Chemotherapeutic Drug Based Metal-Organic Particles for Microvesicle-Mediated Deep Penetration and Programmable pH/NIR/Hypoxia Activated Cancer Photochemotherapy

Copper(II)-based metal-organic framework delivery of calcium ascorbate for enhanced chemodynamic therapy via H2O2 self-supply and glutathione depletion

Chemodynamic therapy (CDT) is a promising cancer treatment strategy. However, mild acidic pH, insufficient H2O2 content, and overexpressed glutathione (GSH) in the tumor microenvironment (TME) severely impair CDT efficiency. In this study, a novel therapeutic nanosystem (Cu/ZIF-8/Vc-Ca/HA) was constructed for H2O2 self-supply and GSH depletion co-enhanced CDT. Typically, calcium ascorbate (Vc-Ca) loaded on the surface of Cu2+-doped ZIF-8 (Cu/ZIF-8) was designed as an original source for H2O2 generation, and a hyaluronic acid (HA) shell was subsequently coated to act as a tumor-targeted "guide" and protective layer. Along with the HA shell disintegrated in the TME, exposed Cu/ZIF-8/Vc-Ca dissociated in the tumor acidic microenvironment, thus triggering the release of Vc-Ca and Cu2+. Vc-Ca selectively produced H2O2 in tumor cells, which provided abundant H2O2 for boosting Fenton-like reactions. Meanwhile, the released Cu2+ could get converted into Cu+ by consuming excess intracellular GSH, which could reduce the tumor antioxidant capability of the nanosystem. Moreover, byproduct Cu+ reacted with abundant H2O2 by a highly efficient Fenton-like reaction to generate toxic ˙OH. Biological assays indicated that the Cu/ZIF-8/HA@Vc-Ca nanosystem showed significant anticancer activity by enhancing the CDT process. This study may provide a new strategy for improving the effectiveness of CDT.

Innovative Design Strategies Advance Biomedical Applications of Phthalocyanines

Owing to their long absorption wavelengths, high molar absorptivity, and tunable photosensitivity, phthalocyanines have been widely used in photodynamic therapy (PDT). However, phthalocyanines still face the drawbacks of poor targeting, "always-on" photosensitizing properties, and unsatisfactory therapeutic efficiency, which limit their wide applications in biomedical fields. Thus, new design strategies such as modification of targeting molecules, formation of nanoparticles, and activating photosensitizers are developed to improve the above defects. Notably, recent studies have shown that novel phthalocyanines are not only used in fluorescence imaging and PDT, but also in photoacoustic imaging, photothermal imaging, sonodynamic therapy, and photothermal therapy. This review focuses on recent design strategies, applications in biomedicine, and clinical development of phthalocyanines, providing ideas and references for the design and application of phthalocyanine, so as to promote their future transformation into clinical applications.

Impairing Tumor Metabolic Plasticity via a Stable Metal-Phenolic-Based Polymeric Nanomedicine to Suppress Colorectal Cancer

Targeting metabolic vulnerability of tumor cells is a promising anticancer strategy. However, the therapeutic efficacy of existing metabolism-regulating agents is often compromised due to tolerance resulting from tumor metabolic plasticity, as well as their poor bioavailability and tumor-targetability. Inspired by the inhibitive effect of N-ethylmaleimide on the mitochondrial function, a dendronized-polymer-functionalized metal-phenolic nanomedicine (pOEG-b-D-SH@NP) encapsulating maleimide-modified doxorubicin (Mal-DOX) is developed to enable improvement in the overall delivery efficiency and inhibition of the tumor metabolism via multiple pathways. It is observed that Mal-DOX and its derived nanomedicine induces energy depletion of CT26 colorectal cancer cells more efficiently than doxorubicin, and shifts the balance of programmed cell death from apoptosis toward necroptosis. Notably, pOEG-b-D-SH@NP simultaneously inhibits cellular oxidative phosphorylation and glycolysis, thus potently suppressing cancer growth and peritoneal intestinal metastasis in mouse models. Overall, the study provides a promising dendronized-polymer-derived nanoplatform for the treatment of cancers through impairing metabolic plasticity.

Normalization of Tumor Vessels by Lenvatinib-Based Metallo-Nanodrugs Alleviates Hypoxia and Enhances Calreticulin-Mediated Immune Responses in Orthotopic HCC and Organoids

Immunocheckpoint inhibitors combined with Lenvatinib is the first line treatment for hepatocellular carcinoma (HCC), but their potency is hampered by the low response rate and adverse events. Herein, a targeted therapeutic strategy through the coassembly of Lenvatinib, Adriamycin, Fe³⁺ ion, and a natural polyphenol (metallo-nanodrugs) is presented by coordination effect for potentiating tumor vascular normalization and systematic chemo-immunotherapy to effectively inhibit the progression of HCC in both orthotopic model and patients-derived organoids. In mice with orthotopic HCC, the obtained metallo-nanodrugs efficiently increase the drug accumulation in orthotopic tumors and can respond to acidic tumor environment. The promotion of tumor vascular normalization by metallo-nanodrugs is observed, which enhances the infiltrating T lymphocytes in tumor, and reinforces the calreticulin-mediated antitumor immunity through alleviating hypoxia, reducing regulatory T cells, and down-regulating PDL1 expression of tumors. The excellent therapeutic efficiency with complete remission of orthotopic tumors (3/6) and long-term survival of mice (4/6, 42 days) are also achieved. Furthermore, the excellent therapeutic effect of metallo-nanodrugs is also validated in 5 patient-derived organoids, and hence can provide a marvelous systemic chemo-immunotherapy strategy for enhancing HCC treatment.

Aptamer modified Zr-based porphyrinic nanoscale metal-organic frameworks for active-targeted chemo-photodynamic therapy of tumors

Active-targeted nanoplatforms could specifically target tumors compared to normal cells, making them a promising therapeutic agent. The aptamer is a kind of short DNA or RNA sequence that can specifically bind to target molecules, and could be widely used as the active targeting agents of nanoplatforms to achieve active-targeted therapy of tumors. Herein, an aptamer modified nanoplatform DOX@PCN@Apt-M was designed for active-targeted chemo-photodynamic therapy of tumors. Zr-based porphyrinic nanoscale metal organic framework PCN-224 was synthesized through a one-pot reaction, which could produce cytotoxic ¹O₂ for efficient treatment of tumor cells. To improve the therapeutic effect of the tumor, the anticancer drug doxorubicin (DOX) was loaded into PCN-224 to form DOX@PCN-224 for tumor combination therapy. Active-targeted combination therapy achieved by modifying the MUC1 aptamer (Apt-M) onto DOX@PCN-224 surface can not only further reduce the dosage of therapeutic agents, but also reduce their toxic and side effects on normal tissues. In vitro, experimental results indicated that DOX@PCN@Apt-M exhibited enhanced combined therapeutic effect and active targeting efficiency under 808 nm laser irradiation for MCF-7 tumor cells. Based on PCN-224 nanocarriers and aptamer MUC1, this work provides a novel strategy for precisely targeting MCF-7 tumor cells.

