pH and Thermal Dual-Sensitive Nanoparticle-Mediated Synergistic Antitumor Effect of Immunotherapy and Microwave Thermotherapy

Magnetic Induction Heating in a Conducting Polymer for Biomedical Applications

In this study, we investigate the magnetic induction heating induced in a conducting polymer (CP) under alternative magnetic fields (AMFs). Experimental results and numerical simulations have proved that the magneto-thermal conversion of the CP is caused by the induced eddy current, which is related to the shape and intensity of the applied external AMF, and the intrinsic electrical conductivity, macrostructure and microstructure of the CP. By employing various fabrication methods, specific temperature distribution and control of thermal field within conducting polymer films and aerogels could be achieved. To exploit the potential of magnetic induction heating in CP for biomedical applications, we designed a conducting polymer aerogel-based self-adaptive heat patch and demonstrated its AMF-enabled localized heating of skin. In addition to the thermal ablation of tumor cells via magneto-thermal conversion of the CP, the promotion of neuronal differentiation at mild temperature by noninvasive magneto-electrical stimulation has also been demonstrated to be an effective strategy for tissue engineering.

Organelle-based immunotherapy strategies for fighting against cancer

Destruction of subcellular organelles can cause dysfunction and even death of cells to elicit immune responses. In this review, the characteristics and functions of important organelles are mainly summarized. Then, the intelligent immunotherapeutic strategies and suggestions based on influencing the organelles are further highlighted. This review will provide ideas for developing novel and effective immunotherapy strategies and advance the development of cancer immunotherapy.

Zwitterionic nanoparticles for thermally activated drug delivery in hyperthermia cancer treatment

Hyperthermia is considered a promising strategy to boost the curative outcome of traditional chemotherapeutic treatments. However, this thermally mediated drug delivery is still affected by important limitations. First, the poor accumulation of the conventional anticancer formulations in the target site limits the bioavailability of the active ingredient and induces off-site effects. In addition, some tumoral scenarios, such as ovarian carcinoma, are characterized by cell thermotolerance, which induces tumoral cells to activate self-protecting mechanisms against high temperatures. To overcome these constraints, we developed thermoresponsive nanoparticles (NPs) with an upper critical solution temperature (UCST) to intracellularly deliver a therapeutic payload and release it on demand through hyperthermia stimulation. These NPs were synthesized via reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization and combine polyzwitterionic stabilizing segments and an oligoester-based biodegradable core. By leveraging the pseudo-living nature of RAFT polymerization, important physicochemical properties of the NPs were controlled and optimized, including their cloud point (Tcp) and size. We have tuned the Tcp of NPs to match the therapeutic needs of hyperthermia treatments at 43 °C and tested the nanocarriers in the controlled delivery of paclitaxel, a common anticancer drug. The NPs released almost entirely the encapsulated drug only following 1 h incubation at 43 °C, whereas they retained more than 95% of the payload in the physiological environment (37 °C), thus demonstrating their efficacy as on-demand drug delivery systems. The administration of drug-loaded NPs to ovarian cancer cells led to therapeutic effects outperforming the conventional administration of non-encapsulated paclitaxel, which highlights the potential of the zwitterionic UCST-type NPs as an innovative hyperthermia-responsive drug delivery system.

An Fe-Cu bimetallic organic framework as a microwave sensitizer for treating tumors using combined microwave thermotherapy and chemodynamic therapy

Microwave thermotherapy (MWTT), as a treatment for tumors, lacks specificity and requires sensitizers. Most reported microwave sensitizers are single metal-organic frameworks (MOFs), which must be loaded with ionic liquids to enhance the performance in MWTT. Meanwhile, MWTT is rarely combined with other treatment modalities. Here, we synthesized a novel Fe-Cu bimetallic organic framework FeCuMOF (FCM) by applying a hydrothermal method and further modified it with methyl polyethylene glycol (mPEG). The obtained FCM@PEG (FCMP) showed remarkable heating performance under low-power microwave irradiation; it also acted as a novel nanospheres enzyme to catalyze H2O2 decomposition, producing abundant reactive oxygen species (ROS) to deplete glutathione (GSH) and prevent ROS clearance from tumor cells during chemodynamic treatment. The FCMP was biodegradable and demonstrated excellent biocompatibility, allowing it to be readily metabolized without causing toxic effects. Finally, it was shown to act as a suitable agent for T2 magnetic resonance imaging (MRI) in vitro and in vivo. This new bimetallic nanostructure could successfully realize two tumor treatment modalities (MWTT and chemodynamic therapy) and dual imaging modes (T2 MRI and microwave thermal imaging). Our findings represent a breakthrough for integrating the diagnosis and treatment of tumors and provides a reference for developing new microwave sensitizers.

Fe-doped Cu-based bimetallic metal-organic frameworks as nanoscale microwave sensitizers for enhancing microwave thermal and dynamic therapy for hepatocellular carcinoma

Microwave ablation (MWA) is recognized as a novel treatment modality that can kill tumor cells by heating the ions and polar molecules in these cells through high-speed rotation and friction. However, the size and location of the tumor affect the effective ablation range of microwave hyperthermia, resulting in residual tumor tissue and a high recurrence rate. Due to their tunable porous structure and high specific surface area, metal-organic frameworks (MOFs) can serve as microwave sensitizers, promoting microwave energy conversion owing to ion collisions in the porous structure of the MOFs. Moreover, iron-based compounds are known to possess peroxidase-like catalytic activity. Therefore, Fe-doped Cu bimetallic MOFs (FCMs) were prepared through a hydrothermal process. These FCM nanoparticles not only increased the efficiency of microwave-thermal energy conversion as microwave sensitizers but also promoted the generation of reactive oxygen species (ROS) by consuming glutathione (GSH) and promoted the Fenton reaction to enhance microwave dynamic therapy (MDT). The in vitro and in vivo results showed that the combination of MWA and MDT treatment effectively destroyed tumor tissues via microwave irradiation without inducing significant side effects on normal tissues. This study provides a new approach for the combined application of MOFs and microwave ablation, demonstrating excellent potential for future applications.

