School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241, China.
ACS Appl Mater Interfaces. 2023 May 17;15(19):23489-23500. doi: 10.1021/acsami.3c03176. Epub 2023 May 4.
The real-time detection of nitric oxide (NO) in living cells is essential to reveal its physiological processes. However, the popular electrochemical detection strategy is limited to the utilization of noble metals. The development of new detection candidates without noble metal species still maintaining excellent catalytic performance has become a big challenge. Herein, we propose a spinel oxide doped with heteroatom-Cu-doped CoO (Cu-CoO) for the sensitive and selective detection of NO release from the living cells. The material is strategically designed with Cu occupying the tetrahedral () center of CoO through the formation of a Cu-O bond. The introduced Cu regulates the local coordination environment and optimizes the electronic structure of CoO, hybridizing with the N 2p orbital to enhance charge transfer. The Cu site can well inhibit the current response to nitrite (NO), resulting in a high improvement in the electrochemical oxidation of NO. The selectivity of Cu-CoO can be markedly improved by the pore size of the molecular sieve and the negative charge on the surface. The rapid transmission of electrons is due to the fact that Cu-CoO can be uniformly and densely in situ grown on Ti foil. The rationally designed Cu-CoO sensor displays excellent catalytic activity toward NO oxidation with a low limit of detection of 2.0 nM (S/N = 3) and high sensitivity of 1.9 μA nM cm in cell culture medium. The Cu-CoO sensor also shows good biocompatibility to monitor the real-time NO release from living cells (human umbilical vein endothelial cells: HUVECs; macrophage: RAW 264.7 cells). It was found that a remarkable response to NO was obtained in different living cells when stimulated by l-arginine (l-Arg). Moreover, the developed biosensor could be used for real-time monitoring of NO released from macrophages polarized to a M1/M2 phenotype. This cheap and convenient doping strategy shows universality and can be used for sensor design of other Cu-doped transition metal materials. The Cu-CoO sensor presents an excellent example through the design of proper materials to implement unique sensing requirements and sheds light on the promising strategy for electrochemical sensor fabrication.
活细胞中一氧化氮（NO）的实时检测对于揭示其生理过程至关重要。然而，流行的电化学检测策略仅限于使用贵金属。开发新的检测候选物而不使用贵金属物种，同时保持优异的催化性能，已成为一个巨大的挑战。在此，我们提出了一种掺杂杂原子的尖晶石氧化物-Cu 掺杂的 CoO（Cu-CoO），用于灵敏和选择性地检测活细胞中 NO 的释放。该材料通过形成 Cu-O 键，战略性地设计 Cu 占据 CoO 的四面体（）中心。引入的 Cu 调节局部配位环境并优化 CoO 的电子结构，与 N 2p 轨道杂化，增强电荷转移。Cu 位可以很好地抑制对亚硝酸盐（NO ）的电流响应，从而显著提高 NO 的电化学氧化。Cu-CoO 的选择性可以通过分子筛的孔径和表面的负电荷得到明显改善。由于 Cu-CoO 可以均匀且密集地原位生长在 Ti 箔上，因此电子的快速传输。合理设计的 Cu-CoO 传感器对 NO 氧化具有优异的催化活性，在细胞培养液中的检测限低至 2.0 nM（S/N = 3），灵敏度高达 1.9 μA nM cm。Cu-CoO 传感器对活细胞（人脐静脉内皮细胞：HUVECs；巨噬细胞：RAW 264.7 细胞）中实时 NO 释放的监测也表现出良好的生物相容性。结果发现，在用 l-精氨酸（l-Arg）刺激不同的活细胞时，对 NO 有明显的响应。此外，所开发的生物传感器可用于实时监测极化到 M1/M2 表型的巨噬细胞中释放的 NO。这种廉价方便的掺杂策略具有普遍性，可用于其他 Cu 掺杂过渡金属材料的传感器设计。Cu-CoO 传感器通过设计合适的材料来实现独特的传感要求，为电化学传感器的制造提供了有前途的策略，是一个很好的例子。
