量子点具有亮度高和稳定性好等优异的光学性质,在生物检测、活体成像及光电器件开发等领域有着广泛的应用。然而,当前水相量子点尤其是水相近红外荧光量子点的荧光发射强度相对较低,且荧光稳定性有待进一步提高。金属可以使其邻近荧光物质的激发效率提高且辐射衰减速率增加,荧光发射强度较之自由态荧光发射增强,产生金属增强荧光效应。采用金属纳米结构增强量子点的荧光有望为解决上述问题提供有效途径。本文详细介绍了量子点发光机理及金属增强量子点荧光机理,在此基础上讨论了影响金属增强量子点荧光的关键因素,并对相关研究现状及挑战进行了简短的评述。我们相信随着纳米科技的快速发展,金属增强量子点荧光在不远的将来会吸引越来越多的关注并展现出独特的潜力。
Quantum dots (QDs) have been extensively applied in biological detection, in vivo imaging and optoelectronic devices due to their unique optical properties including broad excitation spectra, tunable and narrow emission spectra, high brightness and excellent resistance to photobleaching. Nevertheless, application of aqueous QDs, especially that of aqueous near-infrared fluorescence QDs, is limited by their relatively weak fluorescence and poor stability. Therefore, the development of new approaches for the enhancement of fluorescence of QDs is urgently needed. In recent years, it has been found that the brightness and photostability of QDs can be favorably enhanced by surface plasmon resulted from the nearby metallic nanostructures, which is termed as metal-enhanced fluorescence (MEF). Thus novel strategies for solving the above problems can be proposed based on MEF from QDs, which can be mainly attributed to the increased excitation rate and the increased radiative rate of the excited QDs. In this review, mechanism of MEF, especially that of MEF related to QDs, is introduced based on the near-field interaction between metallic nanostructures and QDs. Key factors affecting the efficiency of fluorescence emission are reviewed, including the distance between metallic nanostructures and QDs, the type of QDs, the composition, shape, and size of metallic nanostructures, and so forth. Current progresses in the application of MEF from QDs are also summarized. Finally, challenges in the development of MEF from QDs are discussed. We believe that with the rapid development of nanoscience and nanotechnology, MEF from QDs will attract more and more attention and show unique potentials in the near future.