Platinum(IV) prodrug conjugated Pd@Au nanoplates for chemotherapy and photothermal therapy

A review of recent advances in the use of complex metal nanostructures for biomedical applications from diagnosis to treatment

Complex metal nanostructures represent an exceptional category of materials characterized by distinct morphologies and physicochemical properties. Nanostructures with shape anisotropies, such as nanorods, nanostars, nanocages, and nanoprisms, are particularly appealing due to their tunable surface plasmon resonances, controllable surface chemistries, and effective targeting capabilities. These complex nanostructures can absorb light in the near-infrared, enabling noteworthy applications in nanomedicine, molecular imaging, and biology. The engineering of targeting abilities through surface modifications involving ligands, antibodies, peptides, and other agents potentiates their effects. Recent years have witnessed the development of innovative structures with diverse compositions, expanding their applications in biomedicine. These applications encompass targeted imaging, surface-enhanced Raman spectroscopy, near-infrared II imaging, catalytic therapy, photothermal therapy, and cancer treatment. This review seeks to provide the nanomedicine community with a thorough and informative overview of the evolving landscape of complex metal nanoparticle research, with a specific emphasis on their roles in imaging, cancer therapy, infectious diseases, and biofilm treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Diagnostic Nanodevices.

High-Spatial-Resolution Benchtop X-ray Fluorescence Imaging through Bragg-Diffraction-Based Focusing with Bent Mosaic Graphite Crystals: A Simulation Study

X-ray fluorescence imaging (XFI) can localize diagnostic or theranostic entities utilizing nanoparticle (NP)-based probes at high resolution in vivo, in vitro, and ex vivo. However, small-animal benchtop XFI systems demonstrating high spatial resolution (variable from sub-millimeter to millimeter range) in vivo are still limited to lighter elements (i.e., atomic number Z≤45). This study investigates the feasibility of focusing hard X-rays from solid-target tubes using ellipsoidal lens systems composed of mosaic graphite crystals with the aim of enabling high-resolution in vivo XFI applications with mid-Z (42≤Z≤64) elements. Monte Carlo simulations are performed to characterize the proposed focusing-optics concept and provide quantitative predictions of the XFI sensitivity, in silico tumor-bearing mice models loaded with palladium (Pd) and barium (Ba) NPs. Based on simulation results, the minimum detectable total mass of PdNPs per scan position is expected to be on the order of a few hundred nanograms under in vivo conform conditions. PdNP masses as low as 150 ng to 50 ng could be detectable with a resolution of 600 μm when imaging abdominal tumor lesions across a range of low-dose (0.8 μGy) to high-dose (8 μGy) exposure scenarios. The proposed focusing-optics concept presents a potential step toward realizing XFI with conventional X-ray tubes for high-resolution applications involving interesting NP formulations.

Application and progress of nanozymes in antitumor therapy

Tumors remain one of the major threats to public health and there is an urgent need to design new pharmaceutical agents for their diagnosis and treatment. In recent years, due to the rapid development of nanotechnology, biotechnology, catalytic science, and theoretical computing, subtlety has gradually made great progress in research related to tumor diagnosis and treatment. Compared to conventional drugs, enzymes can improve drug distribution and enhance drug enrichment at the tumor site, thereby reducing drug side effects and enhancing drug efficacy. Nanozymes can also be used as tumor tracking imaging agents to reshape the tumor microenvironment, providing a versatile platform for the diagnosis and treatment of malignancies. In this paper, we review the current status of research on enzymes in oncology and analyze novel oncology therapeutic approaches and related mechanisms. To date, a large number of nanomaterials, such as noble metal nanomaterials, nonmetallic nanomaterials, and carbon-based nanomaterials, have been shown to be able to function like natural enzymes, particularly with significant advantages in tumor therapy. In light of this, the authors in this review have systematically summarized and evaluated the construction, enzymatic activity, and their characteristics of nanozymes with respect to current modalities of tumor treatment. In addition, the application and research progress of different types of nicknames and their features in recent years are summarized in detail. We conclude with a summary and outlook on the study of nanozymes in tumor diagnosis and treatment. It is hoped that this review will inspire researchers in the fields of nanotechnology, chemistry, biology, materials science and theoretical computing, and contribute to the development of nano-enzymology.

Fabrication of hyaluronic acid-altered gold complex delivery for head and neck squamous cell carcinoma therapy with high antitumor efficacy and low in vivo toxicity

The use of multifunctional nanomedicines in the treatment of tumors is gaining popularity. Here, we constructed a nanodrug delivery system (HA/Au-PDA@CZT) that targets tumors and responds to pH and near-infrared (NIR) dual stimuli. By precisely interacting with an overexpressed CD44 receptor in specific cancer cells, hyaluronic acid (HA) is coated on the Au-PDA NP surface for tumor-targeting abilities. When exposed to NIR radiation, polydopamine (PDA) and gold nanoshells exhibit exceptional photothermal performance that has the potential to both accelerate and kill HLAC 78 head and neck squamous cell carcinoma cells. Antitumor investigations conducted in vivo and in vitro demonstrated that nanomedicine had remarkable synergistic benefits with chemotherapy and photothermal treatment. Only 25.2% of the cells in the HA/Au-PDA@CZT with a NIR irradiation group were viable. Any group's lowest tumor volume was shown in the tumor mice subjected to HA/Au-PDA@CZT with NIR at 0.3 ± 0.1. Consequently, for synergistic chemo-photothermal therapy, our logically designed nanoplatform would be the potential for a head and neck squamous tumor-targeting drug delivery system.

