Photosensitizer-crosslinked in-situ polymerization on catalase for tumor hypoxia modulation & enhanced photodynamic therapy

Nano-sensitizer with self-amplified drug release and hypoxia normalization properties potentiates efficient chemoradiotherapy of pancreatic cancer

The hypoxic nature of pancreatic cancer, one of the most lethal malignancies worldwide, significantly impedes the effectiveness of chemoradiotherapy. Although the development of oxygen carriers and hypoxic sensitizers has shown promise in overcoming tumor hypoxia. The heterogeneity of hypoxia-primarily caused by limited oxygen penetration-has posed challenges. In this study, we designed a hypoxia-responsive nano-sensitizer by co-loading tirapazamine (TPZ), KP372-1, and MK-2206 in a metronidazole-modified polymeric vesicle. This nano-sensitizer relies on efficient endogenous NAD(P)H quinone oxidoreductase 1-mediated redox cycling induced by KP372-1, continuously consuming periphery oxygen and achieving evenly distributed hypoxia. Consequently, the normalized tumor microenvironment facilitates the self-amplified release and activation of TPZ without requiring deep penetration. The activated TPZ and metronidazole further sensitize radiotherapy, significantly reducing the radiation dose needed for extensive cell damage. Additionally, the coloaded MK-2206 complements inhibition of therapeutic resistance caused by Akt activation, synergistically enhancing the hypoxic chemoradiotherapy. This successful hypoxia normalization strategy not only overcomes hypoxia resistance in pancreatic cancer but also provides a potential universal approach to sensitize hypoxic tumor chemoradiotherapy by reshaping the hypoxic distribution.

Advances in H2O2-supplying materials for tumor therapy: synthesis, classification, mechanisms, and applications

Hydrogen peroxide (H2O2) as a reactive oxygen species produced by cellular metabolism can be used in antitumor therapy. However, the concentration of intracellular H2O2 limits its application. Some materials could enhance the concentration of intracellular H2O2 to strengthen antitumor therapy. In this review, the recent advances in H2O2-supplying materials in terms of promoting intracellular H2O2 production and exogenous H2O2 supply are summarized. Then the mechanism of H2O2-supplying materials for tumor therapy is discussed from three aspects: reconstruction of the tumor hypoxia microenvironment, enhancement of oxidative stress, and the intrinsic anti-tumor ability of H2O2-supplying materials. In addition, the application of H2O2-supplying materials for tumor therapy is discussed. Finally, the future of H2O2-supplying materials is presented. This review aims to provide a novel idea for the application of H2O2-supplying materials in tumor therapy.

Indocyanine green-loaded N-doped carbon quantum dot nanoparticles for effective photodynamic therapy and cell imaging of melanoma cancer: in vitro, ex vivo and in vivo study

BACKGROUND

Indocyanine Green (ICG) as an agent for photodynamic therapy (PDT) of melanoma cancer has low quantum yield, short circulation half-life, poor photo-stability, and tendency to aggregation.

PURPOSE

N-doped carbon quantum dot (CQD) nanoparticle was applied to encapsulate ICG and overcome ICG obstacle in PDT with simultaneous cell imaging property.

METHODS

CQD was prepared using hydrothermal method. Cell culture study and In vivo assessments on C57BL/6 mice containing melanoma cancer cells was performed.

RESULTS

Results showed that CQD size slightly enhanced from 24.55 nm to 42.67 nm after ICG loading. Detection of reactive oxygen species (ROS) demonstrated that CQD improved ICG photo-stability and ROS generation capacity upon laser irradiation. Cell culture study illustrated that ICG@CQD could decrease survival rate of melanoma cancer cells of B16F10 cell line from 48% for pure ICG to 28% for ICG@CQD. Confocal microscopy images approved more cellular uptake and more qualified cell imaging ability of ICG@CQD. In vivo assessments displayed obvious inhibitory effect of tumor growth for ICG@CQD in comparison to free ICG on the C57BL/6 mice. In vivo fluorescence images confirmed that ICG@CQD accumulates remarkably more than free ICG in tumor region. Finally, ICG@CQD was proposed as an innovative nanocarrier for PDT and diagnosis.