Continuous Spatiotemporal Therapy of A Full-API Nanodrug via Multi-Step Tandem Endogenous Biosynthesis

Nanomedicine holds great promise to enhance cancer therapy. However, low active pharmaceutical ingredient (API) loading content, unpredictable drug release, and potential toxicity from excipients limit their translational capability. We herein report a full-API nanodrug composed of FDA-approved 5-aminolevulinic acid (ALA), human essential element Fe³⁺, and natural bioactive compound curcumin with an ideal API content and pH-responsive release profile for continuous spatiotemporal cancer therapy achieved by multi-step tandem endogenous biosynthesis. First, ALA enzymatically converts into photosensitizer protoporphyrin IX (PpIX). Afterward, multiple downstream products including carbon monoxide (CO), Fe²⁺, biliverdin (BV), and bilirubin (BR) are individually biosynthesized through the PpIX-heme-CO/Fe²⁺/BV-BR metabolic pathway, further cooperating with released Fe³⁺ and curcumin, ultimately eliciting mitochondria damage, membrane disruption, and intracytoplasmic injury. This work not only provides a paradigm for exploiting diversified metabolites for tumor suppression, but also presents a safe and efficient full-API nanodrug, facilitating the practical translation of nanodrugs.

Carrier-Free ATP-Activated Nanoparticles for Combined Photodynamic Therapy and Chemotherapy under Near-Infrared Light

The combination of photodynamic therapy (PDT) and chemotherapy (chemo-photodynamic therapy) for enhancing cancer therapeutic efficiency has attracted tremendous attention in the recent years. However, limitations, such as low local concentration, non-suitable treatment light source, and uncontrollable release of therapeutic agents, result in reduced combined treatment efficacy. This study considered adenosine triphosphate (ATP), which is highly upregulated in tumor cells, as a biomarker and developed ingenious ATP-activated nanoparticles (CDNPs) that are directly self-assembled from near-infrared photosensitizer (Cy-I) and amphiphilic Cd(II) complex (DPA-Cd). After selective entry into tumor cells, the positively charged CDNPs would escape from lysosomes and be disintegrated by the high ATP concentration in the cytoplasm. The released Cy-I is capable of producing single oxygen (¹ O₂ ) for PDT with 808 nm irradiation and DPA-Cd can concurrently function for chemotherapy. Irradiation with 808 nm light can lead to tumor ablation in tumor-bearing mice after intravenous injection of CDNPs. This carrier-free nanoparticle offers a new platform for chemo-photodynamic therapy.

Organic metal matrix Mil-88a nano-enzyme for joint repair in the osteoarthritis mouse model

Introduction: In this paper we tried to conduct a novel nanomaterial strategy to overcome osteoarthritis (OA) in a mouse model. Methods: In this regard, after synthesizing the Mil-88a nanozyme, as a certain Fe-MOF, its toxic effects were detected by CCK-8 method and live-dead staining. The OA model of mouse was constructed, and paraffin sections of joints were taken for histological evaluation. In addition, immunofluorescence and immunohistochemistry were used to identify the OA progression and OARSI was used to evaluate the OA grades. We observed that Mil-88a could be easily synthesized and has high biocompatibility. Results: We observed that Mil-88a could significantly promote the expression of OA anabolism-related genes such as Col2 and also significantly inhibit the expression of OA catabolism-related genes MMP13. Besides, we observed better OARSI score in animals treated with Mil-88a nano-enzyme loading on organic metal matrix. Discussion: Overall, Mil-88a nano-enzyme could be used as a novel strategy to treat OA.

Prospects for hypoxia-based drug delivery platforms for the elimination of advanced metastatic tumors: From 3D modeling to clinical concepts

Hypoxia is a unique characteristic of the solid tumor microenvironment. Hypoxia contributes to multi-drug resistance, metastasis and cancer relapse through numerous molecular pathways, but at the same time provides an opportunity for the development of novel drugs or modalities specifically targeting hypoxic tumor regions. Given the high significance of tumor hypoxia in therapeutic results, we here discuss a variety of hypoxia-adopted strategies, and their potential and utility in the treatment of deep-seated hypoxic tumor cells. We discuss the merits and demerits of these approaches, as well as their combination with other approaches such as photodynamic therapy. We also survey the currently available 3D hypoxia modeling systems, in particular organoid-based microfluidics. Finally, we discuss the potential and the current status of preclinical tumor hypoxia approaches in clinical trials for advanced cancer. We believe that multi-modal imaging and therapeutic hypoxia adopted drug delivery platforms could provide better efficacy and safety profiles, and more importantly personalized therapy. Determining the hypoxia status of tumors could offer a second chance for the clinical translation of hypoxia-based agents, such as hypoxia activated prodrugs (HAPs) from bench to bedside.

Nanoparticles and Nanomaterials-Based Recent Approaches in Upgraded Targeting and Management of Cancer: A Review

Along with the extensive improvement in tumor biology research and different therapeutic developments, cancer remains a dominant and deadly disease. Tumor heterogeneity, systemic toxicities, and drug resistance are major hurdles in cancer therapy. Chemotherapy, radiotherapy, phototherapy, and surgical therapy are some prominent areas of cancer treatment. During chemotherapy for cancer, chemotherapeutic agents are distributed all over the body and also damage normal cells. With advancements in nanotechnology, nanoparticles utilized in all major areas of cancer therapy offer the probability to advance drug solubility, and stability, extend drug half-lives in plasma, reduce off-target effects, and quintessence drugs at a target site. The present review compiles the use of different types of nanoparticles in frequently and recently applied therapeutics of cancer therapy. A recent area of cancer treatment includes cancer stem cell therapy, DNA/RNA-based immunomodulation therapy, alteration of the microenvironment, and cell membrane-mediated biomimetic approach. Biocompatibility and bioaccumulation of nanoparticles is the major impediment in nano-based therapy. More research is required to develop the next generation of nanotherapeutics with the incorporation of new molecular entities, such as kinase inhibitors, siRNA, mRNA, and gene editing. We assume that nanotherapeutics will dramatically improve patient survival, move the model of cancer treatment, and develop certainty in the foreseeable future.

Dual Drug Loaded, pH-Sensitive Metal-Organic Particles for Synergistic Cancer Therapy

The strategy for dual drug-loaded nanomedicine with targeting properties was always complex. Herein, a novel strategy for the preparation of metal-organic particle-based nanomedicine has been developed, and combretastatin A4 (CA4) and mitoxantrone (MIT) loaded MOPs (CMMOPs) have been obtained. In this system, using merely Cu(II) as a bridge to connect and coordinate with the dual drugs has resulted in the CMMOPs possessing a fairly high drug load of almost 90%. Moreover, the coordination between Cu(II) and the drugs was stable at physiological pH but easily cleavable in the tumor acidic microenvironment, which would provide a good targeting property for CMMOPs. The in vivo experiments indicated that CMMOPs possessed a significantly enhanced antitumor efficiency with negligible side effects. The results suggest that CMMOPs could be a potential anticancer formulation for tumor-targeted drug delivery.

Vehicle-Free Nanotheranostic Self-Assembled from Clinically Approved Dyes for Cancer Fluorescence Imaging and Photothermal/Photodynamic Combinational Therapy

Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT) has attracted growing attention as a noninvasive option for cancer treatment. At present, researchers have developed various “all-in-one” nanoplatforms for cancer imaging and PTT/PDT combinational therapy. However, the complex structure, tedious preparation procedures, overuse of extra carriers and severe side effects hinder their biomedical applications. In this work, we reported a nanoplatform (designated as ICG-MB) self-assembly from two different FDA-approved dyes of indocyanine green (ICG) and methylene blue (MB) without any additional excipients for cancer fluorescence imaging and combinational PTT/PDT. ICG-MB was found to exhibit good dispersion in the aqueous phase and improve the photostability and cellular uptake of free ICG and MB, thus exhibiting enhanced photothermal conversion and singlet oxygen (¹O₂) generation abilities to robustly ablate cancer cells under 808 nm and 670 nm laser irradiation. After intravenous injection, ICG-MB effectively accumulated at tumor sites with a near-infrared (NIR) fluorescence signal, which helped to delineate the targeted area for NIR laser-triggered phototoxicity. As a consequence, ICG-MB displayed a combinational PTT/PDT effect to potently inhibit tumor growth without causing any system toxicities in vivo. In conclusion, this minimalist, effective and biocompatible nanotheranostic would provide a promising candidate for cancer phototherapy based on current available dyes in clinic.

