  We investigate the use of Bismuth Ferrite (BFO) nanoparticles for tumor
tissue labelling in combination with infrared multi-photon excitation at 1250
nm. We report the efficient and simultaneous generation of second and third
harmonic by the nanoparticles. On this basis, we set up a novel imaging
protocol based on the co-localization of the two harmonic signals and
demonstrate its benefits in terms of increased selectivity against endogenous
background sources in tissue samples. Finally, we discuss the use of BFO
nanoparticles as mapping reference structures for correlative light-electron
microscopy.
