New Methods For The Detection Of Organophosphorus Pesticides And Poly (ADP-Ribose) Polymerase-1

In the modern agricultural production,people usually increase the crop yield by using pesticides to kill pests and weeds.Among them,organophosphorus pesticides（OPs）are widely used in agriculture owing to their high efficiency,short half-life and easy degradation.However,overuse of OPs can cause different harms to the environment and human health.Specifically,the remaining OPs in the environment enter the body through breathing and eating food.On the one hand,OPs will inhibit the activity of acetylcholinesterase（ACh E）.Once the ACh E activity is inhibited by OPs,it will lead to the disorder of the nervous system and then induce the occurrence of neurological diseases.On the other hand,OPs which enter in the human body will damage the genomic DNA.Genomic DNA contains more nucleotide which store the genetic information of human survival and reproduction.If the damage DNA could not be repaired in time,it will induce mutation and deletion,leading to neurological diseases,cancer and even cell death.In order to maintain the integrity of genomic DNA,cells have developed a variety of DNA repair enzymes to quickly identify and efficiently repair various types of DNA damage.Poly（ADP-ribose）polymerase-1（PARP-1）,as an important DNA polymeraser enzyme,is actively involved in the process of DNA repair.But the excessive expression of PARP-1 could also cause the occurrence of tumor and some neurological diseases.Therefore,OPs and PARP-1 as the two major factors that affect human health,it is particularly important to construct sensitive sensor to detect their activity.In this paper,fluorescence and electrochemical methods were used to construct two biosensors to detect the activity of OPs and PARP-1 respectively.The main contents of this paper are as follows:（1）Based on the specific response of Oli Green to T-Hg²⁺-T DNA structure,a sensitive biosensor was constructed to detect OPs.Oli Green is a non-fluorescent dye.However,its fluorescence intensity varies greatly in the presence of different bases or DNA structures.Generally speaking,it emits strong fluorescence at～525 nm in the presence of ss DNA that is rich in T or G bases.In this paper,it was found that Oli Green emitted much stronger fluorescence in rigid T-Hg²⁺-T DNA structure than that in the presence of poly（T）.With these concepts in mind,an Oli Green-responsive fluorescent sensor based on its specific selectivity towards T-Hg²⁺-T DNA structure was developed for the detection of OPs.ACh E was used to hydrolyze acetylthiocholine（ATCh）to produce thiocholine（TCh）which captured Hg²⁺from the rigid T-Hg²⁺-T DNA structure to form TCh-Hg²⁺-TCh.The released poly（30T）subsequently combined with less Oli Green,resulting in weak fluorescence.However,in the presence of OPs,the activity of ACh E was inhibited and more Oli Green was combined with T-Hg²⁺-T DNA structure,leading to increased fluorescence intensity.DDVP were detected with a wide linear range from 5.0 pg/m L to 25.0 ng/m L and the detection limit was 2.9 pg/m L,which is more sensitive than previously reported methods.（2）Based on host-guest recognitionwe we designed a renewable electrochemical sensorforthedetectionofPARP-1activity.Mono-（6-Mercapto-6-deoxy）-beta-Cyclodextrin（SH-β-CD）was modified on the electrode surface to recognize the trans-azobenzene labeled ds DNA（trans-Azo-ds DNA）.Exposed PO₄^3-in trans-Azo-ds DNA would react with Mo O₄^2-to produce little PMo₁₂O₄₀^3-,generating weak current signal.In the presence of PARP-1,PAR with abundant PO₄^3-was generated and then reacted with Mo O₄^2-to form more PMo₁₂O₄₀^3-,producing strong current signal.The proposed method avoided the unspecific adsorption effectively and improved the detection accuracy.Importantly,under UV irradiation,Azo-ds DNA was removed from the electrode surface because of the configuration change of Azo from trans-to cis-structure,allowing the electrode to be recycled.The sensor realized the linear detection of PARP-1,ranging from 0.01 U to 1.0 U with a detection limit of 0.008 U,which is comparable to results from reported methods.It is expected to be a potential tool for clinical detection because of its high sensitivity and selectivity.