Nano-Engineering Strategies for Tumor-Specific Therapy.

Nanodelivery systems (NDSs) provide promising prospects for decreasing drug doses, reducing side effects, and improving therapeutic effects. However, the bioapplications of NDSs are still compromised by their fast clearance, indiscriminate biodistribution, and limited tumor accumulation. Hence, engineering modification of NDSs aiming at promoting tumor-specific therapy and avoiding systemic toxicity is usually needed. An NDS integrating various functionalities, including flexible camouflage, specific biorecognition, and sensitive stimuli-responsiveness, into one sequence would be "smart" and highly effective. Herein, we systematically summarize the related principles, methods, and progress. At the end of the review, we predict the obstacles to precise nanoengineering and prospects for the future application of NDSs.

Metal-polyphenol "prison" attenuated bacterial outer membrane vesicle for chemodynamics promoted in situ tumor vaccines.

As natural adjuvants, the bacterial outer membrane vesicles (OMV) hold great potential in cancer vaccines. However, the inherent immunotoxicity of OMV and the rarity of tumor-specific antigens seriously hamper the clinical translation of OMV-based cancer vaccines. Herein, metal-phenolic networks (MPNs) are used to attenuate the toxicity of OMV, meanwhile, provide tumor antigens via the chemodynamic effect induced immunogenic cell death (ICD). Specifically, MPNs are assembled on the OMV surface through the coordination reaction between ferric ions and tannic acid. The iron-based "prison" is locally collapsed in the tumor microenvironment (TME) with both low pH and high ATP features, and thus the systemic toxicity of OMV is significantly attenuated. The released ferric ions in TME promote the ICD of cancer cells through Fenton reaction and then the generation of abundant tumor antigens, which can be used to fabricate in-situ vaccines by converging with OMV. Together with the immunomodulatory effect of OMV, potent tumor repression on a bilateral tumor model is achieved with good biosafety.

Monitoring the Cascade of Tumor-specific Immune Response in vivo via Chemoenzymatic Proximity Labeling.

Monitoring the highly dynamic and complex immune response remains a great challenge owing to the lack of reliable and specific approaches. Here, we develop a strategy to monitor the cascade of tumor immune response through the cooperation of pore-forming alginate gel with chemoenzymatic proximity-labeling. A macroporous gel containing tumor-associated antigens, adjuvants, and pro-inflammatory cytokines is utilized to recruit endogenous DCs and enhance their maturation in vivo. The mature DCs are then modified with GDP-fucose-fucosyltransferase (GDP-Fuc-Fuct) via the self-catalysis of fucosyltransferase (Fuct). Following the migration of the obtained Fuct-DCs to the draining lymph nodes (dLNs), the molecular recognition mediated interaction of DCs and T cells leads to the successful decoration of T cells with GDP-Fuc-azide through the Fuct catalyzed proximity-labeling. Therefore, the activated tumor-specific T cells in dLNs and tumors can be identified through bioorthogonal labeling, opening up a new avenue for studying the immune mechanism of tumors in situ.

Biomimetic Nanovesicle with Mitochondria-Synthesized Sonosensitizer and Mitophagy Inhibition for Cancer Sono-Immunotherapy.

Mitochondria are crucial for both sonodynamic therapy and antitumor immunity. However, how to accurately damage mitochondria and meanwhile prevent the mitophagy and immune checkpoint inhibition is still a great challenge. Herein, hexyl 5-aminolevulinate hydrochloride (HAL) and 3-methyladenine (3MA) are loaded into the tumor cell-derived microparticle (X-MP), which can direct the target delivery of the prepared HAL/3MA@X-MP to the tumor cells. HAL induces the confined biosynthesis and accumulation of sonosensitizer PpIX in mitochondria, leading to the localized generation of reactive oxygen species (ROS) upon ultrasound irradiation and, thus, the efficient mitochondrial damage. Meanwhile, 3MA not only inhibits mitophagy but also down-regulates the PD-L1 expression, promoting the immunogenic cell death (ICD) while blocking the immune checkpoint recognition. The smart synergism of precise mitochondrial damage, mitophagy inhibition and antitumor immunity results in potent therapeutic efficacy without obvious side effects.

Bacterial outer membrane vesicle based versatile nanosystem boosts the efferocytosis blockade triggered tumor-specific immunity.