Remodeling Tumor-Associated Neutrophils to Enhance Dendritic Cell-Based HCC Neoantigen Nano-Vaccine Efficiency

Hepatocellular carcinoma (HCC) commonly emerges in an immunologically "cold" state, thereafter protects it away from cytolytic attack by tumor-infiltrating lymphocytes, resulting in poor response to immunotherapy. Herein, an acidic/photo-sensitive dendritic cell (DCs)-based neoantigen nano-vaccine has been explored to convert tumor immune "cold" state into "hot", and remodel tumor-associated neutrophils to potentiate anticancer immune response for enhancing immunotherapy efficiency. The nano-vaccine is constructed by SiPCCl₂ -hybridized mesoporous silica with coordination of Fe(III)-captopril, and coating with exfoliated membrane of matured DCs by H22-specific neoantigen stimulation. The nano-vaccines actively target H22 tumors and induce immunological cell death to boost tumor-associated antigen release by the generation of excess ¹ O₂ through photodynamic therapy, which act as in situ tumor vaccination to strengthen antitumor T-cell response against primary H22 tumor growth. Interestingly, the nano-vaccines are also home to lymph nodes to directly induce the activation and proliferation of neoantigen-specific T cells to suppress the primary/distal tumor growth. Moreover, the acidic-triggered captopril release in tumor microenvironment can polarize the protumoral N2 phenotype neutrophils to antitumor N1 phenotype for improving the immune effects to achieve complete tumor regression (83%) in H22-bearing mice and prolong the survival time. This work provides an alternative approach for developing novel HCC immunotherapy strategies.

Tumor Diagnosis and Therapy Mediated by Metal Phosphorus-Based Nanomaterials

Metal phosphorus-based nanomaterials (Metal-P NMs) including metal phosphate nanomaterials, metal phosphide nanomaterials, and metal-black phosphorus (Metal-BP) nanocomposite are widely used in the field of biomedicine owing to their excellent physical and chemical properties, biocompatibility, and biodegradability. In recent years, metal phosphate nanomaterials and Metal-BP nanocomposite acted as medicine delivery system have made breakthroughs in tumor diagnosis including magnetic resonance imaging, fluorescence imaging, photoacoustic imaging, nuclear imaging, and therapies including chemotherapy, gene therapy, photothermal therapy, photodynamic therapy, and radiation therapy. Metal phosphate nanomaterials have good biodegradability, especially calcium-based metal phosphate nanomaterials can be dissolved into nontoxic ions and participate in the metabolisms of normal organs. Compared with metal phosphate nanomaterials, metal phosphide nanomaterials have excellent optical, magnetic, and catalytic properties, which can be used as multifunctional diagnostic nanoplatforms and therapeutic agents for chemodynamic therapy, photothermal therapy, or immunotherapy. The latest developments in Metal-P NMs, covering the range of preparation methods and biological applications, such as serving as drug carriers, tumor diagnosis, and therapy, are focused. All in all, the current trends, key issues, future prospects and challenges of Metal-P NMs are concluded and discussed, which are important for the development of this research field and shining more lights on this direction.

Engineering a Smart Agent for Enhanced Immunotherapy Effect by Simultaneously Blocking PD-L1 and CTLA-4

Combinations of immune checkpoint therapies show encouraging results in the treatment of many human cancers. However, the higher costs and greater side effects of such combinations compared with single-agent immunotherapies limit their further applications. In this work, a novel smart agent, KN046@19 F-ZIF-8, is developed to overcome these limitations. KN046 is a novel recombinant humanized PD-L1/CTLA-4 bispecific single-domain antibody-Fc fusion protein, which can bind to both PD-L1 and CTLA-4 effectively. ZIF-8 is a smart delivery system, which can safely and effectively deliver KN406 to a tumor. In vitro and in vivo results demonstrate that the smart agent KN046@19 F-ZIF-8 not only improves the immune response rate of the antibody drug in treatment of tumors but also reduces its toxic side effects, thereby achieving excellent antitumor efficacy. This study provides an engineering strategy for clinical applications of a more effective immunotherapy.

Metal-Coordinated Supramolecular Self-Assemblies for Cancer Theranostics

Metal-coordinated supramolecular nanoassemblies have recently attracted extensive attention as materials for cancer theranostics. Owing to their unique physicochemical properties, metal-coordinated supramolecular self-assemblies can bridge the boundary between traditional inorganic and organic materials. By tailoring the structural components of the metal ions and binding ligands, numerous multifunctional theranostic nanomedicines can be constructed. Metal-coordinated supramolecular nanoassemblies can modulate the tumor microenvironment (TME), thus facilitating the development of TME-responsive nanomedicines. More importantly, TME-responsive organic-inorganic hybrid nanomaterials can be constructed in vivo by exploiting the metal-coordinated self-assembly of a variety of functional ligands, which is a promising strategy for enhancing the tumor accumulation of theranostic molecules. In this review, recent advancements in the design and fabrication of metal-coordinated supramolecular nanomedicines for cancer theranostics are highlighted. These supramolecular compounds are classified according to the order in which the coordinated metal ions appear in the periodic table. Furthermore, the prospects and challenges of metal-coordinated supramolecular self-assemblies for both technical advances and clinical translation are discussed. In particular, the superiority of TME-responsive nanomedicines for in vivo coordinated self-assembly is elaborated, with an emphasis on strategies that enhance the accumulation of functional components in tumors for an ideal theranostic outcome.

Targeting Hypoxia: Hypoxia-Activated Prodrugs in Cancer Therapy

Hypoxia is an important characteristic of most solid malignancies, and is closely related to tumor prognosis and therapeutic resistance. Hypoxia is one of the most important factors associated with resistance to conventional radiotherapy and chemotherapy. Therapies targeting tumor hypoxia have attracted considerable attention. Hypoxia-activated prodrugs (HAPs) are bioreductive drugs that are selectively activated under hypoxic conditions and that can accurately target the hypoxic regions of solid tumors. Both single-agent and combined use with other drugs have shown promising antitumor effects. In this review, we discuss the mechanism of action and the current preclinical and clinical progress of several of the most widely used HAPs, summarize their existing problems and shortcomings, and discuss future research prospects.

