Xiaojuan Huang

Photothermal Theragnosis Synergistic Therapy Based on Bimetal Sulphide Nanocrystals Rather Than Nanocomposites

A new generation of photothermal theranostic agents is developed based on Cu3BiS3 nanocrystals. A computed tomography imaging response and photothermal effect, as well as near-infrared fluorescence emission, can be simultaneously achieved through Cu3BiS3 nanocrystals rather than frequently used nanocomposites. These results provide some insight into the synergistic effect from bimetal sulphide semiconductor compounds for photothermal theragnosis therapy.

Heterostructures of CuS nanoparticle/ZnO nanorod arrays on carbon fibers with improved visible and solar light photocatalytic properties

CuS nanoparticle/ZnO nanorod heterostructure arrays grown on carbon fibers (CuS/ZnO/CFs) were prepared successfully by a simple combination of a hydrothermal (HT) process and successive ionic layer adsorption and reaction (SILAR). The heterostructures of CuS/ZnO/CFs showed improved photocatalytic activity in the degradation of methylene blue (MB). Under visible light irradiation, the CuS/ZnO/CF heterostructures exhibited remarkable visible light photocatalytic activity, which was 7.1 and 8.0 times higher than those of ZnO/CFs and ZnO, respectively. Under simulated solar light irradiation, the photocatalytic activity of the CuS/ZnO/CF heterostructures was 1.4 and 2.2 times higher than those of ZnO/CFs and ZnO, respectively. The enhanced photocatalytic activity could be ascribed to the effective electron–hole separation and improved visible light utilization from the cooperative effect of the type II CuS/ZnO heterostructures and conductive CFs, as well as the efficient light harvesting and high surface area of the heterostructure arrays. Moreover, the CuS/ZnO/CF heterostructures can be easily separated and recycled with little loss in the photocatalytic activity due to their unique structural features.

Understanding the effect of polypyrrole and poly(3,4-ethylenedioxythiophene) on enhancing the supercapacitor performance of NiCo2O4 electrodes

Herein, two of the most well-known conducting polymers (CP), polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT), were coated onto mesoporous NiCo2O4 nanosheet arrays through an efficient and controllable electrodeposition process. We considered such a unique nanostructure to be an ideal model to accurately compare and understand the effects of PPy and PEDOT on electrochemical performances. Comparing the electrochemical performances of NiCo2O4@CP and pure NiCo2O4 electrodes, we found that the NiCo2O4@PPy electrode possesses the highest areal capacitance of 4.1 F cm−2 at 2 mA cm−2, which is significantly higher than the values obtained for the NiCo2O4@PEDOT (0.86 F cm−2) and NiCo2O4 electrodes (0.65 F cm−2). For rate capability, even at a high current density of 30 mA cm−2, an areal capacitance of 2.7 F cm−2 can be achieved for the NiCo2O4@PPy electrode. Moreover, the NiCo2O4@PPy electrode shows considerably smaller equivalent series resistance (ESR) than that of the NiCo2O4@PEDOT and NiCo2O4 electrodes. Therefore, the NiCo2O4@PPy hybrid composites are considered to be ideal supercapacitor electrode materials with enhanced electrochemical performances, which makes them suitable for many practical applications.

Design and Functionalization of the NIR-Responsive Photothermal Semiconductor Nanomaterials for Cancer Theranostics

