Mesoporous carbon‑manganese nanocomposite for multiple imaging guided oxygen-elevated synergetic therapy

High-performance self-cascade nanoreactors for combined ferroptosis, photothermal therapy, and starving therapy

Despite the great potential of starving therapy caused by nanoreactor based on glucose oxidase (GOX) in tumor therapy, efficiency and uncontrolled reaction rates in vivo lead to inevitable toxicity to normal tissues, which seriously hindering their clinical conversion. Herein, a cascade nanoreactor (GOX/Mn/MPDA) was constructed by coating mesoporous polydopamine nanoparticles (MPDA) with MnO2 shell and then depositing GOX into honeycomb-shaped manganese oxide nanostructures to achieve a combination of ferroptosis, photothermal therapy and starving therapy. Upon uptake of nanodrugs to cancer cells, the MnO2 shell would deplete glutathione (GSH) and produce Mn2+, while a large amount of H2O2 generated from the catalytic oxidation of glucose by GOX would accelerate the Fenton-like reaction mediated by Mn2+, producing high toxic •OH. More importantly, the cascade reaction between GOX and MnO2 would be further strengthened by localized hyperthermia caused by irradiated by near-infrared laser (NIR), inducing significant anti-tumor effects in vitro and in vivo. Regarding the effectiveness of tumor treatment in vivo, the tumor inhibition rate achieved an impressive 64.33%. This study provided a new strategy for anti-tumor therapeutic by designing a photothermal-enhanced cascade catalytic nanoreactor.

Mesoporous carbon nanoparticles embedded with iron in hydrogen-photothermal synergistic therapy

We developed a new method to synthesize polyethylene glycol modified ultra small iron embedded in mesoporous carbon nanoparticle (C/Fe-PEG NP) for hydrogen (H2) assisted photothermal synergistic therapy. Herein, we use a simple in-situ reduction method to obtain the C/Fe NP in one-step carbonizing process, which is further modified by the biocompatible polyethylene glycol (PEG) on the surface of C/Fe NP to acquire high stability in physiological solutions. Utilizing the excellent photothermal property from the mesoporous carbon and the controllable H2 release property in the weakly acidic tumor microenvironment by the ultra-small Fe, the obtained C/Fe-PEG NPs can effective kill the cancer cells, meanwhile, protect normal cells without drugs. This selective anti-cancer mechanism of C/Fe-PEG NPs may because the produced H2 selective change the mitochondrial energy metabolism. In vivo results prove that the C/Fe-PEG NPs achieve excellent tumor ablation therapeutic effect and normal tissue protecting ability benefit from the H2-assisted photothermal therapy, promising the use of novel nanomaterials with more safety method for future cancer therapy.

Enhancing photodynamic immunotherapy by reprograming the immunosuppressive tumor microenvironment with hypoxia relief

Tumor hypoxia impairs the generation of reactive oxygen species and the induction of immunogenic cell death (ICD) for photodynamic therapy (PDT), thus impeding its efficacy and the subsequent immunotherapy. In addition, hypoxia plays a critical role in forming immunosuppressive tumor microenvironments (TME) by regulating the infiltration of immunosuppressive tumor-associated macrophages (TAMs) and the expression of programmed death ligand 1 (PD-L1). To simultaneously tackle these issues, a MnO2-containing albumin nanoplatform co-delivering IR780, NLG919, and a paclitaxel (PTX) dimer is designed to boost photodynamic immunotherapy. The MnO2-catalyzed oxygen supply bolsters the efficacy of PDT and PTX-mediated chemotherapy, collectively amplifying the induction of ICD and the expansion of tumor-specific cytotoxic T lymphocytes (CTLs). More importantly, hypoxia releif reshapes the immunosuppressive TME via down-regulating the intratumoral infiltration of M2-type TAMs and the PD-L1 expression of tumor cells to enhance the infiltration and efficacy of CTLs in combination with immune checkpoint blockade (ICB) by NLG919, consequently eradicating primary tumors and almost completely preventing tumor relapse and metastasis. This study sets an example of enhanced immunotherapy for breast cancers through dual ICD induction and simultaneous immunosuppression modulation via both hypoxia relief and ICB, providing a strategy for the treatment of other hypoxic and immunosuppressive cancers.

