Near-Infrared Upconversion Mesoporous Cerium Oxide Hollow Biophotocatalyst for Concurrent pH-/H2 O2 -Responsive O2 -Evolving Synergetic Cancer Therapy

Lanthanide-Activated Nanoparticles: A Toolbox for Bioimaging, Therapeutics, and Neuromodulation

Owing to their unique features, the past decade has witnessed rapid developments of lanthanide-activated nanoparticles for biological applications. These include highly tunable upconverting and downshifting photoluminescence when illuminated in deep tissue, excellent photostability against blinking and bleaching effects, biocompatibility through versatile surface modification, and ease of achieving multifunctionality, as well as satisfactory signal output. These attributes make lanthanide-doped nanoparticles an ideal toolbox for advanced bioimaging and next-generation therapeutics.The interest in lanthanide-doped nanoparticles for biomedical research arises from their unique optical properties in response to deep-tissue-penetrable light sources. Upon near-infrared irradiation, these nanoparticles with properly doped emitters display photon upconversion with large anti-Stokes shifts and broad-spectrum tunability from the ultraviolet to the visible. It is also possible to achieve orthogonal photoluminescence with variations in wavelength and lifetime. Coupled with surface ligands, dyes, biomolecules, or other types of functional nanomaterials, lanthanide-doped nanoparticles offer new opportunities for applications in bioimaging, advanced oncotherapy, and neuromodulation. Given the possibility of locating downshifting luminescence at "biological transmission windows", exquisite design of lanthanide-doped nanoparticles also enables deep-tissue imaging with high spatial resolution. In addition, these nanoparticles can respond to high-energy photons, such as X-rays, to trigger nonradioactive and radiative pathways, making it possible to develop high-sensitivity X-ray detectors. Precise control of paramagnetic lanthanide ions in nanocrystal lattices also provides advanced materials for high-performance magnetic resonance imaging in medical diagnostics and biomedical research. Full consideration of fundamental attributes of lanthanide-doped nanoparticles will facilitate the design of multifunctional and sensitive probes and improve diagnostic and therapeutic outcomes.In this Account, we categorize various lanthanide-activation strategies into three modes: near-infrared excitation, X-ray irradiation, and magnetic field stimulation. We introduce energy manipulations in upconverting, downshifting, and persistence luminescence in spectral and time domains and discuss how they can be applied in biological practices. We assess general design principles for lanthanide-activated nanosystems with multiple modalities of bioimaging, oncotherapy, and neuromodulation. We also review the current state-of-the-art in the field of lanthanide-based theranostic nanoplatforms, with particular emphasis on energy conversion and nano-/biointerfacing as well as emerging bioapplications. In this context, we also highlight recent advances in controlling optical properties of nanoplatforms for single- or multimodal bioimaging, stimulus-responsive phototherapy, and optogenetics. Finally, we discuss future opportunities and challenges of this exciting research field.

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.

Water-Splitting Based and Related Therapeutic Effects: Evolving Concepts, Progress, and Perspectives

Water-splitting has been extensively studied especially for energy applications. It is often not paid with enough attention for biomedical applications. In fact, several innovative breakthroughs have been achieved in the past few years by employing water-splitting for treating cancer and other diseases. Interestingly, among these important works, only two reports have mentioned the term "water-splitting." For this reason, the importance of water-splitting for biomedical applications is significantly underestimated. This progress work is written with the aims to explain and summarize how the principle of water-splitting is employed to achieve therapeutic results not offered by conventional approaches. It is expected that this progress report will not only explain the importance of water-splitting to scientists in the biomedical fields, it should also draw attention from scientists working on energy applications of water-splitting.

Carbon Monoxide Controllable Targeted Gas Therapy for Synergistic Anti-inflammation

Carbon monoxide (CO) plays an important role in the regulation of a variety of physiological processes and thus is regarded as a promising pharmaceutical agent. Nevertheless, therapeutic applications of CO are severely hampered by the difficulty of the delivery of controlled amounts of CO to biological targets. To address this deficiency, we present a spatiotemporally controllable CO-releasing platform (designated as Neu-MnO2/Fla) for synergistic anti-inflammation. With the assistance of neutrophil membrane coating, Neu-MnO2/Fla can target to inflammatory sites. Subsequently, excess H2O2 at the inflamed tissues can be decomposed into oxygen because of MnO2 as nanozymes possessing catalase (CAT) activity, which not only relieves oxidative stress but also achieves in situ rapid photo-induced CO release. The in vitro and in vivo results indicate our CO-releasing platform exhibits a strong synergistic anti-inflammatory effect. Our work will shed light on targeted CO release to avoid side effects of therapeutic applications of CO.

Construction of a chiral artificial enzyme used for enantioselective catalysis in live cells

Nanozymes as a newcomer in the artificial enzyme family have shown several advantages over natural enzymes such as their high stability in harsh environments, facile production on large scale, long storage time, low costs, and higher resistance to biodegradation. However, compared with natural enzymes, it is still a great challenge to design a nanozyme with high selectivity, especially high enantioselectivity. It is highly desirable and demanding to develop chiral nanozymes with high and on-demand enantioselectivity for practical applications. Herein, we present an unprecedented approach to construct chiral artificial peroxidase with ultrahigh enantioselectivity. Inspired by the structure of the natural enzyme horseradish peroxidase (HRP), we have constructed a series of stereoselective nanozymes (Fe3O4@Poly(AA)) by using the ferromagnetic nanoparticle (Fe3O4 NP) yolk as the catalytic core and amino acid-appended chiral polymer shell as the chiral selector. Among them, Fe3O4@Poly(d-Trp) exhibits the highest enantioselectivity. More intriguingly, their enantioselectivity will be readily reversed by replacing d-Trp with l-Trp. The selectivity factor is up to 5.38, even higher than that of HRP. Kinetic parameters, dialysis experiments, and molecular simulations together with activation energy reveal that the selectivity originates from the d-/l-Trp appended polymer shell, which can result in better affinity and catalytic activity to d-/l-tyrosinol. The artificial peroxidases have been used for asymmetric catalysis to prepare enantiopure d- or l-enantiomers. Besides, by using fluorescent labelled FITC-tyrosinolL and RhB-tyrosinolD, the artificial peroxidases can catalyze green or red fluorescent chiral tyrosinol to selectively label live yeast cells among yeast, S. aureus, E. coli and B. subtilis bacterial cells. This work opens a new avenue for better design of stereoselective artificial enzymes.

