Controllable growth of Au nanostructures onto MoS2 nanosheets for dual-modal imaging and photothermal-radiation combined therapy

An insight into the dual role of MoS2-based nanocarriers in anticancer drug delivery and therapy

Over the years, nanomaterials have been exploited as drug delivery systems and therapeutic agents in cancer treatment. Special emphasis has been placed on structure and shape-mediated drug loading and release. Functional materials, including molybdenum disulfide (MoS2), have shown promising results because of their tunable structure and unmatched physicochemical properties. Specifically, easy surface functionalization and high drug adsorption ability make them ideal candidates. Although the large surface area of nanosheets/nanoflakes may result in high drug loading, the encapsulation efficiency is better for MoS2 nanoflower structures. Due to its high targeting abilities, the loading of chemotherapeutic drugs onto MoS2 may minimize nonspecific cellular death and undesired side effects. Furthermore, due to their strong light-absorption ability, MoS2 nanostructures have been widely exploited as photothermal and photodynamic therapeutic agents. The unexplored dimensions of cancer therapy, including chemodynamic (Fenton-like reaction) and piezo-catalytic (ultrasound-mediated reactive oxygen generation), have been recently unlocked, in which the catalytic properties of MoS2 are utilized to generate toxic free radicals to eliminate cancer. Intriguingly, combining these therapeutic modalities often results in high therapeutic efficacy at low doses and minimizes side effects. With a plethora of recent studies, a thorough analysis of current findings is crucial. Therefore, this review discusses the major advances in this field of research. A brief commentary on the limitations/future outlook/ethical issues of the clinical translation of MoS2-mediated cancer treatments is also deliberated. Overall, in our observations, the MoS2-based nanoformulations hold great potential for future cancer therapy applications. STATEMENT OF SIGNIFICANCE: Development of nanomedicines based on MoS2 has opened new avenues in cancer treatment. The MoS2 with different morphologies (nanosheet/nanoflower/QDs) has shown promising results in controlled and targeted drug delivery, leading to minimized side effects and increased therapeutic efficacy. While existing reviews have primarily focused on the optical/thermal properties utilized in photodynamic/photothermal therapy, the outstanding catalytic properties of MoS2 utilized in cancer therapies (chemodynamic/piezo-catalytic) are often overlooked. This review critically highlights and praises/criticizes individual articles reporting the MoS2-based nanoplatforms for cancer therapy applications. Additionally, MoS2-based combined therapies for synergistic effects are discussed. Furthermore, a brief commentary on the future prospects for clinical translations is also deliberated, which is appealing to various research communities engaged in cancer theranostics and biomedical sciences research.

An inorganic-organic-polymeric nanovehicle for targeting delivery of doxorubicin: Rational assembly, pH-stimulus release, and dual hyperthermia/chemotherapy of hepatocellular carcinoma

Efficiently synergistic therapy of hepatocellular carcinoma (HCC) by chemotherapeutic drug and photothermal agent remains a considerable challenge. Here, we report a nanodrug that integrates specific hepatoma-targeted delivery, pH-triggered drug release, and cooperative photothermal-chemotherapy function. By grafting the easily self-assembled CuS@polydopamine (CuS@PDA) nanocapsulation with polyacrylic acid (PAA), an inorganic-organic-polymeric hybrid nanovehicle was developed as a dual photothermal agent and carrier for loading antitumor drug-doxorubicin (DOX) through electrostatic adsorption and chemical linking antibody against GPC3 commonly overexpressed in HCC, resulting in the nanodrug, CuS@PDA/PAA/DOX/GPC3. The multifunctional nanovehicle had excellent biocompatibility, stability, and high photothermal conversion efficiency, due to the rationally designed binary CuS@PDA photothermal agent. The 72-h accumulative drug release in pH 5.5 tumor microenvironment can reach up to 84%, far higher than 15% measured in pH 7.4 condition. Notably, in contrast to the merely 20% survival rate of H9c2 and HL-7702 cells exposed to free DOX, their viabilities in the nanodrug circumstance can maintain 54% and 66%, respectively, suggesting the abated toxicity to the normal cell lines. When exposed to the hepatoma-targeting nanodrug, the viability of HepG2 cells was found to be 36%, which further drastically declined to 10% plus 808-nm NIR irradiation. Moreover, the nanodrug is potent to cause tumor ablation in HCC-modeled mice, and the therapeutic efficacy can be greatly enhanced under NIR stimulus. Histology analyses reveal that the nanodrug can effectively alleviate the chemical damage to heart and liver, as compared to free DOX. This work thus offers a facile strategy for design of targeting anti-HCC nanodrug toward combined photothermal-chemotherapy.