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

Nanoparticles in Cancer Diagnosis and Treatment

The use of tailored medication delivery in cancer treatment has the potential to increase efficacy while decreasing unfavourable side effects. For researchers looking to improve clinical outcomes, chemotherapy for cancer continues to be the most challenging topic. Cancer is one of the worst illnesses despite the limits of current cancer therapies. New anticancer medications are therefore required to treat cancer. Nanotechnology has revolutionized medical research with new and improved materials for biomedical applications, with a particular focus on therapy and diagnostics. In cancer research, the application of metal nanoparticles as substitute chemotherapy drugs is growing. Metals exhibit inherent or surface-induced anticancer properties, making metallic nanoparticles extremely useful. The development of metal nanoparticles is proceeding rapidly and in many directions, offering alternative therapeutic strategies and improving outcomes for many cancer treatments. This review aimed to present the most commonly used nanoparticles for cancer applications.

Photothermal Nanomaterials: A Powerful Light-to-Heat Converter

All forms of energy follow the law of conservation of energy, by which they can be neither created nor destroyed. Light-to-heat conversion as a traditional yet constantly evolving means of converting light into thermal energy has been of enduring appeal to researchers and the public. With the continuous development of advanced nanotechnologies, a variety of photothermal nanomaterials have been endowed with excellent light harvesting and photothermal conversion capabilities for exploring fascinating and prospective applications. Herein we review the latest progresses on photothermal nanomaterials, with a focus on their underlying mechanisms as powerful light-to-heat converters. We present an extensive catalogue of nanostructured photothermal materials, including metallic/semiconductor structures, carbon materials, organic polymers, and two-dimensional materials. The proper material selection and rational structural design for improving the photothermal performance are then discussed. We also provide a representative overview of the latest techniques for probing photothermally generated heat at the nanoscale. We finally review the recent significant developments of photothermal applications and give a brief outlook on the current challenges and future directions of photothermal nanomaterials.

Plasmonic nanotechnology for photothermal applications - an evaluation

The application of plasmonic nanoparticles is motivated by the phenomenon of surface plasmon resonance. Owing to the tunability of optothermal properties and enhanced stability, these nanostructures show a wide range of applications in optical sensors, steam generation, water desalination, thermal energy storage, and biomedical applications such as photothermal (PT) therapy. The PT effect, that is, the conversion of absorbed light to heat by these particles, has led to thriving research regarding the utilization of plasmonic nanoparticles for a myriad of applications. The design of conventional nanomaterials for PT conversion has focussed predominantly on the manipulation of photon absorption through bandgap engineering, doping, incorporation, and modification of suitable matrix materials. Plasmonic nanomaterials offer an alternative and attractive approach in this regard, through the flexibility in the excitation of surface plasmons. Specific advantages are the considerable improved bandwidth of the absorption, a higher efficiency of photon absorption, facile tuning, as well as flexibility in the synthesis of plasmonic nanomaterials. This review of plasmonic PT (PPT) research begins with a theoretical discussion on the plasmonic properties of nanoparticles by means of the quasi-static approximation, Mie theory, Gans theory, generic simulations on common plasmonic material morphologies, and the evaluation processes of PT performance. Further, a variety of nanomaterials and material classes that have potential for PPT conversion are elucidated, such as plasmonic metals, bimetals, and metal-metal oxide nanocomposites. A detailed investigation of the essential, but often ignored, concept of thermal, chemical, and aggregation stability of nanoparticles is another part of this review. The challenges that remain, as well as prospective directions and chemistries, regarding nanomaterials for PT conversion are pondered on in the final section of the article, taking into account the specific requirements from different applications.

Albumin-templated platinum (II) sulfide nanodots for size-dependent cancer theranostics

Transition-metal chalcogenides, such as noble metal chalcogenides, hold tremendous potential as efficient agents for photo-induced cancer theranostics due to their unique physicochemical properties. However, a critical bottleneck still lies in exploring simple and controllable methods to synthesize noble metal chalcogenides especially PtS for in vivo photo-induced cancer imaging and simultaneous therapy. Herein, we proposed the albumin-templated synthesis of size-controllable platinum (II) sulfide nanodots (PtS-NDs) for multimodal cancer imaging and potent photothermal therapy. PtS-NDs were precisely synthesized with a tunable size ranging from 2.1 nm to 4.5 nm through a thermodynamically controlled growth inside albumin nanocages. PtS-NDs yielded significant near-infrared (NIR) absorbance and outstanding photothermal conversion under NIR laser irradiation, as well as effective resistance to photobleaching, thereby generating remarkable in vivo photoacoustic signals and distinct hyperthermia at tumor site. Moreover, these nanodots possessed efficient cellular uptake and tumor targeting capabilities in a size-dependent manner, thus leading to controllable diagnostic and thermo-therapeutic efficacy. Specifically, PtS-NDs with core diameter of 4.5 nm displayed preferable in vivo photoacoustic and CT imaging with high sensitivity, spatially and anatomically enhanced imaging contrast, together with hyperthermia mediated tumor ablation. Thus, the albumin-templated biomimetic synthesis provided an insightful strategy on fabricating theranostic PtS-NDs for potential clinical applications. STATEMENT OF SIGNIFICANCE: Noble metal chalcogenides especially PtS are of particular importance in the field of precise nanomedicine to improve both accuracy of cancer diagnosis and efficiency of tumor treatment. However, the intensively preclinical investigation of PtS was limited due to the lack of simple and controllable synthetic methods. Here, we report an albumin-templated biomineralization synthesis of platinum (II) sulfide nanodots (PtS-NDs). Specifically, albumin-templated biomineralization of PtS-NDs was induced by the electrostatic interactions between albumin and Pt²⁺, followed by the nucleation and growth inside the albumin nanocages. The resulting PtS-NDs showed good dispersibility and biosafety, as well as size-dependent photophysical properties and biological behaviors. Therefore, albumin-based biomineralization is a promising and safe strategy to facilely fabricate Pt-based chalcogenide for tumor theranostics.