Self-recognizing and stimulus-responsive carrier-free metal-coordinated nanotheranostics for magnetic resonance/photoacoustic/fluorescence imaging-guided synergistic photo-chemotherapy

Carrier-free nanotheranostics directly assembled by using clinically used photosensitizers and chemotherapeutic drugs are a promising alternative to tumor theranostics. However, the weak interaction-driven assembly still suffers from low structural stability against disintegration, lack of targeting specificity, and poor stimulus-responsive property. Moreover, almost all exogenous ligands possess no therapeutic effect. Enlightened by the concept of metal-organic frameworks, we developed a novel self-recognizing metal-coordinated nanotheranostic agent by the coordination-driven co-assembly of photosensitizer indocyanine green (ICG) and chemo-drug methotrexate (MTX, also served as a specific "targeting ligand" towards folate receptors), in which ferric (FeIII) ions acted as a bridge to tightly associate ICG with MTX. Such carrier-free metal-coordinated nanotheranostics with high dual-drug payload (∼94 wt%) not only possessed excellent structural and physiological stability, but also exhibited prolonged blood circulation. In addition, the nanotheranostics could achieve the targeted on-demand drug release by both stimuli of internal lysosomal acidity and external near-infrared laser. More importantly, the nanotheranostics could self-recognize the cancer cells and selectively target the tumors, and therefore they decreased toxicity to normal tissues and organs. Consequently, the nanotheranostics showed strongly synergistic potency for tumor photo-chemotherapy under the precise guidance of magnetic resonance/photoacoustic/fluorescence imaging, thereby achieving highly effective tumor curing efficiency. Considering that ICG and bi-functional MTX are approved by the Food and Drug Administration, and FeIII ions have high biosafety, the self-recognizing and stimulus-responsive carrier-free metal-coordinated nanotheranostics may hold potential applications in tumor theranostics.

In situ oxygenating and 808 nm light-sensitized nanocomposite for multimodal imaging and mitochondria-assisted cancer therapy

The efficiency of photodynamic therapy (PDT) is severely constrained due to the innate hypoxic environment, besides the elevated level of glutathione (GSH). To get rid of the hypoxic environment and higher concentrations of GSH in the solid tumors, we propose an approach of oxygen self-sufficient multimodal imaging-guided nanocomposite CaO₂-MnO₂-UCNPs-Ce6/DOX (abbreviated as CaMn-NUC), in which CaO₂ nanoparticles in the hydrophobic layer were seated on the hydrophilic MnO₂ sheet and conjugated with chlorin e6 (Ce6) loaded upconversion nanoparticles (UCNPs-Ce6) via the click chemistry approach. CaMn-NUC was presented to overcome hypoxia and GSH-associated photodynamic resistance due to in situ oxygen generation and GSH reduction of MnO₂ upon endocytosis, and a bulk amount of Mn²⁺ ions generated in the process under acidic tumor environment acts as the MRI contrast agent. Moreover, the MnO₂ sheet protects Ce6 from self-degradation under irradiation; thus, it can be used to switch control of cellular imaging. Afterwards, in a regulated and targeted manner, the chemotherapeutic drug (doxorubicin hydrochloride, DOX) can be released with the degradation of CaMn-NUC in the acidic tumor microenvironment (TME). Thus, we testify a competent nanoplatform employing 808 nm-excited UCNPs-Ce6 for concurrent imaging and PDT in consideration of the large anti-Stokes shifts, deep penetration into biological tissues, narrow emission bands, and high spatial-temporal resolution of the UCNPs. Thus, our proposed nanoplatform postulates a strategy to efficiently kill cancer cells in a concentration- and time-dependent manner via the in situ oxygenation of solid tumor hypoxia to enhance the efficiency of multimodal imaging-guided chemo-photodynamic therapy.

Tumor acidity-responsive carrier-free nanodrugs based on targeting activation via ICG-templated assembly for NIR-II imaging-guided photothermal–chemotherapy

Novel tumor microenvironment-driven self-targeting supramolecular nanodrugs via ICG-templated small-molecule self-assembly for NIR-II imaging-guided synergistic photothermal–chemotherapy.

Advanced nanomaterials for hypoxia tumor therapy: challenges and solutions

In recent years, nanomaterials and nanotechnology have emerged as vital factors in the medical field with a unique contribution to cancer medicine. Given the increasing number of cancer patients, it is necessarily required to develop innovative strategies and therapeutic modalities to tackle hypoxia, which forms a hallmark and great barrier in treating solid tumors. The present review details the challenges in nanotechnology-based hypoxia, targeting the strategies and solutions for better therapeutic performances. The interaction between hypoxia and tumor is firstly introduced. Then, we review the recently developed engineered nanomaterials towards multimodal hypoxia tumor therapies, including chemotherapy, radiotherapy, and sonodynamic treatment. In the next part, we summarize the nanotechnology-based strategies for overcoming hypoxia problems. Finally, current challenges and future directions are proposed for successfully overcoming the hypoxia tumor problems.

Dual-Responsive Polyprodrug Nanoparticles with Cascade-Enhanced Magnetic Resonance Signals for Deep-Penetration Drug Release in Tumor Therapy

Smart transformable nanocarriers are promising to treat deep-seated diseases but require adaptable diagnostic/imaging potency to reflect the morphology change and therapeutic feedback, yet their design and synthesis remains challenging. Herein, stimuli-responsive polyprodrug nanoparticles (SPNs) are formulated from the co-assembly of negatively charged corona and positively charged polyprodrug cores, exhibiting high loading content of camptothecin (CPT, ∼28.6 wt %) tethered via disulfide linkages in the core. SPNs are sequentially sensitive to tumor acidic condition and elevated reductive milieu in the cytosol for deep-penetration drug delivery. Upon accumulation at acidic tumor sites, SPNs dissociate to release smaller positively charged polyprodrug nanoparticles, which efficiently enter deep-seated tumor cells to trigger high-dosage parent CPT release in the reductive cytosolic milieu. Meanwhile, the polyprodrug cores of SPNs labeled with DTPA(Gd), a magnetic resonance imaging contrast agent, can trace the cascade degradation and biodistribution of SPNs as well as the resulting intracellular CPT release. The longitudinal relaxivity of SPNs increases stepwise in the above two processes. The size-switchable polyprodrug nanoparticles exhibit remarkable tumor penetration and noteworthy tumor inhibition in vitro and in vivo, which are promising for endogenously activated precision diagnostics and therapy.

Design of Targeted Nanostructured Coordination Polymers (NCPs) for Cancer Therapy

Conventional cancer chemotherapy presents notable drug side effects due to non-selective action of the chemotherapeutics to normal cells. Nanoparticles decorated with receptor-specific ligands on the surface have shown an important role in improving site-selective binding, retention, and drug delivery to the cancer cells. This review summarizes the recent reported achievements using nanostructured coordination polymers (NCPs) with active targeting properties for cancer treatment in vitro and in vivo. Despite the controversy surrounding the effectivity of active targeting nanoparticles, several studies suggest that active targeting nanoparticles notably increase the selectivity and the cytotoxic effect in tumoral cells over the conventional anticancer drugs and non-targeted nanoparticle platform, which enhances drug efficacy and safety. In most cases, the nanocarriers have been endowed with remarkable capabilities such as stimuli-responsive properties, targeting abilities, or the possibility to be monitored by imaging techniques. Unfortunately, the lack of preclinical studies impedes the evaluation of these unique and promising findings for the translation of NCPs into clinical trials.

Reduction/Oxidation-Responsive Hierarchical Nanoparticles with Self-Driven Degradability for Enhanced Tumor Penetration and Precise Chemotherapy

Deep tumor penetration, long blood circulation, rapid drug release, and sufficient stability are the most concerning dilemmas of nano-drug-delivery systems for efficient chemotherapy. Herein, we develop reduction/oxidation-responsive hierarchical nanoparticles co-encapsulating paclitaxel (PTX) and pH-stimulated hyaluronidase (pSH) to surmount the sequential biological barriers for precise cancer therapy. Poly(ethylene glycol) diamine (PEG-dia) is applied to collaboratively cross-link the shell of nanoparticles self-assembled by a hyaluronic acid-stearic acid conjugate linked via a disulfide bond (HA-SS-SA, HSS) to fabricate the hierarchical nanoparticles (PHSS). The PTX and pSH coloaded hierarchical nanoparticles (PTX/pSH-PHSS) enhance the stability in normal physiological conditions and accelerate drug release at tumorous pH, and highly reductive or oxidative environments. Functionalized with PEG and HA, the hierarchical nanoparticles preferentially prolong the circulation time, accumulate at the tumor site, and enter MDA-MB-231 cells via CD44-mediated endocytosis. Within the acidic tumor micro-environment, pSH would be partially reactivated to decompose the dense tumor extracellular matrix for deep tumor penetration. Interestingly, PTX/pSH-PHSS could be degraded apace by the completely activated pSH within endo/lysosomes and the intracellular redox micro-environment to facilitate drug release to produce the highest tumor inhibition (93.71%) in breast cancer models.