Despite the development of medical technology, cancer still remains a great threat to the survival of people all over the world. Photothermal therapy (PTT) is a minimally invasive method for selective photothermal ablation of cancer cells without damages to normal cells. Recently, copper chalcogenide semiconductors have emerged as a promising photothermal agent attributed to strong absorbance in the near-infrared (NIR) region and high photothermal conversion efficiency. An earlier study witnessed a rapid increase in their development for cancer therapy, including CuS, Cu2-xSe and CuTe nanocrystals. However, a barrier is that the minimum laser power intensity for effective PTT is still significantly higher than the conservative limit for human skin exposure. Improving the photothermal conversion efficiency and reducing the laser power density has become a direction for the development of PTT. Furthermore, in an effort to improve the therapeutic efficacy, many multimode therapeutic nanostuctures have been formulated by integrating the photothermal agents with antitumor drugs, photosensitizers, or radiosensitizers, resulting in a synergistic effect. Various functional materials also have been absorbed, attached, encapsulated, or coated on the photothermal nanostructures, including fluorescence, computed tomography, magnetic resonance imaging, realizing cancer diagnosis, tumor location, site-specific therapy, and evaluation of therapeutic responses via incorporation of diagnosis and treatment. In this Account, we present an overview of the NIR-responsive photothermal semiconductor nanomaterials for cancer theranostics with a focus on their design and functionalization based on our own work. Our group has developed a series of chalcogenides with greatly improved NIR photoabsorption as photothermal agents, allowing laser exposure within regulatory limits. We also investigated the photothermal bioapplications of hypotoxic oxides including WO3-x, MoO3-x, and RuO2, expanding their applications into a new field of photothermal materials. Furthermore, considering a much more enhanced therapeutic effect of multifunctional nanoagents, our group elaborately designed many nanocomposites, such as core-shell nanoparticles of Fe3O4@Cu2-xS and Cu9S5@mSiO2, based on the integration of photothermal agents with contrast agents or other anticancer medicines, achieving cancer theranostic and synergistic treatment. Ternary compound nanocrystals were also prepared with synthetic simplicity for multimodal imaging-guided therapy for cancer. This Account summarizes our past work, including the design and concept, synthesis, and characterization for in vitro and in vivo applications. Then, we analyzed the tendencies of the NIR-responsive photothermal semiconductor nanomaterials for clinical applications, highlighting their prospects and challenges. We believe that the photothermal technology from the NIR-responsive photothermal semiconductor nanomaterials would promote cancer theranostics to result in giant strides forward in the future.

Hydrophilic bismuth sulfur nanoflower superstructures with an improved photothermal efficiency for ablation of cancer cells

Nanomaterials with intense near-infrared (NIR) absorption exhibit effective photon-to-thermal energy transfer capabilities and can generate heat to ablate cancer cells, thus playing a pivotal role in photothermal cancer therapeutics. Herein, hydrophilic flower-like bismuth sulfur (Bi2S3) superstructures with uniform size and improved NIR absorption were controllably synthesized via a facile solvothermal procedure assisted by polyvinylpyrrolidone (PVP), which could adjust the product morphology. Induced by an 808-nm laser, the as-prepared Bi2S3 nanoflowers exhibited much higher photothermal conversion efficiency (64.3%) than that of Bi2S3 nanobelts (36.5%) prepared in the absence of PVP. This can be attributed not only to the Bi2S3 nanoflower superstructures assembled by 3-dimensional crumpled-paper-like nanosheets serving as many laser-cavity mirrors with improved reflectivity and absorption of NIR light but also to the amorphous structures with a lower band gap. Thus, to achieve the same temperature increase, the concentration or laser power density could be greatly reduced when using Bi2S3 nanoflowers compared to when using Bi2S3 nanobelts, which makes them more favorable for use in therapy due to decreased toxicity. Furthermore, these Bi2S3 nanoflowers effectively achieved photothermal ablation of cancer cells in vitro and in vivo. These results not only supported the Bi2S3 nanoflowers as a promising photothermal agent for cancer therapy but also paved an approach to exploit new agents with improved photothermal efficiency.

A Novel Photothermal Nanocrystals of Cu7S4 Hollow Structure for Efficient Ablation of Cancer Cells

Cu2-xS nanocrystals (NCs), characterized by low cost, low toxicity, high stability and high photothermal conversion efficiency, provide promising platforms as photothermal agents. Herein, a novel two-step synthesis has been developed for Cu7S4 nanocrystals with hollow structure using the as-prepared copper nanoparticles as starting a solid precursor followed by hot-injection of sulfide source.The Cu7S4 NCs exhibit intense absorption band at Near-infrared (NIR) wavelengths due to localized surface plasmon resonance (LSPR) mode, which can effectively convert 980 nm-laser energy into heat.Moreover, the localized high temperature created by Cu7S4 NCs under NIR irradiation could result in efficient photothermal ablation (PTA) of cancer cells in vivo, demonstrating a novel and promising photothermal nanomaterials.

SnS nanosheets for efficient photothermal therapy

A novel photothermal agent based on PEGylated SnS nanosheets is developed via a simple solvothermal route and the subsequent exfoliation is carried out using an ultrasonication method. The PEGylated SnS nanosheets exhibit much higher extinction coefficient and photothermal conversion efficiency than bulk SnS. With the irradiation of the NIR light, cancer cells in vitro can be efficiently killed by the photothermal effects of the SnS nanosheets. The findings reported here show promising potential for further exploration of 2D nanomaterials as a nanoplatform for cancer therapy.

