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

Tailored Functionalization of Plasmonic AgNPs/C:H:N:O Nanocomposite for Sensitive and Selective Detection

We report here on the development of tailored plasmonic AgNPs/C:H:N:O plasma polymer nanocomposites for the detection of the pathogenic bacterium Borrelia afzelii , with high selectivity and sensitivity. Silver (Ag) nanoparticles, generated by a gas aggregation source, are incorporated onto a C:H:N:O plasma polymer matrix, which is deposited by magnetron sputtering of a nylon 6.6. These anchored Ag nanoparticles propagate localized surface plasmon resonance (LSPR), optically responding to changes caused by immobilized pathogens near the nanoparticles. The tailored functionalization of AgNPs/C:H:N:O nanocomposite surface allows both high selectivity for the pathogen and high sensitivity with an LSPR red-shift Δλ > (4.20 ± 0.71) nm for 50 Borrelia per area 0.785 cm2. The results confirmed the ability of LSPR modulation for the rapid and early detection of (not only) tested pathogens.

Protein-functionalized and intrinsically radiolabeled [188Re]ReOx nanoparticles: advancing cancer therapy through concurrent radio-photothermal effects

PURPOSE

Enhancing therapeutic effectiveness is crucial for translating anticancer nanomedicines from laboratory to clinical settings. In this study, we have developed radioactive rhenium oxide nanoparticles encapsulated in human serum albumin ([188Re]ReOx-HSA NPs) for concurrent radiotherapy (RT) and photothermal therapy (PTT), aiming to optimize treatment outcomes.

METHODS

[188Re]ReOx-HSA NPs were synthesized by a controlled reduction of 188ReO4- in HSA medium and extensively characterized. The anticancer effect of [188Re]ReOx-HSA NPs was demonstrated in vitro in murine melanoma (B16F10) cell line. In vivo SPECT/CT imaging, autoradiography and biodistribution studies were performed after intratumoral injection of [188Re]ReOx-HSA NPs in melanoma tumor-bearing C57BL/6 mice. The potential of [188Re]ReOx-HSA NPs for combined RT and PTT treatment was also demonstrated in the aforesaid mice model.

RESULTS

[188Re]ReOx-HSA NPs (size 4-6 nm) were synthesized with high colloidal and radiochemical stability. Upon laser (808 nm) exposure on B16F10 cells incubated with [188Re]ReOx-HSA NPs, only < 20% of cells were alive demonstrating high therapeutic efficacy under in vitro settings. Uniform dose distribution and retention of the radiolabeled NPs in the tumor volume were observed via SPECT/CT imaging and autoradiography studies. Tumor growth in mice model was significantly arrested with ~ 1.85 MBq dose of [188Re]ReOx-HSA NPs and simultaneous laser irradiation, demonstrating synergistic benefit of RT and PTT.

CONCLUSIONS

These results demonstrate that intrinsically radiolabeled [188Re]ReOx-HSA NPs having unique features such as high photothermal effects and favorable nuclear decay characteristics for combined RT/PTT, hold great promise for clinical translation.

Three Strategies in Engineering Nanomedicines for Tumor Microenvironment-Enabled Phototherapy

Canonical phototherapeutics have several limitations, including a lack of tumor selectivity, nondiscriminatory phototoxicity, and tumor hypoxia aggravation. The tumor microenvironment (TME) is characterized by hypoxia, acidic pH, and high levels of H2 O2 , GSH, and proteases. To overcome the shortcomings of canonical phototherapy and achieve optimal theranostic effects with minimal side effects, unique TME characteristics are employed in the development of phototherapeutic nanomedicines. In this review, the effectiveness of three strategies for developing advanced phototherapeutics based on various TME characteristics is examined. The first strategy involves targeted delivery of phototherapeutics to tumors with the assistance of TME-induced nanoparticle disassembly or surface modification. The second strategy involves near-infrared absorption increase-induced phototherapy activation triggered by TME factors. The third strategy involves enhancing therapeutic efficacy by ameliorating TME. The functionalities, working principles, and significance of the three strategies for various applications are highlighted. Finally, possible challenges and future perspectives for further development are discussed.

Recent Development of Rhenium-Based Materials in the Application of Diagnosis and Tumor Therapy

Rhenium (Re) is widely used in the diagnosis and treatment of cancer due to its unique physical and chemical properties. Re has more valence electrons in its outer shell, allowing it to exist in a variety of oxidation states and to form different geometric configurations with many different ligands. The luminescence properties, lipophilicity, and cytotoxicity of complexes can be adjusted by changing the ligand of Re. This article mainly reviews the development of radionuclide 188Re in radiotherapy and some innovative applications of Re as well as the different therapeutic approaches and imaging techniques used in cancer therapy. In addition, the current application and future challenges and opportunities of Re are also discussed.

Biodegradable nanomaterials for diagnosis and therapy of tumors

Although degradable nanomaterials have been widely designed and applied for cancer bioimaging and various cancer treatments, few reviews of biodegradable nanomaterials have been reported. Herein, we have summarized the representative research advances of biodegradable nanomaterials with respect to the mechanism of degradation and their application in tumor imaging and therapy. First, four kinds of tumor microenvironment (TME) responsive degradation are presented, including pH, glutathione (GSH), hypoxia and matrix metalloproteinase (MMP) responsive degradation. Second, external stimulation degradation is summarized briefly. Next, we have outlined the applications of nanomaterials in bioimaging. Finally, we have focused on some typical examples of biodegradable nanomaterials in radiotherapy (RT), photothermal therapy (PTT), starvation therapy, photodynamic therapy (PDT), chemotherapy, chemodynamic therapy (CDT), sonodynamic therapy (SDT), gene therapy, immunotherapy and combination therapy.