RBC Membrane Camouflaged Semiconducting Polymer Nanoparticles for Near-Infrared Photoacoustic Imaging and Photothermal Therapy

Semiconducting conjugated polymer nanoparticles (SPNs) represent an emerging class of phototheranostic materials with great promise for cancer treatment. In this report, low-bandgap electron donor-acceptor (D-A)-conjugated SPNs with surface cloaked by red blood cell membrane (RBCM) are developed for highly effective photoacoustic imaging and photothermal therapy. The resulting RBCM-coated SPN (SPN@RBCM) displays remarkable near-infrared light absorption and good photostability, as well as high photothermal conversion efficiency for photoacoustic imaging and photothermal therapy. Particularly, due to the small size (< 5 nm), SPN@RBCM has the advantages of deep tumor penetration and rapid clearance from the body with no appreciable toxicity. The RBCM endows the SPNs with prolonged systematic circulation time, less reticuloendothelial system uptake and reduced immune-recognition, hence improving tumor accumulation after intravenous injection, which provides strong photoacoustic signals and exerts excellent photothermal therapeutic effects. Thus, this work provides a valuable paradigm for safe and highly efficient tumor photoacoustic imaging and photothermal therapy for further clinical translation.

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

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

Tumor-Specific Endogenous FeII-Activated, MRI-Guided Self-Targeting Gadolinium-Coordinated Theranostic Nanoplatforms for Amplification of ROS and Enhanced Chemodynamic Chemotherapy

Low drug payload and lack of tumor-targeting for chemodynamic therapy (CDT) result in an insufficient reactive oxygen species (ROS) generation, which seriously hinders its further clinical application. Therefore, how to improve the drug payload and tumor targeting for amplification of ROS and combine it with chemotherapy has been a huge challenge in CDT. Herein, methotrexate (MTX), gadolinium (Gd), and artesunate (ASA) were used as theranostic building blocks to be coordinately assembled into tumor-specific endogenous Fe^II-activated and magnetic resonance imaging (MRI)-guided self-targeting carrier-free nanoplatforms (NPs) for amplification of ROS and enhanced chemodynamic chemotherapy. The obtained ASA-MTX-Gd^III NPs exhibited extremely high drug payload (∼96 wt %), excellent physiological stability, long circulating ability (half-time: ∼12 h), and outstanding tumor accumulation. Moreover, ASA-MTX-Gd^III NPs could be specifically uptaken by tumor cells via folate (FA) receptors and subsequently be disassembled via lysosomal acidity-induced coordination breakage, resulting in drug burst release. Most strikingly, the produced ASA could be catalyzed by tumor-specific overexpressed endogenous Fe^II ions to generate sufficient ROS for enhancing the main chemodynamic efficacy, which could exert a synergistic effect with the assistant chemotherapy of MTX. Interestingly, ASA-MTX-Gd^III NPs caused a lower ROS generation and toxicity on normal cell lines that seldom expressed endogenous Fe^II ions. Under MRI guidance with assistance of self-targeting, significantly superior synergistic tumor therapy was performed on FA receptor-overexpressed tumor-bearing mice with a higher ROS generation and an almost complete elimination of tumor. This work highlights ASA-MTX-Gd^III NPs as an efficient chemodynamic-chemotherapeutic agent for MRI imaging and tumor theranostics.

pH and Glutathione Synergistically Triggered Release and Self-Assembly of Au Nanospheres for Tumor Theranostics

Theranostic agents based on near-infrared absorption which integrate both imaging and therapeutic functions have attracted considerable attention. However, because of the interference signal, indiscriminate treatment usually causes side effects on normal tissues during tumor treatment. To address this limitation, we propose a new synergistically triggered mechanism, release and self-assembly of Au nanospheres, for tumor theranostics based on the synergistic effect of H⁺ and glutathione on the tumor microenvironment. In vitro experiments reveal that Au nanospheres release from Au@ZIF-8 at a high concentration of H⁺ or glutathione. Importantly, Au aggregation only appears in the synergistic effect of glutathione and lower pH and exhibits strong coupling plasmonic resonance absorption in the near-infrared region and can be used as the theranostics agent. This statement was further verified by biological transmission electron microscopy and in vivo imaging. Au@ZIF-8 is stable and produces no photoacoustic signal in normal tissue; in contrast, in the presence of overexpressed glutathione and H⁺, Au nanospheres release from Au@ZIF-8, assemble to aggregates, and exhibit a strong signal at the tumor site for imaging and efficient photothermal therapy. This work provides a new strategy for designing theranostic agents with sequentially responsive steps to avoid interference diagnosis signals from normal tissues and reduce damage to normal tissue during treatment.

Synthesis, characterization, DNA binding, topoisomerase inhibition, and apoptosis induction studies of a novel cobalt(III) complex with a thiosemicarbazone ligand

In this study, 9-anthraldehyde-N(4)-methylthiosemicarbazone (MeATSC) 1 and [Co(phen)2(O2CO)]Cl·6H2O 2 (where phen = 1,10-phenanthroline) were synthesized. [Co(phen)2(O2CO)]Cl·6H2O 2 was used to produce anhydrous [Co(phen)2(H2O)2](NO3)33. Subsequently, anhydrous [Co(phen)2(H2O)2](NO3)33 was reacted with MeATSC 1 to produce [Co(phen)2(MeATSC)](NO3)3·1.5H2O·C2H5OH 4. The ligand, MeATSC 1 and all complexes were characterized by elemental analysis, FT IR, UV-visible, and multinuclear NMR (1H, 13C, and 59Co) spectroscopy, along with HRMS, and conductivity measurements, where appropriate. Interactions of MeATSC 1 and complex 4 with calf thymus DNA (ctDNA) were investigated by carrying out UV-visible spectrophotometric studies. UV-visible spectrophotometric studies revealed weak interactions between ctDNA and the analytes, MeATSC 1 and complex 4 (Kb = 8.1 × 105 and 1.6 × 104 M-1, respectively). Topoisomerase inhibition assays and cleavage studies proved that complex 4 was an efficient catalytic inhibitor of human topoisomerases I and IIα. Based upon the results obtained from the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay on 4T1-luc metastatic mammary breast cancer cells (IC50 = 34.4 ± 5.2 μM when compared to IC50 = 13.75 ± 1.08 μM for the control, cisplatin), further investigations into the molecular events initiated by exposure to complex 4 were investigated. Studies have shown that complex 4 activated both the apoptotic and autophagic signaling pathways in addition to causing dissipation of the mitochondrial membrane potential (ΔΨm). Furthermore, activation of cysteine-aspartic proteases3 (caspase 3) in a time- and concentration-dependent manner coupled with the ΔΨm, studies implicated the intrinsic apoptotic pathway as the major regulator of cell death mechanism.