Colorimetric Detection of Salicylic Acid in Aspirin Using MIL-53(Fe) Nanozyme

The impurity of salicylic acid (SA) in aspirin is a required inspection item for drug quality control. Since free SA is significantly toxic for humans, the content determination of free SA is absolutely necessary to ensure people's health. In this work, a facile colorimetric method was developed for the detection of SA in aspirin by utilizing the MIL-53(Fe) nanozyme. As MIL-53(Fe) possesses enzyme mimicking catalytic activity, 3,3,5,5-tetramethylbenzidine (TMB) can be easily oxidized to blue-oxidized TMB (oxTMB) with the existence of H2O2. Moreover, an inhibition effect on the catalytic activity of the MIL-53(Fe) nanozyme is induced due to the specific complexation between SA and Fe3+ in the center of MIL-53(Fe), which results in a lighter color in the oxTMB. The color change of oxTMB can be seen easily by the naked eye with the addition of different concentrations of SA. Thus, a simple colorimetric platform was established for effectively monitoring SA. A good linear relationship (R 2 = 0.9990) was obtained in the concentration range of 0.4-28 μmol L-1, and the detection limit was 0.26 μmol L-1. In particular, the rationally designed system has been well-applied to the detection of SA impurity in aspirin. Satisfyingly, the detection results are highly in accord with those of HPLC. This novel colorimetric platform broadens the application prospects of nanozymes in the field of pharmaceutical analysis.

Near-Infrared Upconversion Mesoporous Tin Oxide Bio-Photocatalyst for H2O2-Activatable O2-Generating Magnetic Targeting Synergetic Treatment

Tumor hypoxia compromises the therapeutic efficacy of oxygen (O₂)-dependent treatment methods as the endogenous O₂ levels have an important influence on the production of reaction oxygen species. Herein, a synergistic multifunctional mesoporous Fe@Sn-UCNPs bio-photocatalytic nanoplatform is provided to comprehensively realize endogenous hydrogen peroxide (H₂O₂)-activatable, self-supplied O₂, photothermal performance, and near-infrared-mediated magnetic targeting PDT/PTT simultaneously for relieving tumor hypoxia. Such a nanoplatform is constructed by encapsulating magnetic Fe₃O₄ with lanthanide-ion-doped mesoporous tin oxide upconversion nanoparticles and further modified with phosphorylated serine and poly(ethylene glycol) for enhancing the biocompatibility and solubility. The nanoparticles can be activated by endogenous H₂O₂ and in situ generated O₂ to relieve hypoxia through catalytic reaction. Therefore, H₂O₂-responsive/O₂-evolving nanoparticles can elevate the O₂ level in the tumor site for an apparently enhanced PDT effect in vitro and in vivo. What is more, Fe@Sn-UCNPs demonstrate enhanced photothermal conversion efficiency based on the special nanostructure and much more circuit loops for electron transitions between Fe₃O₄ and Sn-UCNPs, and the electronic structure of Fe@Sn-UCNPs was calculated. In addition, such Fe@Sn-UCNPs also exhibit multimodality imaging performance (including photothermal, magnetic resonance, and computed tomography imaging) for monitoring and tracking the in vivo tumor therapeutic process. This work provides novel insight into the smart Fe@Sn-UCNPs as an "all-in-one" theranostic nanosystem for cancer therapy.

Polyaniline Nanovesicles for Photoacoustic Imaging-Guided Photothermal-Chemo Synergistic Therapy in the Second Near-Infrared Window

Photoacoustic imaging-guided photothermal therapy in the second near-infrared (NIR-II) window shows promise for clinical deep-penetrating tumor phototheranostics. However, ideal photothermal agents in the NIR-II window are still rare. Here, the emeraldine salt of polyaniline (PANI-ES), especially synthesized by a one-pot enzymatic reaction on sodium bis(2-ethylhexyl) sulfosuccinate (AOT) vesicle surface (PANI-ES@AOT, λ_max  ≈ 1000 nm), exhibits excellent dispersion in physiological environment and remarkable photothermal ability at pH 6.5 (photothermal conversion efficiency of 43.9%). As a consequence of the enhanced permeability and retention effect of tumors and the doping-induced photothermal effect of PANI-ES@AOT, this pH-sensitive NIR-II photothermal agent allows tumor acidity phototheranostics with minimized pseudosignal readout and subdued normal tissue damage. Moreover, the enhanced fluidity of vesicle membrane triggered by heating is beneficial for drug release and allows precise synergistic therapy for an improved therapeutic effect. This study highlights the potential of template-oriented (or interface-confined) enzymatic polymerization reactions for the construction of conjugated polymers with desired biomedical applications.

All-in-One Theranostic Nanomedicine with Ultrabright Second Near-Infrared Emission for Tumor-Modulated Bioimaging and Chemodynamic/Photodynamic Therapy

Reactive oxygen species (ROS)-based therapeutic modalities including chemodynamic therapy (CDT) and photodynamic therapy (PDT) hold great promise for conquering malignant tumors. However, these two methods tend to be restricted by the overexpressed glutathione (GSH) and hypoxia in the tumor microenvironment (TME). Here, we develop biodegradable copper/manganese silicate nanosphere (CMSN)-coated lanthanide-doped nanoparticles (LDNPs) for trimodal imaging-guided CDT/PDT synergistic therapy. The tridoped Yb³⁺/Er³⁺/Tm³⁺ in the ultrasmall core and the optimal Yb³⁺/Ce³⁺ doping in the shell enable the ultrabright dual-mode upconversion (UC) and downconversion (DC) emissions of LDNPs under near-infrared (NIR) laser excitation. The luminescence in the second near-infrared (NIR-II, 1000-1700 nm) window offers deep-tissue penetration, high spatial resolution, and reduced autofluorescence when used for optical imaging. Significantly, the CMSNs are capable of relieving the hypoxic TME through decomposing H₂O₂ to produce O₂, which can react with the sample to generate ¹O₂ upon excitation of UC photons (PDT). The GSH-triggered degradation of CMSNs results in the release of Fenton-like Mn²⁺ and Cu⁺ ions for ^•OH generation (CDT); simultaneously, the released Mn²⁺ ions couple with NIR-II luminescence imaging, computed tomography (CT) imaging, and magnetic resonance (MR) imaging of LDNPs, performing a TME-amplified trimodal effect. In such a nanomedicine, the TME modulation, bimetallic silicate photosensitizer, Fenton-like nanocatalyst, and NIR-II/MR/CT contrast agent were achieved "one for all", thereby realizing highly efficient tumor theranostics.

