量子点荧光免疫和磁弛豫时间传感检测沙门氏菌的研究

Fluorescent and Magnetic Relaxation Switch Immunosensor for the Detecting Foodborne Pathogen Salmonella entericain Water Samples

基于量子点和超顺磁纳米颗粒分别构建了沙门氏菌的荧光免疫和磁驰豫时间(magnetic resonance switch,MRS)免疫传感的分析方法,并应用于水样中沙门氏菌的检测。在荧光免疫分析方法中,利用偶联有沙门氏菌捕获抗体的磁探针对样品中沙门氏菌进行富集,然后加入偶联有沙门氏菌检测抗体的量子点荧光探针,基于双抗夹心的模式对水样中沙门氏菌的含量进行了测定。量子点的荧光强度和样品中沙门氏菌的浓度呈正相关,检出限是102 cfu·mL-1,检测时间为2h。在MRS免疫反应过程中,偶联有沙门氏菌捕获抗体的超顺纳米磁珠会特异性地结合沙门氏菌,导致超顺纳米磁珠由原来的分散状态转变为聚集状态,从而引起其相邻水分子的质子横向弛豫时间(spin-spin relaxation time,T2)的改变,通过测定T2的改变量ΔT2实现水样中沙门氏菌的检测。结果表明MRS传感器检测沙门氏菌的检测限是103 cfu·mL-1,检测时间是0.5h。比较了这两种方法在检测沙门氏菌方面的优劣及应用潜力。

Fluoroimmunoassay based on quantum dots（QDs）and magnetic relaxation switch（MRS）immunoassay based on superparamagnetic nanoparticles（SMN）were constructed to detect Salmonella enterica（S.enterica）in water samples.In fluoroimmunoassay,magnetic beads was conjugated with S.entericacapture antibody（MB-Ab2）to enrich S.entericafrom sample solution,then the QDs was conjugated with the S.entericadetection antibody（QDs-Ab1）to detect S.entericabased on sandwich immunoassay format.And the fluorescence intensity is positive related to the bacteria concentration of the sample.Results showed that the limit of detection（LOD）of this method was 102 cfu·mL-1 and analysis time was 2h.In MRS assay,magnetic nanoparticle-antibody conjugate（MN-Ab1）can switch their dispersed and aggregated state in the presence of the target.This state of change can modulate the spin-spin relaxation time（T2）of the neighboring water molecule.The change in T2（ΔT2）positively correlates with the amount of the target in the sample.Thus,ΔT2can be used as a detection signal in MRS immunosensors.Results showed that LOD of MRS sensor for S.enterica was 103 cfu·mL-1 and analysis time was 0.5h.Two methods were compared in terms of advantages and disadvantages in detecting S.enterica.