Surface modification of silica nanoparticles: a new strategy for the realization of self-organized fluorescence chemosensors
作者:Enrico Rampazzo、Elena Brasola、Silvia Marcuz、Fabrizio Mancin、Paolo Tecilla、Umberto Tonellato
DOI:10.1039/b502052b
日期:——
The self-organization of the proper subunits of a fluorescence chemosensor on the surface of silica nanoparticles allows the easy design and realization of new effective sensing systems. Commercially available silica particles (20 nm diameter) were functionalized with triethoxysilane derivatives of selective Cu(II) ligands and fluorescent dyes. Grafting of the sensor components to the particle surface ensures the spatial proximity between the sensor components and, as a consequence, binding of Cu(II) ions by the ligand subunits leads to quenching of the fluorescent units emission. In 9 : 1 DMSO–water solution, the coated silica nanoparticles (CSNs) selectively detect copper ions down to nanomolar concentrations. The operative range of the sensors can be tuned either by switching the ligand units or by modification of the components ratio. Sensors with the desired photophysical properties can be easily prepared by using different fluorescent dyes. Moreover, the organization of the network of sensor components gives rise to cooperative and collective effects: on one hand, the ligand subunits bound to the particle surfaces cooperate to form multivalent binding sites with an increased affinity for the Cu(II) ions; on the other hand, binding of a single metal ion leads to the quenching of several fluorescent groups producing a remarkable signal amplification.
二氧化硅纳米颗粒表面上荧光化学传感器的适当亚基的自组装使得易于设计和实现新的有效传感系统。商业可获得的二氧化硅颗粒(20nm直径)通过三乙氧基硅烷衍生的选择性Cu(II)配体和荧光染料进行功能化。将传感器组件嫁接到颗粒表面上确保传感器组件之间的空间接近,因此,配体亚基结合Cu(II)离子导致荧光单元的荧光发射熄灭。在9:1 DMSO-水溶液中,涂层的二氧化硅纳米颗粒(CSNs)能够选择性地检测铜离子,检测极限达到纳摩尔浓度。传感器的操作范围可以通过切换配体单元或通过改变组件比例来进行调节。通过使用不同的荧光染料,可以很容易地制备具有所需光物理性质的传感器。此外,传感器组件的网络组织导致协同和集体效应:一方面,连接在颗粒表面上的配体亚基协作形成具有增加的亲和力的多价结合位点用于Cu(II)离子;另一方面,单个金属离子的结合导致几个荧光基团的熄灭,产生显著的信号增强。