Advances in Single-component inorganic nanostructures for photoacoustic imaging guided photothermal therapy

Phototheranostic based on photothermal therapy (PTT) and photoacoustic imaging (PAI), as one of avant-garde medical techniques, have sparked growing attention because it allows noninvasive, deeply penetrative, and highly selective and effective therapy. Among a variety of phototheranostic nanoagents, single-component inorganic nanostructures are found to be novel and attractive PAI and PTT combined nanotheranostic agents and received tremendous attention, which not only exhibit structural controllability, high tunability in physiochemical properties, size-dependent optical properties, high reproducibility, simple composition, easy functionalization, and simple synthesis process, but also can be endowed with multiple therapeutic and imaging functions, realizing the superior therapy result along with bringing less foreign materials into body, reducing systemic side effects and improving the bioavailability. In this review, according to their synthetic components, conventional single-component inorganic nanostructures are divided into metallic nanostructures, metal dichalcogenides, metal oxides, carbon based nanostructures, upconversion nanoparticles (UCNPs), metal organic frameworks (MOFs), MXenes, graphdiyne and other nanostructures. On the basis of this category, their detailed applications in PAI guide PTT of tumor treatment are systematically reviewed, including synthesis strategies, corresponding performances, and cancer diagnosis and therapeutic efficacy. Before these, the factors to influence on photothermal effect and the principle of in vivo PAI are briefly presented. Finally, we also comprehensively and thoroughly discussed the limitation, potential barriers, future perspectives for research and clinical translation of this single-component inorganic nanoagent in biomedical therapeutics.

Plasmonic metal oxides and their biological applications

Metal oxides modified with dopants and defects are an emerging class of novel materials supporting the localized surface plasmon resonance across a wide range of optical wavelengths, which have attracted tremendous research interest particularly in biological applications in the past decade. Compared to conventional noble metal-based plasmonic materials, plasmonic metal oxides are particularly favored for their cost efficiency, flexible plasmonic properties, and improved biocompatibility, which can be important to accelerate their practical implementation. In this review, we first explicate the origin of plasmonics in dopant/defect-enabled metal oxides and their associated tunable localized surface plasmon resonance through the conventional Mie-Gans model. The research progress of dopant incorporation and defect generation in metal oxide hosts, including both in situ and ex situ approaches, is critically discussed. The implementation of plasmonic metal oxides in biological applications in terms of therapy, imaging, and sensing is summarized, in which the uniqueness of dopant/defect-driven plasmonics for inducing novel functionalities is particularly emphasized. This review may provide insightful guidance for developing next-generation plasmonic devices for human health monitoring, diagnosis and therapy.

Degradable Magnetic Nanoplatform with Hydroxide Ions Triggered Photoacoustic, MR Imaging, and Photothermal Conversion for Precise Cancer Theranostic

Theranostic agents based on inorganic nanomaterials are still suffered from the nonbiodegradable substances with long-term retention in body and unavoidable biological toxicity, as well as nonspecificity biodistribution with potential damage toward normal tissues. Here, we develop magnetic ions (Fe^III, Fe^II, Gd^III, Mn^II, and Mn^III) coordinated nanoplatform (MICN) with framework structure and modify them with PEG (MICN-PEG). Notably, MICN-PEG demonstrates hydroxide ions (OH^-) triggered the structure collapse along with responsive near-infrared photoacoustic (PA) signal, magnetic resonance imaging (MRI), and photothermal therapy (PTT) performances. Thereby, MICN-PEG is able to remain stable in tumors and exert excellent PA/MRI and PTT effects for multimodal imaging-guided cancer treatment. In contrast, MICN-PEG is gradually collapsed in normal tissues, resulting in the significant improvement of imaging accuracy and treatment specificity. MICN-PEG is gradually cleared after administration, minimizing concerns about the long-term toxicity.

Heterogenous nanocomposite catalysts with rhenium nanostructures for the catalytic reduction of 4-nitrophenol

Stable and efficient heterogenous nanocatalysts for the reduction of 4-nitrophenol (4-NP) has attracted much attention in recent years. In this context, a unique and efficient in situ approach is used for the production of new polymeric nanocomposites (pNCs) containing rhenium nanostructures (ReNSs). These rare materials should facilitate the catalytic decomposition of 4-NP, in turn ensuring increased catalytic activity and stability. These nanomaterials were analyzed using Fourier-Transformation Infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). The efficiency of the catalytic reaction was estimated based on the acquired UV-Vis spectra, which enabled the estimation of the catalytic activity using pseud-first order modelling. The applied method resulted in the successful production and efficient loading of ReNSs in the polymeric matrices. Amino functionalities played a primary role in the reduction process. Moreover, the functionality that is derived from 1.1'-carbonyl imidazole improved the availability of the ReNSs, which resulted in 90% conversion of 4-NP with a maximum rate constant of 0.29 min-1 over 11 subsequent catalytic cycles. This effect was observed despite the trace amount of Re in the pNCs (~ 5%), suggesting a synergistic effect between the polymeric base and the ReNSs-based catalyst.