Microwave Encounters Ionic Liquid: Synergistic Mechanism, Synthesis and Emerging Applications

Progress in microwave (MW) energy application technology has stimulated remarkable advances in manufacturing and high-quality applications of ionic liquids (ILs) that are generally used as novel media in chemical engineering. This Review focuses on an emerging technology via the combination of MW energy and the usage of ILs, termed microwave-assisted ionic liquid (MAIL) technology. In comparison to conventional routes that rely on heat transfer through media, the contactless and unique MW heating exploits the electromagnetic wave-ions interactions to deliver energy to IL molecules, accelerating the process of material synthesis, catalytic reactions, and so on. In addition to the inherent advantages of ILs, including outstanding solubility, and well-tuned thermophysical properties, MAIL technology has exhibited great potential in process intensification to meet the requirement of efficient, economic chemical production. Here we start with an introduction to principles of MW heating, highlighting fundamental mechanisms of MW induced process intensification based on ILs. Next, the synergies of MW energy and ILs employed in materials synthesis, as well as their merits, are documented. The emerging applications of MAIL technologies are summarized in the next sections, involving tumor therapy, organic catalysis, separations, and bioconversions. Finally, the current challenges and future opportunities of this emerging technology are discussed.

Microwave-responsive gadolinium metal-organic frameworks nanosystem for MRI-guided cancer thermotherapy and synergistic immunotherapy

The clinical application of cancer immunotherapy is unsatisfied due to low response rates and systemic immune-related adverse events. Microwave hyperthermia can be used as a synergistic immunotherapy to amplify the antitumor effect. Herein, we designed a Gd-based metal-organic framework (Gd-MOF) nanosystem for MRI-guided thermotherapy and synergistic immunotherapy, which featured high performance in drug loading and tumor tissue penetration. The PD-1 inhibitor (aPD-1) was initially loaded in the porous Gd-MOF (Gd/M) nanosystem. Then, the phase change material (PCM) and the cancer cell membrane were further sequentially modified on the surface of Gd/MP to obtain Gd-MOF@aPD-1@CM (Gd/MPC). When entering the tumor microenvironment (TME), Gd/MPC induces immunogenic death of tumor cells through microwave thermal responsiveness, improves tumor suppressive immune microenvironment and further enhances anti-tumor ability of T cells by releasing aPD-1. Meanwhile, Gd/MPC can be used for contrast-enhanced MRI. Transcriptomics data revealed that the downregulation of MSK2 in cancer cells leads to the downregulation of c-fos and c-jun, and ultimately leads to the apoptosis of cancer cells after treatment. In general, Gd/MPC nanosystem not only solves the problem of system side effect, but also achieves the controlled drug release via PCM, providing a promising theranostic nanoplatform for development of cancer combination immunotherapy.

Advancements in Microwave Absorption Motivated by Interdisciplinary Research

Microwave absorption materials (MAMs) are originally developed for military purposes, but have since evolved into versatile materials with promising applications in modern technologies, including household use. Despite significant progress in bench-side research over the past decade, MAMs remain limited in their scope and have yet to be widely adopted. This review explores the history of MAMs from first-generation coatings to second-generation functional absorbers, identifies bottlenecks hindering their maturation. It also presents potential solutions such as exploring broader spatial scales, advanced characterization, introducing liquid media, utilizing novel toolbox (machine learning, ML), and proximity of lab to end-user. Additionally, it meticulously presents compelling applications of MAMs in medicine, mechanics, energy, optics, and sensing, which go beyond absorption efficiency, along with their current development status and prospects. This interdisciplinary research direction differs from previous research which primarily focused on meeting traditional requirements (i.e., thin, lightweight, wide, and strong), and can be defined as the next generation of smart absorbers. Ultimately, the effective utilization of ubiquitous electromagnetic (EM) waves, aided by third-generation MAMs, should be better aligned with future expectations.

Biomimetic inducer enabled dual ferroptosis of tumor and M2-type macrophages for enhanced tumor immunotherapy

Tumor-associated macrophages (TAMs) are abundant in the tumor microenvironment which promotes the formation of the immunosuppressive tumor microenvironment (ITME) through multiple mechanisms, severely counteracting the therapeutic efficacy of immunotherapy. In this study, a novel biomimetic ferroptosis inducer (D@FMN-M) capable of ITME regulation for enhanced cancer ferroptosis immunotherapy is reported. Upon tumor accumulation of D@FMN-M, the intratumoral mild acidity triggers the biodegradation of Fe-enriched nanocarriers and the concurrent co-releases of dihydroartemisinin (DHA) and Fe3+. The released Fe3+ is reduced to Fe2+ by consuming intratumoral glutathione (GSH), which promotes abundant free radical generation via triggering Fenton and Fe2+-DHA reactions, thus inducing ferroptosis of both cancer cells and M2-type TAMs. Resultantly, the anticancer immune response is strongly activated by the massive tumor-associated antigens released by ferroptositic cancer cells. Also importantly, the ferroptosis-sensitive M2-type TAMs will be either damaged or gradually domesticated to ferroptosis-resistant M1 TAMs under the ferroptosis stress, favoring the normalization of ITME and finally amplifying cancer ferroptosis immunotherapeutic efficacy. This work provides a novel strategy for ferroptosis immunotherapy of solid tumors featuring TAMs infiltration and immunosuppression by inducing dual ferroptosis of tumor cells and M2-type TAMs.

