A Porous Bimetallic Au@Pt Core-Shell Oxygen Generator to Enhance Hypoxia-Dampened Tumor Chemotherapy Synergized with NIR-II Photothermal Therapy

NIR-triggered arsenic-loaded layered double hydroxide-based films for localized thermal synergistic chemotherapy

Portal vein tumor thrombus (PVTT) formed by cancer cell invasion is a major cause of high mortality in hepatocellular carcinoma (HCC), and the formation of thrombus will be accelerated by bacterial colonization on the surface of the implant after surgery. In this work, Polypyrrole-coated arsenic-loaded layered double hydroxide films were in situ constructed on the nickel-titanium alloy for the efficient killing of tumour cells by thermo-therapeutic synergistic chemotherapy. The good near-infrared photothermal conversion ability of polypyrrole enables the sample surface temperature to be raised to about 51 °C at a low photothermal power (0.5 w/cm2), while the elevated temperature could further accelerate the release of drug arsenic. In addition, when NIR light is not applied, the polypyrrole coating also cleverly acts as a "barrier layer" to reduce the natural release of arsenic in normal tissues to avoid toxicity issues. In vivo and in vitro experiments have demonstrated that the platform exhibits excellent antitumor and antibacterial abilities. In contrast to the systemic toxicity issues associated with systemic circulation of nanotherapeutic drugs, this in situ functional film is expected to be used in localised interventions for precise drug delivery, and is also more suitable for surgical treatment scenarios in PVTT surgeries.

In Situ Oxygen Generation via a Platinum-Based Wireless Nanopore Electrode for Single-Cell Manipulation

Oxygen production within human cells plays a critical role in cellular metabolism and is implicated in various diseases, including cancer. Investigating cellular heterogeneity under oxygen stimulation is crucial for elucidating disease mechanisms and advancing early therapeutic design. In this study, the platinum-based wireless nanopore electrode (WNE) with a diameter of ≈200 nm is employed as a powerful tool to produce oxygen molecules near the cell nucleus. The oxygen production can be quantitatively controlled by adjusting the applied voltage. Through delivering oxygen near the cancer cell nucleus, this technique shows the capacity to alleviate the hypoxia microenvironment, a key factor in chemotherapy resistance. Furthermore, by modulating oxygen levels within individual living cells and delivering chemotherapeutic agents to the cancer cell nucleus, this approach offers significant potential for single-cell manipulation and the investigation of cellular heterogeneity under oxygen stimulation.

Dual-activity nanozyme as an oxygen pump to alleviate tumor hypoxia and enhance photodynamic/ NIR-II photothermal therapy for sniping oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the head and neck region, and its treatment is limited by hypoxia and inadequate oxygen supply. Continuous oxygen delivery combined with photodynamic therapy (PDT) is the key to addressing this issue. Here, a dual-enzyme activity sea urchin-like Au@Pt-Ce6-HN-1 nanoplatform was designed to serve as an "oxygen pump" to alleviate tumor hypoxia for synergistic photodynamic/photothermal therapy (PTT). In this design, the photosensitizer chlorin e6 (Ce6) is covalently linked to the Au@Pt nanozyme for PDT treatment. The Au@Pt nanozyme exhibits catalase-like activity, continuously decomposing H2O2 in the tumor microenvironment to enhance O2 levels, thereby achieving efficient PDT. Furthermore, Au@Pt can perform PTT and increase oxygen levels under NIR-II light to further promote PDT. The Au@Pt nanozyme also exhibits peroxidase-like activity, generating ·OH for chemodynamic therapy (CDT). Additionally, HN-1 guides the direction of "sniping" OSCC, and its high specificity benefits Au@Pt-Ce6-HN-1 at the tumor site. Au@Pt-Ce6-HN-1 exhibits bright fluorescence (FL), strong CT signal, and photothermal imaging capabilities, laying the foundation for subsequent guided PDT/PTT. This nanoplatform, which combines advantages such as continuous oxygen production, tumor targeting, and multimodal imaging, is expected to provide valuable insights into the treatment of OSCC. STATEMENT OF SIGNIFICANCE: Accurate clinical diagnosis and treatment of OSCC are challenging. We report a dual-enzyme activity sea urchin-like Au@Pt-Ce6-HN-1 nanoplatform, serving as an "oxygen pump" to guide photodynamic therapy (PDT) and photothermal therapy (PTT) for OSCC. This nanoplatform targets OSCC for preoperative CT diagnosis and offers fluorescence visualization for surgical navigation, demonstrating potential in clinical cancer detection and surgery guidance. This innovative approach addresses OSCC hypoxia and enhances treatment efficacy through continuous oxygen production, tumor targeting, and multimodal imaging, significantly improving patient outcomes in OSCC treatment.

