Saige Shi

Simultaneous Photodynamic and Photothermal Therapy Using Photosensitizer-Functionalized Pd Nanosheets by Single Continuous Wave Laser

In this work, we prepared chlorin e6 (Ce6)-functionalized Pd nanosheets (Pd-PEI-Ce6) for the photodynamic and photothermal combined therapy that use a single laser. To fabricate the Pd-PEI-Ce6 nanocomposite, photosensitizer Ce6 were chemically conjugated to polyethylenimine (PEI) and the formed Ce6-PEI conjugates were then anchored onto Pd nanosheets by electrostatic and coordination interaction. The prepared Pd-PEI-Ce6 nanocomposite were about 4.5 nm in size, exhibited broad, and strong absorption from 450 to 800 nm, good singlet oxygen generation capacity and photothermal conversion efficiency, and excellent biocompability. Significantly greater cell killing was observed when HeLa cells incubated with Pd-PEI-Ce6 were irradiated with the 660 nm laser, attributable to both Pd nanosheets-mediated photothermal ablation and the photodynamic destruction effect of photosensitizer Ce6. The double phototherapy effect was also confirmed in vivo. It was found that the Pd-PEI-Ce6 treated tumor-bearing mice displayed the enhanced therapeutic efficiency compared to that of Pd-PEI, or Ce6-treated mice. Our work highlights the promise of using Pd nanosheets for potential multimode cancer therapies.

Copper sulfide nanoparticles with phospholipid-PEG coating for in vivo near-infrared photothermal cancer therapy.

In this work, small sizes of hydrophobic copper sulfide nanoparticles (CuS NPs, ∼3.8 nm in diameter) have been successfully prepared from the reaction of copper chloride with sodium diethyldithiocarbamate (SDEDTC) inside a heated oleylamine solution. These CuS NPs displayed strong absorption in the 700-1100 nm near-infrared (NIR) region. By coating CuS NPs with DSPE-PEG2000 on the surface, the as-synthesized CuS@DSPE-PEG NPs exhibited good water solubility, significant stability and biocompatibility, as well as excellent photothermal conversion effects upon exposure to an 808 nm laser. After intravenous administration to mice, the CuS@DSPE-PEG NPs were found to passively target to the tumor site, and tumor tissues could be ablated efficiency under laser irradiation. In addition, CuS@DSPE-PEG NPs do not show significant toxicity by histological and blood chemistry analysis, and can be effectively excreted via metabolism. Our results indicated that CuS@DSPE-PEG NPs can act as an ideal photothermal agent for cancer photothermal therapy.

Preparation and photodynamic therapy application of NaYF4:Yb, Tm–NaYF4:Yb, Er multifunctional upconverting nanoparticles

The preparation, characterization and application of NaYF4:Yb3+, Tm3+–NaYF4:Yb3+, Er3+ core–shell upconversion nanocrystals (UCNPs) with multiple emission peaks (e.g. 539, 654 and 802 nm) have been demonstrated in this work. The monodisperse nanocrystals were prepared via a modified thermal decomposition synthesis. The resulting UCNPs were ∼31 nm in diameter with the lanthanide ions Tm3+ and Er3+ doped in the core and the shell, respectively. Under the laser diode excitation at 980 nm, these core–shell nanocrystals give strong upconversion emissions from the visible to near-infrared (NIR) region. By coating a PEG–phospholipid (PP) layer on the surface of the nanocrystals, the as-prepared UCNPs were favorably endowed with good water solubility for the potential biological applications. Here, a photosensitizer drug of Chlorin e6 (Ce6), which has maximum absorption that overlaps with the red emission of UCNPs, was loaded on these PP-coated UCNPs (UCNP@PP) by physical adsorption. The activity of the Ce6-loaded UCNP@PP (UCNP@PP–Ce6) in photodynamic therapy of cancer cells in vitro has been fully investigated in this work. Our results indicated that these multifunctional UCNP@PP–Ce6 nanoparticles have efficient NIR-to-NIR upconversion luminescence and photodynamic therapy capabilities, which could be potentially employed as a theranostic platform for cancer treatment.