Biomimetic Metal-Chalcogenide Agents Enable Synergistic Cancer Therapy via Microwave Thermal-Dynamic Therapy and Immune Cell Activation

Microwave thermal dynamic therapy (MTDT), which combines thermal effects and reactive oxygen species (ROS) by microwave activation, seems to be a promising anticancer therapeutic method. A multifunctional agent for achieving synergistic localized cancer treatment is the key to exploit the strategy to inhibit tumor cell recurrence and metastasis. In the study, a ZIF-67 based theranostic agent loaded with metal-chalcogenide open framework 3 (MCOF3) and heat shock protein 70 (HSP70) as the inner component was studied, coupled with targeting cancer cell membrane (TCM) as the biomimetic outer shell. We found that metal ions in MCOF3 enabled the composite agents to show peroxide-like activity to produce •OH and destroy cancer cells. And then, the microwave (MW) thermal sensitizer of ZIF-67 was used to specifically convert the MW energy into thermal energy and selectively heat the tumor via the cell's targeting. Additionally, the effect of continuous MW thermal therapy has been shown to promote the expression of HSP70, and further activate the effector of CD4 T cell and CD8α T cell. As such, the agents effectively inhibit the tumor cell growth under MW irradiation in vitro and in vivo due to the synergistic effects of MTDT and immune cell activation. The study provides an emerging strategy to ablation cancer effectively.

Microwave-activated Cu-doped zirconium metal-organic framework for a highly effective combination of microwave dynamic and thermal therapy

Percutaneous microwave ablation (PMA) is a thermoablative method used as a minimally invasive treatment for liver cancer. However, the application of PMA is limited by its insufficient ROS generation efficiency and thermal effects. Herein, a new microwave-activated Cu-doped zirconium metal-organic framework (MOF) (CuZr MOF) used for enhanced PMA has a significantly improved microwave sensitizing effect. Owing to the strong inelastic collisions between ions confined in numerous micropores, CuZr MOF has strong microwave sensitivity and high thermal conversion efficiency, which can significantly improve microwave thermal therapy (MTT). Moreover, because of the existence of Cu2+ ions, a further benefit of CuZr MOF is their Fenton-like activity, in particular, microwaves used as an excitation source for microwave dynamic therapy (MDT) can improve the Fenton-like reaction to maximize the synergistic effectiveness of cancer therapy. Importantly, CuZr MOF can inhibit the production of heat shock proteins (HSPs) by producing abundant ROS to enhance tumor destruction. Mechanistically, we found that CuZr MOF + MW treatment modulates ferroptosis-mediated tumor cell death by targeting the HMOX1/GPX4 axis. In summary, this study develops a novel CuZr MOF microwave sensitizer with great potential for synergistic treatment of liver cancer by MTT and MDT.

Nano-engineering nanomedicines with customized functions for tumor treatment applications

Nano-engineering with unique "custom function" capability has shown great potential in solving technical difficulties of nanomaterials in tumor treatment. Through tuning the size and surface properties controllablly, nanoparticles can be endoewd with tailored structure, and then the characteristic functions to improve the therapeutic effect of nanomedicines. Based on nano-engineering, many have been carried out to advance nano-engineering nanomedicine. In this review, the main research related to cancer therapy attached to the development of nanoengineering nanomedicines has been presented as follows. Firstly, therapeutic agents that target to tumor area can exert the therapeutic effect effectively. Secondly, drug resistance of tumor cells can be overcome to enhance the efficacy. Thirdly, remodeling the immunosuppressive microenvironment makes the therapeutic agents work with the autoimmune system to eliminate the primary tumor and then prevent tumor recurrence and metastasis. Finally, the development prospects of nano-engineering nanomedicine are also outlined.

Enhancing Microwave Dynamic Effects via Surface States of Ultrasmall 2D MOF Triggered by Interface Confinement for Antibiotics-Free Therapy

Microwave (MV)-trigged dynamic therapy based on MV-responsive materials is promising for treating deep infection diseases that cannot be effectively treated by antibiotics, like life-threatening osteomyelitis. Surface states of materials affect the generation of free charges under the excitation source with energy less than the band gap, consequently influencing the MV dynamic effects. Herein, an MV responsive system with interface confined 2D metal-organic framework (2D MOF) on oxidized carbon nanotube (CNT) is prepared, in which the ultrasmall Cu-based 2D MOF possesses sufficient surface/interface defects, endowing the system a large number of surface states. Under MV irradiation, the synthesized CNT-2D MOF not only efficiently absorbs and converts the microwave into heat for microwaveocaloric therapy (MCT) via enhanced hetero-interfacial polarization, but also generates excited electrons via surface state for microwave dynamic therapy (MDT). This biocompatible CNT-2D MOF exhibits highly effective broad-spectrum antimicrobial activity against seven pathogenic bacteria, including Gram-negative and Gram-positive pathogens, under 7 min MV irradiation. And this system is proven to efficiently eradicate Staphylococcus aureus infected rabbit tibia osteomyelitis. Significantly, MV-excited MCT and MDT of CNT-CuHHTP developed in this study makes a major step forward in antibiotic-free MV therapy in deep tissue bacterial infection diseases.

Activating Nanomedicines with Electromagnetic Energy for Deep-Tissue Induction of Immunogenic Cell Death in Cancer Immunotherapy

Immunotherapy is an attractive approach for cancer therapy, while its antitumor efficacy is still limited, especially for non-immunogenic tumors. Nanomedicines can be utilized to convert the non-immunogenic "cold" tumors to immunogenic "hot" tumors via inducing immunogenic cell death (ICD), thereby promoting the antitumor immune response. Some nanomedicines that can produce local heat and reactive oxygen species upon the stimulation of electromagnetic energy are the main candidates for inducing the ICD effect. However, their applications are often restricted due to the poor tissue penetration depths of electromagnetic energy, such as light. By contrast, ultrasound, X-ray, alternating magnetic field, and microwave show excellent tissue penetration depths and thereby can be used for sonodynamic therapy, radiotherapy, magnetic hyperthermia therapy, and microwave ablation therapy, all of which can effectively induce ICD. Herein, the combination of deep-tissue electromagnetic energy with nanomedicines for inducing ICD and cancer immunotherapy are summarized. In particular, the designs of nanomedicines to amplify ICD effect in the presence of deep-tissue electromagnetic energy and sensitize tumors to various immunotherapies will be discussed. At the end of this review, a brief conclusion and discussion of current challenges and further perspectives in this subfield are provided.