Design Strategies of Tumor-Targeted Delivery Systems Based on 2D Nanomaterials

Conventional chemotherapy and radiotherapy are nonselective and nonspecific for cell killing, causing serious side effects and threatening the lives of patients. It is of great significance to develop more accurate tumor-targeting therapeutic strategies. Nanotechnology is in a leading position to provide new treatment options for cancer, and it has great potential for selective targeted therapy and controlled drug release. 2D nanomaterials (2D NMs) have broad application prospects in the field of tumor-targeted delivery systems due to their special structure-based functions and excellent optical, electrical, and thermal properties. This review emphasizes the design strategies of tumor-targeted delivery systems based on 2D NMs from three aspects: passive targeting, active targeting, and tumor-microenvironment targeting, in order to promote the rational application of 2D NMs in clinical practice.

Dual anticancer drug-loaded self-assembled nanomaterials delivery system for the treatment of prostate cancer

This study explains the engineering of polylactide-polyethylene succinate glycol nanomaterials (NMs), to achieve superior anticancer effectiveness in prostate cancer therapy as a carriers of crizotinib (CZT) and marizomib (MAR). We have shown that the block polymers and hydrophobic drugs can be self-assembled to construct a highly stable nanocarrier with highly adaptable to support the use of cancer medicines. The Drug Release analysis revealed that the interference in the hydrophobic cores of micelles was a continuous release series. In both PC3pip and LNCAP prostate cancer cells, CZT@MAR NMs demonstrated noticeable cytotoxic effects in a dose-responsive method. In addition, morphology analysis and the AO-EB and nuclear staining assay showed a higher effectiveness in prostate cancer for nanomaterials. The polymeric nanomaterials displayed a prominent existence in the cytoplasmic cell regions, which shows a characteristic cell uptake by endocytosis. A significant apoptosis, compared to free CZT@MAR apoptosis, was found in the FITC-Annexin V/PI staining-based apoptosis analysis. In this juncture, the alternative drug delivery mechanism for the improvement of CZT@MAR chemotherapeutic effectiveness in prostate cancer chemotherapy modification PLA nanoparticles.

The cellular immunotherapy of integrated photothermal anti-oxidation Pd-Se nanoparticles in inhibition of the macrophage inflammatory response in rheumatoid arthritis

Reducing the inflammatory response is a major goal in the therapy of rheumatoid arthritis (RA). Herein, we integrated palladium nanoparticles (Pd NPs) with selenium nanoparticles (Se NPs) and obtained a multiple nanosystem (Pd@Se-HA NPs) that could simultaneously scavenge hydroxyl radicals (⋅OH) and provide a photothermal effect. The Pd@Se-HA NPs were constructed by a simple self-assembly method in which Se NPs were electrostatically bonded to Pd NPs; hyaluronic acid (HA) was linked to the NPs by ester bonding to provide macrophage targeting ability. The experiments show that the combined therapy of eliminating ⋅OH with Se NPs and utilizing PTT with Pd NPs could effectively reduce the inflammatory response in macrophages more effectively than either individual NP treatment. In addition, the outer layer of HA could specifically target the CD44 receptor to enhance the accumulation of Pd@Se NPs at the lesion, further enhancing the therapeutic effect. After treatment for 15 days, the Pd@Se-HA NPs nearly eliminated the inflammatory response in the joints of mice in an induced RA model, and prevented joint damage and degradation.

Recent advances in cancer photo-theranostics: the synergistic combination of transition metal complexes and gold nanostructures

In this mini review, we highlight advances in the last five years in light-activated cancer theranostics by using hybrid systems consisting of transition metal complexes (TMCs) and plasmonic gold nanostructures (AuNPs). TMCs are molecules with attractive properties and high potential in biomedical application. Due to their antiproliferative abilities, platinum-based compounds are currently first-choice drugs for the treatment of several solid tumors. Moreover, ruthenium, iridium and platinum complexes are well-known for their ability to photogenerate singlet oxygen, a highly cytotoxic reactive species with a key role in photodynamic therapy. Their potential is further extended by the unique photophysical properties, which make TMCs particularly suitable for bioimaging. Recently, gold nanoparticles (AuNPs) have been widely investigated as one of the leading nanomaterials in cancer theranostics. AuNPs—being an inert and highly biocompatible material—represent excellent drug delivery systems, overcoming most of the side effects associated with the systemic administration of anticancer drugs. Furthermore, due to the thermoplasmonic properties, AuNPs proved to be efficient nano-sources of heat for photothermal therapy application. Therefore, the hybrid combination TMC/AuNPs could represent a synergistic merger of multiple functionalities for combinatorial cancer therapy strategies. Herein, we report the most recent examples of TMC/AuNPs systems in in-vitro in-vivo cancer tharanostics application whose effects are triggered by light-exposure in the Vis–NIR region, leading to a spatial and temporal control of the TMC/AuNPs activation for light-mediated precision therapeutics.

