Department of Chemistry, National University of Singapore, Singapore 117543.
ACS Appl Mater Interfaces. 2012 Sep 26;4(9):4746-51. doi: 10.1021/am301121k. Epub 2012 Aug 27.
Plasmon coupling is known to enhance the two-photon excitation photoluminescence of metal nanoparticles significantly. Here, Au and Ag nanospheres of different sizes were prepared to systematically investigate the effects of particle size on plasmon coupling enhanced two-photon excitation photoluminescence. An oppositely charged polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA), was used to induce the coupling of Au and Ag nanospheres. The two-photon excitation photoluminescence enhancement factor was found to first increase and then decrease with the increasing particle size for both Au and Ag nanospheres. Optimum enhancement factors of 25-fold and 14-fold were obtained for coupled 55-nm Au nanospheres and 50-nm Ag nanospheres, respectively. The coupled Au and Ag nanospheres displayed two-photon action cross sections of up to 9 × 10(4) GM per particle (where 1 GM = 10(-50) cm(4) s/photon). Similar to Ag nanoparticles, Au nanoparticles also displayed large coupling induced enhancement of two-photon excitation photoluminescence. Considering their excellent biocompatibility, high inertness, and easy preparation, Au nanoparticles are expected to find many new applications in two-photon biosensing and bioimaging.
等离子体耦合被认为可以显著增强金属纳米粒子的双光子激发光致发光。在这里，制备了不同尺寸的 Au 和 Ag 纳米球，以系统地研究颗粒尺寸对等离子体耦合增强双光子激发光致发光的影响。带相反电荷的聚电解质聚二烯丙基二甲基氯化铵（PDDA）被用于诱导 Au 和 Ag 纳米球的耦合。对于 Au 和 Ag 纳米球，双光子激发光致发光增强因子发现先随着颗粒尺寸的增加而增加，然后减小。对于耦合的 55nm Au 纳米球和 50nm Ag 纳米球，分别获得了 25 倍和 14 倍的最佳增强因子。耦合的 Au 和 Ag 纳米球显示出高达每个粒子 9×10（4）GM 的双光子作用截面（其中 1 GM = 10（-50）cm（4）s/光子）。与 Ag 纳米粒子类似，Au 纳米粒子也表现出大的耦合诱导双光子激发光致发光增强。考虑到它们优异的生物相容性、高惰性和易于制备，Au 纳米粒子有望在双光子生物传感和生物成像中找到许多新的应用。
