State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , 410082 , People's Republic of China.
Anal Chem. 2018 Aug 7;90(15):9480-9486. doi: 10.1021/acs.analchem.8b02134. Epub 2018 Jul 23.
Taking the zeolitic imidazolate framework (ZIF-67) as the precursor, p-type semiconducting CoO-Au polyhedra were synthesized and used as the signal amplifier to construct a sensitive photoelectrochemical (PEC) sensor for caspase-3 activity assay. Here, the n-type semiconductor BiS-modified indium-tin oxide (ITO) slice was used as the photoelectrode. After immobilization of the biotin-DEVD-peptide (biotin-Gly-Asp-Gly-Asp-Glu-Val-Asp-Cys) onto the BiS surface, the streptavidin-labeled CoO-Au polyhedra were introduced to the sensing platform via the specific interaction between biotin and streptavidin. The CoO-Au polyhedra can not only quench the photocurrent of the BiS because of the competitive consumption of electron donors and exciting light energy (p-n-type semiconductor quenching effect), but also act as peroxidase mimetics to produce catalytic precipitate. Additionally, the steric hindrance effect from the CoO-Au polyhedra will decrease the PEC response of the BiS. Ingeniously, the precipitates can not only deposit on the ITO electrode to decrease the photocurrent of PEC sensor, but also act as electron acceptors to scavenge the photogenerated electrons of CoO-Au polyhedra, leading to enhanced quenching ability of the CoO-Au polyhedra. When caspase-3 exists, caspase-3 can specifically recognize and cleave the biotin-DEVD-peptide, resulting in the increase of PEC response. Based on the multifunctional CoO-Au polyhedra, caspase-3 is detected sensitively with a linear range from 0.5 to 50 ng mL and limit of detection down to 0.10 ng mL. The CoO-Au polyhedra provide a novel signal amplifier to construct PEC sensing platform and may have potential applications in bioanalysis, disease diagnostics, and clinical biomedicine.
以沸石咪唑酯骨架（ZIF-67）为前驱体，合成了 p 型半导体 CoO-Au 多面体，并将其用作信号放大器，构建了用于检测 caspase-3 活性的灵敏光电化学（PEC）传感器。在此，使用 n 型半导体 BiS 修饰的氧化铟锡（ITO）片作为光电电极。将生物素-DEVD-肽（生物素-Gly-Asp-Gly-Asp-Glu-Val-Asp-Cys）固定在 BiS 表面后，通过生物素和链霉亲和素之间的特异性相互作用，将标记有链霉亲和素的 CoO-Au 多面体引入传感平台。CoO-Au 多面体不仅可以由于电子供体和激发光能的竞争消耗而猝灭 BiS 的光电流（p-n 型半导体猝灭效应），还可以作为过氧化物酶模拟物产生催化沉淀物。此外，CoO-Au 多面体的空间位阻效应会降低 BiS 的 PEC 响应。巧妙地，沉淀物不仅可以沉积在 ITO 电极上，从而降低 PEC 传感器的光电流，还可以作为电子受体来清除 CoO-Au 多面体的光生电子，从而增强 CoO-Au 多面体的猝灭能力。当 caspase-3 存在时，caspase-3 可以特异性识别并切割生物素-DEVD-肽，导致 PEC 响应增加。基于多功能 CoO-Au 多面体，caspase-3 被灵敏地检测，线性范围为 0.5 至 50 ng mL，检测限低至 0.10 ng mL。CoO-Au 多面体为构建 PEC 传感平台提供了一种新型信号放大器，并可能在生物分析、疾病诊断和临床生物医学中有潜在应用。
