Study On Ultrasensitive Detection Of Biomarkers Based On Nanocomposite

Nano porous material has been the research hotspot in many fields,and nano-enzyme as a enzymology characteristics of nano material because of its special structure and excellent performance,compared to natural enzyme,it has outstanding advantages of high catalytic activity,low production cost and good stability.In many fields especially in disease diagnosis and biochemical detection,nano enzyme has great application potential.Nanocomposite material refers to the nanomaterials in a certain form as a dispersed phase distributed in a continuous phase,through the combination of two or more materials with different properties of a single nanomaterial functionalization,to meet the needs of various special uses.Compared with single nanomaterials,nano-composite materials have better comprehensive properties and are the main source of nano-enzyme.In this paper,the functionalization design and modification of nano-composite materials were carried out based on metal nanoparticles,graphene carbon quantum dots,covalent organic framework（COF）and metal organic framework（MOF）,and successfully applied to the construction of chemical ultradetection method based on enzyme-linked immunosorbent（ELISA）.Three biomarkers,banded krait venom（β-BGT）,prostatic specific antigen（PSA）and porcine epidemic diarrhea virus（PEDV）were detected.The main content of the paper is divided into the following four parts:（1）TAPB-COF was synthesized by solvothermal method with two organic ligands.Gold nanoparticles（Au NPs）were loaded on the surface of TAPB-COF to improve its catalytic performance and serve as the anchor site of β-BGT aptamer（Apt）.Sulfur-doped carbon quantum dots（S-GQDs）with reducibility were prepared by using mercaptopropionic acid as sulfur source and citric acid as carbon source,respectively.The catalytic reduction performance of S-GQDs was further improved by gold nanoparticles on the surface of COF material.Then,using 4-nitrophenol（4-NP）as signal molecule,Apt@Au@COF biological complex was synthesized as probe material and S-GQDS as reducing agent.Based on ELISA,a proportional dual-signal chemical ultradetection method was successfully constructed for the detection of human serum cyclinus bungeii venom.The detection range of the method is0.0032-100ng mL^-1,and the detection limit is 347.8 fg mL^-1.（2）The organic ligand L was synthesized by two different ligands,and the ultraviolet-induced supramolecular oxidase-like nanocages L-Pd was synthesized by palladium（Pd）ligands.With 3,3’,5,5’-tetramethylbenzidine（TMB）as signal molecules,the bioprobe material Ab2@L-Pd was synthesized based on amide bond.Under the induction of ultraviolet light,a visual chemical ultradetection method for PSA detection was constructed based on ELISA.The change of PSA concentration could be determined by the color depth of TMB catalyzed to ox TMB.The detection range of the method is 10^-4-10³ng mL^-1 and the detection limit is20.9 fg mL^-1.（3）Prussian Blue Cube（PBA）was prepared by using two metal compounds as raw materials and sodium citrate as reducing agent.PBA has laccase like and peroxidase like effects.A biocomposite probe Ab2@Au Pt@L-Pd@PBA was prepared by synthesizing supramolecular nanocage L-Pd and recombining it with PBA through amide bond.Au Pt NPs were loaded on the surface of L-Pd as the anchor site of PEDV secondary antibody.With 2,4-dichlorophenol（2,4-DP）,4-antipyrine（4-AP）and TMB as signal molecules,a sandwich type visual dual-signal chemical ultradetection method for PEDV detection was prepared based on ELISA.The detection range of the method is 10^-4-32 ng mL^-1,and the detection limit is 79.4fg mL^-1.（4）Via nickel-iron metal compound,sodium citrate and L-Pd as raw materials,the irregular porous nanomaterials NFP were synthesized by one-pot method.The materials of NFP were not different from those in（3）,but the preparation methods were different,and their morphology and properties were different.NFP also has peroxidase-like,oxidase-like and laccase-like effects.Biocomposite probe Ab2@NFP was obtained by amide bond anchored PEDV secondary antibody.With 2,4-DP,4-AP and TMB as signal molecules,a visual dual-signal chemical ultradetection method for PEDV detection was prepared based on ELISA.These results provide new ideas and new methods for the ultrasensitive detection of biomarker and make it possible for the application of nano-enzyme in the detection of biomarkers.These ultrasensitive detection strategies have the advantages of low cost,high sensitivity,low detection limit and high stability.Three biomarkers were successfully analyzed and detected,providing more possibilities for the establishment of new methods for ultrasensitive detection strategies.At the same time,its good performance in the actual sample detection shows that it has great practical application potential and provides a new feasible strategy for the detection of biomarkers.At the same time,the composite nano-enzyme prepared in the experiment has excellent performance,both good catalytic activity and a variety of functions,and has broad application prospects.Future chemical biosensor and paper-based,electrochemistry and other technology,combining can create a low cost,portable,visual sensing platform,can be further made it possible to its practical application,its simple and quick means make patients self-check possible,effectively reduce the disease detection and treatment of medical treatment cost,improve the efficiency of clinical diagnosis,It is helpful for early diagnosis and follow-up treatment of the disease.