Synthesis And Bioapplications Of Catalytic Chemiluminescent Polymer Dots

Chemiluminescence?CL?detection is a highly sensitive method due to no interferences of light source and autofluorescence.So far,it has been widely used for the analysis of small molecules and biomolecules.However,compared with fluorescence analysis,chemiluminescence method owned weak emission intensity and short emission time,which limits its bioapplications.It is important to design and synthesize highly efficient catalytic chemiluminescence probe with strong emission intensity and long emission time.Metalloporphyrins have attracted the interest of many researchers because of their highly efficient catalytic chemiluminescence activity and unique structure.However,most metalloporphyrins such as hemin are hydrophobic compounds,which are easily aggregated in aqueous solution.It is difficult to use metalloporphyrins directly in biological systems for greatly reduced catalytic performance.In this paper,the water-soluble catalytic chemiluminescence polymer dots containing hemin were successfully synthesized and applied to cell imaging,in vivo imaging and immunoassay.The main contents of our work are as follows:?1?We synthesized highly sensitive catalytic chemiluminescent polymer dots encapsulating multiple hemin molecules by nano-co-deposition method.The polymer dots?Hemin-PS dots?were composed of amphiphilic compound polystyrene-polyethylene glycol?PS-PEG-COOH?,polystyrene?PS?and hemin.The diameter of the polymer dots was 36.0±10.3 nm and the dots are highly stable in the solution.Hemin-PS dots own a strong catalytic activity on the reaction of luminol analog L-012 with hydrogen peroxide,and the CL intensity was a little stronger catalyzed by 5 nM Hemin-PS dots than that of100 nM HRP.Hemin-PS dots were conjugated with cRGD as a nanoprobe for chemiluminescence imaging of three integrin?_v?₃ high-expressing tumor cells and normal cell.The results showed that the CL intensities were more than 7times for tumor cells than that of normal cell.It was also used to monitor reactive oxygen species?ROS?within normal and inflammation mice by in vivo CL imaging.?2?Hemin-PS dots own higher catalytic activity under alkaline condition.The CL intensity catalyzed by 20 nM Hemin-PS dots was a little stronger than that of 1?M HRP under their optimum conditions.Therefore we designed a novelchemiluminescentimmunoprobecalledHemin-PS dots-Streptavidin-Biotin-AFP antibody for the detection of alpha-fetoprotein?AFP?,which can react with alpha-fetoprotein antigen through antigen-antibody reaction.It's successfully used for quantitative analysis of the cancer marker alpha-fetoprotein with a linear relationship of 0.1 to 10ng·mL^-1 and a detection limit of 0.1 ng·mL^-1.The detection limit is reduced by a factor of 10 compared to the commercial chemiluminescence kit of 1.8ng·mL^-1.Catalytic chemiluminescence polymer dots may have great application prospects in the fields of chemiluminescence imaging and clinical diagnosis.