Functionalisation of TiO2 nanoparticles with a fluorescent organosilane: A synergy enabling their visualisation in biological cells and an enhanced photocatalytic activity

Nanoparticles, such as TiO2 particles, have a great potential for biomedical applications due to their ultra-small size and large specific surface area. However, their detection within cells is to date more than challenging. Thus, implementing fluorescence properties to nanoparticles via their controlled functionalisation with an organic chromophore is an original and efficient strategy to enable their visualization. In this work, a silylated coupling agent bearing a luminescent rhodamine B group was synthesised and grafted on the surface of anatase nanoparticles. The successful functionalisation was demonstrated via zeta potential, dynamic light scattering and diffuse reflectance infrared Fourier transform analyses. Remarkably, the obtained luminescent TiO2 particles showed an improved photocatalytic activity compared to the pristine nanoparticles. Both, as-synthesised and functionalised TiO2 nanoparticles samples appear to be non-toxic towards malignant and non-malignant cells. Moreover, the detection of the functionalised particles within cultured cells was proven to be easy and efficient via confocal fluorescence microscopy.