The Graphene Quantum Dots Gated Nanoplatform for Photothermal-Enhanced Synergetic Tumor Therapy

Currently, the obvious side effects of anti-tumor drugs, premature drug release, and low tumor penetration of nanoparticles have largely reduced the therapeutic effects of chemotherapy. A drug delivery vehicle (MCN-SS-GQDs) was designed innovatively. For this, the mesoporous carbon nanoparticles (MCN) with the capabilities of superior photothermal conversion efficiency and high loading efficiency were used as the skeleton structure, and graphene quantum dots (GQDs) were gated on the mesopores via disulfide bonds. The doxorubicin (DOX) was used to evaluate the pH-, GSH-, and NIR-responsive release performances of DOX/MCN-SS-GQDs. The disulfide bonds of MCN-SS-GQDs can be ruptured under high glutathione concentration in the tumor microenvironment, inducing the responsive release of DOX and the detachment of GQDs. The local temperature of a tumor increases significantly through the photothermal conversion of double carbon materials (MCN and GQDs) under near-infrared light irradiation. Local hyperthermia can promote tumor cell apoptosis, accelerate the release of drugs, and increase the sensitivity of tumor cells to chemotherapy, thus increasing treatment effect. At the same time, the detached GQDs can take advantage of their extremely small size (5-10 nm) to penetrate deeply into tumor tissues, solving the problem of low permeability of traditional nanoparticles. By utilizing the photothermal properties of GQDs, synergistic photothermal conversion between GQDs and MCN was realized for the purpose of synergistic photothermal treatment of superficial and deep tumor tissues.

Mesoporous carbon hemispheres integrated with Fe-Gd nanoparticles for potential MR/PA imaging-guided photothermal therapy

Asymmetric carbon has emerged as an important material to enrich morphologies as well as enhance functions for bioapplications. Here, asymmetric mesoporous carbon hemispheres (CHS) integrated with γ-Fe2O3 and GdPO4 (Fe-Gd) nanoparticles are proposed and prepared for potential imaging-guided photothermal therapy (PTT). Interestingly, Fe-Gd/CHS contributes to an almost 1.5 times enhancement in light harvesting and photothermal conversion efficiency as compared with its corresponding spherical analogue. The possible underlying mechanism is discussed in view of the unique asymmetric structure-featured carbon. Further identification of the inherited photoacoustic (PA) and magnetic resonance (MR) imaging properties leads to the consequent in vivo evaluation of its imaging and PTT performances, which demonstrates its capability as a function-integrated system for potential theranostics.

Design of manganese-based nanomaterials for pharmaceutical and biomedical applications

In the past few years, manganese-based nanostructures have been extensively investigated in the biomedical field particularly to design highly biocompatible theranostics, which can not only act as efficient diagnostic imaging contrast agents but also deliver the drugs to the target sites. The nanoscale size, large surface area-to-volume ratio, availability of cheap precursors, flexibility to synthesize nanostructures with reproducible properties and high yield, and easy scale up are the major reasons for the attraction towards manganese nanostructures. Along with these properties, the nontoxic nature, pH-sensitive degradation, and easy surface functionalization are additional benefits for the use of manganese nanostructures in biomedical and pharmaceutical sciences. Therefore, in this review, we discuss the recent progress made in the synthesis of manganese nanostructures, describe the attempts made to modify their surfaces to impart biocompatibility and stability in biological fluids, and critically discuss their use in magnetic resonance imaging, drug and gene delivery, hyperthermia, photothermal/photodynamic, immunotherapy, biosensing and tumor diagnosis.

Optimized strategies of ROS-based nanodynamic therapies for tumor theranostics

Reactive oxygen species (ROS) play a crucial role in regulating the metabolism of tumor growth, metastasis, death and other biological processes. ROS-based nanodynamic therapies (NDTs) are becoming attractive due to non-invasive, low side effects and tumor-specific advantages. NDTs have rapidly developed into numerous branches, such as photodynamic therapy, chemodynamic therapy, sonodynamic therapy and so on. However, the complexity of the tumor microenvironment and the limitations of existing sensitizers have greatly restricted the therapeutic effects of NDTs, which heavily rely on ROS levels. To address the limitations of NDTs, various strategies have been developed to increase ROS yield, which is an urgent aspect for the positive development of NDTs. In this review, the nanodynamic potentiation strategies in terms of unique properties and universalities of NDTs are comprehensively outlined. We mainly summarize the current dilemmas faced by each NDT and the respective solutions. Meanwhile, the NDTs universalities-based potentiation strategies and NDTs-based combined treatments are elaborated. Finally, we conclude with a discussion of the key issues and challenges faced in the development and clinical transformation of NDTs.