A biodegradable "Nano-donut" for magnetic resonance imaging and enhanced chemo/photothermal/chemodynamic therapy through responsive catalysis in tumor microenvironment

Prussian blue (PB) is a safe photothermal agent for tumor therapy, yet poor photothermal effect and single therapeutic function severely restrict its further clinical applications. Herein, a biodegradable "Nano-donut" (CMPB-MoS₂-PEG) is fabricated for magnetic resonance (MR) imaging and enhanced photothermal therapy (PTT)/ chemodynamic therapy (CDT)/chemotherapy through responsive catalysis in tumor microenvironment (TME). The "Nano-donut" is organically composed of Cu/Mn ions doped-PB and MoS₂. The porous donut structure of CMPB-MoS₂-PEG endows them as a carrier for delivery of doxorubicin hydrochloride (DOX) to tumor site. The framework of Nano-donut specifically decomposes in TME due to the reaction between Fe²⁺/Fe³⁺ and H₂O₂. The multivalent elements (Cu/Fe/Mn ions) decrease the bandgap and then enhance CDT by synergistically catalyzing H₂O₂ into toxic ·OH. Meanwhile, the Mn⁴⁺ also reacts with H₂O₂ to generate O₂, improving the hypoxia of TME and enhancing the chemotherapy effect of released DOX. The MoS₂ mingles in the PB, which significantly enhances photothermal conversion efficiency (η) effect of PB from 16.02% to 38.0%. In addition, Fe³⁺ as T2-weighted MR imaging agent can achieve MR imaging-guided therapy. The data clearly shows Nano-donut/DOX nanocomposites (NCs) have a remarkable inhibition for cancer cells and excellent biological safety in tumor treatment.

Exogenous Contrast Agents in Photoacoustic Imaging: An In Vivo Review for Tumor Imaging

The field of cancer theranostics has grown rapidly in the past decade and innovative 'biosmart' theranostic materials are being synthesized and studied to combat the fast growth of cancer metastases. While current state-of-the-art oncology imaging techniques have decreased mortality rates, patients still face a diminished quality of life due to treatment. Therefore, improved diagnostics are needed to define in vivo tumor growths on a molecular level to achieve image-guided therapies and tailored dosage needs. This review summarizes in vivo studies that utilize contrast agents within the field of photoacoustic imaging-a relatively new imaging modality-for tumor detection, with a special focus on imaging and transducer parameters. This paper also details the different types of contrast agents used in this novel diagnostic field, i.e., organic-based, metal/inorganic-based, and dye-based contrast agents. We conclude this review by discussing the challenges and future direction of photoacoustic imaging.

All-in-One Nanomedicine: Multifunctional Single-Component Nanoparticles for Cancer Theranostics

The development of cancer diagnostic imaging and treatment is a major concern worldwide. By integrating imaging and therapy into one theranostic nanoplatform for simultaneously detecting tumors, evaluating the targeting ability and timely monitoring therapeutic responses provide more opportunities for precision medicine. Among various theranostic nanosystems, a series of single-component nanoparticles (NPs) have been developed for "all-in-one" theranostics, which presents the unique properties of facile preparation, simple composition, defined structure, high reproducibility, and excellent biocompatibility. Specifically, utilizing single-component NPs for both diagnostics and therapeutics can reduce the possible numerous untoward side effects and risks to the living body. In this review, the recent progress of multifunctional single-component NPs in the applications of cancer theranostics is systematically summarized. Notably, the structure design, categories of NPs, targeted strategies, biomedical applications, potential barriers, challenges, and prospects for the future clinical practice of this rapidly growing field are discussed.

Non-thermal atmospheric pressure plasma as a powerful tool for the synthesis of rhenium-based nanostructures for the catalytic hydrogenation of 4-nitrophenol

Here we have presented a new method for the synthesis of Re nanostructures with defined optical, structural, and catalytic properties. The Re-based nanoparticles (NPs) were obtained using a reaction-discharge system that is unique in its class, because of its working in the high-throughput mode. Within this application, direct current atmospheric pressure glow discharge (dc-APGD) was used as a non-thermal atmospheric pressure plasma (NTAP) source, which led to the reduction of Re(vii) ions and the formation of Re nanostructures through the plasma-liquid interactions. The Re-based NPs were synthesized in a flow-mode reaction-discharge system, where their precursor solution was a flowing liquid anode (FLA) or a flowing liquid cathode (FLC). The resultant NPs were analyzed using UV/Vis absorption spectrophotometry and transmission electron microscopy (TEM), which were supported by selected area X-ray diffraction (SAED) and the energy dispersive X-ray spectroscopy (EDX). Additionally, the mechanism for the reduction of Re(vii) ions was explained by the differences in the concentrations of the selected reactive nitrogen species (RNS) and reactive oxygen species (ROS) produced by dc-APGD. It was found that the application of dc-APGD, operating in a FLA configuration (FLA-dc-APGD), resulted in the formation of ReNPs with Re0, while the use of dc-APGD operating in a FLC configuration (FLC-dc-APGD) led to the formation of Re oxide NPs. In the latter case, a much greater oxidizing environment was likely provided, therefore the RNS and ROS contributed to the formation of Re oxide nanostructures. The ReNPs with Re0 were characterized by a size of 6.02 ± 3.01 nm, and the Re oxide NPs were characterized by a size of 4.97 ± 3.82 nm. Both types of nanostructures were then employed in the catalytic hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Based on the results, both of the nanocatalysts effectively reduced 4-NP with an apparent rate constant (k app) of 2.6 × 10-3 s-1. At the same time, the catalytic activity was linked with the average size distribution of the Re nanostructures, as opposed to their morphology.