Efferocytosis inhibition is emerging as an attractive strategy for antitumor immune therapy because of the subsequent leak of abundant immunogenic contents. However, the practical efficacy is seriously impeded by the immunosuppressive tumor microenvironments. Here, we construct a versatile nanosystem that can not only inhibit the efferocytosis but also boost the following antitumor immunity. MerTK inhibitor UNC2025 is loaded into the bacterial outer membrane vesicles (OMVs), which are then modified with maleimide (mU@OMVs). The prepared mU@OMVs effectively inhibits the efferocytosis by promoting the uptake while preventing the MerTK phosphorylation of tumor associated macrophages, and then captures the released antigens through forming universal thioether bonds. The obtained in situ vaccine effectively transfers to lymph nodes by virtue of the intrinsic features of OMVs, and then provokes intense immune responses that can efficiently prevent the growth, metastasis and recurrence of tumors in mice, providing a generalizable strategy for cancer immunotherapy.

In Vivo Imaging for the Visualization of Extracellular Vesicle-Based Tumor Therapy.

Extracellular vesicles (EVs) exhibiting versatile biological functions provide promising prospects as natural therapeutic agents and drug delivery vehicles. For future clinical translation, revealing the fate of EVs in vivo, especially their accumulation at lesion sites, is very important. The continuous development of in vivo imaging technology has made it possible to track the real-time distribution of EVs. This article reviews the applications of mammal-, plant-, and bacteria-derived EVs in tumor therapy, the labeling methods of EVs for in vivo imaging, the advantages and disadvantages of different imaging techniques, and possible improvements for future work.

Phytochemical natural killer cells reprogram tumor microenvironment for potent immunotherapy of solid tumors.

Natural killer cells (NKs) hold great promise in cancer treatment, but their application in solid tumors remains a great challenge because current solutions hardly can overcome various difficulties that faced. Herein, we endow NKs with the phytochemical feature for effective immunotherapy of solid tumors. NKs are decorated with natural thylakoid (Tk) membranes through an efficient and convenient membrane fusion strategy. Tk engineering effectively activates NKs, because the antioxidase on Tk induce glycogen synthase kinase-3ß inhibition, and subsequently increase the expression of activating receptor and cytotoxic effector molecules in NKs. After systemic administration, the phytochemical NKs (PC-NKs) can target tumor tissues, and then profoundly reprogram tumor microenvironment (TME) with the help of catalase on Tk, resulting in significantly enhanced direct killing of PC-NKs and immune activated TME. Therefore, potent therapeutic effects with few abnormalities are achieved, providing a novel idea for the development of highly efficient NKs for solid tumors.

Study on the coupling coordination mechanism of green technology innovation, environmental regulation, and green finance.

Green technology innovation is the basic driving force of green economic development. The compatibility of the composite system composed of green technology innovation, green finance, and environmental regulation is the decisive factor of whether regional economy can achieve sustainable development. Based on the data of regional green technology innovation in China from 2012 to 2020, this paper discusses the coupling coordination mechanism and coupling coordination level among green technology innovation, green finance, and environmental regulation based on entropy method. It is found that the coupling and coordinated development of regional green technology innovation-green finance-environmental regulation system in China is above medium level. However, there is a big gap in the coupling coordination level among different regions. The coupling coordination level in eastern China is relatively high, and the coupling coordination level in other regions is deviated. Most regions of China have a great potential for improvement. On this basis, this paper puts forward policy suggestions for improving the overall coupling and coordination level of the system to promote national green development.

Phytochemical Engineered Bacterial Outer Membrane Vesicles for Photodynamic Effects Promoted Immunotherapy.

Cancer vaccines are emerging as an attractive modality for tumor immunotherapy. However, their practical application is seriously impeded by the complex fabrication and unsatisfactory outcomes. Herein, we construct bacterial outer membrane vesicles (OMVs)-based in situ cancer vaccine with phytochemical features for photodynamic effects-promoted immunotherapy. By simply fusing thylakoid membranes with OMVs, bacteria-plant hybrid vesicles (BPNs) are prepared. After systemic administration, BPNs can target tumor tissues and stimulate the activation of immune cells, including dendritic cells (DCs). The photodynamic effects derived from thylakoid lead to the disruption of local tumors and then the release of tumor-associated antigens that are effectively presented by DCs, inducing remarkable tumor-specific CD8+T cell responses. Moreover, BPNs can efficiently ameliorate the immunosuppressive tumor microenvironment and further boost immune responses. Therefore, both tumor development and metastasis can be efficiently prevented. This work provides a novel idea for developing a versatile membrane-based hybrid system for highly efficient tumor treatment.