Biotemplated Platinum Nanozymes: Synthesis, Catalytic Regulation and Biomedical Applications

Platinum (Pt) nanozymes with multiple intrinsic enzyme-mimicking activities have attracted extensive attention in biomedical fields due to their high catalytic activity, ease of modification, and convenient storage. However, the Pt nanozymes synthesized by the traditional method often suffer from uncontrollable morphology and poor stability under physicochemical conditions, resulting in unsatisfactory catalytic behavior in practical applications. To optimize the catalytic ability, biological templates have been introduced recently, which can guide the deposition of platinum ions on their surface to form specific morphologies and then stabilize the resulting Pt nanozymes. Given the promising potential of biotemplated Pt nanozymes in practical applications, it is essential to conduct a systematic and comprehensive review to summarize their recent research progress. In this review, we first categorize the biological templates and discuss the mechanisms as well as characteristics of each type of biotemplate in directing the growth of Pt nanozyme. Factors that impact the growth of biotemplated Pt nanozymes are then analyzed, followed by summarizing their biomedical applications. Finally, the challenges and opportunities in this field are outlined. This review article aims to provide theoretical guidance for developing Pt nanozymes with robust functionalities in biomedical applications.

Targeted Delivery of Quinoxaline-Based Semiconducting Polymers for Tumor Photothermal Therapy

Photothermal therapy (PTT) holds great potential in the field of cancer treatment due to its high specificity and low invasiveness. However, the low conversion efficiency, inadequate tumor accumulation, and limited cellular uptake continue to impede PTT effectiveness in treating tumors. The present study focuses on the utilization of quinoxaline and its nanoparticles to develop an organic semiconducting photothermal agent (PAQI-BDTT) for tumor photothermal therapy. To achieve this, PAQI-BDTT was encapsulated within liposomes modified with cyclic Arg-Gly-Asp (cRGD) peptide targeting tumors (named T-BDTT-Lipo). Notably, T-BDTT-Lipo demonstrated a positive photothermal conversion efficiency of 74% when exposed to an 808 nm laser, along with NIR-II fluorescence imaging capabilities. The efficacy of T-BDTT-Lipo in tumor tissue accumulation and precise targeting of malignant cells has been confirmed through both in vitro and in vivo experiments guided by fluorescence imaging. Under single dose and 808 nm light irradiation, T-BDTT-Lipo generated local intracellular hyperthermia at the tumor site. The elevated temperature additionally exerted a significant inhibitory effect on tumor growth and recurrence, thereby extending the survival duration of mice harboring tumors. The therapeutic nanosystem (T-BDTT-Lipo) proposed in this work demonstrates the enormous potential of semiconducting photothermal agents in photothermal therapy, laying the foundation for the next clinical application.

Homology-Activated Ultrasensitive Nanomedicines for Precise NIR-II FL/MRI Imaging-Guided "Knock-On" Dynamic Therapy in Rheumatoid Arthritis

Stimuli-responsive nanomedicines represent a pivotal technology for in situ on-demand drug release and offer multiple advantages over conventional drug delivery systems to combat rheumatoid arthritis(RA). However, the lack of sensitivity to a single-stimuli source or the inability to synchronize multi-stimuli responses can easily lead to challenges in achieving precise-theranostics of RA. Herein, a homology-activated ultrasensitive nanomedicines MnO2-CQ4T-GOx(MCG NMs) is designed for NIR-II fluorescence(NIR-II FL)/magnetic resonance imaging(MRI)-guided effective "knock-on" dynamic anti-RA therapy. Building upon the characteristics of the RA-microenvironment, the MCG innovatively construct a MnO2-Mn2+ system, which can normalized activation sites. The ultrasensitive-responsive degradation is achieved using the multi-stimuli processes in the RA-microenvironment, triggering release of functional small molecules. The produced Mn2+ can exert Fenton-like activity to generate •OH from H2O2, thus providing the effective chemodynamic therapy(CDT). Moreover, the up-regulation of H2O2 by GOx-catalysis not only sensitizes the MnO2-Mn2+ system but also achieves self-enhancing CDT efficacy. The NIR-II FL quenching of CQ4T-BSA in the aggregated state occurs in MCG NMs, which can be rapidly and precisely "turn-on" via the MnO2-Mn2+ system. Meanwhile, the integration of activated Mn2+-based MRI imaging has successfully developed an activatable dual-modal imaging. Feedback imaging-guided precise photodynamic therapy of CQ4T-BSA can achieve efficient "knock-on" dynamic therapy for RA.