Rhenium Nanostructures Loaded into Amino-Functionalized Resin as a Nanocomposite Catalyst for Hydrogenation of 4-Nitrophenol and 4-Nitroaniline

The present work presents a new nanocomposite catalyst with rhenium nanostructures (ReNSs) for the catalytic hydrogenation of 4-nitrophenol and 4-nitroaniline. The catalyst, based on an anion exchange resin with functionality derived from 1,1'-carboimidazole, was obtained in the process involving anion exchange of ReO4- ions followed by their reduction with NaBH4. The amino functionality present in the resin played a primary role in the stabilization of the resultant ReNSs, consisting of ≈1% (w/w) Re in the polymer mass. The synthesized and capped ReNSs were amorphous and had the average size of 3.45 ± 1.85 nm. Then, the obtained catalyst was used in a catalytic reduction of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA). Following the pseudo-first-order kinetics, 5 mg of the catalyst led to a 90% conversion of 4-NP with the mass-normalized rate constant (km1) of 6.94 × 10-3 min-1 mg-1, while the corresponding value acquired for 4-NA was 7.2 × 10-3 min-1 mg-1, despite the trace amount of Re in the heterogenous catalyst. The obtained material was also conveniently reused.

PEGylated Indium Nanoparticles: A Metallic Contrast Agent for Multiwavelength Photoacoustic Imaging and Second Near-Infrared Photothermal Therapy

Indium, a low melting point metal, is well-known for constructing eutectic gallium-indium liquid metal. However, unlike liquid metal nanoparticles, the biomedical applications of metallic indium nanoparticles (In NPs) remain in their infancy. Herein, an ultrasound-assisted liquid-reduction synthesis strategy was developed to prepare PEGylated In NPs, which were then used as a high-performance contrast agent for enhancing multiwavelength photoacoustic imaging and second near-infrared (NIR-II) photothermal therapy of the 4T1 breast tumor. The obtained In NPs depicted remarkable optical absorption from the first near-infrared (NIR-I) to NIR-II region and a high photothermal conversion efficiency of 41.3% at 1064 nm, higher than the majority of conventional NIR-II photothermal agents. Upon injection into the tumor, the photoacoustic intensities of the tumor section post-injection were obviously increased by 2.59-, 2.62-, and 4.27-fold of those of pre-injection by using excitation wavelengths of 750, 808, and 970 nm, respectively, depicting an excellent multiwavelength contrast capability of photoacoustic imaging. In addition, efficient ablation of the 4T1 tumor was achieved through the photothermal performance of PEGylated In NPs under NIR-II laser irradiation. Importantly, as the widely used element in the clinic, In NPs were highly biocompatible in vitro and in vivo. Therefore, this work pioneered the biomedical applications of PEGylated In NPs for cancer diagnosis and treatment.

Inorganic nanomaterials with rapid clearance for biomedical applications

Inorganic nanomaterials that have inherently exceptional physicochemical properties (e.g., catalytic, optical, thermal, electrical, or magnetic performance) that can provide desirable functionality (e.g., drug delivery, diagnostics, imaging, or therapy) have considerable potential for application in the field of biomedicine. However, toxicity can be caused by the long-term, non-specific accumulation of these inorganic nanomaterials in healthy tissues, preventing their large-scale clinical utilization. Over the past several decades, the emergence of biodegradable and clearable inorganic nanomaterials has offered the potential to prevent such long-term toxicity. In addition, a comprehensive understanding of the design of such nanomaterials and their metabolic pathways within the body is essential for enabling the expansion of theranostic applications for various diseases and advancing clinical trials. Thus, it is of critical importance to develop biodegradable and clearable inorganic nanomaterials for biomedical applications. This review systematically summarizes the recent progress of biodegradable and clearable inorganic nanomaterials, particularly for application in cancer theranostics and other disease therapies. The future prospects and opportunities in this rapidly growing biomedical field are also discussed. We believe that this timely and comprehensive review will stimulate and guide additional in-depth studies in the area of inorganic nanomedicine, as rapid in vivo clearance and degradation is likely to be a prerequisite for the future clinical translation of inorganic nanomaterials with unique properties and functionality.

