Cauda Valentina, Schlossbauer Axel, Kecht Johann, Zürner Andreas, Bein Thomas
Department of Chemistry and Biochemistry and Center for NanoScience, University of Munich, Butenandtstrasse 5-13 (E), 81377 Munich, Germany.
J Am Chem Soc. 2009 Aug 19;131(32):11361-70. doi: 10.1021/ja809346n.
The selective functionalization of the inner and outer surfaces of colloidal mesoporous silica (CMS) nanoparticles with different trialkoxysilanes, following a newly developed delayed co-condensation approach, results in bifunctional CMS. Complementary CMS nanoparticles were prepared with two different functional groups located either on the outer shell or in the inner core of the particle. The identification and localization of the functional groups was achieved by means of different techniques including zeta potential, nitrogen sorption measurements, and fluorescence spectroscopy. This last technique was applied to fluorescein isothiocyanate (FITC)-labeled CMS featuring aminopropyl functional groups on the periphery or the internal pore surface of the particles. Fluorescence quenching experiments were carried out with dodecanethiolate-stabilized gold nanoparticles having a diameter greater than the pore size of the CMS. It could be shown that fluorescence quenching occurs only when the FITC is positioned on the outer surface of the CMS nanoparticles, whereas no quenching was observed for FITC located in the inner core of the nanoparticle. These results clearly confirm the controlled localization of the aminopropyl groups in the nanometer space of the CMS particles. Our approach thus offers the opportunity to synthesize, in a novel multistep co-condensation strategy, various bifunctional mesoporous nanoparticles with controlled localization of different functional groups in the inner core or on the outer shell of the nanoparticle.
采用新开发的延迟共缩合方法，用不同的三烷氧基硅烷对胶体介孔二氧化硅（CMS）纳米颗粒的内表面和外表面进行选择性功能化，可得到双功能CMS。制备了互补的CMS纳米颗粒，其两个不同的官能团分别位于颗粒的外壳或内核中。通过包括zeta电位、氮吸附测量和荧光光谱在内的不同技术实现了官能团的识别和定位。最后一种技术应用于在颗粒外围或内部孔表面具有氨丙基官能团的异硫氰酸荧光素（FITC）标记的CMS。用直径大于CMS孔径的十二烷硫醇稳定的金纳米颗粒进行荧光猝灭实验。结果表明，只有当FITC位于CMS纳米颗粒的外表面时才会发生荧光猝灭，而位于纳米颗粒内核中的FITC则未观察到猝灭现象。这些结果清楚地证实了氨丙基在CMS颗粒纳米空间中的可控定位。因此，我们的方法提供了一个机会，通过一种新颖的多步共缩合策略，合成各种双功能介孔纳米颗粒，使不同官能团在纳米颗粒的内核或外壳中实现可控定位。
