Shaoheng Tang

Freestanding palladium nanosheets with plasmonic and catalytic properties

Ultrathin metal films can exhibit quantum size and surface effects that give rise to unique physical and chemical properties. Metal films containing just a few layers of atoms can be fabricated on substrates using deposition techniques, but the production of freestanding ultrathin structures remains a significant challenge. Here we report the facile synthesis of freestanding hexagonal palladium nanosheets that are less than 10 atomic layers thick, using carbon monoxide as a surface confining agent. The as-prepared nanosheets are blue in colour and exhibit a well-defined but tunable surface plasmon resonance peak in the near-infrared region. The combination of photothermal stability and biocompatibility makes palladium nanosheets promising candidates for photothermal therapy. The nanosheets also exhibit electrocatalytic activity for the oxidation of formic acid that is 2.5 times greater than that of commercial palladium black catalyst.

Controlled Formation of Concave Tetrahedral/Trigonal Bipyramidal Palladium Nanocrystals

Novel concave Pd nanocrystals with uniform diameter were successfully prepared in the presence of formaldehyde. While the outer surfaces of the as-prepared concave Pd nanocrystals are {111}, the faces concave toward the polyhedral center are high-surface-energy {110} faces. The degree of concavity and therefore the percentage of {110} of the nanocrystals are tunable by varying the amount of formaldehyde and the reaction temperature. Owing to the existence of active {110} facets, the electrocatalytic activity of the concave Pd nanocrystals displays dependency on their degree of concavity.

Core–Shell Pd@Au Nanoplates as Theranostic Agents for In-Vivo Photoacoustic Imaging, CT Imaging, and Photothermal Therapy

Uniform plasmonic Pd@Au core-shell bimetallic nanoplates are synthesized by seeded growth strategy. Surface modified with SH-PEG makes it good biocompatibility, prolonged blood circulation, and relatively high tumor accumulation. Enhanced tumor contrast effects can be obtained for in vivo photoacoustic/CT imaging after intravenous injection of Pd@Au-PEG. Moreover, efficient photothermal tumor ablation is achieved, guided by the imaging techniques. This work promises further exploration of the superiority of 2D nanostructures for in vivo biomedical applications.

Polypyrrole nanoparticles for high-performance in vivo near-infrared photothermal cancer therapy

Polypyrrole nanoparticles (PPy NPs) exhibit strong absorption in the near infrared (NIR) region. With an excellent photothermal efficiency of ~45% at 808 nm, sub-100 nm PPy NPs are demonstrated to be a promising photothermal agent for in vivo cancer therapy using NIR irradiation.

Enhancing the Photothermal Stability of Plasmonic Metal Nanoplates by a Core‐Shell Architecture

通讯作者地址: Zheng, NF (通讯作者),Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: nfzheng@xmu.edu.cn

Sub‐10‐nm Pd Nanosheets with Renal Clearance for Efficient Near‐Infrared Photothermal Cancer Therapy

Efficient renal clearance is of fundamentally important property of nanoparticles for their in vivo biomedical applications. In this work, we report the successful synthesis of ultra-small Pd nanosheets (SPNS) with an average diameter of 4.4 nm and their application in photothermal cancer therapy using a near infrared laser. The ultra-small Pd nanosheets have strong optical absorption in the NIR region and high photothermal conversion efficiency (52.0%) at 808 nm. After being surface-functionalized with reduced glutathione (GSH), the SPNS-GSH was administered to mice to investigate the biodistribution, photothermal efficacy and tumor ablation in vivo. The in vivo photothermal therapy studies clearly demonstrate that surface modification with GSH allows the nanosheets to exhibit prolonged blood circulation and thus high accumulation in tumors. Upon 808 nm NIR irradiation, the tumors can be completely ablated. More importantly, with the size below the renal filtration limit (<10 nm), the GSHylated Pd nanosheets can be nicely cleared from body through the renal excretion route and into urine. Together with the high efficacy of NIR photothermal therapy, the unique renal clearance properties make the ultra-small Pd nanosheets promising for practical use in photothermal cancer therapy.

Pd Nanosheet-Covered Hollow Mesoporous Silica Nanoparticles as a Platform for the Chemo-Photothermal Treatment of Cancer Cells

A versatile system combining chemotherapy with photothermal therapy for cancer cells using Pd nanosheet-covered hollow mesoporous silica nanoparticles is reported. While the hollow mesoporous silica core can be used to load anticancer drugs (i.e., doxorubicin) for chemotherapy, the Pd nanosheets on the surface of particles can convert NIR light into heat for photothermal therapy. More importantly, the loading of Pd nanosheets on hollow mesoporous silica nanospheres can dramatically increase the amount of cellular internalization of the Pd nanosheets: almost 11 times higher than the unloaded Pd nanosheets. The as-prepared nanocomposites efficiently deliver both drugs and heat to cancer cells to improve the therapeutic efficiency with minimal side effects. Compared with chemotherapy or photothermal therapy alone, the combination of chemotherapy and phototherapy can significantly improve the therapeutic efficacy, exhibiting a synergistic effect.

Etching Growth under Surface Confinement: An Effective Strategy To Prepare Mesocrystalline Pd Nanocorolla

An etching growth strategy was developed to prepare corolla-like Pd mesocrystals consisting of unidirectionally aligned, well-spaced, and connected ultrathin (1.8-nm-thick) Pd nanosheets. The combined use of CO and Fe(3+) is critical to the successful synthesis of the branched corolla-like Pd mesocrystals. While CO functions as the surface-confining agent to allow anisotropic growth of the 1.8-nm-thick Pd nanosheets as branches, Fe(3+) etches the Pd seeds at the early stage of the reaction to induce formation of the branched structure. Inheriting the unique properties of 1.8-nm-thick Pd nanosheets, the as-prepared Pd mesocrystals display well-defined surface plasmon resonance absorption in the near-infrared region, a high electrochemically active surface area, and a significant photothermal effect when irradiated with a near-infrared laser. Owing to the presence of internal voids and increased apparent thickness, the Pd mesocrystals also exhibit several features superior to those of single-domain Pd nanosheets, making them promising for electrocatalysis and cancer photothermal therapy applications.

Synthesis of magnetic, fluorescent and mesoporous core-shell-structured nanoparticles for imaging, targeting and photodynamic therapy

A synthetic method to prepare novel multifunctional core-shell-structured mesoporous silica nanoparticles for simultaneous magnetic resonance (MR) and fluorescence imaging, cell targeting and photosensitization treatment has been developed. Superparamagnetic magnetite nanoparticles and fluorescent dyes are co-encapsulated inside nonporous silica nanoparticles as the core to provide dual-imaging capabilities (MR and optical). The photosensitizer molecules, tetra-substituted carboxyl aluminum phthalocyanine (AlC4Pc), are covalently linked to the mesoporous silica shell and exhibit excellent photo-oxidation efficiency. The surface modification of the core-shell silica nanoparticles with folic acid enhances the delivery of photosensitizers to the targeting cancer cells that overexpress the folate receptor, and thereby decreases their toxicity to the surrounding normal tissues. These unique advantages make the prepared multifunctional core-shell silica nanoparticles promising for cancer diagnosis and therapy.

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.