Engineering a hyaluronic acid-encapsulated tumor-targeted nanoplatform with sensitized chemotherapy and a photothermal effect for enhancing tumor therapy

Chemotherapy remains one of the most widely used cancer treatment modalities in clinical practice. However, the characteristic microenvironment of solid tumors severely limits the anticancer efficacy of chemotherapy. In addition, a single treatment modality or one death pathway reduces the antitumor outcome. Herein, tumor-targeting O2 self-supplied nanomodules (CuS@DOX/CaO2-HA) are proposed that not only alleviate tumor microenvironmental hypoxia to promote the accumulation of chemotherapeutic drugs in tumors but also exert photothermal effects to boost drug release, penetration and combination therapy. CuS@DOX/CaO2-HA consists of copper sulfide (CuS)-loaded calcium peroxide (CaO2) and doxorubicin (DOX), and its surface is further modified with HA. CuS@DOX/CaO2-HA underwent photothermal treatment to release DOX and CaO2. Hyperthermia accelerates drug penetration to enhance chemotherapeutic efficacy. The exposed CaO2 reacts with water to produce Ca2+, H2O2 and O2, which sensitizes cells to chemotherapy through mitochondrial damage caused by calcium overload and a reduction in drug efflux via the alleviation of hypoxia. Moreover, under near infrared (NIR) irradiation, CuS@DOX/CaO2-HA initiates a pyroptosis-like cell death process in addition to apoptosis. In vivo, CuS@DOX/CaO2-HA demonstrated high-performance antitumor effects. This study provides a new strategy for synergistic enhancement of chemotherapy in hypoxic tumor therapy via combination therapy and multiple death pathways.

Dumbbell-shaped bimetallic AuPd nanoenzymes for NIR-II cascade catalysis-photothermal synergistic therapy

The noble metal NPs that are currently applied to photothermal therapy (PTT) have their photoexcitation location mainly in the NIR-I range, and the low tissue penetration limits their therapeutic effect. The complexity of the tumor microenvironment (TME) makes it difficult to inhibit tumor growth completely with a single therapy. Although TME has a high level of H2O2, the intratumor H2O2 content is still insufficient to catalyze the generation of sufficient hydroxide radicals (‧OH) to achieve satisfactory therapeutic effects. The AuPd-GOx-HA (APGH) was obtained from AuPd bimetallic nanodumbbells modified by glucose oxidase (GOx) and hyaluronic acid (HA) for photothermal enhancement of tumor starvation and cascade catalytic therapy in the NIR-II region. The CAT-like activity of AuPd alleviates tumor hypoxia by catalyzing the decomposition of H2O2 into O2. The GOx-mediated intratumoral glucose oxidation on the one hand can block the supply of energy and nutrients essential for tumor growth, leading to tumor starvation. On the other hand, the generated H2O2 can continuously supply local O2, which also exacerbates glucose depletion. The peroxidase-like activity of bimetallic AuPd can catalyze the production of toxic ‧OH radicals from H2O2, enabling cascade catalytic therapy. In addition, the high photothermal conversion efficiency (η = 50.7 %) of APGH nanosystems offers the possibility of photothermal imaging-guided photothermal therapy. The results of cell and animal experiments verified that APGH has good biosafety, tumor targeting, and anticancer effects, and is a precious metal nanotherapeutic system integrating glucose starvation therapy, nano enzyme cascade catalytic therapy, and PTT therapy. This study provides a strategy for photothermal-cascade catalytic synergistic therapy combining both exogenous and endogenous processes. STATEMENT OF SIGNIFICANCE: AuPd-GOx-HA cascade nanoenzymes were prepared as a potent cascade catalytic therapeutic agent, which enhanced glucose depletion, exacerbated tumor starvation and promoted cancer cell apoptosis by increasing ROS production through APGH-like POD activity. The designed system has promising photothermal conversion ability in the NIR-II region, simultaneously realizing photothermal-enhanced catalysis, PTT, and catalysis/PTT synergistic therapy both in vitro and in vivo. The present work provides an approach for designing and developing catalytic-photothermal therapies based on bimetallic nanoenzymatic cascades.

Biodegradable hollow mesoporous bimetallic nanoreactors to boost chemodynamic therapy

As an endogenous catalytic treatment, chemodynamic therapy (CDT) was attracting considerable attention, but the weak catalytic efficiency of Fenton agents and the non-degradation of nanocarriers severely limited its development. In this work, a biodegradable bimetallic nanoreactor was developed for boosting CDT, in which Fe-doped hollow mesoporous manganese dioxide (HMnO2) was selected as nanocarrier, and the Fe/HMnO2@DOX-GOD@HA nanoprobe was constructed by loading doxorubicin (DOX) and modifying glucose oxidase (GOD) and hyaluronic acid (HA). The glutathione (GSH) responsive degradation of HMnO2 promoted the release of DOX, by which the release rate significantly increased to 96.6%. Moreover, by the GSH depletion, the reduction of Mn2+/Fe2+ achieved strong bimetallic Fenton efficiency, and the hydroxyl radicals (·OH) generation was further enhanced using the self-supplying H2O2 of GOD. Through the active targeting recognition of HA, the bimetallic nanoreactor significantly enriched the tumor accumulation, by which the enhanced antitumor efficacy was realized. Thus, this work developed biodegradable bimetallic nanoreactor by consuming GSH and self-supplying H2O2, and provided a new paradigm for enhancing CDT.

