Abstract
This work is the first to describe a bioimaging method that uses highly uniformly sized TiO 2 submicrometer and micrometer spheres based on Mie scattering. Trans-membrane proteins (HER2) located on the surface of cancer cells were detected by bonded antibody-linked TiO 2 spheres using optic microscopy and UV-vis spectroscopy. A particular HER2 bond on cancer cells, which has a weaker binding affinity than the biotin/avidin interaction, can be identified between TiO 2 spheres that are linked to anti-HER2 antibodies and those that are linked to nonspecific mouse IgG antibodies by observing the cells under an optical microscope or by measuring absorbance from a UV-vis spectrum. The TiO 2 spheres used in this work was prepared by reacting TTIP with carboxylic acid, as described elsewhere and the uniformity of the TiO 2 sphere was further improved by adjusting the amount of water used. The water content was inversely related to particle size and the size distribution: as more water was used, smaller spheres with a narrower size distribution were obtained. The most uniform sphere obtained had a diameter of about 1 μm with a size variation of 3%. © 2009 American Chemical Society.