The combination of eddy thermal effect of biodegradable magnesium with immune checkpoint blockade shows enhanced efficacy against osteosarcoma

Osteosarcoma (OS) patients have a poor prognosis due to its high degree of heterogeneity and high rate of metastasis. Magnetic hyperthermia therapy (MHT) combined with immunotherapy is an effective strategy to treat solid and metastatic tumors. Here, we combined biodegradable magnesium (Mg) macroscale rods, which acted as an eddy thermo-magnetic agent under a low external alternating magnetic field, and immunotherapy to achieve a radical cure for OS. The eddy thermal effect (ETE) of the Mg rods (MgR) showed outstanding cytotoxic effects and enhanced the maturation of dendritic cells (DCs), and the mild MHT induced the immunogenic cell death (ICD) in the OS cells. Combined with immune checkpoint blockade (ICB) therapy, we obtained an excellent curative effect against OS, and a further evaluation demonstrated that the local MHT induced by the MgR increased T cells infiltration and the polarization of M1 macrophages. Interestingly, the biodegradable MgR also promoted bone osteogenesis. Our work highlighted the uneven ETE mediated by the biodegradable MgR induced a comprehensive immunologic activation in the OS tumor microenvironment (TME), which would inspire the application of MHT for the effective treatment of OS.

Inducing Autophagy and Blocking Autophagic Flux via a Virus-Mimicking Nanodrug for Cancer Therapy

Maximizing the therapeutic capacity of drugs by allowing them to escape lysosomal degradation is a long-term challenge for nanodrug delivery. Japanese encephalitis virus (JEV) has evolved the ability to escape the endosomal region to avoid degradation of internal genetic material by lysosomes and further induce upregulation of cellular autophagy for the purpose of their mass reproduction. In this work, to exploit the lysosome escape and autophagy-inducing properties of JEV for cancer therapy, we constructed a virus-mimicking nanodrug consisting of anti-PDL1 antibody-decorated JEV-mimicking virosome encapsulated with a clinically available autophagy inhibitor, hydroxychloroquine (HCQ). Our study indicated that the nanodrug can upregulate the autophagy level and inhibit the autophagic flux, thereby inducing the apoptosis of tumor cells, and further activating the immune response, which can greatly improve the antitumor and tumor metastasis suppression effects and provide a potential therapeutic strategy for tumor treatment.

Nanotherapeutics for immune network modulation in tumor microenvironments

Immunotherapy has shown promise in cancer treatment, and is thus drawing increasing interest in this field. While the standard chemotherapy- and/or radiotherapy-based cancer treatments aim to directly kill cancer cells, immunotherapy uses host immune cell surveillance to fight cancer. In the tumor environment, there is a close relationship between tumor cells and the adjacent immune cells, which are largely suppressed by cancer-related regulation of immune checkpoints, immune-suppressive cytokines, and metabolic factors. The immune modulators currently approved for cancer treatment remain limited by issues with dose tolerance and insufficient efficacy. Researchers have developed and tested various nano-delivery systems with the goal of improving the treatment outcome of these drugs. By encapsulating immune modulators in particles and directing their tissue accumulation, some such systems have decreased immune-related toxicity while sharpening the antitumor response. Surface-ligand modification of nanoparticles has allowed drugs to be delivered to specific immune cells types. Researchers have also studied strategies for depleting or reprogramming the immune-suppressive cells to recover the immune environment. Combining a nanomaterial with an external stimulus has been used to induce immunogenic cell death; this favors the inflammatory environment found in tumor tissues to promote antitumor immunity. The present review covers the most recent strategies aimed at modulating the tumor immune environment, and discusses the challenges and future perspectives in developing nanoparticles for cancer immunotherapy.

Applications of phase change materials in smart drug delivery for cancer treatment

Phase change materials (PCMs) are materials that are stimulated by the external enthalpy change (temperature) to realize solid-liquid and liquid-solid phase transformation. Due to temperature sensitivity, friendly modification, and low toxicity, PCMs have been widely used in smart drug delivery. More often than not, the drug was encapsulated in a solid PCMs matrix, a thermally responsive material. After the trigger implementation, PCMs change into a solid-liquid phase, and the loading drug is released accordingly. Therefore, PCMs can achieve precise release control with different temperature adjustments, which is especially important for small molecular drugs with severe side effects. The combination of drug therapy and hyperthermia through PCMs can achieve more accurate and effective treatment of tumor target areas. This study briefly summarizes the latest developments on PCMs as smart gate-keepers for anti-tumor applications in light of PCMs becoming a research hot spot in the nanomedicine sector in recent years.

Micro-Opening Ridged Waveguide Tumor Hyperthermia Antenna Combined with Microwave-Sensitive MOF Material for Tumor Microwave Hyperthermia Therapy

Microwave hyperthermia is an emerging minimally invasive therapy in which thermal damage and apoptosis of tumor cells are induced by local heating of tissues with microwave radiation. Recently, microwave hyperthermia has been widely used in clinical practice; however, uneven aggregation and dispersion of malignant tumors after microwave hyperthermia are the main problems associated with this method. In this work, a microridged waveguide tumor hyperthermia antenna with an operating frequency of 915 MHz was designed. Although its volume is only 6.6 cm3, it exhibited a highly focused heating effect, achieving rapid heating in a small area. However, microwave hyperthermia has several shortcomings. Microwaves cannot specifically identify and target tumors; this decreases the efficiency of the treatment if the temperature of the tumor site is not sufficiently high for its size and location. Therefore, Zr metal-organic framework (ZrMOF)-derived composite ZCNC was synthesized using the ultrasonic aerosol flow method, which has good microwave sensitization and biosafety. ZCNC reduced the damage to normal cells and greatly improved the tumor treatment effect of microwave hyperthermia (tumor inhibition rate reached 78.01%). Thus, the proposed strategy effectively improves the current clinical microwave hyperthermia treatment method.