Thermoresponsive injectable self-healing hydrogel containing polydopamine-coated Fe/Mo-doped TiO2 nanoparticles for efficient synergistic sonodynamic-chemodynamic-photothermal-chemo therapy

A smart hydrogel loading multifunctional nanoparticles and anticancer drugs was designed to achieve synergistic therapy against tumors with high efficiency and specificity. The thermoresponsive injectable self-healing hydrogel was prepared through the Schiff base between aldehyde-functionalized poly(2-(2-methoxyethoxy) ethyl methacrylate)-co-oligo(ethylene glycol) methacrylate-co-2-hydroxyethyl methacrylate) (P(MEO2MA-co-OEGMA-co-HEMA), APMOH) and hydroxypropyl chitosan (HPCS). The polydopamine-coated Fe/Mo-doped titanium dioxide nanoparticles (PDA@dTiO2 NPs) were prepared and dispersed into the hydrogel with anticancer drug doxorubicin (DOX). PDA@dTiO2 NPs as sonosensitizers can convert oxygen into singlet oxygen (1O2) under ultrasound (US) irradiation, achieving sonodynamic therapy (SDT). They were also considered nanoenzymes, generating oxygen to supply an oxygen source for SDT, producing hydroxyl radical (·OH) to achieve chemodynamic therapy (CDT), and eliminating glutathione (GSH) to enhance the level of oxidative stress. After near-infrared (NIR) irradiation, the temperature of the hydrogel increased due to the photothermal ability of the polydopamine (PDA) layer. When the temperature reached the hydrogel's lower critical solution temperature (LCST), the hydrophilic-hydrophobic transformation occurred, and the hydrogel volume contracted. Consequently, the release rate of PDA@dTiO2 NPs and DOX increased, improving the therapeutic effects. The nanocomposite hydrogel system can achieve synergistic sonodynamic-chemodynamic-photothermal-chemo therapy (SDT-CDT-PTT-CT) for tumors, providing a novel platform for synergistic tumor treatment.

Nanodelivery Systems as a Novel Strategy to Overcome Treatment Failure of Cancer

Despite the tremendous progress in cancer treatment in recent decades, cancers often become resistant due to multiple mechanisms, such as intrinsic or acquired multidrug resistance, which leads to unsatisfactory treatment effects or accompanying metastasis and recurrence, ultimately to treatment failure. With a deeper understanding of the molecular mechanisms of tumors, researchers have realized that treatment designs targeting tumor resistance mechanisms would be a promising strategy to break the therapeutic deadlock. Nanodelivery systems have excellent physicochemical properties, including highly efficient tissue-specific delivery, substantial specific surface area, and controllable surface chemistry, which endow nanodelivery systems with capabilities such as precise targeting, deep penetration, responsive drug release, multidrug codelivery, and multimodal synergy, which are currently widely used in biomedical researches and bring a new dawn for overcoming cancer resistance. Based on the mechanisms of tumor therapeutic resistance, this review summarizes the research progress of nanodelivery systems for overcoming tumor resistance to improve therapeutic efficacy in recent years and offers prospects and challenges of the application of nanodelivery systems for overcoming cancer resistance.

Multifunctional AuPt Nanoparticles for Synergistic Photothermal and Radiation Therapy

Background

Photothermal therapy (PTT) has gained considerable interest as an emerging modality for cancer treatment in recent years. Radiation therapy (RT) has been widely used in the clinic as a traditional treatment method. However, RT and PTT treatments are limited by side effects and penetration depth, respectively. In addition, hypoxia within the tumor can lead to increased resistance to treatment.

Methods

We synthesized multiple sizes of AuPt by modulating the reaction conditions. The smallest size of AuPt was selected and modified with folic acid (FA) for PTT and RT synergy therapy. Various methods including transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FITR) are used to determine the structure and composition of AuPt-FA (AF). In addition, we researched the photothermal properties of AF with IR cameras and infrared lasers. Flow cytometry, colony formation assays, CCK8, and fluorescent staining for probing the treatment effect in vitro. Also, we explored the targeting of AF by TEM and In Vivo Imaging Systems (IVIS). In vivo experiments, we record changes in tumor volume and weight as well as staining of tumor sections (ROS, Ki67, and hematoxylin and eosin).

Results

The AuPt with particle size of 16 nm endows it with remarkably high photothermal conversion efficiency (46.84%) and catalase activity compared to other sizes of AuPt (30 nm and 100 nm). AF alleviates hypoxia in the tumor microenvironment, leading to the production of more reactive oxygen species (ROS) during the treatment. In addition, the therapeutic effect was significantly enhanced by combining RT and PTT, with an apoptosis rate of 81.1% in vitro and an in vivo tumor volume reduction rate of 94.0% in vivo.