Intelligent Fe-Mn Layered Double Hydroxides Nanosheets Anchored with Upconversion Nanoparticles for Oxygen-Elevated Synergetic Therapy and Bioimaging

Multimodal synergistic therapy based on photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) has attracted increasing attention in cancer therapy. However, the scant therapeutic efficiency is always a barrier for further application. Herein, a smart tumor microenvironment (TME) responsive nanocatalysts are developed by adopting Fe-Mn layered double hydroxides (FeMn-LDH) as an effective photothermal nanocarrier to load mesoporous silica and chlorin e6 (Ce6)-covalently coated upconversion nanoparticles (UCSP) for multimodal imaging for directed therapy. Under acidic TME, FeMn-LDH degrades into Fe³⁺ and Mn²⁺ ions to initiate a Fenton-like reaction inducing CDT and enhancing magnetic resonance imaging. Additionally, Fe³⁺ can decompose H₂ O₂ to oxygen (O₂ ), enhancing PDT guided by UCSP. As a representative noninvasive imaging probe, the upconversion luminescence will recover after decomposition of FeMn-LDH, and provide high-resolution upconversion luminescent imaging guidance for pinpointed PDT. Moreover, the photothermal properties of FeMn-LDH can further enhance CDT effects. The synergistic therapy and multifunctional imaging can realize the integration of diagnosis and treatment.

Defect-engineered transition metal hydroxide nanosheets realizing tumor-microenvironment-responsive multimodal-imaging-guided NIR-II photothermal therapy

Exploiting two-dimensional nanomaterials as photo-based theranostic agents is promising for the highly efficient ablation of deep-tissue-buried tumors. However, they are limited by their poor absorption in the second near-infrared-light (NIR-II) bio-window (1000-1300 nm) and intrinsic nonbiodegradability. Herein, defect-rich sulfur-doped Ni(OH)2 (S-Ni(OH)2) nanosheets decorated with bovine serum albumin (BSA) as a novel theranostic agent is developed, which can accomplish multimodal-imaging-guided photothermal ablation of mouse cancers in the NIR-II bio-window. Sulfur doping extends the absorption spectra of Ni(OH)2 nanosheets from the visible to NIR-II bio-window, affording highly efficient photothermal conversion (58.20% for 1064 nm), entailing it to become an excellent contrast agent for photoacoustic imaging. Further, because of their intrinsic paramagnetic property, they can be applied for magnetic resonance imaging. Owing to the abundant defective sites in S-Ni(OH)2 nanosheets, they exhibit response to the tumor microenvironment, resulting in effective biodegradation and excretion from the body. In vivo toxicity experiments indicated that S-Ni(OH)2-BSA NSs delivered no appreciable toxicity and good biocompatibility. This work provides an avenue for the rational design of effective theranostics agents.

High-efficiency and safe sulfur-doped iron oxides for magnetic resonance imaging-guided photothermal/magnetic hyperthermia therapy

Heat therapy is a promising therapeutic modality for cancer treatment due to the minimum adverse effects of selective local hyperthermia; however, the low heating efficiency of heat therapy under safe conditions is an issue for its bioapplication. Here, we report the synthesis of water-dispersible sulfur doped iron oxides (SDIOs) with different phase structures and the exploration of the relationships between the different SDIOs and their induction heating capacities as a guideline to obtain a photo-magnetic hyperthermia agent. The agent exhibits good biocompatibility, excellent photothermal conversion efficiency (55.8%) and great T₂ weighted magnetic resonance imaging (63.7 mM^-1 s^-1). Significantly, the SDIOs effectively eliminate tumours in a biologically safe AC magnetic field range (H·f = 4.3 < 5.0 × 10⁶ kA m^-1 s^-1) and with 808 nm laser irradiation at a safe density of 0.33 W cm^-2; also, they can be mostly metabolized from the body after one month. The work presented here adopts anion-doped iron oxides to dramatically improve photo-magnetic hyperthermia effects and may enable further exploration in thermotherapeutic research.

Rod-based urchin-like hollow microspheres of Bi2S3: Facile synthesis, photo-controlled drug release for photoacoustic imaging and chemo-photothermal therapy of tumor ablation

Hollow nanostructures have been evoked considerable attention owing to their intriguing hollow interior for important and potential applications in drug delivery, lithium battery, catalysis and etc. Herein, Bi₂S₃ hollow microspheres with rod-based urchin-like nanostructures (denoted as U-BSHM) were synthesized through a facile and rapid ion exchanging method using a particular hard template. The growth mechanism of the U-BSHM has been investigated and illustrated by the morphological evolution of the different samples at early stages. The obtained U-BSHM exhibited strong and wide UV-vis-NIR absorption ability and outstanding photothermal conversion efficiency. Thus, the U-BSHM can be used as spatio-temporal precisely controlled carrier by loading the mixture of 1-tetradecanol (phase change material, PCM) with melting point around 38 °C and hydrophilic chemotherapeutic doxorubicin hydrochloride (denoted as DOX) into the hollow interior to form (PCM + DOX)@Bi₂S₃ nanocomposites (denoted as PD@BS) for photoacoustic (PA) imaging and chemo-photothermal therapy of the tumors. When exposed to 808 nm near infrared light (NIR) laser irradiation, this nanocomposites could elevate the temperature of the surroundings by absorption and conversion of the NIR photons into heat energy, which inducing the triggered release of DOX from the hollow interior once the temperature reach up to the melting point of PCM. The killing efficiency of the chemo-photothermal therapy was systematically validated both in vitro and in vivo. In the meanwhile, the implanted tumor was completely restrained through PA imaging and combined therapies. Therefore, this kind of urchin-like hollow nanostructures would be used as important candidates for the multimodal bioimaging and therapy of tumors.