Smart Tumor-Cell-Derived Microparticles Provide On-Demand Photosensitizer Synthesis and Hypoxia Relief for Photodynamic Therapy.

Positioning essential elements of photodynamic therapy (PDT) near to mitochondria can conquer the rigorous spatiotemporal limitations of reactive oxygen species (ROS) transfer and make considerable differences in PDT. However, precise accumulation of photosensitizer (PS) and oxygen within mitochondria is still challenging. We simultaneously encapsulated hexyl 5-aminolevulinate hydrochloride (HAL) and 3-bromopyruvic acid (3BP) into microparticles collected from X-ray-irradiated tumor cells (X-MP). After systemic administration, the developed HAL/3BP@X-MP can specifically target and recognize tumor cells, where HAL induces efficient accumulation of PpIX in mitochondria via the intrinsic haem biosynthetic pathway. Meanwhile, 3BP remarkably increases the oxygen supply by inhibiting mitochondrial respiration. The accurate co-localization and prompt encounter of PpIX and oxygen produce sufficient ROS to directly disrupt mitochondria, resulting in significantly improved PDT outcomes.

Self-Activatable Photo-Extracellular Vesicle for Synergistic Trimodal Anticancer Therapy.

Extracellular vesicles (EVs) hold great potential in both disease treatment and drug delivery. However, accurate drug release from EVs, as well as the spontaneous treatment effect cooperation of EVs and drugs at target tissues, is still challenging. Here, an engineered self-activatable photo-EV for synergistic trimodal anticancer therapy is reported. M1 macrophage-derived EVs (M1 EVs) are simultaneously loaded with bis[2,4,5-trichloro-6-(pentyloxycarbonyl) phenyl] oxalate (CPPO), chlorin e6 (Ce6), and prodrug aldoxorubicin (Dox-EMCH). After administration, the as-prepared system actively targets tumor cells because of the tumor-homing capability of M1 EVs, wherein M1 EVs repolarize M2 to M1 macrophages, which not only display immunotherapy effects but also produce H2 O2 . The reaction between H2 O2 and CPPO generates chemical energy that activates Ce6, creating both chemiluminescence for imaging and singlet oxygen (1 O2 ) for photodynamic therapy (PDT). Meanwhile, 1 O2 -induced membrane rupture leads to the release of Dox-EMCH, which is then activated and penetrates the deep hypoxic areas of tumors. The synergism of immunotherapy, PDT, and chemotherapy results in potent anticancer efficacy, showing great promise to fight cancers.

Membrane vesicles nanotheranostic systems: sources, engineering methods, and challenges.

Extracellular vesicles (EVs) are cell secretory native components with long-circulation, good biocompatibility, and physiologic barriers cross ability. EVs derived from different donor cells inherit varying characteristics and functions from their original cells and are favorable to serve as vectors for diagnosing and treating various diseases. However, EVs nanotheranostics are still in their infancy because of their limited accumulation at lesion sites and compromised therapy efficiency. Hence, engineering modification of EVs is usually needed to further enhance their stability, biological activity, and lesion-targeting capacity. Herein, we overview the characteristics of EVs from different sources, as well as the latest developments of surface engineering and cargo loading methods. We also focus especially on advances in EVs-based disease theranostics. At the end of the review, we predict the obstacles and prospects of the future clinical application of EVs.

A self-driven bioinspired nanovehicle by leukocyte membrane-hitchhiking for early detection and treatment of atherosclerosis.

Atherosclerosis, as a silent killer, remains one of the most common causes of human morbidity and mortality worldwide due to the lack of efficient strategy for early detection and targeted therapy. In this work, a self-driven bioinspired nanovehicle is developed, which can accurately manage early atherosclerosis with simultaneously multiple-targeting, dual-modality therapy as well as noninvasive magnetic resonance imaging (MRI). The magnetic nanoclusters (MNCs) with satisfactory superparamagnetism are camouflaged with leukocyte membranes, thus acquiring inherently targeting and transmigrating capabilities to intimal foam cells in early atherosclerotic lesions, which is validated using tailor-made microfluidic devices and transwell assays. Upon sequentially embedding an anti-inflammatory drug simvastatin (ST) and decorating a targetable apolipoprotein A-I mimetic 4F peptide (AP), the as-fabricated MNC@M-ST/AP exhibits excellent anti-atherosclerotic effects by alleviating inflammation and oxidative stress as well as promoting cholesterol efflux via RCT pathways. This bioinspired leukocyte membrane-hitchhiking strategy will open new perspectives for the future clinical translations of biocompatible nanosystem in early detection and treatment of atherosclerosis.