ZnO/SiO2 core/shell nanowires for capturing CpG rich single-stranded DNAs

Atomic layer deposition (ALD) is capable of providing an ultrathin layer on high-aspect ratio structures with good conformality and tunable film properties. In this research, we modified the surface of ZnO nanowires through ALD for the fabrication of a ZnO/SiO2 (core/shell) nanowire microfluidic device which we utilized for the capture of CpG-rich single-stranded DNAs (ssDNA). Structural changes of the nanowires while varying the number of ALD cycles were evaluated by statistical analysis and their relationship with the capture efficiency was investigated. We hypothesized that finding the optimum number of ALD cycles would be crucial to ensure adequate coating for successful tuning to the desired surface properties, besides promoting a sufficient trapping region with optimal spacing size for capturing the ssDNAs as the biomolecules traverse through the dispersed nanowires. Using the optimal condition, we achieved high capture efficiency of ssDNAs (86.7%) which showed good potential to be further extended for the analysis of CpG sites in cancer-related genes. This finding is beneficial to the future design of core/shell nanowires for capturing ssDNAs in biomedical applications.

Nano liposomal and cubosomal formulations with platinum-based anticancer agents: therapeutic advances and challenges

Nephrotoxicity, neurotoxicity and multidrug resistance in tumor cells can result from platinum-based anticancer (PBA) agents which can be reduced by nano formulations. Recently, novel formulations based on liposomes and cubosomes have been described as efficient strategies to overcome nephrotoxicity, ototoxicity, neurotoxicity, cardiotoxicity, hematological toxicities, hepatotoxicity and gastrointestinal toxicity as well as multidrug resistance. The co-delivery of anticancer agents concomitant with PBAs via biocompatible and biodegradable smart liposomes and cubosomes can augment therapeutic results of chemotherapy as well as radiotherapy owing to their high accessibility of surface and internal modification. For this purpose, surface, bilayer or core sections of these formulations can be functionalized by pure PBAs or modified PBAs. In this review, recent significant advances and challenges related to various liposomal and cubosomal formulations of PBA are presented in order to emphasize suitable formulations for anticancer applications with critical thoughts provided on how the field can progress.

Palladium-based nanomaterials for cancer imaging and therapy

In recent decade, palladium-based (Pd-based) nanomaterials have shown significant potential for biomedical applications because of their unique optical properties, excellent biocompatibility and high stability in physiological environment. Compared with other intensively studied noble nanomaterials, such as gold (Au) and silver (Ag) nanomaterials, research on Pd-based nanomaterials started late, but the distinctive features, such as high photothermal conversion efficiency and high photothermal stability, have made them getting great attention in the field of nanomedicine. The goal of this review is to provide a comprehensive and critical perspective on the recent progress of Pd-based nanomaterials as imaging contrast agents and therapeutic agents. The imaging section focuses on applications in photoacoustic (PA) imaging, single-photon emission computed tomography (SPECT) imaging, computed tomography (CT) imaging and magnetic resonance (MR) imaging. For treatment of cancer, single photothermal therapy (PTT) and PTT combined with other therapeutic modalities will be discussed. Finally, the safety concerns, forthcoming challenges and perspective of Pd-based nanomaterials on biomedical applications will be presented.

Recent Advances in Nanotheranostics for Treat-to-Target of Rheumatoid Arthritis

Early diagnosis, standardized treatment, and regular monitoring are the clinical treatment principle of rheumatoid arthritis (RA). The overarching principles and recommendations of treat-to-target (T2T) in RA advocate remission as the optimum aim, especially for patients with very early disease who are initiating therapy with anti-RA medications. However, traditional anti-RA drugs cannot selectively target the inflammatory areas and may cause serious side effects due to its short biological half-life and poor bioavailability. These limitations have significantly driven the research and application of nanomaterial-based drugs in theranostics of RA. Nanomedicines have appropriate sizes and easily modified surfaces which can enhance their biological compatibility and prolong circulation time of drug-loading systems in vivo. Traditional T2T regimens cannot evaluate the efficacy of drugs in real time, while clinical drug nanosizing can realize the integration of diagnosis and treatment of RA. This review bridges clinically proposed T2T concepts and nanomedicine in an integrated system for RA early-stage diagnosis and treatment. The most advanced progress in various nanodrug delivery systems for theranostics of RA is summarized, establishing a clear path and a new perspective for further optimization of T2T. Finally, the key facing challenges are discussed and prospects are addressed.