A Multifunctional Lipid Incorporating Active Targeting and Dual-Control Release Capabilities for Precision Drug Delivery

Active targeting and precise control of drug release based on nanoparticle therapies are urgently required to precisely treat cancer. We have custom-synthesized a functional lipid (termed Fa-ONB) by introducing a folic acid-targeting group into an o-nitro-benzyl ester lipid. As designed, the liposomes formed by Fa-ONB combine active targeting and dual trigger release capabilities, which help to improve drug efficacy and reduce the toxicity of traditional liposomes. We first verified that both pH-induced hydrolysis and light treatment were able to cleave the Fa-ONB lipid. We then prepared a series of liposomes (termed FOBD liposomes) by compounding the Fa-ONB lipid with DOPC at different ratios. After encapsulation of doxorubicin (DOX), we found that the particle size of DOX-loaded FOBD liposomes (DOX/FOBD) first increased (290 to 700 nm) and then decreased again (to 400 nm) under continuous UV irradiation (120 min). The photocatalytic release efficiency under different pH conditions was investigated by dialysis experiments, and it was found that the release efficiency in an acidic environment was significantly increased relative to neutral pH. This pH-triggered release response helps distinguish pathological tissues such as lysosomal compartments and tumors. The light-induced formation of a DOX precipitate increases in efficiency with increasing UV exposure time as well as with increasing environmental acidity or alkalinity. In addition, confocal imaging and flow cytometry showed that the ability of FOBD lipids to actively target HeLa cells increased with increasing Fa-ONB lipid content. Real-time in vivo fluorescence small animal experiments proved targeting to tumors and pH- and photo-induced release properties. Furthermore, therapeutic experiments using a mouse model found a significant tumor inhibitory effect for DOX/FOBD55 liposomes with UV irradiation, clearly demonstrating the benefit of light treatment: the tumor size of the control (PBS) group was 7.59 times that of the light treatment group. Therefore, this research demonstrates the benefits of combining triggerable release functions and effective active tumor targeting in one small lipid molecule for precise cancer treatment.

Engineered extracellular vesicles and their mimetics for clinical translation

Cells secrete extracellular vesicles (EVs) to external environments to achieve cellular homeostasis and cell-to-cell communication. Their therapeutic potential has been constantly spotlighted since they mirror both cytoplasmic and membranous components of parental cells. Meanwhile, growing evidence suggests that EV engineering could further promote EVs with a maximized capacity. In this review, a range of engineering techniques as well as upscaling approaches to exploit EVs and their mimetics are introduced. By laying out the pros and cons of each technique from different perspectives, we sought to provide an overview potentially helpful for understanding the current state of the art EV engineering and a guideline for choosing a suitable technique for engineering EVs. Furthermore, we envision that the advances in each technique will give rise to the combinatorial engineering of EVs, taking us a step closer to a clinical translation of EV-based therapeutics.

A multifunctional lipid that forms contrast-agent liposomes with dual-control release capabilities for precise MRI-guided drug delivery

Monitoring of nanoparticle-based therapy in vivo and controlled drug release are urgently needed for the precise treatment of disease. We have synthesized a multifunctional Gd-DTPA-ONB (GDO) lipid by introducing the Gd-DTPA contrast agent moiety into an o-nitro-benzyl ester lipid. By design, liposomes formed from the GDO lipid combine MRI tracking ability and dual-trigger release capabilities with maximum sensitivity (because all lipids bear the cleavable moiety) without reducing the drug encapsulation rate. We first confirmed that both photo-treatment and pH-triggered hydrolysis are able to cleave the GDO lipid and lyse GDO liposomes. We then investigated the efficiency of drug release via the combined release processes for GDO liposomes loaded with doxorubicin (DOX). Relative to neutral pH, the release efficiency in acidic environment increased by 10.4% (at pH = 6.5) and 13.3% (at pH = 4.2). This pH-dependent release response is conducive to distinguishing pathological tissue such as tumors and endolysosomal compartments. The photo-induced release efficiency increases with illumination time as well as with distance of the pH from neutral. Photolysis increased the release efficiency by 13.8% at pH = 4.2, which is remarkable considering the already increased amount of drug release in the acidic environment. In addition, the relaxation time of GDO liposomes was 4.1 times that of clinical Gd-DTPA, with brighter T₁-weighted imaging in vitro and in vivo. Real-time MRI imaging and in vivo fluorescence experiments demonstrated tumor targeting and MRI guided release. Furthermore, significant tumor growth inhibition in a treatment experiment using DOX-loaded GDO liposomes clearly demonstrated the benefit of photo-treatment for efficacy: the tumor size in the photo-treatment group was 3.7 times smaller than in the control group. The present study thus highlights the benefit of the design idea of combining efficient imaging/guiding, targeting, and triggerable release functions in one lipid molecule for drug delivery applications.

Facile synthesis of urchin-like LaWO4Cl assemblies and their near-infrared photothermal conversion

The construction of the hierarchical nanostructures of inorganic materials with high stability has attracted great attention for photothermal therapy. In this paper, we presented the preparation of urchin-like LaWO4Cl nanostructures assembled with nanoribbons via a facile solvothermal reaction. X-ray diffraction (XRD) analysis confirmed the formation of good crystalline urchin-like LaWO4Cl assemblies. Energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) revealed the element composition of the prepared urchin-like nanostructures. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations showed that the urchin-like LaWO4Cl assemblies were composed of single crystalline nanoribbons with diameters less than 10 nm. When excited with an 808 nm near-infrared (NIR) laser at the power density of 1.91 W cm-2 for 5 min, the temperature quickly increased to 52 °C. The in vitro cytotoxicity of urchin-like LaWO4Cl was tested with human cervical cancer cells (HeLa), revealing excellent biocompatibility. More importantly, the photothermal treatment with urchin-like LaWO4Cl displayed great therapeutic efficacy in vitro. Thus, urchin-like LaWO4Cl would be a new promising NIR light-driven photothermal agent, which can also pave a new way for the material design of PTT agents.

Programmable Therapeutic Nanodevices with Circular Amplification of H2 O2 in the Tumor Microenvironment for Synergistic Cancer Therapy

Tumor microenvironment activated nanodevices have remarkable superiority to enhance therapeutic efficacy and minimize side effects, but their practical applications are dramatically reduced by the low abundance and heterogeneous distribution of specific stimuli at the tumor site. Herein, programmable vesicular nanodevices based on the triblock copolymer containing poly(ethylene glycol) (PEG) and poly(caprolactone) (PCL) with peroxalate esters (PO) as hydrogen peroxide-responsive linkage (PEG-PO-PCL-PO-PEG), are developed for co-delivery of hypoxia-activated prodrug (AQ4N) and glucose oxidase (GOD). The obtained nanodevices (PAG) can be activated by the high level of H₂ O₂ in tumor microenvironment to improve the permeability of membranes for glucose entrance. Afterward, the oxidation of glucose catalyzed by GOD produces amplified H₂ O₂ amounts which in turn induce complete destruction of PAG for fast release of AQ4N and GOD. Ultimately, the PAG can exert programmable therapeutic effects from the following aspects: 1) starvation therapy by cutting off the energy supply from glucose through GOD catalysis; 2) oxidative cytotoxicity after H₂ O₂ amplification; 3) chemotherapy of AQ4N activated by the intensified tumor hypoxia microenvironment after oxygen consumption. The stimuli amplification, controlled drug release, synergistic therapy, and corresponding mechanisms of PAG are demonstrated. Therefore, the presented work could provide significant new insights for cancer treatment.

