Silver Enhancement for Transmission Electron Microscopy Imaging of Antibody Fragment鈥揋old Nanoparticles Conjugates Immobilized on Ordered Mesoporous Silica

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• 作者：Marco Piludu ; Luca Medda ; Francesca Cugia ; Maura Monduzzi ; Andrea Salis
• 刊名：Langmuir
• 出版年：2015
• 出版时间：September 1, 2015
• 年：2015
• 卷：31
• 期：34
• 页码：9458-9463
• 全文大小：370K
• ISSN：1520-5827

文摘

Ordered mesoporous silica (OMS) materials are receiving great attention as possible carriers for valuable but unstable drugs as, for example, therapeutic proteins. A key issue is to prove that the therapeutic protein is effectively able to penetrate the pores of OMS during the adsorption step. Here, we immobilized an antibody fragment [F(ab鈥?GAMIgG] conjugated with ultrasmall gold nanoparticles (GNPs) onto amino-functionalized SBA-15 (SBA鈥揘H₂) mesoporous silica. The aim of this work is the visualization of the location of the conjugates adsorbed onto SBA鈥揘H₂ with transmission electron microscopy (TEM). Because of the ultrasmall size of GNPs (<1 nm), we use the silver enhancement procedure to amplify their size. In this procedure, ultrathin sections of conjugate-loaded SBA鈥揘H₂ particles are prepared by a ultramicrotome sectioning technique. The ultrasmall GNPs located on the top side of the 70鈥?0 nm thick slices act as microcrystallization nucleation sites for the deposition of reduced metallic silver. Consequently, the ultrasmall GNPs increase their size. This allows for the direct imaging of the conjugates adsorbed. We clearly localize the F(ab鈥?GAMIgG鈥揋NPs conjugates either on the external surface of the particles or inside the mesopores of SBA鈥揘H₂ through TEM.