Energy-converting biomaterials for cancer therapy: Category, efficiency, and biosafety

Energy-converting biomaterials (ECBs)-mediated cancer-therapeutic modalities have been extensively explored, which have achieved remarkable benefits to overwhelm the obstacles of traditional cancer-treatment modalities. Energy-driven cancer-therapeutic modalities feature their distinctive merits, including noninvasiveness, low mammalian toxicity, adequate therapeutic outcome, and optimistical synergistic therapeutics. In this advanced review, the prevailing mainstream ECBs can be divided into two sections: Reactive oxygen species (ROS)-associated energy-converting biomaterials (ROS-ECBs) and hyperthermia-related energy-converting biomaterials (H-ECBs). On the one hand, ROS-ECBs can transfer exogenous or endogenous energy (such as light, radiation, ultrasound, or chemical) to generate and release highly toxic ROS for inducing tumor cell apoptosis/necrosis, including photo-driven ROS-ECBs for photodynamic therapy, radiation-driven ROS-ECBs for radiotherapy, ultrasound-driven ROS-ECBs for sonodynamic therapy, and chemical-driven ROS-ECBs for chemodynamic therapy. On the other hand, H-ECBs could translate the external energy (such as light and magnetic) into heat for killing tumor cells, including photo-converted H-ECBs for photothermal therapy and magnetic-converted H-ECBs for magnetic hyperthermia therapy. Additionally, the biosafety issues of ECBs are expounded preliminarily, guaranteeing the ever-stringent requirements of clinical translation. Finally, we discussed the prospects and facing challenges for constructing the new-generation ECBs for establishing intriguing energy-driven cancer-therapeutic modalities. This article is categorized under: Nanotechnology Approaches to Biology >Nanoscale Systems in Biology.

Recent progress of hypoxia-modulated multifunctional nanomedicines to enhance photodynamic therapy: opportunities, challenges, and future development

Hypoxia, a salient feature of most solid tumors, confers invasiveness and resistance to the tumor cells. Oxygen-consumption photodynamic therapy (PDT) suffers from the undesirable impediment of local hypoxia in tumors. Moreover, PDT could further worsen hypoxia. Therefore, developing effective strategies for manipulating hypoxia and improving the effectiveness of PDT has been a focus on antitumor treatment. In this review, the mechanism and relationship of tumor hypoxia and PDT are discussed. Moreover, we highlight recent trends in the field of nanomedicines to modulate hypoxia for enhancing PDT, such as oxygen supply systems, down-regulation of oxygen consumption and hypoxia utilization. Finally, the opportunities and challenges are put forward to facilitate the development and clinical transformation of PDT.

A novel progress of drug delivery system for organelle targeting in tumour cells

At present, malignant tumours have become one of the most serious diseases that endanger human health. According to a survey on causes of death in Chinese population in early 1990s, the malignant tumours were the second leading cause of death. In the treatment of tumours, the ideal situation is that drugs should target and accumulate at tumour sites and destroy tumour cells specifically, without affecting normal cells and stem cells with regenerative capacity. This requires drugs to be specifically transported to the target organs, tissues, cells, and even specific organelles, like mitochondria, nuclei, lysosomes, endoplasmic reticulum (ER), and Golgi apparatus (GA). The nano drug delivery system can not only protect drugs from degradation but also facilitate functional modification and targeted drug delivery to the tumour site. This article mainly reviews the targeting of nano drug delivery systems to tumour cytoplasmic matrix, nucleus, mitochondria, ER, and lysosomes. Organelle-specific drug delivery system will be a major mean of targeting drug delivery with lower toxicity, less dosage and higher drug concentration in tumour cells.

Hollow Mesoporous Bi@PEG-FA Nanoshell as a Novel Dual-Stimuli-Responsive Nanocarrier for Synergistic Chemo-Photothermal Cancer Therapy

The development of stimuli-responsive multifunctional nanocarriers for therapeutic drug delivery is extremely desirable for highly specific treatment of disease. Herein, thiol-polyethylene glycol-folate acid-modified hollow mesoporous bismuth nanoshells (HM-Bi@PEG-FA NSs) were developed as the new dual-stimuli-responsive single-"elemental" photothermal nanocarriers for synergistic chemo-photothermal therapy of tumor. The designed hollow-mesoporous-type nanocarriers present excellent photothermal conversion capacity (∼34.72%) and good biocompatibility. Meanwhile, acidic pH and near-infrared (NIR) laser dual-stimulated doxorubicin (DOX) release is successfully achieved. More importantly, the DOX-loaded HM-Bi@PEG-FA NSs hold an efficient in vitro/in vivo antitumor effect through the synergistic chemo-photothermal therapy. Therefore, our findings provide the possibility of designing a dual-stimuli-responsive hollow mesoporous Bi-based photothermal nanocarrier for synergistically enhanced antitumor therapy.

Multifunctional DNA Polymer-Assisted Upconversion Therapeutic Nanoplatform for Enhanced Photodynamic Therapy

Although considerable clinical attempts on various kinds of cancers have been made, photodynamic therapy (PDT) still suffers from attenuated therapeutic effects because of the developed resistance of cancer cells. As a novel antiapoptosis protein, survivin has been demonstrated to be selectively overexpressed in a great number of human malignancies and plays a significant part in cancer progression and therapeutic resistance. Herein, we present an upconversion nanoplatform for enhanced PDT by DNAzyme-mediated gene silencing of survivin. In our system, a long single-stranded DNA (ssDNA) with a repetitive aptamer (AS1411) and survivin-targeted DNAzyme was fabricated by rolling circle amplification (RCA) and adsorbed on the upconversion nanoparticles (UCNPs) by electrostatic attraction. The multivalence of the ssDNA endows the upconversion nanoplatform with high recognition and loading capacity of photosensitizers and DNAzymes. When the nanoplatform is targeted internalized into cancer cells, PDT can be triggered by near-infrared (NIR) light to generate reactive oxygen species (ROS) for killing the cancer cells. Moreover, the encoded DNAzyme can efficiently inhibit the gene expression of survivin, providing the potential to enhance the efficiency of PDT. This study thus highlights the promise of an upconversion photodynamic nanoplatform for admirable combination therapy in cancer.