Photothermal antibacterial materials to promote wound healing

Wound healing is a crucial process that restores the integrity and function of the skin and other tissues after injury. However, external factors, such as infection and inflammation, can impair wound healing and cause severe tissue damage. Therefore, developing new drugs or methods to promote wound healing is of great significance. Photothermal therapy (PTT) is a promising technique that uses photothermal agents (PTAs) to convert near-infrared radiation into heat, which can eliminate bacteria and stimulate tissue regeneration. PTT has the advantages of high efficiency, controllability, and low drug resistance. Hence, nanomaterial-based PTT and its related strategies have been widely explored for wound healing applications. However, a comprehensive review of PTT-related strategies for wound healing is still lacking. In this review, we introduce the physiological mechanisms and influencing factors of wound healing, and summarize the types of PTAs commonly used for wound healing. Then, we discuss the strategies for designing nanocomposites for multimodal combination treatment of wounds. Moreover, we review methods to improve the therapeutic efficacy of PTT for wound healing, such as selecting the appropriate wound dressing form, controlling drug release, and changing the infrared irradiation window. Finally, we address the challenges of PTT in wound healing and suggest future directions.

Recent Advances of Tumor Microenvironment-Responsive Nanomedicines-Energized Combined Phototherapy of Cancers

Photodynamic therapy (PDT) has emerged as a powerful tumor treatment tool due to its advantages including minimal invasiveness, high selectivity and thus dampened side effects. On the other side, the efficacy of PDT is severely frustrated by the limited oxygen level in tumors, thus promoting its combination with other therapies, particularly photothermal therapy (PTT) for bolstered tumor treatment outcomes. Meanwhile, nanomedicines that could respond to various stimuli in the tumor microenvironment (TME) provide tremendous benefits for combined phototherapy with efficient hypoxia relief, tailorable drug release and activation, improved cellular uptake and intratumoral penetration of nanocarriers, etc. In this review, we will introduce the merits of combining PTT with PDT, summarize the recent important progress of combined phototherapies and their combinations with the dominant tumor treatment regimen, chemotherapy based on smart nanomedicines sensitive to various TME stimuli with a focus on their sophisticated designs, and discuss the challenges and future developments of nanomedicine-mediated combined phototherapies.

Functionalized nanohybrids with rod shape for improved chemo-phototherapeutic effect against cancer by sequentially generating singlet oxygen and carbon dioxide bubbles

The application of hybrid nanocarriers is expected to play an active role in improving treatment of chemotherapy and phototherapy. Herein, a nanohybrid with a core of mesoporous silica nanorods and shell of folate-functionalized zeolite imidazole framework (ZIF-8/FA) was synthesized via polydopamine (PDA)-mediated integration. A chemotherapeutic drug (DOX), bubble generator (NH4HCO3, ABC), and photosensitive agent (ICG) were simultaneously loaded into the delivery system to construct smart ZIF-8/FA-coated mesoporous silica nanorods (IDa-PRMSs@ZF). We found that ICG endowed the designed delivery system with a moderate photothermal conversion efficiency of 26.06% and the capacity to release 1O2. The produced hyperthermia caused ABC to decompose and further generate carbon dioxide bubbles, thereby facilitating DOX release, sequentially. Importantly, the underlying mechanism was also investigated using mathematical kinetic modeling. The tumor inhibition rate of IDa-PRMSs@ZF under NIR irradiation reached 83.8%. This study provides a promising strategy based on rod-shaped nanohybrids for effective combination antitumor therapy.

