Surface characterization of covalently functionalized carbon based nanomaterials using comprehensive XP and NEXAFS spectroscopies

Reliable and straightforward characterization and analysis of carbon based nanomaterials on the atomic level is essential to exploring their potential for application. Here we use a combination of highly surface sensitive x ray photoelectron XP spectroscopy and near edge x ray absorption fine structure spectroscopy NEXAFS to study and quantify the covalent functionalization of nanographene and single walled carbon nanotubes with nitrene [2 1] cycloaddition. With this comprehensive analytical approach, we demonstrate that the amp; 960; conjugated system of functionalized carbon based nanomaterials is preserved according to NEXAFS analysis, which is challenging to prove with XP spectroscopy investigation alone. Using this combination of analytical approaches, we show significant similarities after functionalization for various carbon based nanomaterials. Both analytical methods are strongly suited to study possible post modification reactions of functionalized carbon based nanomaterial

A New Support Film for Cryo Electron Microscopy Protein Structure Analysis Based on Covalently Functionalized Graphene

Protein adsorption at the air water interface is a serious problem in cryogenic electron microscopy cryoEM as it restricts particle orientations in the vitrified ice film and promotes protein denaturation. To address this issue, the preparation of a graphene based modified support film for coverage of conventional holey carbon transmission electron microscopy TEM grids is presented. The chemical modification of graphene sheets enables the universal covalent anchoring of unmodified proteins via inherent surface exposed lysine or cysteine residues in a one step reaction. Langmuir Blodgett LB trough approach is applied for deposition of functionalized graphene sheets onto commercially available holey carbon TEM grids. The application of the modified TEM grids in single particle analysis SPA shows high protein binding to the surface of the graphene based support film. Suitability for high resolution structure determination is confirmed by SPA of apoferritin. Prevention of protein denaturation at the air water interface and improvement of particle orientations is shown using human 20S proteasome, demonstrating the potential of the support film for structural biolog

Controlled Covalent Functionalization of Thermally Reduced Graphene Oxide To Generate Defined Bifunctional 2D Nanomaterials

A controlled, reproducible, gram‐scale method is reported for the covalent functionalization of graphene sheets by a one‐pot nitrene [2+1] cycloaddition reaction under mild conditions. The reaction between commercially available 2,4,6‐trichloro‐1,3,5‐triazine and sodium azide with thermally reduced graphene oxide (TRGO) results in defined dichlorotriazine‐functionalized sheets. The different reactivities of the chlorine substituents on the functionalized graphene allow stepwise post‐modification by manipulating the temperature. This new method provides unique access to defined bifunctional 2D nanomaterials, as exemplified by chiral surfaces and multifunctional hybrid architectures