Fabrication Of Gold Nanoparticles And Their Applications In The Detection Of Biomolecules

Biomolecules are the basic units of life.Biomolecules can be divided into biomacromolecule and biological small molecules,which can maintain the dynamic balance of organ system and regulate metabolism of organism.Abnormal levels of biomolecules in the body may cause related diseases.Therefore,development of early detection of biomolecules is of great significance for clinical treatment and research.In recent years,gold nanoparticles(AuNPs)in inorganic nanomaterials have attracted wide attention in the field of analysis and detection due to their unique physicochemical properties,such as good biocompatibility,high specific surface area,easy synthesis and favorable stability.In view of this,according to the excellent physical and chemical properties of AuNPs,this paper aims to design the detection system of AuNPs for simple and low-cost detection of biomolecules.There are three main parts in this dissertation as follows:Chapter 1 is an introduction of the some knowledge of biomolecules and AuNPs,the research background of fluorescence assay and colorimetric assay for the detection of biomolecules,as well as the research status of AuNPs material based on detection of biomolecules at home and abroad in recent years,and the research ideas for this dissertation.In chapter 2,we proposed a rapid,sensitive and low-cost fluorescent assay to achieve lysozyme detection in the presence of AuNPs and rhodamine 6G(R6G).When R6G and AuNPs aqueous solutions were mixed,fluorescence of R6G was quenched via the inner filter effect(IFE).Whereas,upon addition of lysozyme into AuNPs solution,lysozyme with positive charge bound to the negatively-charged AuNPs,leading to the aggregation of AuNPs.After that,R6G as a fluorescence indicator was introduced into the above-mentioned mixture.In this case,weakened IFE occurred between AuNPs and R6G.It is found that the fluorescent intensity of R6G enhanced as the concentration of lysozyme increased.Based on the above,lysozyme could be detected and its detection limit is about 1 ng/mL.Quantitative evaluation of lysozyme could be performed within a concentration range of 0.1-10?g/mL.This strategy was also applied to monitor lysozyme in urine samples with a pleased result.It provides a great promise for the diagnosis and prognosis by fluorescence for lysozyme-related diseases.In chapter 3,based on AuNPs,coupled with single-stranded DNA(ssDNA)and nano CeO2,we developed a novel colorimetric method to detect H2O2 and glucose.In the absence of H2O2,ssDNA was adsorbed on the surface of nano CeO2.Since AuNPs are not protected by ssDNA,they accumulate in salt solution,which turns the solution purple.Because of the stronger binding force between H2O2 and nano CeO2,ssDNA adsorbed on the surface of nano CeO2 could be released in the presence of H2O2,and then the released ssDNA was modified to the AuNPs surface to prevent AuNPs from accumulating in the salt solution,resulting in a distinct red color of the aqueous solution,which could be observed by naked eyes.In the UV-vis spectrum,the intensity of the absorption peak at?523 nm gradually increased,and the intensity of the absorption peak at?625 nm gradually decreased.Based on this,H2O2 detection can be realized.Since H2O2 can be produced in the process of glucose oxidation by glucose oxidase(GOx),this approach can also be employed to detect glucose.By employing this sensing system,the detection limits for H2O2 and glucose are about 0.21 ?M and 3.01 ?M,respectively.Additionally,monitoring the content of glucose in blood serum samples was successfully achieved by the proposed strategy.This approach has potential applications in the diagnosis of H2O2 and glucose-related diseases.