Surface-enhanced superquenching of cyanine dyes as J-aggregates on Laponite clay nanoparticles
Surface-enhanced superquenching of cyanine dyes as J-aggregates on Laponite clay nanoparticles
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DOI：
10.1021/la0259306
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发表时间：
2002-10-01
期刊：
影响因子：
3.9
通讯作者：
Whitten, D
中科院分区：
文献类型：
--
作者：
Lu, LD;Jones, RM;Whitten, D
合成Laponite粘土的纳米颗粒可以用单独或混合的花青染料涂覆以在水中形成J聚集的组装体。这些J-聚集体的吸收和荧光特性与在晶体或胶体中形成的J-聚集体的吸收和荧光特性基本上不同，这表明在盘形纳米颗粒上存在较小的J-聚集体域。混合的花青/Laponite聚集体表现出类似的，但不相同的吸收和荧光相比，个别染料聚集体，这表明一个混合的电子结构。从纳米颗粒吸附的花青的荧光受到各种电子和能量接受淬灭剂的超淬灭。这些猝灭剂可以通过与粘土上的供体共吸附（混合聚集体）或通过将受体添加到水性悬浮液中的预先形成的供体聚集体来引入。对于一些能量接受花青，它被发现，观察到强烈的敏化荧光（主要）受体状态，即使在单体染料是非或非常弱的发射的情况下。在有限的情况下，在1个猝灭剂/类似于400个单体或4个猝灭剂/纳米颗粒的水平下观察到50%猝灭。
Nanoparticles of synthetic Laponite clay can be coated with individual or mixed cyanine dyes to form J-aggregated assemblies in water. The absorption and fluorescence characteristics of these J-aggregates are substantially different from those of J-aggregates formed in crystals or colloids, suggesting that smaller J-aggregate domains are present on the disk-shaped nanoparticles. The mixed cyanine/Laponite aggregates exhibit similar but nonidentical absorption and fluorescence as compared to the individual dye aggregates, suggesting a mixed electronic structure. The fluorescence from the nanoparticle-adsorbed cyanines is subject to superquenching by a variety of electron- and energy-accepting quenchers. These quenchers can be introduced by coadsorption with donors on the clay (mixed aggregates) or by addition of acceptors to preformed donor aggregates in aqueous suspensions. For some of the energy-accepting cyanines, it is found that strong sensitization of fluorescence from a (mostly) acceptor state is observed, even in cases where the monomer dye is non- or very weakly emissive. In limiting cases, 50% quenching is observed at levels of 1 quencher per similar to400 monomers or 4 quenchers per nanoparticle.