ICAM-1 targeted thermal-sensitive micelles loaded with tofacitinib for enhanced treatment of rheumatoid arthritis via microwave assistance

Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease without effective treatment. Tofacitinib (TOF) is a JAK inhibitor that can be used for RA therapy, but it still faces the problems of nonspecific distribution and relatively low therapeutic effect. Herein, ICAM-1-modified TOF-loaded P(AN-co-AAm)-PEG micelles (AI-TM) were developed, which can result in an enhanced RA therapy when combining with microwave hyperthermia (MH). It was found that AI-TM could rapidly release the encapsulated TOF under a thermal condition of >43 °C, which was due to the fact that the polymeric micelles has an upper critical solution temperature (UCST) of 43 °C. AI-TM could specifically distribute into the inflamed joints of RA mice, which is associated with the high affinity between anti-ICAM-1 and overexpressed ICAM-1 receptors. Moreover, the combination of AI-TM and MH could result in a remarkably enhanced anti-rheumatic activity, which was related to the RA-targeted ability of AI-TM, the rapid TOF release under MH, and the combined effect between TOF and MH treatment. Our study definitely provides a novel strategy for effective treatment of RA.

Self-assembly and disassembly mechanisms of biomimetic peptides: Molecular dynamics simulation and experimental measurement

Drug-loaded pH-responsive nanoparticles are potential drug carriers in nanotherapeutics delivery because they can remain stable in normal tissues but can disassemble and release drug molecules in tumors. In this study, the mechanisms of self-assembly and disassembly were investigated by analyzing the characteristics of three kinds of biomimetic peptides with different components and sequences. The structural parameters and energy changes during self-assembly and disassembly were calculated by molecular dynamics simulation. Transmission electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy were used to observe morphological changes and measure the strength of hydrophobic and hydrophilic interactions between peptides. Results show that the hydrophobic and hydrophilic interactions play crucial roles in the self-assembly and disassembly processes of peptides. The structure of the peptide clusters after self-assembly became tighter as the difference between hydrophobic and hydrophilic interactions increased, whereas a decrease in this difference led to the increased disassembly of the peptides. In general, polyethylene glycol chain modification was necessary in disassembly, and peptides with straight structures had stronger disassembly ability than that with branched structures with the same components. The morphology of peptide clusters can be controlled under different pH values by changing the composition and structure of the peptides for enhanced drug retention and sustained release.

Lanthanide europium MOF nanocomposite as the theranostic nanoplatform for microwave thermo-chemotherapy and fluorescence imaging

Backgrounds

Microwave sensitization nanoplatform, integrating multiple functional units for improving tumor selectivity, is of great significance for clinical tumor microwave treatment. Lanthanide europium metal organic framework (EuMOF) is expected to be a theranostic nanoplatform owing to its unique luminescent and microwave sensitization properties. However, it is difficult to be applied to complicated biological systems for EuMOF due to its rapid degradation induced by the solvent molecular and ionic environment. In this work, a luminescent EuMOF nanocomposite (EuMOF@ZIF/AP-PEG, named EZAP) was designed, which brought the multifunctional characteristics of microwave sensitization, fluorescence imaging and drug loading.

Results

Lamellar EuMOF was synthesized by a hydrothermal method. Through the charge adsorption mechanism, the zeolite imidazole framework (ZIF) structure was intensively assembled on the surface of EuMOF to realize the protection. Then, through in-situ Apatinib drug loading and PEG modification, EZAP nanocomposite was finally obtained. Apatinib (AP) was a kind of chemotherapy drug approved by Food and Drug Administration for targeted therapy of tumors. PEG modification increased long-term circulation of EZAP nanocomposite. The physical and chemical structure and properties of EuMOF@ZIF (EZ) were systematically represented, indicating the successful synthesis of the nanocomposite. The toxic and side effects were negligible at a safe dose. The growth of human liver cancer cells and murine liver cancer cells in vitro was significantly inhibited, and the combined microwave-thermal therapy and chemotherapy in vivo achieved high anti-cancer efficacy. Moreover, EZAP nanocomposite possessed bright red fluorescence, which can be applied for tumor imaging in tumor-bearing mice in vivo.

Conclusion

Therefore, EZAP nanocomposite showed high microwave sensitization, excellent fluorescence properties and outstanding drug loading capacity, establishing a promising theranostic nanoplatform for tumor therapy and fluorescence imaging. This work proposes a unique strategy to design for the first time a multifunctional nanoplatform with lanthanide metal organic frameworks for biological applications in tumor therapy and diagnosis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01335-7.

Stimuli-Responsive Nanoparticles for Controlled Drug Delivery in Synergistic Cancer Immunotherapy

Cancer immunotherapy has achieved promising clinical progress over the recent years for its potential to treat metastatic tumors and inhibit their recurrences effectively. However, low patient response rates and dose-limiting toxicity remain as major dilemmas for immunotherapy. Stimuli-responsive nanoparticles (srNPs) combined with immunotherapy offer the possibility to amplify anti-tumor immune responses, where the weak acidity, high concentration of glutathione, overexpressions of enzymes, and reactive oxygen species, and external stimuli in tumors act as triggers for controlled drug release. This review highlights the design of srNPs based on tumor microenvironment and/or external stimuli to combine with different anti-tumor drugs, especially the immunoregulatory agents, which eventually realize synergistic immunotherapy of malignant primary or metastatic tumors and acquire a long-term immune memory to prevent tumor recurrence. The authors hope that this review can provide theoretical guidance for the construction and clinical transformation of smart srNPs for controlled drug delivery in synergistic cancer immunotherapy.