Cell-Membrane-Based Biomimetic Systems with Bioorthogonal Functionalities.

During the past decade, there was a fast development of cell-based biomimetic systems, which are commonly derived from cell membranes, cell vesicles, or living cells. Such systems have unique and inherent bioinspired features originating from their parent biological systems. In particular, they are capable of (i) prolonging blood circulation time, (ii) avoiding immune response, (iii) targeting desired sites, (iv) providing antigens in cancer immunotherapy, and (v) loading and delivering therapeutic or imaging agents. Thus, these biomimetic systems are promising as prevention, detection, diagnosis, and therapeutic modalities. Though promising, these cell-based biomimetic systems are still far from wide application. One of the important reasons is the inevitable difficulty in their further efficient and precise functionalization. Bioorthogonal chemistry results in fast, specific, and high-yielding ligation under mild biological conditions without interactions with surrounding biomolecules or disturbance of the whole biosystem. Moreover, bioorthogonal chemical groups can be introduced into cells, especially into cell membranes, through cellular biosynthesis and metabolic incorporation. Hence, a specific and reliable approach for cell membrane functionalization based on bioorthogonal chemistry has been opportunely put forward and rapidly developed. In this Account, we summarize our recent research on the development of biomimetic systems by integrating bioorthogonal chemistry with biomimetic approaches. First, an exogenously supplied unnatural biosynthetic precursor (e.g., an amino acid or lipid) bearing a bioorthogonal group (e.g., azide or tetrazine) is fed to living cells and metabolically incorporated into targeted biomolecules via cellular biosynthesis regardless of the cell phenotype. After that, different functional molecules can be anchored to the cell membranes through bioorthogonal chemical reactions by using previously inserted "artificial chemical groups". Therefore, this safe, direct, and long-term engineering strategy endows the natural cell-based biomimetic systems with additional chemical or biological performances such as labeling, targeting, imaging, and therapeutic capabilities, providing a powerful tool for the construction of biomimetic systems. Interestingly, we have successfully fabricated various biomimetic systems and applied them in (1) living virus labeling, (2) targeting delivery and enrichment of drugs/imaging agents, and (3) disease theranostics. This Account may contribute to the further development of biomimetic systems and facilitate their biological and biomedical applications in the future. With this Account we also hope to attract more cooperative interests from different fields such as chemistry, materials science, biology, pharmacy, and medicine in promoting lab-to-clinic translation of cell-based biomimetic systems combined with these two cutting-edge techniques.

Responsive Exosome Nano-bioconjugates for Synergistic Cancer Therapy.

Exosomes hold great potential in therapeutic development. However, native exosomes usually induce insufficient effects in vivo and simply act as drug delivery vehicles. Herein, we synthesize responsive exosome nano-bioconjugates for cancer therapy. Azide-modified exosomes derived from M1 macrophages are conjugated with dibenzocyclooctyne-modified antibodies of CD47 and SIRPα (aCD47 and aSIRPα) through pH-sensitive linkers. After systemic administration, the nano-bioconjugates can actively target tumors through the specific recognition between aCD47 and CD47 on the tumor cell surface. In the acidic tumor microenvironment, the benzoic-imine bonds of the nano-bioconjugates are cleaved to release aSIRPα and aCD47 that can, respectively, block SIRPα on macrophages and CD47, leading to abolished "don't eat me" signaling and improved phagocytosis of macrophages. Meanwhile, the native M1 exosomes effectively reprogram the macrophages from pro-tumoral M2 to anti-tumoral M1.

Biomimetic Microfluidic System for Fast and Specific Detection of Circulating Tumor Cells.

Improving the specific capture efficiency of CTCs, and meanwhile preventing the nonspecific adsorption of surrounding background cells, is the main focus of CTCs detection. Herein, a novel biomimetic microfluidic system was developed by combining the unique benefits of biomimetic nanoparticles and microfluidic techniques. The magnetic nanoclusters were camouflaged with leukocyte membrane fragments and decorated with aptamer SYL3C specific for EpCAM positive tumor cells and then loaded into the microfluidic chip with the help of magnets. By use of this system, more than 90% of the rare tumor cells in blood could be captured and detected within 20 min with almost no leukocyte background, indicating a great practical application potential for CTCs detection.