Cancer therapy improvement with mesoporous silica nanoparticles combining photodynamic and photothermal therapy.

In this work, we develop novel mesoporous silica composite nanoparticles (hm-SiO2(AlC4Pc)@Pd) for the co-delivery of photosensitizer (PS) tetra-substituted carboxyl aluminum phthalocyanine (AlC4Pc) and small Pd nanosheets as a potential dual carrier system to combine photodynamic therapy (PDT) with photothermal therapy (PTT). In the nanocomposite, PS AlC4Pc was covalently conjugated to a mesoporous silica network, and small Pd nanosheets were coated onto the surface of mesoporous silica by both coordination and electrostatic interaction. Since small Pd nanosheets and AlC4Pc display matched maximum absorptions in the 600-800 nm near-infrared (NIR) region, the fabricated hm-SiO2(AlC4Pc)@Pd nanocomposites can generate both singlet oxygen and heat upon 660 nm single continuous wavelength (CW) laser irradiation. In vitro results indicated that the cell-killing efficacy by simultaneous PDT/PTT treatment using hm-SiO2(AlC4Pc)@Pd was higher than PDT or PTT treatment alone after exposure to a 660 nm CW-NIR laser.

Photothermally enhanced photodynamic therapy based on mesoporous Pd@Ag@mSiO2 nanocarriers

In this work, we have demonstrated that mesoporous silica-coated Pd@Ag nanoparticles (Pd@Ag@mSiO2) can be used as an excellent nanoplatform for photodynamic therapy (PDT) drug delivery. Photosensitizer molecules, Chlorin e6 (Ce6), are covalently linked to the mesoporous shell and the prepared Pd@Ag@mSiO2-Ce6 nanoparticles exhibit excellent water solubility, good stability against leaching and high efficiency in photo-generating cytotoxic singlet oxygen. More importantly, the photothermal effect of Pd@Ag nanoplates under the irradiation of a NIR laser can enhance the uptake of Pd@Ag@mSiO2-Ce6 nanoparticles by cells, further increasing the PDT efficiency toward cancer cells. The photothermally enhanced PDT effects were demonstrated both in vitro and in vivo. When the Pd@Ag@mSiO2-Ce6 nanoparticles were injected intratumorally into the S180 tumor-bearing mice, the tumors were completely destroyed without recurrence of tumors upon irradiation with both 808 nm and 660 nm lasers, while the irradiation with 808 nm or 660 nm alone did not. These results indicate that the Pd@Ag@mSiO2 nanoparticles may be a valuable new tool for application in cancer phototherapy.

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

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.

Effect of glutathione on in vivo biodistribution and clearance of surface-modified small Pd nanosheets

Plasmonic Pd nanosheets have been emerging as promising materials for applying in near-infrared (NIR) photothermal therapy (PTT) of cancer. However, animal in mice studies indicated that the original synthesized poly(vinylpyrrolidone) (PVP)-protected small Pd nanosheets (Pd-PVP) and some further surface-modified small Pd nanosheets such as Pd-PEG(SH) easily accumulated in reticuloendothelial system (RES) organs (liver, spleen, etc.) and were difficult to be cleared from these organs quickly. In the work, we surprisingly found that glutathione (GSH) could promote the clearance of surface-modified small Pd nanosheets (e.g. Pd-PVP, Pd-PEG(SH) and Pd-GSH) from the RES organs efficiently. The effects of GSH on the biodistribution and clearance of different surface-modified Pd nanosheets were investigated. Our results indicated that these surface-modified Pd nanosheets with or without GSH added caused no morbidity at target primary organs, and GSH can promote the clearance of different surface-modified Pd nanosheets in the order of Pd-PVP≈Pd-PEG(SH)>Pd-GSH. This study suggests that glutathione could be an attractive reagent for promoting nanomaterials eliminated from the reticuloendothelial systems (RES).