Synergistic Cascade Strategy Based on Modifying Tumor Microenvironment for Enhanced Breast Cancer Therapy

Background: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with very few treatment options. Although tumor-targeted nanomedicines hold great promise for the treatment of TNBC, the tumor microenvironment (TME) continues to be a major cause of failure in nanotherapy and immunotherapy. To overcome this barrier, we designed a new synergistic cascade strategy (SCS) that uses mild hyperthermia and smart drug delivery system (SDDS) to alter TME resistance in order to improve drug delivery and therapeutic efficacy of TNBC. Methods: Mild hyperthermia was produced by microwave (MW) irradiation. SDDS were formulated with thermosensitive polymer-lipid nanoparticles (HA-BNPs@Ptx), composed of polymer PLGA, phospholipid DPPC, hyaluronic acid (HA, a differentiation-44-targeted molecule, also known as CD44), 1-butyl-3-methylimidazolium-L-lactate (BML, a MW sensitizer), and paclitaxel (Ptx, chemotherapy drug). 4T1 breast tumor-bearing mice were treated with two-step MW combined with HA-BNPs@Ptx. Tumors in mice were pretreated with first MW irradiation prior to nanoparticle injection to modify and promote TME and promoting nanoparticle uptake and retention. The second MW irradiation was performed on the tumor 24 h after the injection of HA-BNPs@Ptx to produce a synergistic cascade effect through activating BML, thus, enhancing a hyperthermia effect, and instantly releasing Ptx at the tumor site. Results: Multifunctional CD44-targeted nanoparticles HA-BNPs@Ptx were successfully prepared and validated in vitro. After the first MW irradiation of tumors in mice, the intratumoral perfusion increased by two times, and the nanoparticle uptake was augmented by seven times. With the second MW irradiation, remarkable antitumor effects were obtained with the inhibition rate up to 88%. In addition, immunohistochemical analysis showed that SCS therapy could not only promote tumor cell apoptosis but also significantly reduce lung metastasis. Conclusion: The SCS using mild hyperthermia combined with SDDS can significantly improve the efficacy of TNBC treatment in mice by modifying TME and hyperthermia-mediated EPR effects.

Laser/GSH-Activatable Oxaliplatin/Phthalocyanine-Based Coordination Polymer Nanoparticles Combining Chemophotodynamic Therapy to Improve Cancer Immunotherapy

There are two severe obstacles in cancer immunotherapy. The first is that the low response rate challenges the immune response owing to the immunosuppressive tumor microenvironment (ITM) and poor immunogenicity of the tumor. The second obstacle is that the dense and intricate pathophysiology barrier seriously restricts deep drug delivery in solid tumors. A laser/glutathione (GSH)-activatable nanosystem with tumor penetration for achieving highly efficient immunotherapy is reported. The core of the nanosystem was synthesized by coordinating zinc ions with GSH-activatable oxaliplatin (OXA) prodrugs and carboxylated phthalocyanine. Such an OXA/phthalocyanine-based coordination polymer nanoparticle (OPCPN) was wrapped by a phospholipid bilayer and NTKPEG. NTKPEG is a PEGylated indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor prodrug containing a thioketal (TK) linker, which was modified on the OPCPN (OPCPN@NTKPEG). Upon the laser irradiation tumor site, ROS production of the OPCPN@NTKPEG triggers cleavage of NTKPEG by degradation of TK for promoted tumor penetration and uptake. OXA, phthalocyanine, and IDO1 inhibitor were released by the intracellular high-level GSH. OXA inhibits cell growth and is combined with photodynamic therapy (PDT) to induce immunogenic cell death (ICD). The IDO1 inhibitor reversed the ITM by suppressing IDO1-mediated Trp degradation and exhaustion of cytotoxic T cells. Laser/GSH-activatable drug delivery was more conducive to enhancing ICD and reversing ITM in deep tumors. Chemo-PDT with OPCPN@NTKPEG significantly regressed tumor growth and reduced metastasis by improved cancer immunotherapy.

Rediscovery of nanoparticle-based therapeutics: boosting immunogenic cell death for potential application in cancer immunotherapy

Immunogenic cell death (ICD) occurring by chemical and physical stimuli has shown the potential to activate an adaptive immune response in the immune-competent living body through the release of danger-associated molecular patterns (DAMPs) into the tumor microenvironment (TME). However, limitations to the long-term immune responses and systemic toxicity of conventional ICD inducers have led to unsatisfactory therapeutic efficacy in ICD-based cancer immunotherapy. Until now, various nanoparticle-based ICD-inducers have been developed to induce an antitumor immune response without severe toxicity, and to efficiently elicit an anticancer immune response against target cancer cells. In this review, we introduce a recent advance in the designs and applications of nanoparticle-based therapeutics to elicit ICD for effective cancer immunotherapy. In particular, combination strategies of nanoparticle-based ICD inducers with typical theranostic modalities are introduced intensively. Subsequently, we discuss the expected challenges and future direction of nanoparticle-based ICD inducers to provide strategies for boosting ICD in cancer immunotherapy. These versatile designs and applications of nanoparticle-based therapeutics for ICD can provide advantages to improve the therapeutic efficacy of cancer immunotherapy.