2D nanostructures beyond graphene: preparation, biocompatibility and biodegradation behaviors

The research advances of the preparation, biocompatibility and biodegradation of 2D nanomaterials are introduced. The prospects and challenges of the biomedical applications of 2D nanomaterials are summarized.

Metallic Ti3O5 hierarchical porous microspheres with an enhanced photothermal property

γ-Ti₃O₅ is one kind of prominent non-stoichiometric metal oxide due to its intriguing ability in electric and electrochemical behaviors. This work reports another attractive property of γ-Ti₃O₅ hierarchical porous microspheres, the extremely effective photothermal property with a high photothermal conversion efficiency. Theory and experimental results indicate that γ-Ti₃O₅ hierarchical porous microspheres possess metallic features and display very strong localized surface plasma resonance effects over the visible and near-infrared region. Under simulated sunlight or near infrared light, the metallic γ-Ti₃O₅ exhibits a photothermal conversion efficiency of up to 65.29%. Under irradiation by a near-infrared laser with a wavelength of 808 nm, the γ-Ti₃O₅ hierarchical porous microspheres can significantly inhibit cancer cell viability in vitro and disrupt tumor tissue growth in vivo in a short period. In vitro and in vivo toxicity experiments demonstrate that it has good biocompatibility. The ultrahigh photothermal conversion efficiency and biocompatibility make the γ-Ti₃O₅ very attractive for technological uses in photothermal therapy, solar energy utilization, and infrared light detection and so on.

Metallic γ-Ti₃O₅ hierarchical porous microspheres with strong localized surface plasmon resonance are reported, which can inhibit cancer cell viability in vitro and disrupt tumor tissue growth in vivo under the irradiation of near infrared light.

Nanobiomaterials: from 0D to 3D for tumor therapy and tissue regeneration

Nanobiomaterials have attracted tremendous attention in the biomedical field. Especially in the past few years, a large number of low dimensional nanobiomaterials, including 0D nanostructures, 1D nanotubes and 2D nanosheets, were employed for tumor therapy due to their optically triggered tumor therapy effects and drug loading capacities. However, these low dimensional nanobiomaterials cannot support cell adhesion and possess poor tissue regeneration ability, thus they are not suitable for application in regenerative medicine. Three dimensional (3D) nanofiber scaffolds have attracted extensive attention in tissue regeneration, including bone, skin, nerve and cardiac tissues, due to their similar extracellular matrix structures. Additionally, many 3D scaffolds displayed bone and cartilage regeneration abilities. Therefore, to obtain materials with both tumor therapy and tissue regeneration abilities, it is meaningful and necessary to develop 3D nanobiomaterials with multifunctions. In this review, we systematically review the research progress of nanobiomaterials with varied dimensional structures including 0D, 1D, 2D and 3D, as well as evolutional functions from single tumor therapy to simultaneous tumor therapy and tissue regeneration. This review may pave the way for developing an interdisciplinary research of nanobiomaterials in combination of tumor therapy and regenerative medicine.

Inorganic nanomaterials for chemo/photothermal therapy: a promising horizon on effective cancer treatment

During the last few decades, nanotechnology has established many essential applications in the biomedical field and in particular for cancer therapy. Not only can nanodelivery systems address the shortcomings of conventional chemotherapy such as limited stability, non-specific biodistribution and targeting, poor water solubility, low therapeutic indices, and severe toxic side effects, but some of them can also provide simultaneous combination of therapies and diagnostics. Among the various therapies, the combination of chemo- and photothermal therapy (CT-PTT) has demonstrated synergistic therapeutic efficacies with minimal side effects in several preclinical studies. In this regard, inorganic nanostructures have been of special interest for CT-PTT, owing to their high thermal conversion efficiency, application in bio-imaging, versatility, and ease of synthesis and surface modification. In addition to being used as the first type of CT-PTT agents, they also include the most novel CT-PTT systems as the potentials of new inorganic nanomaterials are being more and more discovered. Considering the variety of inorganic nanostructures introduced for CT-PTT applications, enormous effort is needed to perform translational research on the most promising nanomaterials and to comprehensively evaluate the potentials of newly introduced ones in preclinical studies. This review provides an overview of most novel strategies used to employ inorganic nanostructures for cancer CT-PTT as well as cancer imaging and discusses current challenges and future perspectives in this area.

Quercetin-modified gold-palladium nanoparticles as a potential autophagy inducer for the treatment of Alzheimer's disease

At present, autophagic dysfunction has been considered to be involved in the pathogenesis of Alzheimer's disease (AD). Thus, the activation of autophagy provides a potential means of eliminating the intracellular amyloid-β (Aβ) and slows down the neurotoxicity induced by Aβ. Here, we synthesize a Quercetin (Qu) modified polysorbate 80 (P-80)-coated AuPd core-shell structure. Our results indicate that Concave cubic Qu@P-80@AuPd can activate autophagy of SH-SY5Y cells, promote the fusion of autophagosomes and lysosomes, accelerate the clearance of Aβ, and protect SH-SY5Y cells from Aβ-induced cytotoxicity damage. Furthermore, Concave cubic Qu@P-80@AuPd also has good biocompatibility and high blood-brain barrier (BBB) permeability. Therefore, we anticipate that Concave cubic Qu@P-80@AuPd will be used as a potential autophagy inducer to treat AD.

