Multifunctional single-atom catalysts (SACs) have been extensively investigated as outstanding signal amplifiers in bioanalysis field. Herein, a type of Fe single-atom catalysts with Fe-nitrogen coordination sites in nitrogen-doped carbon (Fe–N/C SACs) was synthesized and demonstrated to possess both catalase and peroxidase-like activity. Utilizing Fe–N/C SACs as dual signal amplifier, an efficient bipolar electrode (BPE)-based electrochemiluminescence (ECL) immunoassay was presented for determination of prostate-specific antigen (PSA). The cathode pole of the BPE-ECL platform modified with Fe–N/C SACs is served as the sensing side and luminol at the anode as signal output side. Fe–N/C SACs could catalyze decomposition of HO via their high catalase-like activity and then increase the Faraday current, which can boost the ECL of luminol due to the electroneutrality in a closed BPE system. Meanwhile, in the presence of the target, glucose oxidase (GOx)-Au NPs-Ab was introduced through specific immunoreaction, which catalyzes the formation of HO. Subsequently, Fe–N/C SACs with peroxidase-like activity catalyze the reaction of HO and 4-chloro-1-naphthol (4-CN) to generate insoluble precipitates, which hinders electron transfer and then inhibits the ECL at the anode. Thus, dual signal amplification of Fe–N/C SACs was achieved by increasing the initial ECL and inhibiting the ECL in the presence of target. The assay exhibits sensitive detection of PSA linearly from 1.0 pg/mL to 100 ng/mL with a detection limit of 0.62 pg/mL. The work demonstrated a new ECL enhancement strategy of SACs via BPE system and expands the application of SACs in bioanalysis field.

中文翻译：

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Fe-单原子催化剂通过双极电极增强电化学发光，并结合其过氧化物酶样活性进行生物分析


多功能单原子催化剂（SAC）作为生物分析领域出色的信号放大器已被广泛研究。在此，合成了一种在氮掺杂碳中具有铁-氮配位位点的铁单原子催化剂（Fe-N/C SAC），并被证明具有过氧化氢酶和过氧化物酶样活性。利用 Fe-N/C SAC 作为双信号放大器，提出了一种基于双极电极 (BPE) 的高效电化学发光 (ECL) 免疫测定法，用于测定前列腺特异性抗原 (PSA)。用 Fe-N/C SAC 修饰的 BPE-ECL 平台的阴极作为传感侧，阳极鲁米诺作为信号输出侧。 Fe-N/C SACs 可以通过其高过氧化氢酶活性催化 H2O 分解，然后增加法拉第电流，由于封闭 BPE 系统中的电中性，可以提高鲁米诺的 ECL。同时，在靶标存在的情况下，通过特异性免疫反应引入葡萄糖氧化酶（GOx）-Au NPs-Ab，催化H2O的形成。随后，具有类过氧化物酶活性的 Fe-N/C SAC 催化 H2O 和 4-氯-1-萘酚 (4-CN) 的反应，生成不溶性沉淀物，阻碍电子转移，从而抑制阳极的 ECL。因此，Fe-N/C SAC 的双重信号放大是通过增加初始 ECL 和在目标存在时抑制 ECL 来实现的。该测定可对 1.0 pg/mL 至 100 ng/mL 的 PSA 进行线性灵敏检测，检测限为 0.62 pg/mL。该工作展示了通过BPE系统对SACs进行ECL增强的新策略，拓展了SACs在生物分析领域的应用。