Conclusion

These results demonstrate that AF potentiates the synergistic effect of PTT and RT and has the potential for clinical translation.

Liposome-Templated Green Synthesis of Mesoporous Metal Nanostructures with Universal Composition for Biomedical Application

Porous noble metal nanoparticles have received particular attention recently for their unique optical, thermal, and catalytic functions in biomedicine. However, limited progress has been made to synthesize such porous metallic nanostructures with large mesopores (≥25 nm). Here, a green yet facile synthesis strategy using biocompatible liposomes as templates to mediate the formation of mesoporous metallic nanostructures in a controllable fashion is reported. Various monodispersed nanostructures with well-defined mesoporous shape and large mesopores (≈ 40 nm) are successfully synthesized from mono- (Au, Pd, and Pt), bi- (AuPd, AuPt, AuRh, PtRh, and PdPt), and tri-noble metals (AuPdRh, AuPtRh, and AuPdPt). Along with a successful demonstration of its effectiveness in synthesis of various mesoporous nanostructures, the possible mechanism of liposome-guided formation of such nanostructures via time sectioning of the synthesis process (monitoring time-resolved growth of mesoporous structures) and computational quantum molecular modeling (analyzing chemical interaction energy between metallic cations and liposomes at the enthalpy level) is also revealed. These mesoporous metallic nanostructures exhibit a strong photothermal effect in the near-infrared region, effective catalytic activities in hydrogen peroxide decomposition reaction, and high drug loading capacity. Thus, the liposome-templated method provides an inspiring and robust avenue to synthesize mesoporous noble metal-based nanostructures for versatile biomedical applications.

DNA-Templated Ag@Pd Nanoclusters for NIR-II Photoacoustic Imaging-Guided Photothermal-Augmented Nanocatalytic Therapy

Developing multifunctional nanozymes with photothermal-augmented enzyme-like reaction dynamics in the second near-infrared (NIR-II) biowindow is of significance for nanocatalytic therapy (NCT). Herein, DNA-templated Ag@Pd alloy nanoclusters (DNA-Ag@Pd NCs) are prepared as a kind of novel noble-metal alloy nanozymes by using cytosine-rich hairpin-shaped DNA structures as growth templates. DNA-Ag@Pd NCs exhibit high photothermal conversion efficiency (59.32%) under 1270 nm laser and photothermally augmented peroxidase-mimicking activity with synergetic enhancement between Ag and Pd. In addition, hairpin-shaped DNA structures on the surface of DNA-Ag@Pd NCs endow them with good stability and biocompatibility in vitro and in vivo, and enhanced permeability and retention effect at tumor sites. Upon intravenous injection, DNA-Ag@Pd NCs demonstrate high-contrast NIR-II photoacoustic imaging-guided efficient photothermal-augmented NCT of gastric cancer. This work provides a strategy to synthesize versatile noble-metal alloy nanozymes in a bioinspired way for highly efficient therapy of tumors.

Preventing the Galvanic Replacement Reaction toward Unconventional Bimetallic Core-Shell Nanostructures

A bimetallic core-shell nanostructure is a versatile platform for achieving intriguing optical and catalytic properties. For a long time, this core-shell nanostructure has been limited to ones with noble metal cores. Otherwise, a galvanic replacement reaction easily occurs, leading to hollow nanostructures or completely disintegrated ones. In the past few years, great efforts have been devoted to preventing the galvanic replacement reaction, thus creating an unconventional class of core-shell nanostructures, each containing a less-stable-metal core and a noble metal shell. These new nanostructures have been demonstrated to show unique optical and catalytic properties. In this work, we first briefly summarize the strategies for synthesizing this type of unconventional core-shell nanostructures, such as the delicately designed thermodynamic control and kinetic control methods. Then, we discuss the effects of the core-shell nanostructure on the stabilization of the core nanocrystals and the emerging optical and catalytic properties. The use of the nanostructure for creating hollow/porous nanostructures is also discussed. At the end of this review, we discuss the remaining challenges associated with this unique core-shell nanostructure and provide our perspectives on the future development of the field.

