Vapor-phase Deposition and Silane Functionality to Address Issues in Silane Capping of ZnO Nanoparticles for Use in Neurological Disorder Treatment

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Sean Bedingfield, Utah State University


The delivery of zinc ions using ZnO nanoparticles within the body has been shown to cause the destruction of tumor cells and may also treat neurodegenerative disorders. The silane capping of ZnO nanoparticles is employed as a post-synthesis method to protect them from dissolution in polar solvents. Preliminary research demonstrates standard methods of silane capping result in aggregation of nanoparticles. Aggregation produces particles significantly larger than the original diameter of the nanoparticles, making them too large for some medical applications.

Silanes with distinct functionalities were selected for vapor-phase deposition to address nanoparticle aggregation and create smaller nanoparticles. Three vapor-phase deposition methods were tested with five commercially available silanes and three solvents. The use of silanes with a varied number of functional groups in liquid-phase deposition was also compared with standard methods. Performance of methods was evaluated using dynamic light scattering, Fourier transform infrared spectroscopy, and fluorometric analysis.

Vapor-phase deposition was shown to be a feasible means by successful silane capping using three silane molecules with distinct benefits. These capped nanoparticles were shown to retain the stability of ZnO in water better than untreated nanoparticles. Efficiency and generated particle size of methods tested are discussed. Key influences in vapor-phase silanization were identified for future implementation of process in scale-up production. Additionally, the use of vapor phase deposition for ZnO nanoparticle capping with alternative molecules such as dopamine is also discussed.