Synthesis and functionalization of SHG active Barium Titanate (BaTiO3): Towards biomedical imaging

Abstract

Tetragonal barium titanate (BaTiO3) has a non-centrosymmetric crystal structure, making it capable of emitting SHG-light by frequency doubling. Therefore, Second Harmonic Generation (SHG) microscopy has turned out to be a promising method for visualization in the field of (bio-)medical imaging [1], making e.g. intracellular diffusion monitoring and tracking of proteins accessible. However, nanometer sized particles are necessary for adequate imaging resolutions, their dispersion in aqueous media and cellular uptake. Also, the particles have to be properly functionalized for further attachment to a targeting protein. This work focuses on the synthesis of small BaTiO3 particles capable of generating the second harmonic of excitation (SHG). Oxide particles obtained from different synthesis routes are compared, as crystallinity and SHG activity are very synthesis dependent. Following the synthesis, the surface of the particles is modified with the objective of future linking to a biological sensing protein. The applied surface modification encompasses hydroxylation, followed by silanization of the surface [2]. The SHG activity of few obtained oxides is studied ex-vivo and discussed. In further work, nanobodies will be attached to be applied as a biological sensor [3].