Fast wavefront shaping for two-photon brain imaging with large field of view correction

In-vivo optical imaging with diffraction-limited resolution deep inside scattering biological tissues is obtained by non-linear fluorescence microscopy. Active compensation of tissue-induced aberrations and light scattering through adaptive wavefront correction further extends depth penetration by restoring high resolution at large depth. However, at large depths those corrections are only valid over a very limited field of view within the angular memory effect. To overcome this limitation, we introduce an acousto-optic light modulation technique for fluorescence imaging with simultaneous wavefront correction at pixel scan speed. Biaxial wavefront corrections are first learned by adaptive optimization at multiple locations in the image field. During image acquisition, the learned corrections are then switched on-the-fly according to the position of the excitation focus during the raster scan. The proposed microscope is applied to in-vivo transcranial neuron imaging and demonstrates correction of skull-induced aberrations and scattering across large fields of view at 40 kHz data acquisition speed.

FITC-Functionalized TiO2 Nanoparticles for Simultaneous Neuron Imaging and in Cell Photocatalysis

ABSTRACTCrystalline TiO2 nanoparticles were produced by scalable flame spray pyrolysis of organometallic solutions. A protocol is presented for the optimized functionalization of these particles with fluorescein isothiocyanate (FITC), an important biomedical dye via a lysine linker. The pH, stoichiometry and time for lysine reaction were determined for highest dye loading and minimized degree of polylysine formation. Acidic reaction conditions, low lysine concentration and short reaction times were found to meet this aim. The resulting particles were used for imaging single neurons, showing high fluorescence emission and ability for the particles to diffuse into small neuron structures such as dendrites.