Synergistic effect of tumor chemo-immunotherapy induced by leukocyte-hitchhiking thermal-sensitive micelles

Some specific chemotherapeutic drugs are able to enhance tumor immunogenicity and facilitate antitumor immunity by inducing immunogenic cell death (ICD). However, tumor immunosuppression induced by the adenosine pathway hampers this effect. In this study, E-selectin-modified thermal-sensitive micelles are designed to co-deliver a chemotherapeutic drug (doxorubicin, DOX) and an A2A adenosine receptor antagonist (SCH 58261), which simultaneously exhibit chemo-immunotherapeutic effects when applied with microwave irradiation. After intravenous injection, the fabricated micelles effectively adhere to the surface of leukocytes in peripheral blood mediated by E-selectin, and thereby hitchhiking with leukocytes to achieve a higher accumulation at the tumor site. Further, local microwave irradiation is applied to induce hyperthermia and accelerates the release rate of drugs from micelles. Rapidly released DOX induces tumor ICD and elicits tumor-specific immunity, while SCH 58261 alleviates immunosuppression caused by the adenosine pathway, further enhancing DOX-induced antitumor immunity. In conclusion, this study presents a strategy to increase the tumor accumulation of drugs by hitchhiking with leukocytes, and the synergistic strategy of chemo-immunotherapy not only effectively arrested primary tumor growth, but also exhibited superior effects in terms of antimetastasis, antirecurrence and antirechallenge.

Targeting the adenosinergic pathway represents a therapeutic option to overcome tumor-induced immunosuppression. Here the authors design E-selectin-modified thermal-sensitive micelles loaded with doxorubicin and an adenosine A2 receptor antagonist to enhance chemotherapy-induced anti-tumor immune responses.

Recent Advances in Engineered Materials for Immunotherapy-Involved Combination Cancer Therapy

Immunotherapy that can activate immunity or enhance the immunogenicity of tumors has emerged as one of the most effective methods for cancer therapy. Nevertheless, single-mode immunotherapy is still confronted with several critical challenges, such as the low immune response, the low tumor infiltration, and the complex immunosuppression tumor microenvironment. Recently, the combination of immunotherapy with other therapeutic modalities has emerged as a powerful strategy to augment the therapeutic outcome in fighting against cancer. In this review, recent research advances of the combination of immunotherapy with chemotherapy, phototherapy, radiotherapy, sonodynamic therapy, metabolic therapy, and microwave thermotherapy are summarized. Critical challenges and future research direction of immunotherapy-based cancer therapeutic strategy are also discussed.

Nanomaterials responding to microwaves: an emerging field for imaging and therapy

In recent years, new microwave-based imaging, sensing and hyperthermia applications have emerged in the field of diagnostics and therapy. For diagnosis, this technology involves the application of low power microwaves, utilising contrast between the relative permittivity of tissues to identify pathologies. This contrast can be further enhanced through the implementation of nanomaterials. For therapy, this technology can be applied in tissues either through hyperthermia, which can help anti-cancer drug tumour penetration or as ablation to destroy malignant tissues. Nanomaterials can absorb electromagnetic radiation and can enhance the microwave hyperthermic effect. In this review we aim to introduce this area of renewed interest and provide insights into current developments in its technologies and companion nanoparticles, as well as presenting an overview of applications for diagnosis and therapy.

Refining the Design of Diblock Elastin-Like Polypeptides for Self-Assembly into Nanoparticles

Diblock copolymers based-on elastin-like polypeptide (ELP) have the potential to undergo specific phase transitions when thermally stimulated. This ability is especially suitable to form carriers, micellar structures for instance, for delivering active cargo molecules. Here, we report the design and study of an ELP diblock library based on ELP-[M1V3-i]-[I-j]. First, ELP-[M1V3-i]-[I-j] (i = 20, 40, 60; j = 20, 90) that showed a similar self-assembly propensity (unimer-to-aggregate transition) as their related monoblocks ELP-[M1V3-i] and ELP-[I-j]. By selectively oxidizing methionines of ELP-[M1V3-i] within the different diblocks structures, we have been able to access a thermal phase transition with three distinct regimes (unimers, micelles, aggregates) characteristic of well-defined ELP diblocks.

Combination Cancer Immunotherapy of Nanoparticle-Based Immunogenic Cell Death Inducers and Immune Checkpoint Inhibitors

Cancer immunotherapy is a promising treatment strategy that aims to strengthen immune responses against cancer. However, the low immunogenicity of tumor cells and inhibition of effector T cells in the tumor immunosuppressive microenvironment remain two major challenges. Immunogenic cell death (ICD) inducers not only directly kill cancer cells but also increase the tumor immunogenicity and induce antitumor immune responses. Immune checkpoint inhibitors can alleviate the inhibition of immune cells. Significantly, the combination of ICD inducers and immune checkpoint inhibitors elicits a remarkable antitumor effect. Nanoparticles confer the ability to modulate systemic biodistribution and achieve targeted accumulation of administered therapeutic agents, thereby facilitating the clinical translation of immunotherapies based on ICD inducers in a safe and effective manner. In this review, we summarize the nanoparticle-based chemical and physical cues that induce effective tumor ICD and elicit an antitumor immune response. In particular, combination of ICD inducers with immune checkpoint inhibitors can further reverse immunosuppression and prevent tumor metastasis and recurrence. An overview of the future challenges and prospects is also provided.

A Review of Bioactive Peptides: Chemical Modification, Structural Characterization and Therapeutic Applications

In recent years, the development and applications of protein drugs have attracted extensive attention from researchers. However, the shortcomings of protein drugs also limit their further development. Therefore, bioactive peptides isolated or simulated from protein polymers have broad application prospects in food, medicine, biotechnology, and other industries. Such peptides have a molecular weight distribution between 180 and 1000 Da. As a small molecule substance, bioactive peptide is usually degraded by various enzymes in the organism and have a short half-life. At the same time, such substances have poor stability and are difficult to produce and store. Therefore, these active peptides may be modified through phosphorylation, glycosylation, and acylation. Compared with other protein drugs, the modified active peptides are more easily absorbed by the body, have longer half-life, stronger targeting, and fewer side effects in addition to higher bioavailability. In the light of their functions, bioactive peptide can be divided into antimicrobial, anti-tumour, anti-angiogenic, antioxidant, anti-fatigue, and anti-hypertensive peptides. This article mainly focuses on the introduction of several promising biologically active peptides functioning as antimicrobial, anti-tumour, antiangiogenic, and antioxidant peptides from the three aspects modification, structural characteristics and mechanism of action.

