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摘要
The proof of concept of a simple sensing platform based on the fluorescence of a gold cluster consisting of eight atoms, which is easily manipulated by reduction and oxidation of a specific molecule in the absence of chemical linkers, is demonstrated. Without using any coupling reagents to arrange the distance of the donoracceptor pair, the fluorescence of the Au8-cluster is immediately switched off in the presence of 2-pyridinethiol (2-PyT) quencher. Through an upward-curving SternVolmer plot, the system shows complex fluorescence quenching with a combination of static and dynamic quenching processes. To analyze the static quenching constant (V) by a sphere of action model, the collisional encounter between the Au8-cluster and 2-PyT presents a quenching radius (r) similar to 5.8 nm, which is larger than the sum of the radii of the Au8-cluster and 2-PyT. This implies that fluorescence quenching can occur even though the Au8-cluster and 2-PyT are not very close to each other. The quenching pathway may be derived from a photoinduced electron-transfer process of the encounter pair between the Au8-cluster (as an electron donor) and 2-PyT (as an electron acceptor) to allow efficient fluorescence quenching in the absence of coupling reagents. Interestingly, the fluorescence is restored by oxidation of 2-PyT to form the corresponding disulfide compound and then quenched again after the reduction of the disulfide. This redox-switchable fluorescent Au8-cluster platform is a novel discovery, and its utility as a promising sensor for detecting H2O2-generating enzymatic transformations is demonstrated.
- 出版日期2012-7-9