Cu-doped polypyrrole hydrogel with tumor catalyst activity for NIR-II thermo-radiotherapy

Introduction: Radiotherapy (RT) is one of the key methods for treating breast cancer. However, the effect of single RT is often poor because of insufficient deposition of X-rays in tumor sites and radiation resistance induced by the abnormal tumor microenvironment (overexpression of glutathione (GSH)). The development of multifunctional RT sensitizers and synergetic therapeutic strategies is, therefore, a promising area for enhancing the anticancer effect of RT. Methods: In this study, a multifunctional nanozyme hydrogel based on Cu-doped polypyrrole (CuP) was designed to work concertedly with a second near-infrared thermal RT. The CuP-based hydrogel (CH) reached the tumor site when injected in-situ and achieved long-term storage. Results: Once stimulated with 1064-nm laser irradiation, the heated and softened hydrogel system released CuP nanozyme to provide photothermal therapy, thereby inhibiting the repair of DNA damage caused by RT. In addition, CuP with dual nanozyme activity depleted the intracellular GSH to reduce the antioxidant capacity of the tumor. Moreover, CuP converted H₂O₂ to produce ·OH to directly kill the tumor cells, thus enhancing the capability of low-dose RT to inhibit tumor growth. In vivo experiments showed that the CH system used in combination with a low-power 1064-nm laser and low-dose RT (4 Gy) exhibited good synergistic anticancer effects and biological safety. Discussion: As a new light-responsive hydrogel system, CH holds immense potential for radio-sensitization.

A three-in-one hybrid nanozyme for sensitive colorimetric biosensing of pathogens

Pathogen screening is an important step in preventing foodborne diseases. In this study, a hybrid nanozyme, metal organic framework decorated with palladium (Pd) and platinum (Pt) (MIL-88@Pd/Pt), was innovatively synthesized and used with immune magnetic nanobeads (MNBs) for sensitive biosensing of Salmonella. First, immune MIL-88@Pd/Pt nanozymes and immune MNBs were mixed with target pathogens in a large-volume sample, resulting in effective isolation and specific label of target pathogens to form nanobead-Salmonella-nanozyme conjugates. Then, these conjugates were used to catalyze H₂O₂-TMB, and its color was changed from colorless to blue. Finally, catalysate absorption was measured to determine pathogen concentration. This colorimetric immunoassay could determine Salmonella typhimurium from 4 × 10¹ to 4 × 10⁵ CFU/mL in 60 min with a detection limit of 32 CFU/mL.

Nanomaterials for photothermal cancer therapy

Cancer has emerged as a pressing global public health issue, and improving the effectiveness of cancer treatment remains one of the foremost challenges of modern medicine. The primary clinical methods of treating cancer, including surgery, chemotherapy and radiotherapy, inevitably result in some adverse effects on the body. However, the advent of photothermal therapy offers an alternative route for cancer treatment. Photothermal therapy relies on photothermal agents with photothermal conversion capability to eliminate tumors at high temperatures, which offers advantages of high precision and low toxicity. As nanomaterials increasingly play a pivotal role in tumor prevention and treatment, nanomaterial-based photothermal therapy has gained significant attention owing to its superior photothermal properties and tumor-killing abilities. In this review, we briefly summarize and introduce the applications of common organic photothermal conversion materials (e.g., cyanine-based nanomaterials, porphyrin-based nanomaterials, polymer-based nanomaterials, etc.) and inorganic photothermal conversion materials (e.g., noble metal nanomaterials, carbon-based nanomaterials, etc.) in tumor photothermal therapy in recent years. Finally, the problems of photothermal nanomaterials in antitumour therapy applications are discussed. It is believed that nanomaterial-based photothermal therapy will have good application prospects in tumor treatment in the future.

Second Near-Infrared Plasmonic Nanomaterials for Photoacoustic Imaging and Photothermal Therapy

Photoacoustic imaging (PAI) and imaging-guided photothermal therapy (PTT) in the second near-infrared window (NIR-II, 1000-1700 nm) have received increasing attention owing to their advantages of greater penetration depth and higher signal-to-noise ratio. Plasmonic nanomaterials with tunable optical properties and strong light absorption provide an alternative to dye molecules, showing great prospects for phototheranostic applications. In this review, the research progress in principally modulating the optical properties of plasmonic nanomaterials, especially affecting parameters such as size, morphology, and surface chemical modification, is introduced. The commonly used plasmonic nanomaterials in the NIR-II window, including noble metals, semiconductors, and heterostructures, are then summarized. In addition, the biomedical applications of these NIR-II plasmonic nanomaterials for PAI and PTT in phototheranostics are highlighted. Finally, the perspectives and challenges for advancing plasmonic nanomaterials for practical use and clinical translation are discussed.

