Porous Pd nanoparticles with high photothermal conversion efficiency for efficient ablation of cancer cells

Abstract

Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 10(7) M(-1) cm(-1)), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water and illuminated with an 808 nm laser, the porous Pd NPs give a photothermal conversion efficiency as high as 93.4%, which is comparable to the efficiency of Au nanorods we synthesized (98.6%). As the porous Pd NPs show broadband NIR absorption (650-1200 nm), this allows us to choose multiple laser wavelengths for photothermal therapy. In vitro photothermal heating of HeLa cells in the presence of porous Pd NPs leads to 100% cell death under 808 nm laser irradiation (8 W cm(-2), 4 min). For photothermal heating using 730 nm laser, 70% of HeLa cells were killed after 4 min irradiation at a relative low power density of 6 W cm(-2). These results demonstrated that the porous Pd nanostructure is an attractive photothermal agent for cancer therapy.

Palladium: a future key player in the nanomedical field?

“…35,36 Porous Pd nanoparticles (22.8 nm) were also recently reported as attractive PT agents with PT conversion efficiency as high as 93.4%, which is comparable to typical Au nanorods. 37 …”

PEDOT nanocomposites mediated dual-modal photodynamic and photothermal targeted sterilization in both NIR I and II window

“…Photothermal coupling agents, which convert light energy into heat energy, include metal nanomaterials (Au [11,12], Ag [13], Pd [14,15], Ge [16], Ni [17] and Fe [18]), semiconductor nanoparticles (CuS) [19e22], carbon-based (carbon nanotubes [23] and graphenes [24]), and tungsten-based nanomaterials [25,26]. Recently, more attention has been paid to conjugated polymeric nanoparticles as photothermal coupling agents due to their high photothermal conversion efficiency, excellent photostability, outstanding biocompatibility, and low cost [27].…”

In vitro biomechanical properties, fluorescence imaging, surface-enhanced Raman spectroscopy, and photothermal therapy evaluation of luminescent functionalized CaMoO4:Eu@Au hybrid nanorods on human lung adenocarcinoma epithelial cells

“…[9–11] These types of particles can be efficiently used for diagnosis and selective PTT of cancer cells. Recently, PTT agents such as GNRs,[12] Au nanoshells,[13] zinc ferrite spinel reduced graphene oxide (ZnFe 2 O 4 –rGO),[14] palladium nanostructures,[15] CuS nanoparticles (NPs),[16] Cu 9 S 5 nanocrystals,[17] and other inorganic NPs have been intensively investigated. However, none of these nanostructured materials have fluorescence properties.…”