Nanoparticle-mediated synergistic anticancer effect of ferroptosis and photodynamic therapy: Novel insights and perspectives

Current antitumor monotherapy has many limitations, highlighting the need for novel synergistic anticancer strategies. Ferroptosis is an iron-dependent form of nonapoptotic cell death that plays a pivotal regulatory role in tumorigenesis and treatment. Photodynamic therapy (PDT) causes irreversible chemical damage to target lesions and is widely used in antitumor therapy. However, PDT's effectiveness is usually hindered by several obstacles, such as hypoxia, excess glutathione (GSH), and tumor resistance. Ferroptosis improves the anticancer efficacy of PDT by increasing oxygen and reactive oxygen species (ROS) or reducing GSH levels, and PDT also enhances ferroptosis induction due to the ROS effect in the tumor microenvironment (TME). Strategies based on nanoparticles (NPs) can subtly exploit the potential synergy of ferroptosis and PDT. This review explores recent advances and current challenges in the landscape of the underlying mechanisms regulating ferroptosis and PDT, as well as nano delivery system-mediated synergistic anticancer activity. These include polymers, biomimetic materials, metal organic frameworks (MOFs), inorganics, and carrier-free NPs. Finally, we highlight future perspectives of this novel emerging paradigm in targeted cancer therapies.

Customized multi-stimuli nanovehicles with dissociable 'bomblets' for photothermal-enhanced synergetic tumor therapy

Recently, the therapeutic effect of chemotherapy has been obviously impaired due to premature drug release, low tumor penetration, and multidrug resistance of nanoplatforms. In this paper, a novel multiple-sensitive drug delivery system (MC-ss-CDs) was developed by gating long-wavelength emitting carbon dots (CDs) on the openings of mesoporous carbon nanoparticles (MC) through disulfide bonds. The MC with excellent photothermal transition efficiency and high drug storage capacity for doxorubicin (DOX) was used as the delivery carrier. The CDs had multiple functions, including intelligent switching to hinder unwanted release, photothermal therapy (PTT) agents to improve the heat generation effect of MCs and bioimaging trackers to monitor drug delivery. The disulfide bonds, as the linkers between MC carriers and CDs, are stable under normal physical conditions and relatively labile under high GSH concentrations in the cytoplasm of tumor cells. After arriving at the tumor microenvironment, DOX/MC-ss-CDs can rapidly break into DOX/MC and CDs under high GSH concentrations. DOX/MC could realize efficient integration of PTT and chemotherapy on the surface of the tumor by stimuli-responsive DOX release and synergetic heating of MC and CDs. The small-sized CDs with excellent penetrating ability could effectively enter the deep tumor and realize NIR-triggered photothermal ablation. The DOX/MC-ss-CDs showed a chemophotothermal effect with a combination index of 0.38 in vitro and in vivo. Therefore, the DOX/MC-ss-CDs could be employed as a trackable nanovehicle for synergistic chemotherapy and PTT at different depths.

Mesoporous carbon nanoenzyme as nano-booster for photothermal-enhanced photodynamic therapy compared with graphene oxide

The over-expressed GSH in tumor microenvironment significantly weakens the lethal reactive oxygen species (ROS) generated by photodynamic therapy (PDT) and catalysis of nanoenzyme. Hence, it is necessary to excavate a versatile and effective vehicle with oxidative stress-enhancement and GSH-depletion capacity to break the redox homeostasis in tumor microenvironment. GO has been reported to possess GSH-depletion and peroxidase (POD)-like capacity. Based on this, PEGylated mesoporous carbon (MC-PEG) was prepared as ICG vehicle to compare with PEGylated graphene oxide (GO-PEG). Excitingly, MC-PEG was found to exhibit three times higher oxidative capacity by POD-like process than GO-PEG, and owned more effective and continuous GSH-depletion capacity to further amplify the oxidative stress. Meanwhile, MC-PEG exhibited better protective effect on the loaded ICG against unwanted light excitation than GO-PEG. Together with the higher photothermal conversion effect, under the NIR light irradiation, MC-PEG could markedly improve the temperature of tumor cells and produce more hydroxyl radical, continuously consume GSH and provide more better protection for ICG compared with GO-PEG, thus further boosting the combination of photothermal and photodynamic effects. The anti-tumor experiment in cell and in-vivo level both validated that ICG/MC-PEG showed better synergistic effect with lower IC₅₀ value and higher tumor suppression rate than ICG/GO-PEG.