Polymeric functionalization of mesoporous silica nanoparticles: Biomedical insights

Mesoporous silica nanoparticles (MSNs) endowed with polymer coatings present a versatile platform, offering notable advantages such as targeted, pH-controlled, and stimuli-responsive drug delivery. Surface functionalization, particularly through amine and carboxyl modification, enhances their suitability for polymerization, thereby augmenting their versatility and applicability. This review delves into the diverse therapeutic realms benefiting from polymer-coated MSNs, including photodynamic therapy (PDT), photothermal therapy (PTT), chemotherapy, RNA delivery, wound healing, tissue engineering, food packaging, and neurodegenerative disorder treatment. The multifaceted potential of polymer-coated MSNs underscores their significance as a focal point for future research endeavors and clinical applications. A comprehensive analysis of various polymers and biopolymers, such as polydopamine, chitosan, polyethylene glycol, polycaprolactone, alginate, gelatin, albumin, and others, is conducted to elucidate their advantages, benefits, and utilization across biomedical disciplines. Furthermore, this review extends its scope beyond polymerization and biomedical applications to encompass topics such as surface functionalization, chemical modification of MSNs, recent patents in the MSN domain, and the toxicity associated with MSN polymerization. Additionally, a brief discourse on green polymers is also included in review, highlighting their potential for fostering a sustainable future.

Enzyme-loaded manganese-porphyrin metal-organic nanoframeworks for oxygen-evolving photodynamic therapy of hypoxic cells

Photodynamic therapy (PDT) is attracting great attention for cancer treatments, while its therapeutic efficacy is limited by unsatisfactory photosensitizers and hypoxic tumor microenvironment (TME). To address these problems, we have developed catalase-loaded manganese-porphyrin frameworks (CAT@MnPFs) for catalytically-assisted PDT of cancer cells. CAT@MnPFs were constructed by the assembly of Mn2+ ions and PpIX into MnPFs and the subsequent loading of catalase. Under 650 nm light irradiation, the porphyrin (Protoporphyrin IX) within the structure of CAT@MnPFs can convert oxygen (O2) into singlet oxygen (1O2), showing the photodynamic effect. Importantly, the loaded catalase can decompose hydrogen peroxide (H2O2) into O2 with a huge elevation of O2 level (13.22 mg L-1) in 600 s, thus promoting 1O2 generation via PDT. As a result, CAT@MnPFs combined with 650 nm light can effectively ablate cancer cells due to the catalase-assisted oxygen-evolving PDT, showing a high therapeutic efficacy. Meanwhile, after the incubation with CAT@MnPFs, unobvious damage can be found in normal and red blood cells. Thus, the obtained CAT@MnPFs integrate the advantage of photosensitizers and catalase for oxygen-evolving PDT, which can provide some insight for treating hypoxic cells.

Use of photosensitive molecules in the crosslinking of biopolymers: applications and considerations in biomaterials development

The development of diverse types of biomaterials has significantly contributed to bringing new biomedical strategies to treat clinical conditions. Applications of these biomaterials can range from mechanical support and protection of injured tissues to joint replacement, tissue implants, and drug delivery systems. Among the strategies commonly used to prepare biomaterials, the use of electromagnetic radiation to initiate crosslinking stands out. The predominance of photo-induced polymerization methods relies on a fast, efficient, and straightforward process that can be easily adjusted to clinical needs. This strategy consists of irradiating the components that form the material with photons in the near ultraviolet-visible wavelength range (i.e., ∼310 to 750 nm) in the presence of a photoactive molecule. Upon photon absorption, photosensitive molecules can generate excited species that initiate photopolymerization through different reaction mechanisms. However, this process could promote undesired side reactions depending on the target zone or treatment type (e.g., oxidative stress and modification of biomolecules such as proteins and lipids). This review explores the basic concepts behind the photopolymerization process of ex situ and in situ biomaterials. Particular emphasis was put on the photosensitization initiated by the most employed photosensitizers and the photoreactions that they mediate in aqueous media. Finally, the undesired oxidation reactions at the bio-interface and potential solutions are presented.