Recent advances in nanosized metal organic frameworks for drug delivery and tumor therapy

Metal organic-frameworks (MOFs) are novel materials that have attracted increasing attention for applications in a wide range of research, owing to their unique advantages including their small particle size, porous framework structure and high specific surface area. Because of their adjustable size, nanoscale MOFs (nano-MOFs) can be prepared as carriers of biotherapy drugs, thus enabling biotherapeutic applications. Nano-MOFs' metal ion catalytic activity and organic group functional characteristics can be exploited in biological treatments. Furthermore, the applications of nano-MOFs can be broadened by hybridization with other materials to form composites. This review focuses on the preparation and recent advances in nano-MOFs as drug carriers, therapeutic materials and functionalized materials in drug delivery and tumor therapy based on the single/multiple stimulus response of drug release to achieve the targeted therapy, offering a comprehensive reference for drug carrier design. At the end, the current challenges and prospects are discussed to provide significant insight into the design and applications of nano-MOFs in drug delivery and tumor therapy.

Treatment of MRSA-infected osteomyelitis using bacterial capturing, magnetically targeted composites with microwave-assisted bacterial killing

Owing to the poor penetration depth of light, phototherapy, including photothermal and photodynamic therapies, remains severely ineffective in treating deep tissue infections such as methicillin-resistant Staphylococcus aureus (MRSA)-infected osteomyelitis. Here, we report a microwave-excited antibacterial nanocapturer system for treating deep tissue infections that consists of microwave-responsive Fe₃O₄/CNT and the chemotherapy agent gentamicin (Gent). This system, Fe₃O₄/CNT/Gent, is proven to efficiently target and eradicate MRSA-infected rabbit tibia osteomyelitis. Its robust antibacterial effectiveness is attributed to the precise bacteria-capturing ability and magnetic targeting of the nanocapturer, as well as the subsequent synergistic effects of precise microwaveocaloric therapy from Fe₃O₄/CNT and chemotherapy from the effective release of antibiotics in infection sites. The advanced target-nanocapturer of microwave-excited microwaveocaloric-chemotherapy with effective targeting developed in this study makes a major step forward in microwave therapy for deep tissue infections.

Deep tissue infections can be difficult to treat due to limited light penetration associated with phototherapies. Here, the authors report on a bacterial capture system for antibiotic delivery and microwave-assisted killing of MRSA in osteomyelitis and demonstrate application in vivo.

Cytotoxic and antitumor peptides as novel chemotherapeutics

Covering: up to 2020Treatment resistance and drug-induced refractory malignancies pose significant challenges for current chemotherapy drugs. There have been increasing research efforts aimed at developing novel chemotherapeutics, especially from natural products and related derivatives. Natural cytotoxic peptides, an emerging source of chemotherapeutics, have exhibited the advantage of overcoming drug resistance and displayed broad-spectrum antitumor activities in the clinic. This highlight examines the increasingly popular cytotoxic peptides from isolated natural products. In-depth review of several peptides provides examples for how this novel strategy can lead to the improved anti-tumor effects. The mechanisms and current application of representative natural cytotoxic peptides (NCPs) have also been discussed, with a particular focus on future directions for interdisciplinary research.

Rationally Designed Polymer Conjugate for Tumor-Specific Amplification of Oxidative Stress and Boosting Antitumor Immunity

The crosstalk between tumor and stroma cells is a central scenario in the tumor microenvironment (TME). While the predominant effect of tumor cells on immune cells is establishing an immunosuppressive context, tumor cell death at certain conditions will boost antitumor immunity. Herein, we report a rationally designed tumor specific enhanced oxidative stress polymer conjugate (TSEOP) for boosting antitumor immunity. The TSEOP is prepared by Passerini reaction between cinnamaldehyde (CA), 4-formylbenzeneboronic acid pinacol ester, and 5-isocyanopent-1-yne, followed by azide-alkyne click reaction with poly(l-glutamic acid)-graft-poly(ethylene glycol) monomethyl ether (PLG-g-mPEG). Under tumor stimuli condition, CA and quinone methide (QM) are quickly generated, which cooperatively induce strong oxidative stress, immunogenic tumor cell death (ICD), and activation of antigen presenting cells. In vivo studies show that the TSEOP treatment boosts tumor-specific antitumor immunity and eradicates both murine colorectal and breast tumors. This study should be inspirational for designing polymers as immunotherapeutics in cancer therapy.

Tumor immune microenvironment modulation-based drug delivery strategies for cancer immunotherapy

The past years have witnessed promising clinical feedback for anti-cancer immunotherapies, which have become one of the hot research topics; however, they are limited by poor delivery kinetics, narrow patient response profiles, and systemic side effects. To the best of our knowledge, the development of cancer is highly associated with the immune system, especially the tumor immune microenvironment (TIME). Based on the comprehensive understanding of the complexity and diversity of TIME, drug delivery strategies focused on the modulation of TIME can be of great significance for directing and improving cancer immunotherapy. This review highlights the TIME modulation in cancer immunotherapy and summarizes the versatile TIME modulation-based cancer immunotherapeutic strategies, medicative principles and accessory biotechniques for further clinical transformation. Remarkably, the recent advances of cancer immunotherapeutic drug delivery systems and future prospects of TIME modulation-based drug delivery systems for much more controlled and precise cancer immunotherapy will be emphatically discussed.