Smart Chemical Oxidative Polymerization Strategy To Construct Au@PPy Core-Shell Nanoparticles for Cancer Diagnosis and Imaging-Guided Photothermal Therapy

Imaging-guided photothermal therapy (PTT) in a single nanoscale platform has aroused extensive research interest in precision medicine, yet only a few methods have gained wide acceptance. Thus, it remained an urgent need to facilely develop biocompatible and green probes with excellent theranostic capacity for superior biomedical applications. In this study, a smart chemical oxidative polymerization strategy was successfully developed for the synthesis of Au@PPy core-shell nanoparticles with polyvinyl alcohol (PVA) as the hydrophile. In the reaction, the reactant tetrachloroauric acid (HAuCl₄) was reduced by pyrrole to fabricate a gold (Au) core, and pyrrole was oxidized to deposit around the Au core to form a polypyrrole (PPy) shell. The as-synthesized Au@PPy nanoparticles showed a regular core-shell morphology and good colloidal stability. Relying on the high X-ray attenuation of Au and strong near-infrared (NIR) absorbance of PPy and Au, Au@PPy nanoparticles exhibited excellent performance in blood pool/tumor imaging and PTT treatment by a series of in vivo experiments, in which tumor could be precisely positioned and thoroughly eradicated. Hence, the facile chemical oxidative polymerization strategy for constructing monodisperse Au@PPy core-shell nanoparticles with potential for cancer diagnosis and imaging-guided photothermal therapy shed light on an innovative design concept for the facile fabrication of biomedical materials.

Recent Advances in Transition-Metal Based Nanomaterials for Noninvasive Oncology Thermal Ablation and Imaging Diagnosis

With the developments of nanobiotechnology and nanomedicine, non-invasive thermal ablation with fewer side effects than traditional tumor treatment methods has received extensive attention in tumor treatment. Non-invasive thermal ablation has the advantages of non-invasiveness and fewer side effects compared with traditional treatment methods. However, the clinical efficiency and biological safety are low, which limits their clinical application. Transition-metal based nanomaterials as contrast agents have aroused increasing interest due to its unique optical properties, low toxicity, and high potentials in tumor diagnosis. Transition-metal based nanomaterials have high conversion efficiency of converting light energy into heat energy, good near-infrared absorption characteristics, which also can targetedly deliver those loaded drugs to tumor tissue, thereby improving the therapeutic effect and reducing the damage to the surrounding normal tissues and organs. This article mainly reviews the synthesis of transition-metal based nanomaterials in recent years, and discussed their applications in tumor thermal ablation and diagnosis, hopefully guiding the development of new transition metal-based nanomaterials in enhancing thermal ablation.

Controlling the nucleation and growth of ultrasmall metal nanoclusters with MoS2 grain boundaries

The stabilization of supported nanoclusters is critical for different applications, including catalysis and plasmonics. Herein we investigate the impact of MoS₂ grain boundaries (GBs) on the nucleation and growth of Pt NCs. The optimum atomic structure of the metal clusters is obtained using an adaptive genetic algorithm that employs a hybrid approach based on atomistic force fields and density functional theory. Our findings show that GBs stabilize the NCs up to a cluster size of nearly ten atoms, and with larger clusters having a similar binding to the pristine system. Notably, Pt monomers are found to be attracted to GB cores achieving 60% more stabilization compared to the pristine surface. Furthermore, we show that the nucleation and growth of the metal seeds are facile with low kinetic barriers, which are of similar magnitude to the diffusion barriers of metals on the pristine surface. The findings highlight the need to engineer ultrasmall NCs to take advantage of enhanced stabilization imparted by the GB region, particularly to circumvent sintering behavior for high-temperature applications.

Gold nanoparticles to enhance ophthalmic imaging

The use of gold nanoparticles as diagnostic tools is burgeoning, especially in the cancer community with a focus on theranostic applications to both cancer diagnosis and treatment. Gold nanoparticles have also demonstrated great potential for use in diagnostic and therapeutic approaches in ophthalmology. Although many ophthalmic imaging modalities are available, there is still a considerable unmet need, in particular for ophthalmic molecular imaging for the early detection of eye disease before morphological changes are more grossly visible. An understanding of how gold nanoparticles are leveraged in other fields could inform new ways they could be utilized in ophthalmology. In this paper, we review current ophthalmic imaging techniques and then identify optical coherence tomography (OCT) and photoacoustic imaging (PAI) as the most promising technologies amenable to the use of gold nanoparticles for molecular imaging. Within this context, the development of gold nanoparticles as OCT and PAI contrast agents are reviewed, with the most recent developments described in detail.