Biosynthesis of NIR-II Ag2Se Quantum Dots with Bacterial Catalase for Photoacoustic Imaging and Alleviating-Hypoxia Photothermal Therapy

Developing the second near-infrared (NIR-II) photoacoustic (PA) agent is of great interest in bioimaging. Ag2Se quantum dots (QDs) are one kind of potential probe for applications in NIR-II photoacoustic imaging (PAI). However, the surfaces with excess anions of Ag2Se QDs, which increase the probability of nonradiative transitions of excitons benefiting PA imaging, are not conducive to binding electron donor ligands for potential biolabeling and imaging. In this study, Staphylococcus aureus (S. aureus) cells are driven for the biosynthesis of Ag2Se QDs with catalase (CAT). Biosynthesized Ag2Se (bio-Ag2Se-CAT) QDs are produced in Se-enriched environment of S. aureus and have a high Se-rich surface. The photothermal conversion efficiency of bio-Ag2Se-CAT QDs at 808 and 1064 nm is calculated as 75.3% and 51.7%, respectively. Additionally, the PA signal responsiveness of bio-Ag2Se-CAT QDs is ≈10 times that of the commercial PA contrast agent indocyanine green. In particular, the bacterial CAT is naturally attached to bio-Ag2Se-CAT QDs surface, which can effectively relieve tumor hypoxia. The bio-Ag2Se-CAT QDs can relieve heat-initiated oxidative stress while undergoing effective photothermal therapy (PTT). Such biosynthesis method of NIR-II bio-Ag2Se-CAT QDs opens a new avenue for developing multifunctional nanomaterials, showing great promise for PAI, hypoxia alleviation, and PTT.

Biochemical hallmarks-targeting antineoplastic nanotherapeutics

Tumor microenvironments (TMEs) have received increasing attention in recent years as they play pivotal roles in tumorigenesis, progression, metastases, and resistance to the traditional modalities of cancer therapy like chemotherapy. With the rapid development of nanotechnology, effective antineoplastic nanotherapeutics targeting the aberrant hallmarks of TMEs have been proposed. The appropriate design and fabrication endow nanomedicines with the abilities for active targeting, TMEs-responsiveness, and optimization of physicochemical properties of tumors, thereby overcoming transport barriers and significantly improving antineoplastic therapeutic benefits. This review begins with the origins and characteristics of TMEs and discusses the latest strategies for modulating the TMEs by focusing on the regulation of biochemical microenvironments, such as tumor acidosis, hypoxia, and dysregulated metabolism. Finally, this review summarizes the challenges in the development of smart anti-cancer nanotherapeutics for TME modulation and examines the promising strategies for combination therapies with traditional treatments for further clinical translation.

Innovative Formulation Platform: Paving the Way for Superior Protein Therapeutics with Enhanced Efficacy and Broadened Applications

Protein therapeutics offer high therapeutic potency and specificity; the broader adoptions and development of protein therapeutics, however, have been constricted by their intrinsic limitations such as inadequate stability, immunogenicity, suboptimal pharmacokinetics and biodistribution, and off-target effects. This review describes a platform technology that formulates individual protein molecules with a thin formulation layer of crosslinked polymers, which confers the protein therapeutics with high activity, enhanced stability, controlled release capability, reduced immunogenicity, improved pharmacokinetics and biodistribution, and ability to cross the blood brain barriers. Based on currently approved protein therapeutics, this formulating platform affords the development of a vast family of superior protein therapeutics with improved efficacy and broadened indications at significantly reduced cost.

A Versatile Cryomicroneedle Patch for Traceable Photodynamic Therapy

Photodynamic therapy (PDT) continues to encounter multifarious hurdles, stemming from the ineffectual preservation and delivery system of photosensitizers, the dearth of imaging navigation, and the antioxidant/hypoxic tumor microenvironment. Herein, a versatile cryomicroneedle patch (denoted as CMN-CCPH) is developed for traceable PDT. The therapeutic efficacy is further amplified by catalase (CAT)-induced oxygen (O2) generation and Cu2+-mediated glutathione (GSH) depletion. The CMN-CCPH is composed of cryomicroneedle (CMN) as the vehicle and CAT-biomineralized copper phosphate nanoflowers (CCP NFs) loaded with hematoporphyrin monomethyl ether (HMME) as the payload. Importantly, the bioactive function of HMME and CAT can be optimally maintained under the protection of CCPH and CMN for a duration surpassing 60 days, leading to bolstered bioavailability and notable enhancements in PDT efficacy. The in vivo visualization of HMME and oxyhemoglobin saturation (sO2) monitored by fluorescence (FL)/photoacoustic (PA) duplex real-time imaging unveils the noteworthy implications of CMN-delivered CCPH for intratumoral enrichment of HMME and O2 with reduced systemic toxicity. This versatile CMN patch demonstrates distinct effectiveness in neoplasm elimination, underscoring its promising clinical prospects.

