甲醛选择性反应探针用于表面增强拉曼散射检测脂多糖

Surface Enhanced Raman Scattering Based Detection of Lipopolysaccharide Using Formaldehyde-Selective Reactive Probe

构建了一种依赖于表面增强拉曼散射(SERS)技术检测脂多糖氧化产物甲醛,实现对脂多糖的定量检测。在室温条件下,用NaIO4氧化脂多糖生成甲醛,加入巯基拉曼染料4-氨基-3-肼基-5-巯基-1,2,4-三氮唑(Purpald)与甲醛加合,再加入NaIO4进一步氧化,生成的紫色终产物组装到金纳米颗粒表面,在进行拉曼光谱扫描时产生了SERS增强信号,而在控制实验中没有脂多糖参与时,得到非常弱的SERS信号,由此实现脂多糖的检测。此外,利用紫外可见光谱对脂多糖的氧化产物进行了分析,在540 nm处有甲醛与Purpald加成产物特征的紫外吸收。还对NaIO4、Purpald的反应浓度进行了优化,结果表明,在最优反应条件下,SERS信号随着脂多糖浓度增大而增强,在33～667 mg/L范围内有很好的线性关系,检出限为21 mg/L。本方法无需复杂的实验操作和昂贵的标记试剂。分析速度快,灵敏度高。

A novel analytical method was proposed for the determination of lipopolysaccharide.This strategy relies on surface enhanced Raman scattering based detection of formaldehyde that was produced as the product in the oxidation reactions of lipopolysaccharide and NaIO4.Under room temperature,firstly,the lipopolysaccharide was oxidized by NaIO4,producing formaldehyde.A thiolated reactive probe,Purpald,was used for the selective reaction with formaldehyde,followed further oxidation and the product could self-assemble on gold nanoparticles to deliver the SERS signal.As a control experiment,it showed a quite weak SERS signal in the absence of lipopolysaccharide.Therefore the detection of lipopolysaccharide could be finished by the strategy.In addition,the oxidation product of lipopolysaccharide was analyzed by UV spectrum and the results showed typical UV absorption peak at 540 nm for the reaction products of formaldehyde and purpald.Furthermore,the concentrations of NaIO4 and Purpald were optimized.Under the optimized conditions,the SERS signal increased with the increasing concentrations of the lipopolysaccharide and showed a linear correlation to lipopolysaccharide concentration in the range of 33-667 mg/L and the limit of detection of 21 mg/L.This method was sensitive,without sophisticate experiment procedures and costly labeled reagents,fast and easy to realize.In view of these advantages,this developed strategy was expected to offer a simple,convenient and sensitive homogeneous detection platform for lipopolysaccharide assay.