Plasmonic gold nanostructures for biosensing and bioimaging

As one kind of noble metal nanostructures, the plasmonic gold nanostructures possess unique optical properties as well as good biocompatibility, satisfactory stability, and multiplex functionality. These distinctive advantages make the plasmonic gold nanostructures an ideal medium in developing methods for biosensing and bioimaging. In this review, the optical properties of the plasmonic gold nanostructures were firstly introduced, and then biosensing in vitro based on localized surface plasmon resonance, Rayleigh scattering, surface-enhanced fluorescence, and Raman scattering were summarized. Subsequently, application of the plasmonic gold nanostructures for in vivo bioimaging based on scattering, photothermal, and photoacoustic techniques  has been also briefly covered. At last, conclusions of the selected examples are presented and an outlook of this research topic is given.

Bifunctional, Copper-Doped, Mesoporous Silica Nanosphere-Modified, Bioceramic Scaffolds for Bone Tumor Therapy

In the traditional surgical intervention procedure, residual tumor cells may potentially cause tumor recurrence. In addition, large bone defects caused by surgery are difficult to self-repair. Thus, it is necessary to design a bioactive scaffold that can not only kill residual tumor cells but also promote bone defect regeneration simultaneously. Here, we successfully developed Cu-containing mesoporous silica nanosphere-modified β-tricalcium phosphate (Cu-MSN-TCP) scaffolds, with uniform and dense nanolayers with spherical morphology via 3D printing and spin coating. The scaffolds exhibited coating time- and laser power density-dependent photothermal performance, which favored the effective killing of tumor cells under near-infrared laser irradiation. Furthermore, the prepared scaffolds favored the proliferation and attachment of rabbit bone marrow-derived mesenchymal stem cells and stimulated the gene expression of osteogenic markers. Overall, Cu-MSN-TCP scaffolds can be considered for complete eradication of residual bone tumor cells and simultaneous healing of large bone defects, which may provide a novel and effective strategy for bone tumor therapy. In the future, such Cu-MSN-TCP scaffolds may function as carriers of anti-cancer drugs or immune checkpoint inhibitors in chemo-/photothermal or immune-/photothermal therapy of bone tumors, favoring for effective treatment.

Intelligent MoS2-CuO heterostructures with multiplexed imaging and remarkably enhanced antitumor efficacy via synergetic photothermal therapy/ chemodynamic therapy/ immunotherapy

Rational design of biocompatible nanoplatforms simultaneously realizing multimodal imaging and therapeutic functions is meaningful to cancer treatment. Herein, the MoS₂-CuO heteronanocomposites are designed by integrating semiconductor CuO and flower-like MoS₂ via a two-step hydrothermal method. After loading bovine serum albumin (BSA) and immunoadjuvant imiquimod (R837), the obtained MoS₂-CuO@BSA/R837 (MCBR) nanoplatforms realize the excellent computed tomography/infrared thermal/magnetic resonance multi-mode bioimaging as well as significantly enhanced antitumor efficacy of synergetic photothermal therapy (PTT)/chemodynamic therapy (CDT)/immunotherapy. In this nanoplatform, the semiconductor CuO exhibits peroxidase-like activity, which can react with over-expressed H₂O₂ in tumor microenvironment (TME) to generate OH for CDT via Haber-Weiss and Fenton-like reactions. And this process can be further accelerated by the generated heat of MoS₂ under 808 nm laser irradiation. More importantly, the obtained multifunctional MCBR nanoplatforms under near-infrared (NIR) irradiation would destroy tumor cells to generate tumor associated antigens (TAAs), which combine with R837 as an adjuvant to trigger strong antitumor immune responses for effectively eliminating primary tumors and metastatic tumors.

One Stone Two Birds: Zr-Fc Metal-Organic Framework Nanosheet for Synergistic Photothermal and Chemodynamic Cancer Therapy

Metal-organic frameworks (MOFs) have been identified as promising materials for the delivery of therapeutics to cure cancer owing to their intrinsic porous structure. However, in a majority of cases, MOFs act as only a delivery cargo for anticancer drugs while little attention has been focused on the utilization of their intriguing physical and chemical properties for potential anticancer purposes. Herein for the first time, an ultrathin (16.4 nm thick) ferrocene-based MOF (Zr-Fc MOF) nanosheet has been synthesized for synergistic photothermal therapy (PTT) and Fenton reaction-based chemodynamic (CDT) therapy to cure cancer without additional drugs. The Zr-Fc MOF nanosheet acts not only as an excellent photothermal agent with a prominent photothermal conversion efficiency of 53% at 808 nm but also as an efficient Fenton catalyst to promote the conversion of H₂O₂ into hydroxyl radical (^•OH). As a consequence, an excellent therapeutic performance has been achieved in vitro as well as in vivo through this combinational effect. This work aims to construct an "all-in-one" MOF nanoplatform for PTT and CDT treatments without incorporating any additional therapeutics, which may launch a new era in the investigation of MOF-based synergistic therapy platforms for cancer therapy.