Photocatalysis Enhancement for Programmable Killing of Hepatocellular Carcinoma through Self-Compensation Mechanisms Based on Black Phosphorus Quantum-Dot-Hybridized Nanocatalysts

Recently reported black phosphorus quantum dots (BPQDs) possess unique photocatalysis activities. However, the environmental instability accompanied by a hypoxic tumor microenvironment (TME) seriously hindered the bioapplications of BPQDs, especially in oxygen-dependent photodynamic therapy (PDT). Here, we construct a hepatocellular carcinoma (HCC)-specific targeting aptamer "TLS11a"-decorated BPQDs-hybridized nanocatalyst, which can specifically target HCC tumor cells and self-compensate oxygen (O₂) into hypoxic TME for enhancing PDT efficiency. The BPQD-hybridized mesoporous silica framework (BMSF) with in situ synthesized Pt nanoparticles (PtNPs) in the BMSF is simply prepared. After being decorated by TLS11a aptamer/Mal-PEG-NHS, the resultant nanosystem (refer as Apt-BMSF@Pt) exhibits excellent environmental stability, active targeting ability to HCC cells, and self-compensation ability of oxygen. Compared with the PEG-BMSF@Pt without H₂O₂ incubation, the PEG-BMSF@Pt nanocatalyst exhibits 4.2-folds O₂ and 1.6-folds ¹O₂ generation ability in a mimetic closed-system in the presence of both H₂O₂ and near-infrared laser. In a mouse model, the Apt-BMSF@Pt can effectively accumulate into tumor sites, and the core of BMSF subsequently can act as a photosensitizer to generate reactive oxygen species, while the PtNPs can serve as a catalyst to convert H₂O₂ into O₂ for enhancing PDT through self-compensation mechanisms in hypoxic TME. By comparison of the tumor volume/weight, H&E, and immunohistochemical analysis, the excellent antitumor effects with minimized side effects of our Apt-BMSF@Pt could be demonstrated in vivo. Taken together, the current study suggests that our Apt-BMSF@Pt could act as an active targeting nanocatalyst for programmable killing of cancer cells in hypoxic TME.

Artificial chimeric exosomes for anti-phagocytosis and targeted cancer therapy

Development of exosome-based delivery systems is still facing some formidable challenges, including the lack of standardized isolation and purification methods, non-large-scale production and low drug-loading efficiency. Inspired by biomimetic technologies, we turned to the design of artificial chimeric exosomes (ACEs) constructed by integrating cell membrane proteins from multiple cell types into synthetic phospholipid bilayers. For benchmarking, hybrid membrane proteins derived from red blood cells (RBCs) and MCF-7 cancer cells were selected as models. The resulting ACEs were engineered much like "Emperor Qin's Terra-Cotta Warriors", simultaneously equipped with armor (anti-phagocytosis capability from RBCs) and dagger-axes (homologous targeting ability from cancer cells). ACEs demonstrated higher tumor accumulation, lower interception and better antitumor therapeutic effect than plain liposomes in vivo, alongside large-scale standardized preparation, stable structure, high drug-loading capacity and custom-tailored functionality, highlighting the suitability of ACEs as promising alternatives of exosomes in clinical applications.

Self-Luminescing Theranostic Nanoreactors with Intraparticle Relayed Energy Transfer for Tumor Microenvironment Activated Imaging and Photodynamic Therapy

The low tissue penetration depth of external excitation light severely hinders the sensitivity of fluorescence imaging (FL) and the efficacy of photodynamic therapy (PDT) in vivo; thus, rational theranostic platforms that overcome the light penetration depth limit are urgently needed. To overcome this crucial problem, we designed a self-luminescing nanosystem (denoted POCL) with near-infrared (NIR) light emission and singlet oxygen (¹O₂) generation abilities utilizing an intraparticle relayed resonance energy transfer strategy. Methods: Bis[3,4,6-trichloro-2-(pentyloxycarbonyl) phenyl] oxalate (CPPO) as a chemical energy source with high reactivity toward H₂O₂, poly[(9,9'-dioctyl-2,7-divinylene-fluorenylene)-alt-2-methoxy- 5-(2-ethyl-hexyloxy)-1,4-phenylene] (PFPV) as a highly efficient chemiluminescence converter, and tetraphenylporphyrin (TPP) as a photosensitizer with NIR emission and ¹O₂ generation abilities were coencapsulated by self-assembly with poly(ethyleneglycol)-co-poly(caprolactone) (PEG-PCL) and folate-PEG-cholesterol to form the POCL nanoreactor, with folate as the targeting group. A series of in vitro and in vivo analyses, including physical and chemical characterizations, tumor targeting ability, tumor microenvironment activated imaging and photodynamic therapy, as well as biosafety, were systematically investigated to characterize the POCL. Results: The POCL displayed excellent NIR luminescence and ¹O₂ generation abilities in response to H₂O₂. Therefore, it could serve as a specific H₂O₂ probe to identify tumors through chemiluminescence imaging and as a chemiluminescence-driven PDT agent for inducing tumor cell apoptosis to inhibit tumor growth due to the abnormal overproduction of H₂O₂ in the tumor microenvironment. Moreover, the folate ligand on the POCL surface can further improve the accumulation at the tumor site via a receptor-mediated mechanism, thus enhancing tumor imaging and the therapeutic effects both in vitro and in vivo but without any observable systemic toxicity. Conclusion: The nanosystem reported here might serve as a targeted, smart, precise, and noninvasive strategy triggered by the tumor microenvironment rather than by an outside light source for cancer NIR imaging and PDT treatment without limitations on penetration depth.

Hypoxia- and singlet oxygen-responsive chemo-photodynamic Micelles featured with glutathione depletion and aldehyde production

Triggered drug release from anti-tumor nanomedicine is an efficient approach to address the dilemma of systemic nanocarrier stability and on-demand drug liberation in tumor sites.

Self-Luminescing Theranostic Nanoreactors with Intraparticle Relayed Energy Transfer for Tumor Microenvironment Activated Imaging and Photodynamic Therapy

The low tissue penetration depth of external excitation light severely hinders the sensitivity of fluorescence imaging (FL) and the efficacy of photodynamic therapy (PDT) in vivo; thus, rational theranostic platforms that overcome the light penetration depth limit are urgently needed. To overcome this crucial problem, we designed a self-luminescing nanosystem (denoted POCL) with near-infrared (NIR) light emission and singlet oxygen (¹O₂) generation abilities utilizing an intraparticle relayed resonance energy transfer strategy.

Methods: Bis[3,4,6-trichloro-2-(pentyloxycarbonyl) phenyl] oxalate (CPPO) as a chemical energy source with high reactivity toward H₂O₂, poly[(9,9'-dioctyl-2,7-divinylene-fluorenylene)-alt-2-methoxy- 5-(2-ethyl-hexyloxy)-1,4-phenylene] (PFPV) as a highly efficient chemiluminescence converter, and tetraphenylporphyrin (TPP) as a photosensitizer with NIR emission and ¹O₂ generation abilities were coencapsulated by self-assembly with poly(ethyleneglycol)-co-poly(caprolactone) (PEG-PCL) and folate-PEG-cholesterol to form the POCL nanoreactor, with folate as the targeting group. A series of in vitro and in vivo analyses, including physical and chemical characterizations, tumor targeting ability, tumor microenvironment activated imaging and photodynamic therapy, as well as biosafety, were systematically investigated to characterize the POCL.

