Synthesis And Characterization Of Polystyrene Nano Fluorescent Microspheres

Polystyrene fluorescent microspheres(QPs)have a wide range of applications in the field of biomedicine,especially in immunoassay,and are often used to make various types of kits.Quantum dots(QDs),because of their tunable spectral characteristics,high photobleaching threshold and good chemical stability,have become very good fluorescent materials for the preparation of fluorescent microspheres.However,in the actual preparation process of fluorescent microspheres,there are two problems that limit its application and development.(1)Quantum dots are easy to agglomerate,causing fluorescence quenching;(2)The compatibility between quantum dots and the resulting polymer is not good,resulting in a low embedding rate of quantum dots.Therefore,in this paper,the preparation of fluorescent microspheres has been improved,and the specific work is as follows:(1)Polystyrene microspheres(PS)were prepared by precipitation polymerization and emulsion polymerization.1)Precipitation polymerization method.Using ethanol-water as a mixed solvent,positively charged 2,2-azobis(2-methylpropylimidimide)dihydrochloride(AIBA)as the initiator and styrene(St)as the polymerization monomer,using The one-step method of precipitation polymerization produces positively charged PS.And by changing the amount of AIBA,temperature and reaction time,to study its effect on the average particle size,surface potential and apparent morphology of PS.The results show that when the amount of initiator is 3wt%,the temperature is 80?,and the reaction is 8 h,it can not only ensure that the surface of the microsphere has enough positive charge,but also make its particle size have good uniformity.2)Emulsion polymerization method.The effect of the amount of sodium dodecyl sulfate(SDS)on the microspheres was studied.It was found that when the amount of SDS was2 wt.%.The prepared PS had a small and uniform particle size,which could reach 85 nm and PDI = 0.06.(2)Preparation of Polystyrene Fluorescent Microspheres(QPs).Based on emulsion polymerization,three different design ideas were used to prepare QPs.a)P1: Add quantum dots drop by drop to evaporate the solvent to form nano clusters.b)P2: Use positively charged PS as a stabilizer to prevent the agglomeration of quantum dots,and at the same time use its positive charge to adsorb quantum dots.c)P3: Use n-hexane as a co-solvent.The fluorescent properties,thermal stability,and biological applicability of the fluorescent microspheres prepared by three methods were studied.The results show that,first,the maximum emission wavelength of QDs: 601 nm,the half-width: 48 nm;the maximum emission wavelength of QPs:606 nm,the half-width: 47 nm.The fluorescent microspheres prepared by the three methods will not destroy the structure of the quantum dots,and the obvious fluorescence phenomenon can be observed under the ultraviolet lamp.Secondly,P1 with positively charged PS as a stabilizer and P3 with n-hexane as a co-solvent have higher fluorescence intensity,and the embedding rate of quantum dots reaches more than 90%.In addition,the prepared fluorescent microspheres have sufficient carboxyl functional groups on the surface,and the fixed amount of protein after coupling with fluorescein isothiocyanate-labeled bovine serum albumin(BSAFITC)is P1: 0.063 mg / mg,P2: 0.065 mg / mg,P3: 0.072 mg / mg.It can also be covalently coupled with anti-?-HCG monoclonal antibody(anti-?-HCG)to detect human villous gonadotropin antigen(HCG),which proves that it can be used for medical immunoassay.