Laser- synthesized TiN nanoparticles as promising plasmonic alternative for biomedical applications

Exhibiting a
red-shifted absorption/scattering feature compared to conventional plasmonic
metals, titanium nitride nanoparticles (TiN NPs) look as very promising
candidates for biomedical applications, but these applications are still
underexplored despite the presence of extensive data for conventional plasmonic
counterparts. Here, we report the fabrication of ultrapure, size-tunable TiN
NPs by methods of femtosecond laser ablation in liquids and their biological
testing. We show that TiN NPs demonstrate
and broad plasmonic peak around 640–700 nm with a significant tail over 800 nm
even for small
NPs sizes (<7 nm). In vitro tests
of laser-synthesized TiN NPs on cellular models evidence their low
cytotoxicity and excellent cell uptake. We finally demonstrate a
strong photothermal therapy effect on U87–MG cancer cell cultures using TiN NPs
as sensitizers of local hyperthermia under near-infrared
laser excitation. Based on absorption band in the region of
relative tissue transparency and acceptable biocompatibility, laser-synthesized
TiN NPs promise the advancement of biomedical modalities
employing plasmonic effects, including absorption/scattering
contrast imaging, photothermal therapy,
imaging and SERS.

(a) Schematics of laser ablation setup. A laser beam is focused on the surface of the TiN target, which is placed in the vessel filled with a liquid. The vessel is mounted on a moving translation stage to avoid ablation from the same area of the target. (b) Schematic of laser fragmentation setup to minimize size dispersion of NPs. Ar bubbling used optionally to remove dissolved oxygen.

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