A full-spectrum-absorption from nickel sulphide nanoparticles for efficient NIR-II window photothermal therapy

Near-infrared (NIR) light has been widely applied in the field of photothermal therapy (PTT). Recent advances in the light wavelength for efficient cancer PTT have gradually shifted from the first NIR (NIR-I) biowindow (700-1000 nm) to the second NIR (NIR-II) biowindow (1000-1350 nm) owing to its intrinsic deeper tissue penetration ability and a higher maximum permissible exposure (MPE) value. Herein, we have prepared nickel sulphide (Ni₉S₈) nanoparticles (NPs) with a full-spectrum-absorption (400 nm-1100 nm) in the NIR region. By a fair comparison, it is found that the PTT using the NPs upon irradiation from an NIR-II (i.e., 1064 nm) laser is more efficient than that from an NIR-I (i.e., 808, 915, and 976 nm) laser. The large mass extinction coefficient value (22.18 L g^-1 cm^-1) and high photothermal conversion efficiency (46%) at 1064 nm make these NPs promising candidates for NIR-II photo-thermal therapy. This study will benefit future exploration and optimization of nickel-based photoabsorbers utilizing NIR-II light for photothermal applications.

Janus Ag/Ag2S beads as efficient photothermal agents for the eradication of inflammation and artery stenosis

Janus heterostructural materials as photothermal agents with enhanced optical conversion capability are promising for artery inflammation treatment by the hyperthermia of macrophages, a primordial part in the artery inflammation response that can deteriorate into atherosclerosis and even break the vessels. Herein, a synthesis route of Janus Ag/Ag₂S beads with hydrophilic ligands has been developed with a precise control over concentration, time and surface functionalization. These Ag/Ag₂S heterodimers show desirable sizes of around 90 nm in diameter, in which Ag nanocrystals have a diameter of around 25 nm, and they exhibit a photothermal conversion efficiency of up to 50.0% as well as relatively low biotoxicity and good biocompatibility. Importantly, the as-prepared Janus Ag/Ag₂S beads with a high biological safety can be effectively swallowed by macrophages and have a remarkable benefit of eliminating these cells from the original state of artery inflammation through the excellent photothermal effect of this material, without causing any further damage to the arteries and major organs in vivo. This study further promotes the development of treatment for vascular inflammation by the photothermal melting of macrophage cells in intima environments.

Construction of Urokinase-Type Plasminogen Activator Receptor-Targeted Heterostructures for Efficient Photothermal Chemotherapy against Cervical Cancer To Achieve Simultaneous Anticancer and Antiangiogenesis

Rational design and construction of theranostic nanomedicines based on clinical characteristics of cervical cancer is an important strategy to achieve precise cancer therapy. Herein, we fabricate a cervical cancer-targeting gold nanorod-mesoporous silica heterostructure for codelivery of synergistic cisplatin and antiangiogenic drug Avastin (cisplatin-AuNRs@SiO₂-Avastin@PEI/AE105) to achieve synergistic chemophotothermal therapy. Based on database analysis and clinical sample staining, conjugation of the AE105-targeting peptide obviously improves the intracellular uptake of the nanosystem and enhances the cancer-killing ability and selectivity between cervical cancer and normal cells. It could also be used to specifically monitor the urokinase-type plasminogen activator receptor (uPAR) expression level in clinical cervical specimens, which would be an early indicator of prognosis in cancer treatment. Under 808 nm laser irradiation, the nanosystem demonstrates smart NIR-light-triggered drug release and prominent photodynamic activity via induction of reactive oxygen species overproduction-mediated cell apoptosis. The nanosystem also simultaneously suppresses HeLa tumor growth and angiogenesis in vivo, with no evident histological damage observed in the major organs. In short, this study not only provides a clinical data-based rational design strategy of smart nanomedicine for precise treatment and rapid clinical diagnosis of cervical cancer but also contributes to the development of the clinical translation of nanomedicines.

Fluorescent Silicon Nanorods-Based Nanotheranostic Agents for Multimodal Imaging-Guided Photothermal Therapy

The utilization of diagnosis to guide/aid therapy procedures has shown great prospects in the era of personalized medicine along with the recognition of tumor heterogeneity and complexity. Herein, a kind of multifunctional silicon-based nanostructure, i.e., gold nanoparticles-decorated fluorescent silicon nanorods (Au@SiNRs), is fabricated and exploited for tumor-targeted multimodal imaging-guided photothermal therapy. In particular, the prepared Au@SiNRs feature high photothermal conversion efficiency (~ 43.9%) and strong photothermal stability (photothermal performance stays constant after five-cycle NIR laser irradiation), making them high-performance agents for simultaneously photoacoustic and infrared thermal imaging. The Au@SiNRs are readily modified with targeting peptide ligands, enabling an enhanced tumor accumulation with a high value of ~ 8.74% ID g-1. Taking advantages of these unique merits, the Au@SiNRs are superbly suitable for specifically ablating tumors in vivo without appreciable toxicity under the guidance of multimodal imaging. Typically, all the mice treated with the Au@SiNRs remain alive, and no distinct tumor recurrence is observed during 60-day investigation.