Engineering Magnetosomes for Ferroptosis/Immunomodulation Synergism in Cancer.

As traditional anticancer treatments fail to significantly improve the prognoses, exploration of therapeutic modalities is urgently needed. Herein, a biomimetic magnetosome is constructed to favor the ferroptosis/immunomodulation synergism in cancer. This magnetosome is composed of an Fe3O4 magnetic nanocluster (NC) as the core and pre-engineered leukocyte membranes as the cloak, wherein TGF-ß inhibitor (Ti) can be loaded inside the membrane and PD-1 antibody (Pa) can be anchored on the membrane surface. After intravenous injection, the membrane camouflage results in long circulation, and the NC core with magnetization and superparamagnetism enables magnetic targeting with magnetic resonance imaging (MRI) guidance. Once inside the tumor, Pa and Ti cooperate to create an immunogenic microenvironment, which increases the amount of H2O2 in polarized M1 macrophages and thus promotes the Fenton reaction with Fe ions released from NCs. The generated hydroxyl radicals (•OH) subsequently induce lethal ferroptosis to tumor cells, and the exposed tumor antigen, in turn, improves the microenvironment immunogenicity. The synergism of immunomodulation and ferroptosis in such a cyclical manner therefore leads to potent therapeutic effects with few abnormalities, which supports the engineered magnetosomes as a promising combination modality for anticancer therapy.

Engineering Magnetosomes for High-Performance Cancer Vaccination.

A novel cancer vaccine is developed by using Fe3O4 magnetic nanoclusters (MNCs) as the core and cancer cell membranes decorated with anti-CD205 as the cloak. Because of the superparamagnetism and magnetization of MNCs, it is first achieved for the magnetic retention of vaccine in the lymph nodes with a magnetic resonance imaging (MRI) guide, which opened the time window for antigen uptake by dendritic cells (DCs). Meanwhile, the camouflaged cancer cell membranes serve as a reservoir of various antigens, enabling subsequent multiantigenic response. Additionally, the decorated anti-CD205 direct more vaccine into CD8+ DCs, facilitating the major histocompatibility complex (MHC) I cross-presentation. These unique advantages together lead to a great proliferation of T cells with superior clonal diversity and cytotoxic activity. As a result, potent prophylactic and therapeutic effects with few abnormalities are observed on five different tumor models. Therefore, such a cancer-derived magnetosome with the integration of various recent nanotechnologies successfully demonstrates its promise for safe and high-performance cancer vaccination.

Magnetic Nanoclusters Armed with Responsive PD-1 Antibody Synergistically Improved Adoptive T-Cell Therapy for Solid Tumors.

Although adoptive T-cell therapy has been successful in hematological malignancy treatment, its application in solid tumors remains a great challenge. Here, using a pH-sensitive benzoic-imine bond and inverse electron-demand Diels-Alder cycloaddition, we prepared magnetic nanoclusters (NCs) armed with responsive PD-1 antibody (aP), which could then bind onto effector T cells due to their PD-1 expression. After adoptive transfer, the magnetization and superparamagnetism of NCs enabled us to magnetically recruit effector T cells and aP simultaneously to tumor sites with MRI guidance. Owing to the acidic intratumoral microenvironment, the benzoic-imine bond then hydrolyzed, leading to the release of aP. The therapeutic effects of adoptive T cells and free aP could thus be spatiotemporally coupled. As a result, we achieved inhibition of tumor growth with few side effects, demonstrating the great promise of such a chemical approach for safe and high-performance adoptive T-cell therapy against solid tumors.

Green Mass Production of Pure Nanodrugs via an Ice-Template-Assisted Strategy.

To make nanomedicine potentially applicable in a clinical setting, several methods have been developed to synthesize pure nanodrugs (PNDs) without using any additional inert carriers. In this work, we report a novel green, low-cost, and scalable ice-template-assisted approach which shows several unique characteristics. First, the whole process only requires adding a drug solution into an ice template and subsequent melting (or freeze-drying), allowing easy industrial mass production with low capital investment. Second, the production yield is much higher than that of the traditional reprecipitation approach. The yield of Curcumin (Cur) PNDs is over two orders (∼140 times) magnitude higher than that obtained in a typical reprecipitation preparation. By adjusting simple processing parameters, PNDs with different sizes (∼20-200 nm) can be controllably obtained. Finally, the present approach can be easily applicable for a wide range of hydrophobic therapeutic drugs without any structural modification.