Combating the Coronavirus Pandemic: Early Detection, Medical Treatment, and a Concerted Effort by the Global Community

The World Health Organization (WHO) has declared the outbreak of 2019 novel coronavirus, known as 2019-nCoV, a pandemic, as the coronavirus has now infected over 2.6 million people globally and caused more than 185,000 fatalities as of April 23, 2020. Coronavirus disease 2019 (COVID-19) causes a respiratory illness with symptoms such as dry cough, fever, sudden loss of smell, and, in more severe cases, difficulty breathing. To date, there is no specific vaccine or treatment proven effective against this viral disease. Early and accurate diagnosis of COVID-19 is thus critical to curbing its spread and improving health outcomes. Reverse transcription-polymerase chain reaction (RT-PCR) is commonly used to detect the presence of COVID-19. Other techniques, such as recombinase polymerase amplification (RPA), loop-mediated isothermal amplification (LAMP), clustered regularly interspaced short palindromic repeats (CRISPR), and microfluidics, have allowed better disease diagnosis. Here, as part of the effort to expand screening capacity, we review advances and challenges in the rapid detection of COVID-19 by targeting nucleic acids, antigens, or antibodies. We also summarize potential treatments and vaccines against COVID-19 and discuss ongoing clinical trials of interventions to reduce viral progression.

SiO2@Cu7S4 nanotubes for photo/chemodynamic and photo-thermal dual-mode synergistic therapy under 808 nm laser irradiation

Photodynamic therapy (PDT) is a light-based modality for tumor treatment that involves the generation of reactive oxygen species (ROS) by the combination of light, a photosensitizer, and molecular oxygen. Nevertheless, the therapeutic effects of PDT are limited by hypoxic conditions that worsen with oxygen consumption during the PDT process. Photo/chemodynamic therapy (PCDT) based on the Fenton reaction is one strategy to improve ROS generation, provided a highly effective Fenton reagent is developed. In this research, SiO₂@Cu₇S₄ nanotubes (NTs) were synthesized as a PCDT agent. This double-valence metal-sulfide composite material can react with H₂O₂ at the tumor site. SiO₂@Cu₇S₄ NTs can produce more ROS than the traditional PDT agents, and besides, they can also be used as a photothermal therapy (PTT) agent. SiO₂@Cu₇S₄ NTs will trigger the PTT effect under 808 nm irradiation and generate a large amount of heat to eradicate cancer cells. This heat will also promote the PCDT effect by increasing the reaction rate. Thus, the SiO₂@Cu₇S₄ NT is a suitable material for PCDT and PTT synergistic oncotherapy. The 808 nm laser is selected as the appropriate excitation source, providing adequate penetration and minimal harm to normal cells. The experimental data presented herein demonstrate the promising photosensitive, Fenton-like, and photothermal performance of SiO₂@Cu₇S₄ NTs. Furthermore, the findings could promote the development of PCDT and PTT synergistic therapy. Thus, this research provides a feasible method to design a single, multifunctional material for cancer treatment.

Metal Oxide Nanoparticles as Biomedical Materials

The development of new nanomaterials with high biomedical performance and low toxicity is essential to obtain more efficient therapy and precise diagnostic tools and devices. Recently, scientists often face issues of balancing between positive therapeutic effects of metal oxide nanoparticles and their toxic side effects. In this review, considering metal oxide nanoparticles as important technological and biomedical materials, the authors provide a comprehensive review of researches on metal oxide nanoparticles, their nanoscale physicochemical properties, defining specific applications in the various fields of nanomedicine. Authors discuss the recent development of metal oxide nanoparticles that were employed as biomedical materials in tissue therapy, immunotherapy, diagnosis, dentistry, regenerative medicine, wound healing and biosensing platforms. Besides, their antimicrobial, antifungal, antiviral properties along with biotoxicology were debated in detail. The significant breakthroughs in the field of nanobiomedicine have emerged in areas and numbers predicting tremendous application potential and enormous market value for metal oxide nanoparticles.

Designing Stimuli-Responsive Upconversion Nanoparticles that Exploit the Tumor Microenvironment

Tailoring personalized cancer nanomedicines demands detailed understanding of the tumor microenvironment. In recent years, smart upconversion nanoparticles with the ability to exploit the unique characteristics of the tumor microenvironment for precise targeting have been designed. To activate upconversion nanoparticles, various bio-physicochemical characteristics of the tumor microenvironment, namely, acidic pH, redox reactants, and hypoxia, are exploited. Stimuli-responsive upconversion nanoparticles also utilize the excessive presence of adenosine triphosphate (ATP), riboflavin, and Zn²⁺ in tumors. An overview of the design of stimulus-responsive upconversion nanoparticles that precisely target and respond to tumors via targeting the tumor microenvironment and intracellular signals is provided. Detailed understanding of the tumor microenvironment and the personalized design of upconversion nanoparticles will result in more effective clinical translation.

Protein-Based Artificial Nanosystems in Cancer Therapy

Proteins, like actors, play different roles in specific applications. In the past decade, significant achievements have been made in protein-engineered biomedicine for cancer therapy. Certain proteins such as human serum albumin, working as carriers for drug/photosensitizer delivery, have entered clinical use due to their long half-life, biocompatibility, biodegradability, and inherent nonimmunogenicity. Proteins with catalytic abilities are promising as adjuvant agents for other therapeutic modalities or as anticancer drugs themselves. These catalytic proteins are usually defined as enzymes with high biological activity and substrate specificity. However, clinical applications of these kinds of proteins remain rare due to protease-induced denaturation and weak cellular permeability. Based on the characteristics of different proteins, tailor-made protein-based nanosystems could make up for their individual deficiencies. Therefore, elaborately designed protein-based nanosystems, where proteins serve as drug carriers, adjuvant agents, or therapeutic drugs to make full use of their intrinsic advantages in cancer therapy, are reviewed. Up-to-date progress on research in the field of protein-based nanomedicine is provided.

A Porous Au@Rh Bimetallic Core-Shell Nanostructure as an H2 O2 -Driven Oxygenerator to Alleviate Tumor Hypoxia for Simultaneous Bimodal Imaging and Enhanced Photodynamic Therapy

In treatment of hypoxic tumors, oxygen-dependent photodynamic therapy (PDT) is considerably limited. Herein, a new bimetallic and biphasic Rh-based core-shell nanosystem (Au@Rh-ICG-CM) is developed to address tumor hypoxia while achieving high PDT efficacy. Such porous Au@Rh core-shell nanostructures are expected to exhibit catalase-like activity to efficiently catalyze oxygen generation from endogenous hydrogen peroxide in tumors. Coating Au@Rh nanostructures with tumor cell membrane (CM) enables tumor targeting via homologous binding. As a result of the large pores of Rh shells and the trapping ability of CM, the photosensitizer indocyanine green (ICG) is successfully loaded and retained in the cavity of Au@Rh-CM. Au@Rh-ICG-CM shows good biocompatibility, high tumor accumulation, and superior fluorescence and photoacoustic imaging properties. Both in vitro and in vivo results demonstrate that Au@Rh-ICG-CM is able to effectively convert endogenous hydrogen peroxide into oxygen and then elevate the production of tumor-toxic singlet oxygen to significantly enhance PDT. As noted, the mild photothermal effect of Au@Rh-ICG-CM also improves PDT efficacy. By integrating the superiorities of hypoxia regulation function, tumor accumulation capacity, bimodal imaging, and moderate photothermal effect into a single nanosystem, Au@Rh-ICG-CM can readily serve as a promising nanoplatform for enhanced cancer PDT.