Results: The POCL displayed excellent NIR luminescence and ¹O₂ generation abilities in response to H₂O₂. Therefore, it could serve as a specific H₂O₂ probe to identify tumors through chemiluminescence imaging and as a chemiluminescence-driven PDT agent for inducing tumor cell apoptosis to inhibit tumor growth due to the abnormal overproduction of H₂O₂ in the tumor microenvironment. Moreover, the folate ligand on the POCL surface can further improve the accumulation at the tumor site via a receptor-mediated mechanism, thus enhancing tumor imaging and the therapeutic effects both in vitro and in vivo but without any observable systemic toxicity.

Conclusion: The nanosystem reported here might serve as a targeted, smart, precise, and noninvasive strategy triggered by the tumor microenvironment rather than by an outside light source for cancer NIR imaging and PDT treatment without limitations on penetration depth.

pH/hypoxia programmable triggered cancer photo-chemotherapy based on a semiconducting polymer dot hybridized mesoporous silica framework

Although photothermal therapy (PTT) has become a compelling strategy for cancer therapy, few studies concern the physiological consequences of PTT ablation. Herein, we discover that PTT-induced hyperthermia can aggravate tumor hypoxia, which may increase the risk of tumor recurrence and reduce PTT efficacy. We thus integrated the pH/hypoxia-triggered Fe(iii)-banoxantrone (AQ4N) prodrug and semiconducting polymer dots (SPs) for programmable triggered cancer photothermal-chemotherapy. A SP-hybridized mesoporous silica framework, decorated by dopamine and polyethylene glycol, named PPMSF, was synthesized by a simple method, and then served as an efficient photo-absorbing agent (PTA) and drug carrier. Fe(iii)-AQ4N and Mn(ii) were then coordinated with PPMSF (abbreviated Mn-APPMSF) via coordination effects. The nanohybrids exhibited tumor micro-environment pH triggered drug release. Under the irradiation of NIR light, magnetic resonance imaging (MRI) tracked the accumulation of the nanohybrids in tumors which then destroyed tumor cells by local hyperthermia, this can consequently aggravate the tumor hypoxia levels. Intriguingly, the aggravated hypoxia can further enhance the reduction of AQ4N to significantly improve therapeutic efficacy and effectively inhibit tumor growth when compared with traditional PTT. These results indicate the potential of our nanohybrids as a programmable synergistic agent for cancer therapy.

Self-Quenched Metal-Organic Particles as Dual-Mode Therapeutic Agents for Photoacoustic Imaging-Guided Second Near-Infrared Window Photochemotherapy

The nanosized metal-organic particles (NMOPs) recently have attracted tremendous attentions in biomedical applications. However, few studies have developed metal-organic nanoparticles (NMOPs) as near-infrared (NIR) II phototherapeutic agents and as Fenton-like agents for cancer theranostics. Herein, directly using organic dye and Cu(II)-ion complexes to construct NMOPs, as dual-mode therapeutic agent for PA imaging-guided photochemotherapy in NIR II window, is reported. The NMOPs are simply an assembly of Cu(II) ion and tetrahydroxyanthraquinone (THQ) complexes [Cu(II)-THQ] _n through the coordination effect, van der Waals force, and π-π interactions. After modification of polyethylene glycol (PEG-(NH₂)₂), the obtained Cu-THQNPs endow excellent biocompatibility and stability in physiological conditions. Because of the strong absorption at NIR II window and photoinduced electrontransfer (PET) mechanism, the Cu-THQNPs not only acted as an excellent photothermal agent with extremely high light-to-heat conversion ability (51.34%) at 1064 nm for phototherapy but also explored as the PA contrast agent for precisely tracking and guiding the therapy in vivo. Most strikingly, our Cu-THQNPs can be degraded by tumor-specific acidic-cleaving of the coordination bonds and follow by the slow release of Cu(II) into tumors, which can act as Fenton-like agents to generate ^•OH from H₂O₂ for enhancing the antitumor efficacy in vivo. With almost 100% prevention of the tumor growth for ca. 14 days and no obvious toxicity based on blood biochemical/histological analysis, this work highlights the Cu-THQNPs as an efficient NIR II therapeutic agent for precise cancer theranostics.

Light-Enhanced Hypoxia-Response of Conjugated Polymer Nanocarrier for Successive Synergistic Photodynamic and Chemo-Therapy

The tumor hypoxic environment as well as photodynamic therapy (PDT)-induced hypoxia could severely limit the therapeutic efficacy of traditional PDT. Fortunately, the smart integration of hypoxia-responsive drug delivery system with PDT might be a promising strategy to enhance the PDT efficiency that is hindered by the hypoxic environment. Herein, a novel azobenzene (AZO) containing conjugated polymers (CPs)-based nanocarriers (CPs-CPT-Ce6 NPs) was constructed for the combination of PDT with chemotherapy, as well as to enhance the hypoxia-responsive drug release by light. The conjugated polymer chains, used as a matrix to prepare the CPs-CPT-Ce6 NPs, were beneficial for loading hydrophobic photosensitizers and chemotherapy drugs, to improve their cellular uptake. Moreover, the AZO group (-N═N-) in CPs, which can be reduced and cleaved by azoreductase (a typical biomarker of hypoxia) under the hypoxic environment of tumor cells, acts as the hypoxia-responsive linker component. Upon laser irradiation, the CPs-CPT-Ce6 NPs could produce ROS for PDT and then facilitate the enhancement of tumor hypoxic condition, which could further promote the dissociation of CPs via reductive cleavage of AZO bridges to subsequently release cargos (chemotherapeutic drug, CPT) and then significantly enhance the killing effects to tumor cells that were resistant to PDT. Both in vitro and in vivo studies confirmed the improvement of synergistic therapeutic effects of our CPs-CPT-Ce6 NPs. This cascade responsive approach provides an excellent complementary mode for PDT and could open new insights for constructing programmable and controllable responsive systems in biomedical applications.

Photoresponsive Nanovehicle for Two Independent Wavelength Light-Triggered Sequential Release of P-gp shRNA and Doxorubicin To Optimize and Enhance Synergistic Therapy of Multidrug-Resistant Cancer

Prerelease of RNA molecules than chemotherapeutic drugs with a sufficient interval is a vital prerequisite for RNA/drug co-delivery strategy to overcome multidrug resistance (MDR) of cancer cells, but how to precisely control their release at different time points is still a grand challenge up to now. This study aims to on-demand remotely manipulate RNA and drug release in real time through single delivery system to sequentially play their respective roles for optimizing and enhancing their synergistic antitumor effects. To this end, a photoresponsive mesoporous silica nanoparticle (PMSN) is fabricated as a co-delivery vehicle of P-glycoprotein (P-gp) short-hairpin RNA (shRNA) and photocaged prodrug of doxorubicin (DOX), by which the orthogonal and sequential release of shRNA and DOX can be achieved using an external light. In our design, the cationic poly[2-( N, N-dimethylaminoethyl)methacrylate] is introduced onto the PMSN surface through a light-sensitive coumarin ester derivative linker to adsorb P-gp shRNA, whereas the photocleavable o-nitrobenzyl ester derivative-caged DOX is loaded into the inner pores of the PMSN. The PMSN is found to be effectively internalized by MDR cancer cells, and the release of the shRNA and DOX is demonstrated to be independently regulated by 405 and 365 nm light irradiations due to selectively cleaved coumarin and o-nitrobenzyl ester, resulting in enhanced drug retention, and finally bring out optimized and significantly improved chemotherapeutic effects both in vitro and in vivo for MDR cancer treatment, which might hold extensive application prospects in MDR cancer treatment in future.