Aslan Kadir, Holley Patrick, Davies Lydia, Lakowicz Joseph R, Geddes Chris D
Institute of Fluorescence, Laboratory for Advanced Medical Plasmonics, Medical Biotechnology Center, University of Maryland Biotechnology Institute, 725 West Lombard Street, Baltimore, Maryland 21201, USA.
J Am Chem Soc. 2005 Aug 31;127(34):12115-21. doi: 10.1021/ja052739k.
We describe an exciting opportunity for affinity biosensing using a ratiometric approach to the angular-dependent light scattering from bioactivated and subsequently aggregated noble metal colloids. This new model sensing platform utilizes the changes in particle scattering from very small colloids, which scatter light according to traditional Rayleigh theory, as compared to the changes in scattering observed by much larger colloidal aggregates, formed due to a bioaffinity reaction. These larger aggregates no longer scatter incident light in a Cos(2) theta dependence, as is the case for Rayleigh scattering, but instead scatter light in an increased forward direction as compared to the incident geometry. By subsequently taking the ratio of the scattered intensity at two angles, namely 90 degrees and 140 degrees , relative to the incident light, we can follow the association of biotinylated bovine serum albumin-coated 20 nm gold colloids, cross-linked by additions of streptavidin. This new model system can be potentially applied to many other nanoparticle assays and has many advantages over traditional fluorescence sensing and indeed light-scattering approaches. For example, a single nanoparticle can have the equivalent scattered intensity as 10(5) fluorescing fluorescein molecules substantially increasing detection; the angular distribution of scattered light from noble metal colloids is substantially easier to predict as compared to fluorescence; the scattered light is not quenched by biospecies; the ratiometric measurements described here are not dependent on colloid concentration as are other scattering techniques; and finally, the noble metal colloids are not prone to photodestruction, as is the case with organic fluorophores.
我们描述了一个令人兴奋的亲和生物传感机会，该方法采用比例法来检测生物活化并随后聚集的贵金属胶体的角度相关光散射。与生物亲和反应形成的大得多的胶体聚集体所观察到的散射变化相比，这个新的模型传感平台利用了非常小的胶体（根据传统瑞利理论散射光）的粒子散射变化。这些较大的聚集体不再像瑞利散射那样以Cos(2)θ依赖性散射入射光，而是与入射几何形状相比，在向前方向上增加了散射光。通过随后获取相对于入射光在两个角度（即90度和140度）处的散射强度之比，我们可以跟踪添加链霉亲和素交联的生物素化牛血清白蛋白包被的20纳米金胶体的缔合情况。这个新的模型系统有可能应用于许多其他纳米颗粒检测，并且与传统荧光传感以及光散射方法相比有许多优势。例如，单个纳米颗粒可以具有与10(5)个荧光素分子相当的散射强度，大大提高了检测能力；与荧光相比，贵金属胶体散射光的角度分布更容易预测；散射光不会被生物物种淬灭；这里描述的比例测量不像其他散射技术那样依赖于胶体浓度；最后，贵金属胶体不像有机荧光团那样容易发生光破坏。
