CdSe/ZnS Quantum Dot-based Fluorescence-linked Immunosorbent Assay For Detection Inflammation Factors

The conventional and widely used enzyme-linked immunosorbent assays(ELISA),due to specificity and high-sensitive,was suitable in vitro diagnosis.But enzymes are vulnerable to the external conditions,and the complex operation steps limit its application.Quantum dots(QDs),due to excellent optical properties(good monochromaticity and high resistance to photobleaching),have been successfully used in biological and medical research.In this paper,we use aqueous quantum dots as fluorescent probes.By improving ELISA,we have developed a novel quantum dots-labeled based fluorescence immunosorbent assay(FLISA)for accuracy and quantitative detection of inflammation factor: C-reactive protein(CRP)and procalcitonin(PCT).The main work of this paper includes:(1)PMAH-QDs-based fluorescence immunosorbent assay(P-FLISA)for detection of C-reactive protein.The oil CdSe/ZnS QDs were modified by the amphiphilic oligomers(PMAH).Then the aqueous QDs were coupled to the CRP antibody with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide(EDC)and N-Hydroxysulfosuccinimide(S-NHS).We designed a mAb-Ag-mAb sandwich structure according to the specificity reaction between antigen and antibody.In this section,we optimized the experimental conditions in the process,including the coating process,blocking process,and incubating process,etc.And then we realized the quantitative detection for CRP antigen.This in vitro detection method offers a lower LOD and a wide line detection range than those of ELISA.At the same time,it shortened the reaction time and the quantum dot fluorescent probe showed excellent stability.This assay meets the needs feliciously of the simplicity,accurate and high sensitivity,so it has immense potential for the development of rapid and cost-effective in vitro diagnostic kits.(2)Silica-QDs-based fluorescence immunosorbent assay(Si-FLISA)for detection of C-reactive protein.The Silica-coated QDs,obtained by the reversed-phase microemulsion method,have higher fluorescence intensity and better stability.On the basis of this,we carried out the experiment of this chapter.By comparing to PMAH-QDs,the fluorescence recovery rate of Si-QDs enhanced,the particle size of SiQDs increasesd.In addation,the Si-QDs has better stability than PMAH-QDs.By optimizing the experimental condition,the dosage of Si-QDs probe for this Si-FLISA method was 1/16 of PMAH-QDs,and the linear range expand 2.5 times than the P-FLISA method.This method has greater value and significance in clinical.(3)PMAH-QDs-based fluorescence immunosorbent assay(P-FLISA)for detection of PCT.The detection method for PCT is also based on the “mAb-Ag-mAb” sandwich structure,similar to(1).In this chapter,the water-soluble QDs modified by amphiphilic polymer(PMAH)were coupled to PCT antibody.Then we have realized the quantitative detection for PCT antigen.The results show the P-FLISA for PCT has a high sensitivity,a good linear correlation,a good precision and a high accuracy.