson Crick base pairing "A-T" in the presence of Hg2+ When ssDNA*is completely adsorbed on the surface of MGO,the AHN fluorescence quenching effectively,adding cDNA probe and Hg2+ and giving them enough time for mismatch hybridization,as a result,the 5'-teraminal forming a double-stranded structure due to the formation of T-Hg2+-T,and then began to magnetic enrichment,remove the original solution,adding a certain volume of rDNA(different enrichment factors were controlled by changing the volume of solution in the final system),letting rDNA hybridize with the ssDNA*which 3'-terminal still adsorbed on the MGO.This step results in completely separation for ssDNA*out of MGO.Finally,fluorescence recovered.In the proposed method,due to the use of magnetic enrichment and separation step,the method possesses high sensitivity and detection limit of 0.054 nmol/L,and the method has good selectivity and strong anti-interference ability.In addition,it can be effectively applied to the actual water sample detection.