Nanoparticles-based phototherapy systems for cancer treatment: Current status and clinical potential

Remarkable progress in phototherapy has been made in recent decades, due to its non-invasiveness and instant therapeutic efficacy. In addition, with the rapid development of nanoscience and nanotechnology, phototherapy systems based on nanoparticles or nanocomposites also evolved as an emerging hotspot in nanomedicine research, especially in cancer. In this review, first we briefly introduce the history of phototherapy, and the mechanisms of phototherapy in cancer treatment. Then, we summarize the representative development over the past three to five years in nanoparticle-based phototherapy and highlight the design of the innovative nanoparticles thereof. Finally, we discuss the feasibility and the potential of the nanoparticle-based phototherapy systems in clinical anticancer therapeutic applications, aiming to predict future research directions in this field. Our review is a tutorial work, aiming at providing useful insights to researchers in the field of nanotechnology, nanoscience and cancer.

Biomimetic nanomaterial-facilitated oxygen generation strategies for enhancing tumour treatment outcomes

Hypoxia, as a typical hallmark of the tumour microenvironment (TME), has been verified to exist in most malignancies and greatly hinders the outcome of tumour treatments, including chemotherapy, photodynamic therapy, radiotherapy, and immunotherapy. Various approaches to alleviate tumour hypoxia have been reported. Among them, biomimetic nanomaterial-facilitated tumour oxygenation strategies, based on the engagement of human endogenous proteins, red blood cells, the cell membrane, and catalase, are the most impressive due to their excellent tumour active-targeting ability and superior tumour-selective capability, which, however, have not yet been systematically reviewed. Herein, we are ready to describe the current progress in biomimetic nanomaterial-facilitated tumour oxygenation strategies and corresponding improvements in tumour treatment outputs. In this review, the underlying mechanism behind the superior effect of these biomimetic nanomaterials, compared with other materials, on alleviating the hypoxic TME is highlighted. Additionally, the ongoing problems and potential solutions are also discussed.

Combined Chemo-Immuno-Photothermal Therapy for Effective Cancer Treatment via an All-in-One and One-for-All Nanoplatform

Tumor metastasis and recurrence are recognized to be the main causes of failure in cancer treatment. To address these issues, an "all in one" and "one for all" nanoplatform was established for combined "chemo-immuno-photothermal" therapy with the expectation to improve the antitumor efficacy. Herein, Docetaxel (DTX, a chemo-agent) and cynomorium songaricum polysaccharide (CSP, an immunomodulator) were loaded into zein nanoparticles coated by a green tea polyphenols/iron coordination complex (GTP/Fe^III, a photothermal agent). From the result, the obtained nanoplatform denoted as DTX-loaded Zein/CSP-GTP/Fe^III NPs was spherical in morphology with an average particle size of 274 nm, and achieved pH-responsive drug release. Moreover, the nanoplatform exhibited excellent photothermal effect both in vitro and in vivo. It was also observed that the nanoparticles could be effectively up take by tumor cells and inhibited their migration. From the results of the in vivo experiment, this nanoplatform could completely eliminate the primary tumors, prevent tumor relapses on LLC (Lewis lung cancer) tumor models, and significantly inhibit metastasis on 4T1 (murine breast cancer) tumor models. The underlying mechanism was also explored. It was discovered that this nanoplatform could induce a strong ICD effect and promote the release of damage-associated molecular patterns (DAMPs) including CRT, ATP, and HMGB1 by the dying tumor cells. And the CSP could assist the DAMPs in inducing the maturation of dendritic cells (DCs) and facilitate the intratumoral infiltration of T lymphocytes to clear up the residual or disseminated tumor cells. In summary, this study demonstrated that the DTX-loaded Zein/CSP-GTP/Fe^III is a promising nanoplatform to completely inhibit tumor metastasis and recurrence.

Hyaluronic acid coated mesoporous carbon-copper peroxide for H2O2 self-supplying and near-infrared responsive multi-mode breast cancer oncotherapy

It is challenging to develop the synergistic intelligent therapeutic nanoplatform to cure cancer. In the present study, a novel nanotherapeutic platform was constructed for H₂O₂ self-supplying and multimodal breast cancer therapy. In which, copper peroxide nanoparticles (CP NPs) were adsorbed on the surface of mesoporous carbon nanospheres (MCN) through electrostatic attraction, followed by loading doxorubicin (DOX) into the nanocomposite (MCN-CP) and coating hyaluronic acid (HA) on the surface, the DOX/MCN-CP-HA nanoplatform was obtained. In the system, the MCN not only possessed a high DOX loading capacity, but produced excellent photothermal therapy (PTT) effect. Importantly, the ultra-small CP NPs as the Fenton agent not only could selectively self-supplying H₂O₂ in acidic condition, but simultaneously release Cu²⁺ to catalyze the production of ·OH in the presence of H₂O₂. Meantime, the resulting Cu²⁺ possessed GSH-elimination property, which afforded enhanced chemodynamic therapy (CDT). Furthermore, the outer layer HA targeted to CD44 and achieved breast cancer cell targeting. The elevated temperature from PTT and acidic tumor microenvironment accelerated the release of DOX, which enabled DOX/MCN-CP-HA as an intelligent CDT-PTT-chemotherapy synergistic nanoplatform. In vitro and in vivo pharmacodynamic evaluations confirmed the potential of the nanoplatform for CDT-PTT-chemotherapy synergistic oncotherapy of breast cancer.

