Fan Gao-Chao, Zhu Hua, Du Dan, Zhang Jian-Rong, Zhu Jun-Jie, Lin Yuehe
State Key Laboratory of Analytical Chemistry for Life Science, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, People's Republic of China.
School of Mechanical and Materials Engineering, Washington State University , Pullman, Washington 99164, United States.
Anal Chem. 2016 Mar 15;88(6):3392-9. doi: 10.1021/acs.analchem.6b00144. Epub 2016 Mar 4.
A new, ultrasensitive photoelectrochemical immunosensing platform was established on the basis of CdSeTe@CdS:Mn core-shell quantum dots-sensitized TiO2 coupled with signal amplification of CuS nanocrystals conjugated signal antibodies. In this proposal, carcinoembryonic antigen (CEA, Ag) was selected as an example of target analyte to show the analytical performances of the platform. Specifically, TiO2-modified electrode was first assembled with CdSeTe alloyed quantum dots (AQDs) via electrostatic adsorption assisted by oppositely charged polyelectrolyte, and then further deposited with CdS:Mn shells on the surface of CdSeTe AQDs via successive ionic layer adsorption and reaction strategy, forming TiO2/CdSeTe@CdS:Mn sensitization structure, which was used as photoelectrochemical matrix to immobilize capture CEA antibodies (Ab1); signal CEA antibodies (Ab2) were labeled with CuS nanocrystals (NCs) to form Ab2-CuS conjugates, which were employed as signal amplification elements when specific immunoreaction occurred. The ultrahigh sensitivity of this immunoassay resulted from the following two aspects. Before detection of target Ag, the TiO2/CdSeTe@CdS:Mn sensitization structure could adequately harvest the exciting light with different bands, evidently expedite the electron transfer, and effectively depress the charge recombination, resulting in noticeably increased photocurrent. When target Ag existed, the Ab2-CuS conjugates could dramatically decrease the photocurrent due to competitive absorption of exciting light and consumption of electron donor for CuS NCs coupled with steric hindrance of Ab2 molecules. The fabricated photoelectrochemical immunosensor showed a low limit of detection of 0.16 pg/mL and a wide linear range from 0.5 pg/mL to 100 ng/mL for CEA detection, and it also exhibited good specificity, reproducibility, and stability.
基于CdSeTe@CdS:Mn核壳量子点敏化的TiO₂并结合CuS纳米晶体偶联信号抗体的信号放大作用，构建了一种新型的超灵敏光电化学免疫传感平台。在本方案中，选择癌胚抗原（CEA，抗原）作为目标分析物的示例，以展示该平台的分析性能。具体而言，首先通过带相反电荷的聚电解质辅助的静电吸附作用，将TiO₂修饰电极与CdSeTe合金量子点（AQDs）组装在一起，然后通过连续离子层吸附和反应策略，在CdSeTe AQDs表面进一步沉积CdS:Mn壳层，形成TiO₂/CdSeTe@CdS:Mn敏化结构，用作光电化学基质来固定捕获CEA抗体（Ab1）；信号CEA抗体（Ab2）用CuS纳米晶体（NCs）标记，形成Ab2-CuS缀合物，在发生特异性免疫反应时用作信号放大元件。这种免疫测定的超高灵敏度源于以下两个方面。在检测目标抗原之前，TiO₂/CdSeTe@CdS:Mn敏化结构能够充分收集不同波段的激发光，显著加快电子转移，并有效抑制电荷复合，从而导致光电流明显增加。当存在目标抗原时，由于激发光的竞争性吸收以及CuS NCs的电子供体消耗，再加上Ab2分子的空间位阻，Ab2-CuS缀合物会显著降低光电流。所制备的光电化学免疫传感器对CEA检测的检测限低至0.16 pg/mL，线性范围宽，为0.5 pg/mL至100 ng/mL，并且还表现出良好的特异性、重现性和稳定性。