The biobehavior, biocompatibility and theranostic application of SPNS and Pd@Au nanoplates in rats and rabbits

On account of the fascinating surface plasmon resonance (SPR) properties, the ability of passively targeting tumors and remarkable biocompatibility, two-dimensional (2D) Pd-based nanomaterials have demonstrated wide application prospects in cancer theranostics. However, the used animal models for exploring the bioapplications and biosafety of 2D Pd-based nanomaterials were usually limited to mice. To further widen their biomedical applications and promote future clinical transformation, it is necessary to make a breakthrough in animal models. In this work, Sprague Dawley (SD) rats and New Zealand rabbits were used as the experimental animals and orthotopic liver tumors or subcutaneous tumors were induced in these animals. Taking ≈5 nm small Pd nanosheets (SPNS) and 30 nm Pd@Au nanoplates (Pd@Au) as the representative 2D Pd-based nanomaterials, we investigated their biobehaviors and biosafety in rat liver & subcutaneous tumor models and rabbit liver tumors. The results indicated that SPNS and Pd@Au could still effectively accumulate on the tumor sites of these bigger animal models by the enhanced permeability and retention (EPR) effect, and the accumulation effects were closely related to their sizes. Metabolism studies confirmed that SPNS could be excreted out of rats through urine. Moreover, based on the sufficient uptake by cancer cells and passive accumulation of SPNS and Pd@Au in subcutaneous tumors in rats, we performed photothermal therapy (PTT) in vitro and in vivo. Significant tumor growth inhibition illustrated that even though the animal model was dozens of times bigger than the mouse model, the 2D Pd-based nanomaterials satisfied the requirements of being an outstanding photothermal reagent. Finally, the hematological and histological examination results suggested that SPNS and Pd@Au had favorable biocompatibility in rats and rabbits at a given dose. We hope this work will drive the development of 2D Pd-based nanomaterials towards practical clinical applications and provide a guide for other theranostic nanoplatforms that will be applied in bigger animal tumor models in the future.

Facile Fabrication of Magnetic Microrobots Based on Spirulina Templates for Targeted Delivery and Synergistic Chemo-Photothermal Therapy

Magnetic microrobots can be actuated in fuel-free conditions and are envisioned for biomedical applications related to targeted delivery and therapy in a minimally invasive manner. However, mass fabrication of microrobots with precise propulsion performance and excellent therapeutic efficacy is still challenging, especially in a predictable and controllable manner. Herein, we propose a facile technique for mass production of magnetic microrobots with multiple functions using Spirulina ( Sp.) as biotemplate. Core-shell-structured Pd@Au nanoparticles (NPs) were synthesized in Sp. cells by electroless deposition, working as photothermal conversion agents. Subsequently, the Fe₃O₄ NPs were deposited onto the surface of the obtained (Pd@Au)@ Sp. particles via a sol-gel process, enabling them to be magnetically actuated. Moreover, the anticancer drug doxorubicin (DOX) was loaded on the (Pd@Au)/Fe₃O₄@ Sp. microrobots, which endows them with additional chemotherapeutic efficacy. The as-prepared biohybrid (Pd@Au)/Fe₃O₄@ Sp.-DOX microrobots not only possess efficient propulsion performance with the highest speed of 526.2 μm/s under a rotating magnetic field but also have enhanced synergistic chemo-photothermal therapeutic efficacy. Furthermore, they can be structurally disassembled into individual particles under near-infrared (NIR) laser irradiation and exhibit pH- and NIR-triggered drug release. These intriguing properties enable the microrobots to be a very promising and efficient platform for drug loading, targeted delivery, and chemo-photothermal therapy.

Targeted hexagonal Pd nanosheet combination therapy for rheumatoid arthritis via the photothermal controlled release of MTX

Methotrexate (MTX) is a drug that is used for the clinical treatment of rheumatoid arthritis (RA), a stubborn disease caused by over-immunization.

Nano-Based Systems and Biomacromolecules as Carriers for Metallodrugs in Anticancer Therapy

Since the discovery of cisplatin and its potency in anticancer therapy, the development of metallodrugs has been an active area of research. The large choice of transition metals, oxidation states, coordinating ligands, and different geometries, allows for the design of metal-based agents with unique mechanisms of action. Many metallodrugs, such as titanium, ruthenium, gallium, tin, gold, and copper-based complexes have been found to have anticancer activities. However, biological application of these agents necessitates aqueous solubility and low systemic toxicity. This minireview highlights the emerging strategies to facilitate the in vivo application of metallodrugs, aimed at enhancing their solubility and bioavailability, as well as improving their delivery to tumor tissues. The focus is on encapsulating the metal-based complexes into nanocarriers or coupling to biomacromolecules, generating efficacious anticancer therapies. The delivery systems for complexes of platinum, ruthenium, copper, and iron are discussed with most recent examples.

