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- Englisch (4) (entfernen)
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- Click chemistry (2)
- XPS (2)
- Azidation (1)
- Biomineralization (1)
- Biosensors (1)
- Calcium phosphate (1)
- Chemical derivatization (1)
- Copper(II) - phenanthroline - complexe filmss (1)
- Dendritic amphiphile (1)
- H-terminated Si3N4 films (1)
- NEXAFS (1)
- Near edge X-ray absorption fine structure (1)
- Silicon nitride (1)
- Streptavidin binding (1)
- X-ray photoelectron spectroscopy (1)
Organisationseinheit der BAM
In this study, a new direct functionalization method of silicon nitride (Si3N4) using azidation and click chemistry is presented. First, amino groups (NHx) were created on a Si3N4 substrate by fluoride etching. These NHx-terminated Si3N4 surfaces were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) with 4-trifluoromethylbenzaldehyde (TFBA) and a derivatization yield of 20% was concluded. In the second step freshly prepared NHx surfaces were transformed into azides which were used immediately in a click reaction with halogenated alkynes. The presented combination of amination, azidation and click reaction is a promising alternative for common silane-based Si3N4 functionalization methods.
Copper(II)phenanthroline complexes intercalate into DNA and induce DNA cleavage. Here, we investigate the nuclease activity of copper(II)phenanthroline complexes on Silicon nitride films. 1,10-phenanthroline-5-carboxylic acid is immobilized at Si-NHx bonds via amide coupling followed by the formation of copper(II)phenanthroline complexes. XPS and NEXAFS were carried out at the HE-SGM beamline.
Biosensors are of essential importance in medical and biological diagnostics. Often, they are produced using silane chemistry on glass or silicon oxide surfaces.
However, controlling that silane chemistry is challenging. Here, we present an alternative strategy to form functional organic layers and biosensors on silicon Nitride (Si3N4). H-terminated Si3N4 films are used to generate reactive azide groups by various azidation methods. Biomolecular probes can then be immobilized using click chemistry reactions with the azide groups and due to its high sensitivity in XPS a fluorine-substituted test alkyne was utilized to optimize click chemistry conditions. After that a biotinylated alkyne was clicked to Si3N4 surfaces followed by immobilization of streptavidin as analyte in a model assay. The functionalized surfaces were thoroughly characterized by surface chemical analysis using X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS)spectroscopy.
The phase behavior of a dendritic amphiphile containing a Newkome-type dendron as the hydrophilic moiety and a cholesterol unit as the hydrophobic segment is investigated at the air–liquid interface. The amphiphile forms stable monomolecular films at the air–liquid interface on different subphases. Furthermore, the mineralization of calcium Phosphate beneath the monolayer at different calcium and phosphate concentrations versus mineralization time shows that at low calcium and Phosphate concentrations needles form, whereas flakes and spheres dominate at higher concentrations. Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron diffraction confirm the formation of calcium phosphate. High-resolution transmission electron microscopy and electron diffraction confirm the predominant formation of octacalcium phosphate and hydroxyapatite.
The data also indicate that the final products form via a complex multistep reaction, including an association step, where nano-needles aggregate into larger flake-like objects.