School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.
Shenzhen Lifotronic Technology Co., Ltd, Nanshan District, Shenzhen 518055, China.
Anal Chem. 2022 Aug 30;94(34):11934-11939. doi: 10.1021/acs.analchem.2c02737. Epub 2022 Aug 17.
The electrochemiluminescence (ECL) bioassay is prominently carried out with the involvement of the coreactant. To remove the detrimental effects of the coreactant on the ECL of luminophores, herein, a promising ECL immunoassay strategy with biocompatible nanoparticles as the luminophore is proposed, which involves directly and electrochemically oxidizing the luminophore methionine-capped Au (Met@Au) nanocrystals (NCs) without the participation of any coreactant. Met@Au NCs are a kind of n-type nanoparticles, and they can be electrochemically injected with valence band (VB) holes around +0.80 and +1.10 V (vs Ag/AgCl). The electrochemically injected exogenous VB hole can recombine with the endogenous conduction band electron of Met@Au NCs and eventually bring out two coreactant-free and near-infrared ECL processes around 0.80 V (ECL-1) and 1.10 V (ECL-2). The intensity of coreactant-free ECL is primarily determined by the electrochemical oxidation-induced hole-injection process. ECL-2 is considerably stronger than ECL-1 and can be exploited for determining the carcinoembryonic antigen (CEA) in a sandwich immunoassay procedure with a linear range from 0.1 to 50 pg/mL as well as a limit of detection of 0.03 pg/mL (S/N = 3).
电化学发光（ECL）生物分析主要涉及共反应物。为了消除共反应物对发光体 ECL 的不利影响，本研究提出了一种有前景的 ECL 免疫分析策略，该策略以生物相容性纳米粒子作为发光体，涉及直接电化学氧化发光体蛋氨酸封端的金（Met@Au）纳米晶体（NCs），而无需任何共反应物的参与。Met@Au NCs 是一种 n 型纳米粒子，可在+0.80 和+1.10 V（相对于 Ag/AgCl）附近电化学注入价带（VB）空穴。电化学注入的外来 VB 空穴可以与 Met@Au NCs 的本征导带电子复合，并最终引出两个无共反应物的近红外 ECL 过程，分别在 0.80 V（ECL-1）和 1.10 V（ECL-2）处。无共反应物 ECL 的强度主要取决于电化学氧化诱导的空穴注入过程。ECL-2 比 ECL-1 强得多，可以用于夹心免疫分析程序中测定癌胚抗原（CEA），线性范围为 0.1 至 50 pg/mL，检测限为 0.03 pg/mL（S/N = 3）。