A Pd corolla-human serum albumin-indocyanine green nanocomposite for photothermal/photodynamic combination therapy of cancer

In this work, a novel nanoplatform based on Pd corolla-human serum albumin-indocyanine green (PdCs-HSA-ICG) was developed for cancer photothermal/photodynamic combination therapy. Pd corollas (denoted as PdCs) with good near-infrared photothermal conversion efficiency (η≈ 37%) were first prepared and modified with human serum albumin (HSA) and indocyanine green (ICG) to get the PdCs-HSA-ICG nanocomposite. The prepared PdCs-HSA-ICG not only improves the colloid and thermal stability of ICG, but also shows a higher temperature increase than that of PdCs and free ICG as well as a comparable singlet oxygen (¹O₂) generation capability to that of free ICG. Upon single 808 nm laser irradiation, the photothermal (PTT)/photodynamic (PDT) combined therapeutic efficacy of PdCs-HSA-ICG at both cellular and animal levels was superior to PdCs-HSA (PTT) or free ICG (PTT and PDT), respectively. Thus, the designed PdCs-HSA-ICG nanocomposite holds great potential as a new class of photosensitive agent for cancer phototherapy.

Decorating gold nanostars with multiwalled carbon nanotubes for photothermal therapy

Gold nanoparticles and carbon nanotubes have attracted substantial attention in recent years for their potential applications in photothermal therapy (PTT) as an emerging breakthrough in cancer treatment. Herein, a hybrid nanomaterial of gold nanostars/multiwalled carbon nanotubes (MWCNTs) was synthesized by two-step reduction via the control of several synthetic conditions such as the reducing agent, pH value, concentration and ratio of reagents. The material shows good biocompatibility and high photothermal conversion efficiency, demonstrating its applicability in PTT. The lack of surfactant in the synthesis process made the hybrid nanomaterial cell-friendly, with no effects on viability in vitro. The MWCNT/gold nanostars hybrid nanomaterial presented 12.4% higher photothermal efficiency than gold nanostars alone and showed a 2.4-fold increase over gold nanospheres based on a heating test under 808 nm laser irradiation. Moreover, the MWCNTs/gold nanostars at low concentration (0.32 nM) exhibited remarkably improved photothermal cancer cell-killing efficacy, which may be attributed to the surface plasmon resonance absorption of the gold nanostars and the combined effects of enhanced coupling between the MWCNTs and gold nanostars. Collectively, these results demonstrate that the MWCNTs/gold nanostars developed herein show prominent photothermal value, and thus may serve as a novel photothermal agent for cancer therapy.

Hierarchically stimuli-responsive nanovectors for improved tumor penetration and programed tumor therapy

Poor drug delivery to solid tumors remains a great challenge for effective antitumor therapy. Herein, multistage stimuli-responsive nanovectors based on hollow mesoporous silica nanoparticles (HMSNs) were prepared to avoid delivery barriers for improved penetration and programmed tumor therapy. The versatile nanosystem was constructed through electrostatic complexation between the functional HMSNs loaded with gemcitabine (GEM) and the small-sized platinum prodrug-conjugated poly(amidoamine) dendrimer (PAMAM-Pt). The HMSNs were functionalized with dimethylmaleic anhydride tethered chitosan oligosaccharide to endow the particles of HMSN-CS(DMA) with charge-reversal properties. The as-prepared nanosystem had a stable structure of size ∼130 nm at pH 7.4, which is beneficial for blood circulation and tumor vessel extravasation of nanocarriers. Once it reaches the tumor site, the nanosystem can dissociate into HMSN@GEM-CS (∼120 nm) and PAMAM-Pt dendrimer nanocarriers (∼5 nm) in response to the acidic tumor microenvironment because of the acid-mediated charge-reversal, then the HMSN@GEM can play the antitumor role in surface tumor tissues. The dissociated PAMAM-Pt showed excellent performance in tumor penetration, cell uptake and intracellular trafficking due to the small size and positive charge, which was supported by the study of three-dimensional multicellular spheroids in vitro. Finally, the active cisplatin was released from the PAMAM-Pt dendrimer under the intracellular reducing environment to kill cells in deep tumor tissues. The significant tumor suppression of this system in vivo was validated in the A549 tumor xenografted mouse model. Such a stimuli-responsive nanosystem that integrates simple preparation, biocompatibility, biodegradability and programmed tumor therapy manifests great potential for clinical trials.

Erythrocyte–platelet hybrid membranes coating polypyrrol nanoparticles for enhanced delivery and photothermal therapy

A dual-membrane coating technique was developed to camouflage polypyrrole nanoparticles with red blood cells and platelet membranes for enhanced delivery and photothermal tumor therapy.

Double-mesoporous core-shell nanosystems based on platinum nanoparticles functionalized with lanthanide complexes for in vivo magnetic resonance imaging and photothermal therapy

A double-mesoporous nanosystem was synthesized for treating as well as imaging cancer cells by using a simple and mild method. The mesoporous platinum (Pt) nanoparticles acting as a core show excellent photothermal effect under illumination with an 808 nm near infrared (NIR) laser. The mesoporous silica linked with a lanthanide (Gd) complex acting as a shell displays potential applications as a contrast agent for magnetic resonance imaging (MRI). The final mPt@mSiO₂-GdDTPA nanosystems exhibit good biocompatibility in vitro and in vivo, when investigated by methyl thiazolyl tetrazolium assay and histological and serum biochemistry analysis. The investigation of the photothermal effect shows that the mPt@mSiO₂-GdDTPA nanosystems exhibit an excellent photothermal therapy effect on HeLa cells and tumor-bearing mice. As theranostic agents, the nanosystems display a higher r₁ value than the medical contrast agent magnevist and were successfully applied to in vivo MRI of Kunming mice. Therefore, the first systematic study on the photothermal effect of nanosystems based on mesoporous Pt nanoparticles does encourage the potential applications of metal nanoparticles and hybrid nanocomposites for cancer bioimaging and therapy.

