New methods for improved characterization of silica nanoparticle-based drug delivery systems

The incorporation of silica nanoparticles into drug delivery vehicles, and other nanotech platforms, has experienced rapid and significant growth over the past decade. However, as these nanoparticle-based systems become more and more complex, the methods used to analyze these systems have evolved at a comparatively much slower pace, resulting in the need for researchers to expand their toolbox and devise new strategies to characterize these materials. This article describes how X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were recently employed in the analysis of two separate drug delivery systems which contain organic compounds covalently attached to the surfaces of silica nanoparticles. These techniques provided a deluge of qualitative and quantitative information about these drug delivery systems, and have several clear advantages over more common characterization procedures such as Fourier transform infrared spectroscopy (FT-IR) and solid state nuclear magnetic resonance (SSNMR). Thus, XPS and ToF-SIMS should be an integral component of the standard characterization protocol for any nanoparticle-based assemblies-particularly silica-based drug delivery systems-as this field of research continues to develop.