本文首次合成了基于蛋氨酸（Met）/乙酰-L-半胱氨酸（NAC）模板的可调谐近红外（NIR）电化学发光（ECL）发射波长的铜纳米团簇（Met/NAC-Cu NCs），作为超灵敏检测基质金属蛋白酶-2（MMP-2）的发射器。显著的是，NAC在模板和还原镀铜过程中起到了作用，通过-S-S-键将表面缺陷调控剂Met与NAC连接在一起，可以增加铜纳米团簇的表面缺陷，通过连续调控Met和NAC的摩尔比重来调节最大ECL发射，导致铜纳米团簇的ECL发射波长范围从680 nm到750 nm。此外，通过有序均等地排列发夹来构建了快速目标触发的催化发夹组装（CHA）循环放大策略，以增加其局部浓度，从而大大加速信号放大效率和反应速率。作为概念证明，基于Met/NAC-Cu NCs作为NIR ECL发射器和有效信号放大策略，构建了超灵敏的ECL生物传感器，检测限为1.65 fg/mL，并成功用于检测来自Hela和MCF-7癌细胞的MMP-2。这项研究为调控基于金属纳米团簇的ECL发射器的光学性能提供了良好途径，而具有较小光化学损伤和更深组织穿透深度的新型NIR ECL发射器在超灵敏生物传感和高清晰度ECL成像中展现了巨大潜力。版权所有© 2023 Elsevier B.V. 保留所有权利。

Herein, the methionine (Met)/N-acetyl-L-cysteine (NAC) templated copper nanoclusters (Met/NAC-Cu NCs) with tunable near-infrared region (NIR) electrochemiluminescence (ECL) emission wavelength was firstly synthesized as emitter for the ultrasensitive detection of matrix metalloproteinase-2 (MMP-2). Significantly, the NAC played the role of template and reductant of cupric to acquire Cu NCs, and the surface defect regulator Met was used to connect NAC through -S-S- bond, which could heighten the surface defect of Cu NCs to continuously regulate the maximum ECL emission by successively controlling the molar ratio of Met and NAC, leading to the ECL emission wavelength of Cu NCs ranged from 680 nm to 750 nm. In addition, a rapid target triggered catalyst hairpin assembly (CHA) recycling amplification strategy was constructed through orderly and equidistantly arranging hairpin to increase its local concentration, resulting in greatly accelerated signal amplification efficiency and reaction rate. As a proof of concept, based on Met/NAC-Cu NCs as NIR ECL emitter and effective signal amplification tactic, a super-sensitive ECL biosensor was fabricated to detect target MMP-2 with the detection limit (LOD) as low as 1.65 fg/mL and successfully utilized for detecting of MMP-2 that from Hela and MCF-7 cancer cells. This research provided a wonderful avenue for regulating the optical performance of metal nanoclusters-based ECL emitters, and the developed neoteric NIR ECL emitter with the merits of less photochemical damage and deeper tissue penetration exhibited great potential in ultrasensitive biosensing and high-definition ECL imaging.Copyright © 2023 Elsevier B.V. All rights reserved.