Design and Fabrication of Temperature-Sensitive Nanogels with Controlled Drug Release Properties for Enhanced Photothermal Sterilization

For better removal of excessive free radicals and harmful bacteria from the human body, the development of synergistic antioxidant and antibacterial agents is urgently required. Herein, we designed novel temperature-sensitive, curcumin (Cur)-loaded nanogels for the application of scavenging reactive oxygen species and killing pathogenic bacteria. Photothermal sterilization, different from traditional antibiotics, is a promising and effective treatment for pathogenic bacterial infection. The nanogels were fabricated by using poly(N-isopropylacrylamide) (a temperature-sensitive hydrogel) to encapsulate poly(3,4-ethylenedioxythiophene) nanoparticles (photothermal agents) and Cur through a reformative precipitation polymerization. When triggered by near-IR light, the Cur-loaded nanogels exhibited high (56.8 %), and excellent temperature-sensitive effects. Moreover, the light-induced temperature increase can also weaken the interaction between the networks of PNIPAAm and Cur, to show excellent antioxidant and antibacterial performance (90 % cell death) of the nanogels.

Two-dimensional Pd-based nanomaterials for bioapplications

Noble metal nanomaterials have been extensively explored in cancer diagnostic and therapeutic applications owing to their unique physical and chemical properties, such as facile synthesis, straightforward surface functionalization, strong photothermal effect, and excellent biocompatibility. Herein, we summarize the recent development of two-dimensional (2D) Pd-based nanomaterials and their applications in cancer diagnosis and therapy. Different synthetic strategies for Pd nanosheets and the related nanostructures, including Pd@Au, Pd@Ag nanoplates and mesocrystalline Pd nanocorolla, are first discussed. Together with their unique properties, the potential bioapplications of these 2D Pd nanomaterials are then demonstrated. With strong absorption in near-infrared (NIR) region, these nanomaterials have great potentials in cancer photothermal therapy (PTT). They also readily act as contrast agents in photoacoustic (PA) imaging or X-ray computed tomography (CT) to achieve image-guided cancer therapy. Moreover, significant efforts have been devoted to studying the combination of PTT and other treatment modalities (e.g., chemotherapy or photodynamic therapy) based on Pd nanomaterials. The remarkable synergistic or collaborative effects to achieve better therapeutic efficacy are discussed as well. Additionally, the biosafety of 2D Pd-based nanomaterials in vitro and in vivo was evaluated. Finally, challenges for the applications of Pd-based nanomaterials in cancer diagnosis and therapy, and future research prospects are highlighted.

Smart Nanostructures for Cargo Delivery: Uncaging and Activating by Light

Nanotechnology has begun to play a remarkable role in various fields of science and technology. In biomedical applications, nanoparticles have opened new horizons, especially for biosensing, targeted delivery of therapeutics, and so forth. Among drug delivery systems (DDSs), smart nanocarriers that respond to specific stimuli in their environment represent a growing field. Nanoplatforms that can be activated by an external application of light can be used for a wide variety of photoactivated therapies, especially light-triggered DDSs, relying on photoisomerization, photo-cross-linking/un-cross-linking, photoreduction, and so forth. In addition, light activation has potential in photodynamic therapy, photothermal therapy, radiotherapy, protected delivery of bioactive moieties, anticancer drug delivery systems, and theranostics (i.e., real-time monitoring and tracking combined with a therapeutic action to different diseases sites and organs). Combinations of these approaches can lead to enhanced and synergistic therapies, employing light as a trigger or for activation. Nonlinear light absorption mechanisms such as two-photon absorption and photon upconversion have been employed in the design of light-responsive DDSs. The integration of a light stimulus into dual/multiresponsive nanocarriers can provide spatiotemporal controlled delivery and release of therapeutic agents, targeted and controlled nanosystems, combined delivery of two or more agents, their on-demand release under specific conditions, and so forth. Overall, light-activated nanomedicines and DDSs are expected to provide more effective therapies against serious diseases such as cancers, inflammation, infections, and cardiovascular disease with reduced side effects and will open new doors toward the treatment of patients worldwide.

The biodistribution, excretion and potential toxicity of different-sized Pd nanosheets in mice following oral and intraperitoneal administration

The biodistribution, excretion and potential toxicity of different-sized Pd nanosheets in mice following oral and intraperitoneal administration were systematically investigated.

Enhancing the photothermal stability and photothermal efficacy of AuNRs and AuNTs by grafting with Ru(ii) complexes

In this paper, we found that the ruthenium complex-functionalized AuNRs (AuNRs@Ru) and AuNTs (AuNTs@Ru) exhibited better photothermal stability and higher photothermal efficiency than AuNRs and AuNTs.In vivotumor model studies showed that AuNRs@Ru and AuNRs@Ru were effective for the photothermal destruction of tumors.

Non-conjugated polyurethane polymer dots based on crosslink enhanced emission (CEE) and application in Fe3+ sensing

A novel non-conjugated polymer dot sensor is developed for Fe³⁺ detection based on crosslink enhanced emission.