Multifunctional nanoparticles as photosensitizer delivery carriers for enhanced photodynamic cancer therapy

Photodynamic therapy (PDT) is an emerging cancer treatment combining light, oxygen, and a photosensitizer (PS) to produce highly cytotoxic reactive oxygen species that cause cancer cell death. However, most PSs are hydrophobic molecules that have poor water solubility and cannot target tumor tissues, causing damage to normal tissues and cells during PDT. Thus, there is a substantial demand for the development of nanocarrier systems to achieve targeted delivery of PSs into tumor tissues and cells. This review summarizes the research progress in PS delivery systems for PDT treatment of tumors and focuses on the recent design and development of multifunctional nanoparticles as PS delivery carriers for enhanced PDT. These multifunctional nanoparticles possess unique properties, including tunable particle size, changeable shape, stimuli-responsive PS activation, controlled PS release, and hierarchical targeting capability. These properties can increase tumor accumulation, penetration, and cellular internalization of nanoparticles to achieve PS activation and/or release in cancer cells for enhanced PDT. Finally, recent developments in multifunctional nanoparticles for tumor-targeted PS delivery and their future prospects in PDT are discussed.

Multifunctional magnetic iron oxide nanoparticles: an advanced platform for cancer theranostics

Multifunctional magnetic nanoparticles and derivative nanocomposites have aroused great concern for multimode imaging and cancer synergistic therapies in recent years. Among the rest, functional magnetic iron oxide nanoparticles (Fe3O4 NPs) have shown great potential as an advanced platform because of their inherent magnetic resonance imaging (MRI), biocatalytic activity (nanozyme), magnetic hyperthermia treatment (MHT), photo-responsive therapy and drug delivery for chemotherapy and gene therapy. Magnetic Fe3O4 NPs can be synthesized through several methods and easily surface modified with biocompatible materials or active targeting moieties. The MRI capacity could be appropriately modulated to induce response between T1 and T2 modes by controlling the size distribution of Fe3O4 NPs. Besides, small-size nanoparticles are also desired due to the enhanced permeation and retention (EPR) effect, thus the imaging and therapeutic efficiency of Fe3O4 NP-based platforms can be further improved. Here, we firstly retrospect the typical synthesis and surface modification methods of magnetic Fe3O4 NPs. Then, the latest biomedical application including responsive MRI, multimodal imaging, nanozyme, MHT, photo-responsive therapy and drug delivery, the mechanism of corresponding treatments and cooperation therapeutics of multifunctional Fe3O4 NPs are also be explained. Finally, we also outline a brief discussion and perspective on the possibility of further clinical translations of these multifunctional nanomaterials. This review would provide a comprehensive reference for readers to understand the multifunctional Fe3O4 NPs in cancer diagnosis and treatment.

"Watson-Crick G[triple bond, length as m-dash]C"-inspired supramolecular nanodrug of methotrexate and 5-fluorouracil for tumor microenvironment-activatable self-recognizing synergistic chemotherapy

Carrier-free nanodrugs, generated via the straightforward small-molecule self-assembly of anticancer drugs, provide a promising route for cancer chemotherapy. However, their low structural stability, lack of targeting specificity, and poor stimulus responsiveness are still limiting their therapeutic effect. Inspired by Watson-Crick G[triple bond, length as m-dash]C base pairing, the FDA-approved chemo-drug methotrexate (MTX, which can bind with folate receptors) and 5-fluorouracil (5-FU, a DNA/RNA synthetase inhibitor) were adopted for direct assembly into self-recognizing MTX-5-FU nanoparticles via "Watson-Crick-like base pairing"-driven precise supramolecular assembly. Sequentially, our synthesized weak acidity-responsive polyethylene glycol (PEG) was inserted onto the nanoparticle surface to temporarily shield the self-targeting function of MTX and prolong the blood circulation time. Once PEG-MTX-5-FU nanoparticles reached the weakly acidic tumor microenvironment, the PEG corona could be cleaved from their surface and then MTX could be re-exposed to recover its self-recognition ability and significantly elevate tumor cell uptake; furthermore, the de-PEGylated MTX-5-FU nanoparticles could respond to the stronger acidity of lysosome, triggering core disassembly and thus the burst release of both MTX and 5-FU. Further in vitro and in vivo studies consistently confirmed that the nanodrugs exhibited preferable accumulation at the tumor sites with highly synergistic chemotherapeutic effects. The supramolecular recognition-inspired, cascade-triggered self-targeting and controlled release of nanodrugs could be a promising strategy to improve synergistic chemotherapy.

Construction of microneedle-assisted co-delivery platform and its combining photodynamic/immunotherapy

Despite advances in photodynamic therapy (PDT) for treating superficial tumor, the prospect of this monotherapy remains challenges in the context of systemic phototoxicity and poor efficacy. In this work, a physiologically self-degradable microneedle (MN)-assisted platform is developed for combining PDT and immunotherapy via controlled co-delivery of photosensitizer (PS) and checkpoint inhibitor anti-CTLA4 antibody (aCTLA4), which generates synergistic reinforcement outcome while reducing side effects. MN is composed of biocompatible hyaluronic acid integrated with the pH-sensitive dextran nanoparticles, which is fabricated to simultaneously encapsulate hydrophobic (Zinc Phthalocyanine) and hydrophilic agents (aCTLA4) via a double emulsion method. This co-loading carrier can aggregate effectively around topical tumor by microneedle-assisted transdermal delivery. In vivo studies using 4T1 mouse models, PDT firstly exerts its effect to killing tumor and triggers the immune responses, subsequently, facilitating the immunotherapy with immune checkpoint inhibitor (aCTLA4). The possible mechanism and systemic effects of the combined therapy are investigated, which demonstrate that this co-administration platform can be a promising tool for focal cancer treatment.

