Barium titanate nanoparticles used as second harmonic radiation imaging probes for cell imaging

Luminescent markers play a key role in imaging techniques for life science since they provide a contrast mechanism between signal and background. We describe a new type of marker using second harmonic generation (SHG) from noncentrosymmetric BaTiO_3 nanocrystals. These nanoparticles are attractive due to their stable, non-saturating and coherent signal with a femtosecond-scale response time and broad flexibility in the choice of excitation wavelength. In this paper, we report the use of nanoparticles for cell imaging. We first stabilized the BaTiO_3 nanoparticles in suspension and characterized the optical properties. We also demonstrated the functionalization of BaTiO_3 nanoparticles by conjugating IgG antibody on the surface of the nanoparticles. These functionalized nanocrystals are capable of specific labeling the antigens of interest.