Protein-templated gold nanoclusters: size dependent inversion of fluorescence emission in the presence of molecular oxygen
Protein-templated gold nanoclusters: size dependent inversion of fluorescence emission in the presence of molecular oxygen
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DOI：
10.1039/c2nr31271a
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发表时间：
2012-01-01
期刊：
影响因子：
6.7
通讯作者：
Purkayastha, Pradipta
中科院分区：
文献类型：
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作者：
Das, Tarasankar;Ghosh, Prasun;Purkayastha, Pradipta
金纳米团簇作为生物标记物是很有前途的候选者，而没有像荧光量子点那样的毒性作用。在此，牛血清白蛋白（BSA）蛋白质稳定的金纳米团簇的两种不同的尺寸发射在410和645 nm已被合成。这些纳米团簇已被证明与分子氧差异相互作用。光谱和化学证据表明，分子氧在纳米团簇上以两种不同的取向吸附。取向图案已被假设为superoxo和peroxo类型的较小和较大的金纳米团簇，分别。由于附着的差异，氧分子显示出纳米团簇的荧光强度的相反变化。蓝色发光纳米团簇的荧光强度显示出丰富的增强，而红色发光物种显示出发射猝灭。氧分子在发蓝光的金纳米团簇上的超氧型吸附诱导单线态氧的形成，单线态氧又增强了物质的荧光强度。这可以通过单线态氧氧化二氨基联苯胺（DAB）来验证。随着分子氧浓度的增加，蓝色发光金纳米团簇的荧光强度增强，可能使它们成为生物成像和检测的良好候选者。
Gold nanoclusters are promising candidates as biological markers without having toxic effects like fluorescent quantum dots. Herein, bovine serum albumin (BSA) protein stabilized gold nanoclusters of two different sizes emitting at 410 and 645 nm have been synthesized. These nanoclusters have been shown to interact with molecular oxygen differentially. Spectroscopic and chemical evidences show that dioxygen molecule gets adsorbed at two different orientations on the nanoclusters. The orientation motifs have been hypothesized to be superoxo and peroxo types on the smaller and the larger gold nanoclusters, respectively. Due to the difference in attachments, the oxygen molecule shows opposite changes in fluorescence intensity for the nanoclusters. The fluorescence intensity of the blue emitting nanocluster shows a profuse enhancement whereas the red emitting species shows quenching of emission. Superoxo type adsorption of the oxygen molecule on the blue emitting gold nanoclusters induce formation of singlet oxygen that in turn enhances the fluorescence intensity of the species. This could be verified by oxidation of diaminobenzidine (DAB) by singlet oxygen. Enhancement in fluorescence intensity of the blue emitting gold nanoclusters with an increase in concentration of molecular oxygen may enable them to be good candidates in bioimaging and detection.