A photothermal-hypoxia sequentially activatable phase-change nanoagent for mitochondria-targeting tumor synergistic therapy

To enhance the specificity and efficiency of anti-tumor therapies, we have designed a multifunctional nanoparticle platform for photochemotherapy using fluorescence (FL) and photoacoustic (PA) imaging guidance. Nanoparticles (NPs) composed of a eutectic mixture of natural fatty acids that undergo a solid-liquid phase transition at 39 °C were used to encapsulate materials for the rapid and uniform release of the hypoxia-activated prodrug tirapazamine (TPZ) and the photosensitizer IR780, which targets the mitochondria of tumor cells and can be used to induce hypoxic cell death via photodynamic therapy and photothermal therapy. In vitro, the NPs containing TPZ and IR7890 exhibited appreciable cell uptake and triggered drug release when irradiated with a NIR laser. In vivo, photochemotherapy of the NPs achieved the best anti-tumor efficacy under PA and FL imaging guidance and monitoring. By combining IR780 mitochondria-targeting phototherapy with TPZ, we observed improved anti-tumor effectiveness and this has the potential to reduce the side effects of traditional chemotherapy. Herein, we demonstrate a new intracellular photochemotherapy nanosystem that co-encapsulates photosensitizers and hypoxia-activated drugs to enhance the overall anti-tumor effect precisely and efficiently.

Fusiform-Like Copper(II)-Based Metal-Organic Framework through Relief Hypoxia and GSH-Depletion Co-Enhanced Starvation and Chemodynamic Synergetic Cancer Therapy

The therapeutic effect of traditional chemodynamic therapy (CDT) agents is severely restricted by their weakly acidic pH and glutathione (GSH) overexpression in the tumor microenvironment. Here, fusiform-like copper(II)-based tetrakis(4-carboxy phenyl)porphyrin (TCPP) nanoscale metal-organic frameworks (nMOFs) were designed and constructed for the first time (named PCN-224(Cu)-GOD@MnO₂). The coated MnO₂ layer can not only avoid conjugation of glucose oxidase (GOD) to damage normal cells but also catalyzes the generation of O₂ from H₂O₂ to enhance the oxidation of glucose (Glu) by GOD, which also provides abundant H₂O₂ for the subsequent Cu⁺-based Fenton-like reaction. Meanwhile, the Cu²⁺ chelated to the TCPP ligand is converted to Cu⁺ by the excess GSH in the tumor, which reduces the tumor antioxidant activity to improve the CDT effect. Next, the Cu⁺ reacts with the plentiful H₂O₂ by enzyme catalysis to produce a toxic hydroxyl radical (^•OH), and singlet oxygen (¹O₂) is synchronously generated from combination with Cu⁺, O₂, and H₂O via the Russell mechanism. Furthermore, the nanoplatform can be used for both TCPP-based in vivo fluorescence imaging and Mn²⁺-induced T₁-weighted magnetic resonance imaging. In conclusion, fusiform-like PCN-224(Cu)-GOD@MnO₂ nMOFs facilitate the therapeutic efficiency of chemodynamic and starvation therapy via combination with relief hypoxia and GSH depletion after acting as an accurate imaging guide.

Engineered Near-Infrared Fluorescent Protein Assemblies for Robust Bioimaging and Therapeutic Applications

Fluorescent proteins are investigated extensively as markers for the imaging of cells and tissues that are treated by gene transfection. However, limited transfection efficiency and lack of targeting restrict the clinical application of this method rooted in the challenging development of robust fluorescent proteins for in vivo bioimaging. To address this, a new type of near-infrared (NIR) fluorescent protein assemblies manufactured by genetic engineering is presented. Due to the formation of well-defined nanoparticles and spectral operation within the phototherapeutic window, the NIR protein aggregates allow stable and specific tumor imaging via simple exogenous injection. Importantly, in vivo tumor metastases are tracked and this overcomes the limitations of in vivo imaging that can only be implemented relying on the gene transfection of fluorescent proteins. Concomitantly, the efficient loading of hydrophobic drugs into the protein nanoparticles is demonstrated facilitating the therapy of tumors in a mouse model. It is believed that these theranostic NIR fluorescent protein assemblies, hence, show great potential for the in vivo detection and therapy of cancer.

Ru@CeO2 yolk shell nanozymes: Oxygen supply in situ enhanced dual chemotherapy combined with photothermal therapy for orthotopic/subcutaneous colorectal cancer

Hypoxia is an important factor in forming multidrug resistance, recurrence and metastasis in solid tumors. Nanozymes respond to tumor microenvironment for tumor-specific treatment is a new and effective strategy. In this study, one-pot method was used to synthesize hollow Ru@CeO2 yolk shell nanozymes (Ru@CeO2 YSNs), which possess excellent light-to-heat conversion efficiency and catalytic performance. Antitumor drug ruthenium complex (RBT) and resveratrol (Res) were dual-loaded in Ru@CeO2 YSNs, and a double outer layer structure using polyethylene glycol was constructed to form dual-drug delivery system (Ru@CeO2-RBT/Res-DPEG) that was released on demand. The double outer layer structure increased the biocompatibility of Ru@CeO2 YSNs and effectively prolong the circulation time in blood. Ru@CeO2-RBT/Res-DPEG catalyzes endogenous H2O2 to produce oxygen, which achieve in situ oxygen supply and enhanced dual-chemotherapy and photothermal therapy (PTT) for colorectal cancer. In vitro studies found that Ru@CeO2-RBT/Res-DPEG has good tumor penetration depth and antitumor effect. In addition, Ru@CeO2-RBT/Res-DPEG can alleviate tumor hypoxia, and inhibit metastasis and recurrence of orthotopic and subcutaneous colorectal cancer. Accordingly, the study shows that yolk shell nanozymes can be used as an efficient synergistic system for dual-chemotherapy and PTT to kill tumor and inhibit orthotopic colorectal cancer metastasis and recurrence.

Core-shell structured 5-FU@ZIF-90@ZnO as a biodegradable nanoplatform for synergistic cancer therapy

High treatment efficiency and low drug toxicity are two key factors in tumor therapy. The development of multifunctional drug carrier systems is of great significance for the diagnosis and therapy of tumors. Herein, a novel biodegradable treatment system based on zeolitic imidazolate framework-90 (ZIF-90) was designed in this study. This 5-FU@ZIF-90@ZnO (FZZ) drug delivery system achieves synergistic treatment with antineoplastic 5-fluorouracil (5-FU) and zinc oxide, and also has good dispersibility in the acidic tumor microenvironment (TME), which enables the drug to achieve pH-controlled delivery in acidic organisms. Interestingly, zinc oxide nanoparticles can play a dual role here. They can prevent the premature leakage of drugs under physiological conditions. Moreover, Zn²⁺ produced after the decomposition of nanoparticles can act as a therapeutic agent, overcoming the tumor resistance to 5-FU and regulating a series of physiological reactions to inhibit tumor growth. It is worth noting that the porous ZIF-90 is an emerging drug carrier with a relatively high drug loading rate of 39% in this study. Synergistic 5-FU and ZnO nanoparticles have achieved tumor inhibition and have shown high therapeutic biosafety. Thus, the FZZ core-shell nanoparticles are a potential pH-controlled drug release system that can be applied to tumor treatment.