Biomimetic smart mesoporous carbon nanozyme as a dual-GSH depletion agent and O2 generator for enhanced photodynamic therapy

Photodynamic therapy (PDT) has been thriving in the theranostics of cancer in recent years. However, due to a series of problems such as high concentration of GSH and insufficient O₂ partial pressure in the tumor micro-environment, it is difficult to achieve the desired therapeutic effects with single PDT. Mesoporous carbon (MC-COOH) has been widely used in photothermal therapy (PTT) due to its high photothermal conversion efficiency and drug loading. In addition, we have discovered that MC-COOH owned high-efficiency glutathione oxidase-like activity for intracellular lasting GSH consumption. Hence, a smart mesoporous carbon nanozyme (CCM) was designed as a dual-GSH depletion agent and O₂ generator combined with PTT to overcome the dilemma of PDT. MnO₂-doped carbon nanozyme (MC-Mn) was developed as the photothermal vehicles for the efficient loading of photosensitizer (Ce6). Subsequently, 4T1 membrane-coated nanozyme (Ce6/CCM) was constructed to achieve homologous targeting capability. The carbon nanozyme owned the sustained dual-GSH depletion function through MC-COOH and MnO₂, which greatly destroyed the antioxidant system of the tumor. Meanwhile, MnO₂ could produce affluent O₂ in the presence of H₂O₂, thereby alleviating the hypoxic state of tumor tissues and further promoting the generation of ROS. In addition, the novel carbon nanozyme was designed as photoacoustic imaging (PAI) agent and magnetic resonance imaging (MRI) contrast for real-time imaging during tumor therapy. In summary, this work showed that the biomimetic carbon nanozyme could be used as dual-GSH depletion agent and O₂ generator for dual-mode imaging-guided PTT-PDT. STATEMENT OF SIGNIFICANCE: - MC-COOH with highly efficient GSH-OXD activity was first discovered and applied in PDT. - MnO₂ acted as an O₂ generator and GSH depletion agent to enhance PDT. - The tumor-targeting ability of the nanozyme was improved by cell membrane camouflage. - CCM nanozyme possesses both PAI and MRI dual-mode imaging modalities to guide PDT/PTT.

H2O2 generation enhancement by ultrasonic nebulisation with a zinc layer for spray disinfection

With the outbreak of COVID-19, microbial pollution has gained increasing attention as a threat to human health. Consequently, many research efforts are being devoted to the development of efficient disinfection methods. In this context, hydrogen peroxide (H₂O₂) stands out as a green and broad-spectrum disinfectant, which can be produced and sprayed in the air directly by cavitation in ultrasonic nebulisation. However, the yield of H₂O₂ obtained by ultrasonic nebulisation is too low to satisfy the requirements for disinfection by spraying and needs to be improved to achieve efficient disinfection of the air and objects. Herein, we report the introduction of a zinc layer into an ultrasonic nebuliser to improve the production of H₂O₂ and generate additional Zn²⁺ by self-corrosion, achieving good disinfecting performance. Specifically, a zinc layer was assembled on the oscillator plate of a commercial ultrasonic nebuliser, resulting in a 21-fold increase in the yield of H₂O₂ and the production of 4.75 μg/mL Zn²⁺ in the spraying droplets. When the generated water mist was used to treat a bottle polluted with Escherichia coli for 30 min, the sterilisation rate reached 93.53%. This ultrasonic nebulisation using a functional zinc layer successfully enhanced the production of H₂O₂ while generating Zn²⁺, providing a platform for the development of new methodologies of spray disinfection.

