Silane Functionalization of Silica Particles

Surface functionalization of silica particles or fluorescent silica particles typically is done using functional alkyl silanes. The process may be used to add a reactive group to the surface of the particles for spontaneous coupling to biomolecules or it may be used to add the appropriate nucleophilic group to the surface, such as an amine or a carboxylate. Silane modification chemistry is discussed in more detail in Chapter 13. 

The following protocol for modification of silica nanoparticles is based on the method of Zhao et al. (2004), which describes the addition of amine functionalities using trimethoxysilyl-propyldiethylenetriamine. Other functional silane modifications may be done similarly. 

Add 32 mg of silica nanoparticles (fluorescent or plain) to 20 ml of 1 mM acetic acid containing 1 percent trimethoxysilyl-propyldiethylenetriamine with stirring. Other concentrations of silane derivatives used for particle modification typically range from 1 to 5 

React with mixing for 30 minutes at room temperature. 

Wash the amine-derivatized particles at least 3 times with water using centrifugation to remove excess reactants. 

---