Advanced nanotechnology for hypoxia-associated antitumor therapy

Hypoxia is a hallmark of the tumor microenvironment, which promotes the proliferation, metastasis and invasion of tumors and stimulates the resistance of cancer treatments, leading to the serious consequence of tumor recurrence. Many nanotechnology-based studies have been conducted to improve the efficacy of cancer treatments using a hypoxia strategy. This is usually achieved by (i) activating bioreductive prodrugs in the tumor hypoxic/exacerbated hypoxic microenvironment, or (ii) delivering therapeutic agents to hypoxic tumor tissue using targeting molecules. Normally, a good therapeutic effect can be expected upon modulating the hypoxic microenvironment for tumor treatments. To achieve this, various nanotechnology strategies based on overcoming hypoxia have been exploited to alleviate tumor hypoxia and enhance the therapeutic efficacy of tumor therapy, including (i) reducing oxygen consumption by inhibiting cell respiration, (ii) normalizing tumor vessels to promote blood flow in the tumor, (iii) carrying exogenous oxygen into the tumor, and (iv) generating oxygen in situ. The strategy of in situ oxygen production is refined, and the scope of this strategy is further expanded. Finally, the inspiration of using advanced nanotechnology in hypoxia-associated antitumor therapy guides the study of tumor hypoxia for clinical use.

Specific Core-Satellite Nanocarriers for Enhanced Intracellular ROS Generation and Synergistic Photodynamic Therapy

The deficiency of reactive oxygen species (ROS) is the main reason for the current poor efficiency of tumor photodynamic therapy (PDT). To solve this problem, a simple light-triggered core-satellite nanoplatform (UPSD@Au) has been developed by loading Au nanoparticles on the surface of mesoporous silica-coated upconversion nanoparticles. Small molecules DC50 (C₁₇H₁₄BrF₂N₃OS) and photosensitizer (silicon phthalocyanine dihydroxide, SPCD) were loaded into the silica shell to improve ROS production. Meanwhile, PDT can be triggered through facile near-infrared laser irradiation given the occurrence of a moderate photothermal transfer process between upconversion nanoparticles and Au. The reasonable increment in temperature induced by Au resulted in the timely release of DC50. The inhibition of copper transfer by DC50 results in reduced ROS scavenging and thus improves light-triggered ROS accumulation. Notably, the expression levels of the human copper-trafficking proteins Atox1 and CCS in cancerous cells exceed those in normal cells, and thus enhanced ROS accumulation effect was achieved in cancerous cells. In vitro and in vivo results demonstrate that the synergism between DC50 and SPCD coloaded in the UPSD@Au nanoplatform increases the efficiency of PDT. The UPSD@Au platform represents an efficient codelivery method for hydrophobic small molecules and improves sensitization to specific cancer therapy.

In Situ Catalytic Reaction for Solving the Aggregation of Hydrophobic Photosensitizers in Tumor

The aggregation of hydrophobic photosensitizers limits the therapeutic effect of photodynamic therapy (PDT). Improving the hydrophilicity of photosensitizers can reduce their aggregation for enhancing PDT. Herein, a nanosystem (TPFcNP) is developed by a hydrophobic photosensitizer 5,10,15,20-tetrakis(4-methacryloyloxyphenyl)porphyrin (TMPP) containing multiple carbon-carbon double bonds and a ferrocene-containing amphiphilic block copolymer (PEG-b-PMAEFc), which catalyzes hydrogen peroxide (H₂O₂) to produce hydroxyl radicals (^•OH) in a tumor microenvironment by the Fenton reaction. The ^•OH could catalyze the addition reaction between the carbon-carbon double bonds of TMPP and overexpressed water-soluble glutathione (GSH) in tumor cells, which greatly improves the hydrophilicity of photosensitizers and reduces their aggregation. Experiments in vitro and in vivo have proved that this strategy significantly enhances the therapeutic efficacy of PDT. Catalyzing intracellular reactions in situ by making use of the tumor microenvironment will open up a new opportunity to solve the aggregation of materials in the tumor for cancer treatment.

Subcellular Performance of Nanoparticles in Cancer Therapy

With the advent of nanotechnology, various modes of traditional treatment strategies have been transformed extensively owing to the advantageous morphological, physiochemical, and functional attributes of nano-sized materials, which are of particular interest in diverse biomedical applications, such as diagnostics, sensing, imaging, and drug delivery. Despite their success in delivering therapeutic agents, several traditional nanocarriers often end up with deprived selectivity and undesired therapeutic outcome, which significantly limit their clinical applicability. Further advancements in terms of improved selectivity to exhibit desired therapeutic outcome toward ablating cancer cells have been predominantly made focusing on the precise entry of nanoparticles into tumor cells via targeting ligands, and subsequent delivery of therapeutic cargo in response to specific biological or external stimuli. However, there is enough room intracellularly, where diverse small-sized nanomaterials can accumulate and significantly exert potentially specific mechanisms of antitumor effects toward activation of precise cancer cell death pathways that can be explored. In this review, we aim to summarize the intracellular pathways of nanoparticles, highlighting the principles and state of their destructive effects in the subcellular structures as well as the current limitations of conventional therapeutic approaches. Next, we give an overview of subcellular performances and the fate of internalized nanoparticles under various organelle circumstances, particularly endosome or lysosome, mitochondria, nucleus, endoplasmic reticulum, and Golgi apparatus, by comprehensively emphasizing the unique mechanisms with a series of interesting reports. Moreover, intracellular transformation of the internalized nanoparticles, prominent outcome and potential affluence of these interdependent subcellular components in cancer therapy are emphasized. Finally, we conclude with perspectives with a focus on the contemporary challenges in their clinical applicability.

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.

