Optimization of Surface Coating on Small Pd Nanosheets for in Vivo near-Infrared Photothermal Therapy of Tumor

Abstract

Palladium nanosheets with strong near-infrared absorption have been recently demonstrated as promising photothermal agents for photothermal therapy (PTT) of cancers. However, systematic assessments of their potential risks and impacts to biological systems have not been fully explored yet. In this work, we carefully investigate how surface coatings affect the in vivo behaviors of small Pd nanosheets (Pd NSs). Several biocompatible molecules such as carboxymethyl chitosan (CMC), PEG-NH2, PEG-SH, and dihydrolipoic acid-zwitterion (DHLA-ZW) were used to coat Pd NSs. The blood circulation half-lives, biodistribution, potential toxicity, clearance, and photothermal effect of different surface-coated Pd NSs in mice after intravenous injection were compared. PEG-SH-coated Pd NSs (Pd-HS-PEG) were found to have ultralong blood circulation half-life and show high uptake in the tumor. We then carry out the in vivo photothermal therapeutic studies on the Pd-HS-PEG conjugate and revealed its outstanding efficacy in in vivo photothermal therapy of cancers. Our results highlight the importance of surface coatings to the in vivo behaviors of nanomaterials and can provide guidelines to the future design of Pd NSs bioconjugates for other in vivo applications.

Strategies to Improve Cancer Photothermal Therapy Mediated by Nanomaterials

“…Fe 3 O 4 nanoparticles), sulfides (FeS nanoplates), diselenides (FeSe 2 nanoparticles) and prussian blue nanostructures (Fe 4 [Fe(CN) 6 ] 3 ; PB) have also revealed suitable properties to act as PTT agents . Regarding Pd‐based nanomaterials, researchers have been mainly focused on the applicability of Pd nanosheets for PTT . On the other hand, the application of organic nanomaterials for cancer PTT is not so developed as for inorganic materials.…”

Photothermal Disintegration of 3T3 Derived Fat Droplets by Irradiated Silica Coated Upconversion Nanoparticles

“…Novel 2D palladium nanosheet (Pd NSs), having a higher melting point and higher photothermal stability, has shown strong near-infrared absorption and promise as a PTT agent. [19] In addition to those mentioned above, a new class of UCNP-based compounds is showing potential as PTT and PDT agents. These lanthanide-doped UCNPs use multiphoton infrared absorption, to emit in the blue-green-yellow-orange band without any bleaching to participate in deep tissue imaging.…”

“…Jang et al reported the use of AuNRs‐photosensitizer (AIPcS 4 ) complex for combined PDT, and PTT, and their study demonstrated that the tumor growth could be reduced by 95% with the dual modality treatment. Novel 2D palladium nanosheet (Pd NSs), having a higher melting point and higher photothermal stability, has shown strong near‐infrared absorption and promise as a PTT agent …”

Two‐Dimensional Nanomaterials for Photothermal Therapy

“…For example, Gu and co‐workers modified graphene oxide (GO) with PEG linker to improve the dispersity and stability of GO . Shi et al . found that PEG‐SH modification could prolong circulation half‐life and improve tumor accumulation of Pd nanosheets, and Pd nanosheets with PEG‐SH modification dispersed better than those with PEG‐NH 2 , because of the stronger coordination interaction between the thiol group and Pd nanosheets.…”