Nanostructured hexagonal ReO3 with oxygen vacancies for efficient electrocatalytic hydrogen generation

We report oxygen vacancies (OVs) rich hexagonal ReO₃ nanostructured electrocatalysts for efficient hydrogen generation. Through a simple argon plasma exposure, OVs are introduced into the ReO₃ nanoparticles (NP) and nanosheets to enhance electrocatalytic activities with decreasing overpotentails from 157 mV and 178 mV to 138 mV and 145 mV at the current density of 10 mA cm^-2, respectively. As-processed OVs rich ReO₃ NP exhibit a good stability during electrochemical measurements for 20 h in acidic electrolyte. The huge active surface area, abundant OVs and excellent conductivity contribute to the performance according to the experimental data. Further theoretical calculations show that the abundant OVs adsorb H with lower Gibbs free energy facilitating hydrogen evolution.

Double Switch Biodegradable Porous Hollow Trinickel Monophosphide Nanospheres for Multimodal Imaging Guided Photothermal Therapy

Due to the limitation of inorganic nanomaterials in present clinical applications induced by their inherent nonbiodegradability and latent long-term side effects, we successfully prepared double switch degradable and clearable trinickel monophosphide porous hollow nanospheres (NiP PHNPs) modified with bovine serum albumin (BSA). Attributed to their acidic and oxidative double switch degradation capacities, NiP PHNPs can be effectively excreted from mice without long-term toxicity. Moreover, because of the paramagnetic and high molar extinction coefficient property resulting from the strong absorption in the second near-infrared light (NIR II) biowindow, NiP PHNPs have potential to be used for photoacoustic imaging (PAI) and T₁-weighted magnetic resonance imaging (MRI) guided photothermal ablation of tumors in the NIR II biowindow. Specifically, it is interesting that the hollow structure and acidic degradation property enable NiP PHNPs to act as intelligent drug carriers with an on-demand release ability. These findings highlight the great potential of NiP PHNPs in the cancer theranostics field and inspire us to further broaden the bioapplications of transition metal phosphides.

New Strategy for Specific Eradication of Implant-Related Infections Based on Special and Selective Degradability of Rhenium Trioxide Nanocubes

The greatest bottleneck for photothermal antibacterial therapy could be the difficulty in heating the infection site directly and specifically to evade the unwanted damage for surrounding healthy tissues. In recent years, infectious microenvironments (IMEs) have been increasingly recognized as a crucial contributor to bacterial infections. Here, based on the unique IMEs and rhenium trioxide (ReO₃) nanocubes (NCs), a new specific photothermal antibacterial strategy is reported. These NCs synthesized by a rapid and straightforward space-confined on-substrate approach have good biocompatibility and exhibit efficient photothermal antibacterial ability. Especially when they are utilized in antibiofilm, the expression levels of biofilm-related genes (icaA, fnbA, atlE, and sarA for Staphylococcus aureus) can be effectively inhibited to block bacterial adhesion and formation of biofilm. Importantly, the ReO₃ NCs can transform into hydrogen rhenium bronze (H_xReO₃) in an aqueous environment, making them relatively stable within the low pH of IMEs for photothermal therapy, while rapidly degradable within the surrounding healthy tissues to decrease photothermal damage. Note that under phosphate-buffered saline (PBS) at pH 7.4 without assistant conditions, these ReO₃ NCs have the highest degradation rate among all known degradable inorganic photothermal nanoagents. This special and IME-sensitive selective degradability of the ReO₃ NCs not only facilitates safe, efficient, and specific elimination of implant-related infections, but also enables effective body clearance after therapy. Solely containing the element (Re) whose atomic number is higher than clinic-applied iodine in all reported degradable inorganic photothermal nanoagents under the PBS (pH 7.4) without any assistant condition, the ReO₃ NCs with high X-ray attenuation ability could be further applied to X-ray computed tomography imaging-guided therapy against implant-related infections. The present work described here is the first to adopt degradable inorganic photothermal nanoagents to achieve specific antibacterial therapy and inspires other therapies on this concept.

A Review of The Lesser-Studied Microemulsion-Based Synthesis Methodologies Used for Preparing Nanoparticle Systems of The Noble Metals, Os, Re, Ir and Rh

This review focuses on the recent advances in the lesser-studied microemulsion synthesis methodologies of the following noble metal colloid systems (i.e., Os, Re, Ir, and Rh) using either a normal or reverse micelle templating system. The aim is to demonstrate the utility and potential of using this microemulsion-based approach to synthesize these noble metal nanoparticle systems. Firstly, some fundamentals and important factors of the microemulsion synthesis methodology are introduced. Afterward, a review of the investigations on the microemulsion syntheses of Os, Re, Ir, and Rh nanoparticle (NP) systems (in all forms, viz., metallic, oxide, mixed-metal, and discrete molecular complexes) is presented for work published in the last ten years. The chosen noble metals are traditionally very reactive in nanosized dimensions and have a strong tendency to aggregate when prepared via other methods. Also, the particle size and particle size distribution of these colloids can have a significant impact on their catalytic performance. It is shown that the microemulsion approach has the capability to better stabilize these metal colloids and can control the size of the synthesized NPs. This generally leads to smaller particles and higher catalytic activity when they are tested in applications.