Current trends in smart mesoporous silica-based nanovehicles for photoactivated cancer therapy

Photoactivated therapeutic strategies (photothermal therapy and photodynamic therapy), due to the adjusted therapeutic area, time and light dosage, have prevailed for the fight against tumors. Currently, the monotherapy with limited treatment effect and undesired side effects is gradually replaced by multimodal and multifunctional nanosystems. Mesoporous silica nanoparticles (MSNs) with unique physicochemical advantages, such as huge specific surface area, controllable pore size and morphology, functionalized modification, satisfying biocompatibility and biodegradability, are considered as promising candidates for multimodal photoactivated cancer therapy. Excitingly, the innovative nanoplatforms based on the mesoporous silica nanoparticles provide more and more effective treatment strategies and display excellent antitumor potential. Given the rapid development of antitumor strategies based on MSNs, this review summarizes the current progress in MSNs-based photoactivated cancer therapy, mainly consists of (1) photothermal therapy-related theranostics; (2) photodynamic therapy-related theranostics; (3) multimodal synergistic therapy, such as chemo-photothermal-photodynamic therapy, phototherapy-immunotherapy and phototherapy-radio therapy. Based on the limited penetration of irradiation light in photoactivated therapy, the challenges faced by deep-seated tumor therapy are fully discussed, and future clinical translation of MSNs-based photoactivated cancer therapy are highlighted.

Polydopamine-carbon dots functionalized hollow carbon nanoplatform for fluorescence-imaging and photothermal-enhanced thermochemotherapy

The low power photothermal therapy can reduce the tissue damage caused by laser irradiation, thus the near-infrared (NIR) absorbing vehicles with high photothermal conversion efficiency are demanded in the low power treatment. Herein, the NIR-absorbing agent polydopamine (PDA) and carbon dots (CDs) were gated on the openings of hollow mesoporous carbon (HMC) to construct a photothermal enhanced multi-functional system (HMC-SS-PDA@CDs). Interestingly, the fluorescence emission wavelength of HMC-SS-PDA@CDs was red-shifted by FRET effect between PDA and CDs, which solved the dilemma of fluorescence quenching of carbon-based materials and was more conducive to cell imaging. The modification of PDA@CDs not only acts as the gatekeepers to realize multi-responsive release of pH, GSH and NIR, but also endows the HMC vehicle with excellent photothermal generation capacity, the possibility for bio-imaging as well as the enhanced stability. Naturally, both the cytological level and the multicellular tumor sphere level demonstrate that the delivery system has good low-power synergistic therapeutic with combination index (CI) of 0.348 and imaging effects. Meanwhile, the combined treatment group showed the highest tumor inhibition rate of 92.6% at 0.75 W/cm². Therefore, DOX/HMC-SS-PDA@CDs nano-platform had broad application prospects in low power therapy and convenient imaging of carbon-based materials.

Advances in Hollow Inorganic Nanomedicines for Photothermal-Based Therapies

Nanotechnology has prompted the development of hollow inorganic nanomedicine. These medicines are now widely investigated as photothermal-based therapies for various diseases due to their high loading capacity, tuneable wavelength, relatively small size and low density. We begin this review with a brief introduction, followed by a summary of the development of imaging-guided photothermal therapy (PTT) for cancer treatment during the last three years (from 2017 to 2020). We then introduce the antibacterial effects of these medicines on some bacterial infections, in which the pathogenic bacteria can be killed by mild photothermal effects, ions and antibiotic release. Other diseases can also be treated using hollow inorganic photothermal agents. Specifically, we discuss the use of PTT for treating Alzheimer's disease, obesity and endometriosis. Finally, we share our perspectives on the current challenges and future prospects of using hollow inorganic materials in clinical PTT for various diseases.

Nanoenabled Tumor Oxygenation Strategies for Overcoming Hypoxia-Associated Immunosuppression

Cancer immunotherapy, which initiates or strengthens innate immune responses to attack cancer cells, has shown great promise in cancer treatment. However, low immune response impacted by immunosuppressive tumor microenvironment (TME) remains a key challenge, which has been found related to tumor hypoxia. Recently, nanomaterial systems are proving to be excellent platforms for tumor oxygenation, which can reverse hypoxia-associated immunosuppression, strengthen the systemic antitumor immune responses, and thus afford a striking abscopal effect to clear metastatic cancer cells. In this review, we would like to survey recent progress in utilizing nanomaterials for tumor oxygenation through approaches such as in situ O₂ generation, O₂ delivery, tumor vasculature normalization, and mitochondrial-respiration inhibition. Their effects on tumor hypoxia-associated immunosuppression are highlighted. We also discuss the ongoing challenges and how to further improve the clinical prospect of cancer immunotherapy.