Dual Nanozyme-Driven PtSn Bimetallic Nanoclusters for Metal-Enhanced Tumor Photothermal and Catalytic Therapy

Specific generation of reactive oxygen species (ROS) within tumors in situ catalyzed by nanozymes is a promising strategy for cancer therapeutics. However, it remains a significant challenge to fabricate highly efficient nanozymes acting in the tumor microenvironment. Herein, we develop a bimetallic nanozyme (Pt₅₀Sn₅₀) with the photothermal enhancement of dual enzymatic activities for tumor catalytic therapy. The structures and activities of PtSn bimetallic nanoclusters (BNCs) with different Sn content are explored and evaluated systematically. Experimental comparisons show that the Pt₅₀Sn₅₀ BNCs exhibit the highest activities among all those investigated, including enzymatic activity and photothermal property, due to the generation of SnO_2-x with oxygen vacancy (O_vac) sites on the surface of Pt₅₀Sn₅₀ BNCs. Specifically, the Pt₅₀Sn₅₀ BNCs exhibit photothermal-enhanced peroxidase-like and catalase-like activities, as well as a significantly enhanced anticancer efficacy in both multicellular tumor spheroids and in vivo experiments. Due to the high X-ray attenuation coefficient and excellent light absorption property, the Pt₅₀Sn₅₀ BNCs also show dual-mode imaging capacity of computed tomography and photoacoustic imaging, which could achieve in vivo real-time monitoring of the therapeutic process. Therefore, this work will advance the development of noble-metal nanozymes with optimal composition for efficient tumor catalytic therapy.

Hypoxic microenvironment in cancer: molecular mechanisms and therapeutic interventions

Having a hypoxic microenvironment is a common and salient feature of most solid tumors. Hypoxia has a profound effect on the biological behavior and malignant phenotype of cancer cells, mediates the effects of cancer chemotherapy, radiotherapy, and immunotherapy through complex mechanisms, and is closely associated with poor prognosis in various cancer patients. Accumulating studies have demonstrated that through normalization of the tumor vasculature, nanoparticle carriers and biocarriers can effectively increase the oxygen concentration in the tumor microenvironment, improve drug delivery and the efficacy of radiotherapy. They also increase infiltration of innate and adaptive anti-tumor immune cells to enhance the efficacy of immunotherapy. Furthermore, drugs targeting key genes associated with hypoxia, including hypoxia tracers, hypoxia-activated prodrugs, and drugs targeting hypoxia-inducible factors and downstream targets, can be used for visualization and quantitative analysis of tumor hypoxia and antitumor activity. However, the relationship between hypoxia and cancer is an area of research that requires further exploration. Here, we investigated the potential factors in the development of hypoxia in cancer, changes in signaling pathways that occur in cancer cells to adapt to hypoxic environments, the mechanisms of hypoxia-induced cancer immune tolerance, chemotherapeutic tolerance, and enhanced radiation tolerance, as well as the insights and applications of hypoxia in cancer therapy.

A Phase-Change Mediated Intelligent Nanoplatform for Chemo/Photothermal/Photodynamic Therapy of Cancer

Up to now, chemotherapy is still the main strategy for cancer treatment. However, the emergence of chemo-resistance and systemic side effects often seriously affects the treatment and prognosis. Herein, an intelligent nanoplatform based on dendritic mesoporous organosilica nanoparticles (DMON) is constructed. The encapsulated phase-change material, 1-tetradecanol (TD) can serve as a "doorkeeper" and enable the responsive release of drugs based on the temperature changes. Meanwhile, polyethylene glycol (PEG) is used to improve the dispersibility and biocompatibility. Cisplatin is chosen as the model of chemotherapy drug, which is co-loaded with indocyanine green (ICG) in DMON to produce DMON-PEG-cisplatin/ICG-TD (DPCIT). Exciting, the hyperthermia and reactive oxygen species induced by ICG under the NIR-laser irradiation will initiate a phase transition of TD to release cisplatin, thus leading a combined therapy (chemo/photothermal/photodynamic therapy). The results indicated that under laser irradiation, DPCIT can kill cancer cells and inhibit tumor growth efficiently. In addition, the designed nanoplatform reveals minimal systemic toxicity in vivo, in contrast, the distinct liver damage can be observed by the direct treatment of cisplatin. Overall, this research may provide a general approach for the targeted delivery and controlled release of chemotherapy drugs to realize a cooperatively enhanced multimodal tumor therapy.

Efficient improvement in chemo/photothermal synergistic therapy against lung cancer using Bi@Au nano-acanthospheres

Novel highly hydrophilic and biocompatible bismuth nanospheres with gold nanoparticles growing outside (Bi@Au nano-acanthospheres, Bi@Au NASs) were synthesized through a simple procedure, which demonstrated to be a promising photothermal agent owing to the ultrahigh photothermal conversion efficiency (η = 46.6 %). The as-prepared Bi@Au NASs showed excellent blood compatibility and fairly low cytotoxicity to human lung cancer A549 cells, as well as efficient photothermal ablation (PTA) therapy induced by a near-infrared laser. Under the 808 nm laser radiation, the tumour temperature could be elevated by ∼25 °C high enough to kill the cancer cells. Moreover, the anticancer drug doxorubicin hydrochloride (DOX) was successfully loaded in Bi@Au NASs with a loading content as high as 16.78 % and released under a pH sensitive release profile, a characteristic beneficial for intravenous delivery of DOX into cancer cells for chemotherapy. The presence of the Bi element enabled Bi@Au NASs to act as a favourable computed tomography (CT) contrast medium for CT imaging-guided tumour treatment. Compared with cancer treatment through either photothermal therapy or chemotherapy, the chemo-photothermal synergistic therapy using Bi@Au NASs as both a photothermal agent and a drug carrier has efficiently enhanced the in vitro and in vivo therapeutic effects in cancer treatment.