Degradable rhenium trioxide nanocubes with high localized surface plasmon resonance absorbance like gold for photothermal theranostics

The applications of inorganic theranostic agents in clinical trials are generally limited to their innate non-biodegradability and potential long-term biotoxicity. To address this problem, herein via a straightforward and tailored space-confined on-substrate route, we obtained rhenium trioxide (ReO3) nanocubes (NCs) that display a good biocompatibility and biosafety. Importantly, their aqueous dispersion has high localized surface plasmon resonance (LSPR) absorbance in near-infrared (NIR) region different from previous report, which possibly associates with the charge transfer and structural distortion in hydrogen rhenium bronze (HxReO3), as well as ReO3s cubic shape. Such a high LSPR absorbance in the NIR region endows them with photoacoustic (PA)/infrared (IR) thermal imaging, and high photothermal conversion efficiency (∼57.0%) for efficient ablation of cancer cells. Also, ReO3 NCs show X-ray computed tomography (CT) imaging derived from the high-Z element Re. More attractively, those ReO3 NCs, with pH-dependent oxidized degradation behaviors, are revealed to be relatively stable in hypoxic and weakly acidic microenvironment of tumor for imaging and treatment whilst degradable in normal physiological environments of organs to enable effective clearance. In spite of their degradability, ReO3 NCs still possess tumor targeting capabilities. We thus develop a simple but powerful, safe and biodegradable inorganic theranostic platform to achieve PA/CT/IR imaging-guided cancer photothermal therapy (PTT) for improved therapeutic efficacy and decreased toxic side effects.

Stabilizing Lithium–Sulfur Batteries through Control of Sulfur Aggregation and Polysulfide Dissolution

Lithium-sulfur (Li-S) batteries are investigated intensively as a promising large-scale energy storage system owing to their high theoretical energy density. However, the application of Li-S batteries is prevented by a series of primary problems, including low electronic conductivity, volumetric fluctuation, poor loading of sulfur, and shuttle effect caused by soluble lithium polysulfides. Here, a novel composite structure of sulfur nanoparticles attached to porous-carbon nanotube (p-CNT) encapsulated by hollow MnO2 nanoflakes film to form p-CNT@Void@MnO2 /S composite structures is reported. Benefiting from p-CNTs and sponge-like MnO2 nanoflake film, p-CNT@Void@MnO2 /S provides highly efficient pathways for the fast electron/ion transfer, fixes sulfur and Li2 S aggregation efficiently, and prevents polysulfide dissolution during cycling. Besides, the additional void inside p-CNT@Void@MnO2 /S composite structure provides sufficient free space for the expansion of encapsulated sulfur nanoparticles. The special material composition and structural design of p-CNT@Void@MnO2 /S composite structure with a high sulfur content endow the composite high capacity, high Coulombic efficiency, and an excellent cycling stability. The capacity of p-CNT@Void@MnO2 /S electrode is ≈599.1 mA h g-1 for the fourth cycle and ≈526.1 mA h g-1 after 100 cycles, corresponding to a capacity retention of ≈87.8% at a high current density of 1.0 C.

Hydrophilic K2Mn4O8 nanoflowers as a sensitive photothermal theragnosis synergistic platform for the ablation of cancer

Achieving cancer diagnosis and treatment simultaneously, multifunctional nanomaterials lead the trend in the development of nanomedicine. Manganese-based compounds have been well developed as excellent magnetic resonance (MR) imaging contrast agents, while they have not been demonstrated as photothermal agents (PTAs) due to their unsatisfactory near-infrared photoabsorption. Herein, we report a hydrophilic flower-like K2Mn4O8 superstructure self-assembled by ultrathin nanosheets that can work simultaneously as a PTA and an ultrasensitive T1-weighted magnetic resonance imaging (T1-MRI) enhancing agent. These K2Mn4O8 nanoflowers are efficient vehicles transforming 808 nm laser energy into thermal energy and then leading to the effective ablation of cancer cells in vitro and in vivo. Importantly, with a high longitudinal relaxivity (r1) of 4.6 mM−1 s−1, they also act as quite impressive T1-MRI enhancing agents. Both in vitro and in vivo experiments confirmed their great biocompatibility, low toxicity and high photothermal conversion capability. This is the first application of K2Mn4O8 as a PTA and would hopefully promote other Mn-based theranostics.