Nanostructured manganese dioxide for anticancer applications: preparation, diagnosis, and therapy

Nanostructured manganese dioxide (MnO₂) has attracted extensive attention in the field of anticancer applications. As we all know, the tumor microenvironment is usually characterized by a high glutathione (GSH) concentration, overproduced hydrogen peroxide (H₂O₂), acidity, and hypoxia, which affect the efficacy of many traditional treatments such as chemotherapy, radiotherapy, and surgery. Fortunately, as one kind of redox-active nanomaterial, nanostructured MnO₂ has many excellent properties such as strong oxidation ability, excellent catalytic activity, and good biodegradability. It can be used effectively in diagnosis and treatment when it reacts with some harmful substances in the tumor site. It can not only enhance the therapeutic effect but also adjust the tumor microenvironment. Therefore, it is necessary to present the recent achievements and progression of nanostructured MnO₂ for anticancer applications, including preparation methods, diagnosis, and treatment. Special attention was paid to photodynamic therapy (PDT), bioimaging and cancer diagnosis (BCD), and drug delivery systems (DDS). This review is expected to provide helpful guidance on further research of nanostructured MnO₂ for anticancer applications.

Anti-tumor evaluation of a novel methoxyphenyl substituted chlorin photosensitizer for photodynamic therapy

Photodynamic therapy (PDT) is a non-invasive and innovative therapeutic approach which has been increasingly applied in clinical cancer therapy. As the central element of PDT, the development of novel photosensitizers (PSs) with longer absorption wavelength, proper lipophilic/hydrophilic profiles, target tissue selectivity, and higher photo-/lowest dark-cytotoxicity is a challenging task. Previously, we designed and synthesized a series of novel long-wavelength chlorin e6 (Ce6)-based PSs via introducing aromatic groups to the vinyl of Ce6 skeleton. The new formed compounds with π-extension system exhibited improved photodynamic effects and spectral characteristics. Among these π-conjugated chlorin PSs, (E)-3²-(4-methoxyphenyl)-chlorin e6, named A15, was expected to be a potent antitumor candidate as a PDT agent due to its good photobiological properties. Herein, in this work, we evaluated the effectiveness of A15 in cancer PDT. In vitro, a novel rare earth probe, ATTA-Eu³⁺ was applied to detect the singlet oxygen (¹O₂) production of A15 in solution and human hepatoma HepG2 cells, respectively. Moreover, A15 exhibited strong phototoxicity and weak dark cytotoxity to HepG2 cells. In H22 tumor bearing mice, A15 showed excellent tumor accumulation ability via i.v. administration and induced tumor regression, followed by laser treatment. These results indicated that A15 is a potential novel π-extension chlorin-type PS for PDT applications.

Chitosan-capped enzyme-responsive hollow mesoporous silica nanoplatforms for colon-specific drug delivery

An enzyme-responsive colon-specific delivery system was developed based on hollow mesoporous silica spheres (HMSS) to which biodegradable chitosan (CS) was attached via cleavable azo bonds (HMSS-N=N-CS). Doxorubicin (DOX) was encapsulated in a noncrystalline state in the hollow cavity and mesopores of HMSS with the high loading amount of 35.2%. In vitro drug release proved that HMSS-N=N-CS/DOX performed enzyme-responsive drug release. The grafted CS could increase the biocompatibility and stability and reduce the protein adsorption on HMSS. Gastrointestinal mucosa irritation and cell cytotoxicity results indicated the good biocompatibility of HMSS and HMSS-N=N-CS. Cellular uptake results indicated that the uptake of DOX was obviously increased after HMSS-N=N-CS/DOX was preincubated with a colonic enzyme mixture. HMSS-N=N-CS/DOX incubated with colon enzymes showed increased cytotoxicity, and its IC₅₀ value was three times lower than that of HMSS-N=N-CS/DOX group without colon enzymes. The present work lays the foundation for subsequent research on mesoporous carriers for oral colon-specific drug delivery.