Synergistically Enhancing Tumor Chemotherapy Using an Aggregation-Induced Emission Photosensitizer on Covalently Conjugated Molecularly Imprinted Polymer Nanoparticles

Due to the polygenic and heterogeneous nature of the tumorigenesis process, traditional chemotherapy is far from desirable. Fabricating multifunctional nanoplatforms integrating photodynamic effect can synergistically enhance chemotherapy because they can make the cancer cells much sensitive to chemotherapeutics. However, how to assemble different units in nanoplatforms and minimize side effects caused by chemodrugs and photosensitizers (PSs) still needs to be explored. Herein, a nanoplatform CPP/PS-MIP@DOX is developed using a simultaneously covalently conjugated new aggregation-induced emission (AIE) PS and a cell-penetrating peptide (CPP) on the surface of silica-based molecularly imprinted polymer (MIP) nanoparticles, prepared with doxorubicin (DOX) as the template in the water system via a sol-gel technique. CPP/PS-MIP@DOX has good biocompatibility, high DOX-loading ability, promoted cellular uptake, and sustained and pH-sensitive drug release capability. Furthermore, it can efficiently penetrate into tumor tissue, accurately home to, and accumulate at the tumor site. As a result, a better efficacy with lower cytotoxicity is achieved with a smaller dosage of DOX by utilizing either the photodynamic effect or unique characteristics of the MIP. It is the first nanoplatform fabricated by chemically conjugating AIE PSs directly on the surface of the scaffold via the surface-decorated strategy and successfully applied in cancer therapy. This work provides an effective strategy by constructing AIE PS-based cancer nanomedicines with MIPs as scaffolds.

Enhanced Immunogenic Cell Death by Apoptosis/Ferroptosis Hybrid Pathway Potentiates PD-L1 Blockade Cancer Immunotherapy

Even though chemotherapy regimens for treating cancer by inducing apoptosis are extensively utilized, their therapeutic effect is hindered by multiple limitations. Thus, a combination of other types of anticancer modalities is urgently needed. Herein, a tannic acid (TA)-Fe³⁺-coated doxorubicin (DOX)-encapsulated 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000] (ammonium salt) (DSPE-PEG) micelle (TFDD) for apoptosis/ferroptosis-mediated immunogenic cell death (ICD) is reported. By coating TA-Fe³⁺ on the surface of DOX-loaded micelles, an apoptotic agent and a ferroptotic agent are simultaneously delivered into the cancer cells and induce cell death. Furthermore, the intracellular oxidative environment generated by the apoptosis/ferroptosis hybrid pathway stimulates the endoplasmic reticulum (ER) and leads to ICD induction. The in vivo results show that the combination treatment of TFDD and anti-programmed death-ligand 1 antibodies (anti-PD-L1) considerably inhibits tumor growth and improves antitumor immunity by activating CD4⁺ and CD8⁺ T cells and decreasing the ratio of regulatory T cells (Treg) to CD4⁺ T cells. This study suggests that the apoptosis/ferroptosis-mediated ICD inducer may offer a potent strategy for enhanced cancer immunotherapy.

Bimetallic Nanomaterials: A Promising Nanoplatform for Multimodal Cancer Therapy

Bimetallic nanomaterials (BMNs) composed of two different metal elements have certain mixing patterns and geometric structures, and they often have superior properties than monometallic nanomaterials. Bimetallic-based nanomaterials have been widely investigated and extensively used in many biomedical fields especially cancer therapy because of their unique morphology and structure, special physicochemical properties, excellent biocompatibility, and synergistic effect. However, most reviews focused on the application of BMNs in cancer diagnoses (sensing, and imaging) and rarely mentioned the application of the treatment of cancer. The purpose of this review is to provide a comprehensive perspective on the recent progress of BNMs as therapeutic agents. We first introduce and discuss the synthesis methods, intrinsic properties (size, morphology, and structure), and optical and catalytic properties relevant to cancer therapy. Then, we highlight the application of BMNs in cancer therapy (e.g., drug/gene delivery, radiotherapy, photothermal therapy, photodynamic therapy, enzyme-mediated tumor therapy, and multifunctional synergistic therapy). Finally, we put forward insights for the forthcoming in order to make more comprehensive use of BMNs and improve the medical system of cancer treatment.