Layered double hydroxide nanosheets: towards ultrasensitive tumor microenvironment responsive synergistic therapy

The tumor microenvironment (TME), which is characterised by high H₂O₂ and glutathione (GSH) levels, low pH value and hypoxia, imposes crucial influences on tumor therapeutic outcomes. Rational design and preparation of nanomaterial systems that are responsive to the intrinsic properties of the TME open a promising avenue towards tumor-specific treatment. Herein, CoMn-layered double hydroxide (CoMn-LDH) nanosheets were synthesized via a bottom-up method followed by surface modification with a photosensitizer, chlorin e6 (Ce6), which exhibited TME-responsive imaging as well as photodynamic and chemodynamic synergistic therapy (PDT/CDT). Due to their ultralow bond energy and large adsorption energy, CoMn-LDH nanosheets show fast self-degradability in a GSH (10 mM) microenvironment, giving an excellent CDT activity in mildly acidic conditions (pH = 6.5), superior GSH removal ability (99.82%) and O₂ production (35.37 μg L^-1 s^-1). Moreover, Ce6/CoMn-LDH nanosheets display satisfactory photoacoustic (PA) imaging and GSH-enhanced magnetic resonance imaging (MRI) with a 45.1-fold T₁-enhancement. In addition, both in vitro and in vivo therapeutic tests based on Ce6/CoMn-LDH demonstrate a satisfactory anticancer activity with complete cancer cell apoptosis and dramatic tumor elimination. This work provides a new perspective for the design of multifunctional 2D nanosheets towards a fully promoted TME-responsive synergistic therapy, which holds great promise for future clinical diagnosis and treatment.

Potential implications of hydrogen peroxide in the pathogenesis and therapeutic strategies of gliomas

Glioma is the most common type of primary brain tumor, and it has a high mortality rate. Currently, there are only a few therapeutic approaches for gliomas, and their effects are unsatisfactory. Therefore, uncovering the pathogenesis and exploring more therapeutic strategies for the treatment of gliomas are urgently needed to overcome the ongoing challenges. Cellular redox imbalance has been shown to be associated with the initiation and progression of gliomas. Among reactive oxygen species (ROS), hydrogen peroxide (H₂O₂) is considered the most suitable for redox signaling and is a potential candidate as a key molecule that determines the fate of cancer cells. In this review, we discuss the potential cellular and molecular roles of H₂O₂ in gliomagenesis and explore the potential implications of H₂O₂ in radiotherapy and chemotherapy and in the ongoing challenges of current glioma treatment. Moreover, we evaluate H₂O₂ as a potential redox sensor and potential driver molecule of nanocatalytic therapeutic strategies for glioma treatment.

Modified ZIF-8 Nanoparticles Attenuate Osteoarthritis by Reprogramming the Metabolic Pathway of Synovial Macrophages

Accumulating evidence suggests that activation of proinflammatory M1-type macrophages in the synovium plays a vital role in the progression of osteoarthritis (OA). Redundant nitric oxide (NO) and hydrogen peroxide (H₂O₂) are key factors that drive macrophages to polarize to the M1 type. Herein, modified zeolitic imidazolate framework-8 (ZIF-8) nanoparticles (NPs) have been synthesized. By regulating intracellular gases and reprogramming the metabolism phenotype, modified NPs transformed macrophage polarization from proinflammatory M1 to anti-inflammatory M2 phenotype. Specifically, S-methylisothiourea hemisulfate salt was loaded into ZIF-8 NPs to inhibit inducible nitric oxide synthase, hence reducing NO production. Catalase was encapsulated to catalyze the production of oxygen (O₂) from H₂O₂. Results demonstrated that modified NPs were capable of catalyzing H₂O₂ to produce O₂ and eliminate NO, hence inhibiting hypoxia-inducible factor 1α, further rescuing mitochondrial function. Moreover, anti-CD16/32 antibody modification could prolong the retention time of NPs in knee joints of OA mice with anterior cruciate ligament transection. More significantly, modified NPs suppressed M1 macrophages and up-regulated M2 macrophage infiltration in the synovium, further inhibiting cartilage degeneration. This ZIF-8 NP-based gas regulation and metabolic reprogramming strategy may pave a new avenue for OA treatment.

Biomineralized Bimetallic Oxide Nanotheranostics for Multimodal Imaging-Guided Combination Therapy

The hypoxia of the tumor microenvironment (TME) often hinders the effectiveness of cancer treatments, especially O₂-dependent photodynamic therapy (PDT).

Methods: An integrated iridium oxide (IrO₂)-manganese dioxide (MnO₂) nanotheranostic agent was fabricated through bovine serum albumin (BSA)-based biomineralization of Ir³⁺ and Mn²⁺. BSA was first covalently modified with chlorin e6 (Ce6), and used to fabricate multifunctional BSA-Ce6@IrO₂/MnO₂ nanoparticles (NPs) for computed X-ray tomography (CT) and photoacoustic (PA) imaging-guided PDT and photothermal (PTT) therapy of cancer. Extensive in vitro and in vivo studies were performed.

Results: The theranostic agent produced can relieve tumor hypoxia by the decomposition of endogenous H₂O₂ in cancer cells to oxygen. The oxygen generated can be exploited for improved PDT. Paramagnetic Mn²⁺ released from the NPs in the acidic TME permits magnetic resonance imaging (MRI) to be performed. The exceptional photothermal conversion efficiency (65.3%) and high X-ray absorption coefficient of IrO₂ further endow the NPs with the ability to be used in computed CT and PA imaging. Extensive antitumor studies demonstrated that the BSA-Ce6@IrO₂/MnO₂ nanoplatform inhibits cancer cell growth, particularly after combined PTT and PDT. Systematic in vivo biosafety evaluations confirmed the high biocompatibility of the nanoplatform.

Conclusion: This work not only provides a novel strategy for designing albumin-based nanohybrids for theranostic applications but also provides a facile approach for extending the biomedical applications of iridium-based materials.

Nanomedicine-Enabled Modulation of Tumor Hypoxic Microenvironment for Enhanced Cancer Therapy

Hypoxia is a common condition of solid tumors that is mainly caused by enhanced tumor proliferative activity and dysfunctional vasculature. In the treatment of hypoxic human solid tumors, many conventional therapeutic approaches (e.g., oxygen-dependent photodynamic therapy, anticancer drug-based chemotherapy or X-ray induced radiotherapy) become considerably less effective or ineffective. In recent years, various strategies have been explored to deliver or generate oxygen inside solid tumors to overcome tumorous hypoxia and show promising evidence to improve the antitumor efficiency. In this review, the extrinsic regulation of tumor hypoxia via nanomaterial delivery is discussed followed by a summary of the mechanisms through which the modulated tumor hypoxic microenvironment improves therapeutic efficacy. The review concludes with future perspectives, to specifically address the translation of nanomaterial-based therapeutic strategies for clinical applications.

Tumor microenvironment responsive mesoporous silica nanoparticles for dual delivery of doxorubicin and chemodynamic therapy (CDT) agent

We engineered a tumor microenvironment-triggered MSN-based anti-cancer nanocarrier for simultaneous delivery of DOX and chemodynamic agent.