PEGylated rhenium nanoclusters: a degradable metal photothermal nanoagent for cancer therapy

A common issue of functional nanoagents for potential clinical translation is whether they are biodegradable or renal clearable. Previous studies have widely explored noble metal nanoparticles (Au and Pd) as the first generation of photothermal nanoagents for cancer therapy, but all of the reported noble metal nanoparticles are non-degradable. On the other hand, rhenium (Re), one of the noble and precious metals with a high atomic number (Z = 75), has been mainly utilized as a jet superalloy or chemical catalyst, but the biological characteristics and activity of Re nanoparticles have never been evaluated until now. To address these issues, here we report a simple and scalable liquid-reduction strategy to synthesize PEGylated Re nanoclusters, which exhibit intrinsically high photothermal conversion efficacy (33.0%) and high X-ray attenuation (21.2 HU mL mg-1), resulting in excellent photothermal ablation (100% tumor elimination) and higher CT enhancement (15.9 HU mL mg-1 for commercial iopromide in clinics). Impressively, biocompatible Re nanoclusters can degrade into renal clearable ReO4 - ions after exposure to H2O2, and thus achieve much higher renal clearance efficiency than conventional gold nanoparticles. This work reveals the potential of theranostic application of metallic Re nanoclusters with both biodegradation and renal clearance properties and provides insights into the design of degradable metallic platforms with high clinical prospects.

"Transformed" Fe3S4 tetragonal nanosheets: a high-efficiency and body-clearable agent for magnetic resonance imaging guided photothermal and chemodynamic synergistic therapy

To retain the agents in tumors for cancer diagnosis and therapy, and then to remove them from the body, are key for the clinical applications of ideal inorganic theranostic agents. To meet these needs, we have developed a transformed theranostic platform, employing PVP coated Fe3S4 tetragonal nanosheets (TNSs), which could effectively accumulate in the tumor under magnetic targeting, whilst gradually transforming to small particles (∼5 nm) over three weeks. These were then effectively excreted from the body in normal physiological conditions after exerting their therapeutic effect. The aqueous dispersion of PVP coated Fe3S4 TNSs had an intense near-infrared absorption, excellent photothermal conversion efficiency (64.3%) and great T2 weighted magnetic resonance imaging properties (71.3 mM-1 S-1). In addition, Fe3S4 TNSs could realize a synergistic photothermal therapy (PTT)/chemodynamic therapy (CDT), because the localized heat produced by PTT from the defect-rich structure could enhance the Fenton process by utilizing the overproduced H2O2 in the tumor microenvironment, and in return, the produced ˙OH could inhibit tumor growth and recurrence after PPT. We thus developed a high-efficiency inorganic theranostic platform which was effectively cleared from the body. This will open up a new avenue for the design of inorganic agents for clinical applications in the future.

An easy-to-fabricate clearable CuS-superstructure-based multifunctional theranostic platform for efficient imaging guided chemo-photothermal therapy

Despite drug delivery systems (DDSs) receiving ever-increasing attention, development of a simple, effective, sensitive and clearable drug delivery and multifunctional theranostic nanoplatform for cancer therapy is still highly desirable and remains a challenge. Herein, using a one-step solvothermal method, hollow acanthosphere-like CuS superstructures assembled from ∼10 nm nanoparticles (NPs) were successfully obtained and used as an efficient drug delivery and theranostic platform for photoacoustic (PA) and infrared (IR) thermal imaging-guided cancer combination therapy. The special hollow characteristic of CuS superstructures with mesoporous shells and large cavities grants them high drug loading capacity; they demonstrate near-infrared (NIR)/pH stimuli-sensitive drug release and pronounced synergetic effects of chemo-photothermal therapy both in vitro and in vivo. In particular, our as-fabricated hollow loose CuS superstructures, with easily breakable characteristic, are biodegradable and able to be cleared from the body when their therapy task is completed. This CuS-superstructure-based clearable drug delivery and "all-in-one" cancer theranostic platform might provide possibilities for improving therapeutic efficacy and minimizing adverse effects.

Bacteria-like mesoporous silica-coated gold nanorods for positron emission tomography and photoacoustic imaging-guided chemo-photothermal combined therapy

Mesoporous silica nanoshell (MSN) coating has been demonstrated as a versatile surface modification strategy for various kinds of inorganic functional nanoparticles, such as gold nanorods (GNRs), to achieve not only improved nanoparticle stability but also concomitant drug loading capability. However, limited drug loading capacity and low tumor accumulation rate in vivo are two major challenges for the biomedical applications of MSN-coated GNRs (GNR@MSN). In this study, by coating uniformly sized GNRs with MSN in an oil-water biphase reaction system, we have successfully synthesized a new bacteria-like GNR@MSN (i.e., bGNR@MSN) with a significantly enlarged pore size (4-8 nm) and surface area (470 m²/g). After PEGylation and highly efficient loading of doxorubicin (DOX, 40.9%, w/w), bGNR@MSN were used for positron emission tomography (PET, via facile and chelator-free ⁸⁹Zr-labeling) and photoacoustic imaging-guided chemo-photothermal cancer therapy in vivo. PET imaging showed that ⁸⁹Zr-labeled bGNR@MSN(DOX)-PEG can passively target to the 4T1 murine breast cancer-bearing mice with high efficiency (∼10 %ID/g), based on enhanced permeability and retention effect. Significantly enhanced chemo-photothermal combination therapy was also achieved due to excellent photothermal effect and near-infrared-light-triggered drug release by bGNR@MSN(DOX)-PEG at the tumor site. The promising results indicate great potential of bGNR@MSN-PEG nanoplatforms for future cancer diagnosis and therapy.