Recent progress in lactate oxidase-based drug delivery systems for enhanced cancer therapy

Lactate oxidase (LOX) is a natural enzyme that efficiently consumes lactate. In the presence of oxygen, LOX can catalyse the formation of pyruvate and hydrogen peroxide (H2O2) from lactate. This process led to acidity alleviation, hypoxia, and a further increase in oxidative stress, alleviating the immunosuppressive state of the tumour microenvironment (TME). However, the high cost of LOX preparation and purification, poor stability, and systemic toxicity limited its application in tumour therapy. Therefore, the rational application of drug delivery systems can protect LOX from the organism's environment and maintain its catalytic activity. This paper reviews various LOX-based drug-carrying systems, including inorganic nanocarriers, organic nanocarriers, and inorganic-organic hybrid nanocarriers, as well as other non-nanocarriers, which have been used for tumour therapy in recent years. In addition, this area's challenges and potential for the future are highlighted.

Cancer cell membrane-coated nanoparticles: a promising anti-tumor bionic platform

Nanoparticle (NP) drug delivery systems have shown promise in tumor therapy. However, limitations such as susceptibility to immune clearance and poor targeting in a complex intercellular environment still exist. Recently, cancer cell membrane-encapsulated nanoparticles (CCM-NPs) constructed using biomimetic nanotechnology have been developed to overcome these problems. Proteins on the membrane surface of cancer cells can provide a wide range of activities for CCM-NPs, including immune escape and homologous cell recognition properties. Meanwhile, the surface of the cancer cell membrane exhibits obvious antigen enrichment, so that CCM-NPs can transmit tumor-specific antigen, activate a downstream immune response, and produce an effective anti-tumor effect. In this review, we first provided an overview of the functions of cancer cell membranes and summarized the preparation techniques and characterization methods of CCM-NPs. Then, we focused on the application of CCM-NPs in tumor therapy. In addition, we summarized the functional modifications of cancer cell membranes and compiled the patent applications related to CCM-NPs in recent years. Finally, we proposed the future challenges and directions of this technology in order to provide guidance for researchers in this field.

Hypoxia Reversion by Low-Immunogenic Ultra-Acid-Sensitive Comicelles of Protein-Polymer Conjugates Sensitizes Tumors to Photodynamic Therapy

Hypoxia is characteristic of the tumor microenvironment, which is correlated with resistance to photodynamic therapy (PDT), radiotherapy, chemotherapy, and immunotherapy. Catalase is potentially useful to catalyze the conversion of endogenous H2O2 to O2 for hypoxia reversion. However, the efficient delivery of catalase into the hypoxia regions of tumors is a huge challenge. Here, we report the self-assembly of ultra-acid-sensitive polymer conjugates of catalase and albumin into nanomicelles that are responsive to the acidic tumor microenvironment. The immunogenicity of catalase is mitigated by the presence of albumin, which reduces the cross-linking of catalase with B cell receptors, resulting in improved pharmacokinetics. The ultra acid sensitivity of the nanomicelles makes it possible to efficiently escape the lysosomal degradation after endocytosis and permeate into the interior of tumors to reverse hypoxia in vitro and in vivo. In mice bearing triple-negative breast cancer, the nanomicelles loaded with a photosensitizer effectively accumulate and penetrate into the whole tumors to generate a sufficient amount of O2 to reverse hypoxia, leading to enhanced efficacy of PDT without detectable side effects. These findings provide a general strategy of self-assembly to design low-immunogenic ultra-acid-sensitive comicelles of protein-polymer conjugates to reverse tumor hypoxia, which sensitizes tumors to PDT.

Bioresponsive and immunotherapeutic nanomaterials to remodel tumor microenvironment for enhanced immune checkpoint blockade

Immune checkpoint blockade (ICB) therapy is a revolutionary approach to treat cancers, but still have limited clinical applications. Accumulating evidence pinpoints the immunosuppressive characteristics of the tumor microenvironment (TME) as one major obstacle. The TME, characterized by acidity, hypoxia and elevated ROS levels, exerts its detrimental effects on infiltrating anti-tumor immune cells. Here, we developed a TME-responsive and immunotherapeutic catalase-loaded calcium carbonate nanoparticles (termed as CAT@CaCO3 NPs) as the simple yet versatile multi-modulator for TME remodeling. CaCO3 NPs can consume protons in the acidic TME to normalize the TME pH. CAT catalyzed the decomposition of ROS and thus generated O2. The released Ca2+ led to Ca2+ overload in the tumor cells which then triggered the release of damage-associated molecular patterns (DAMP) signals to initiate anti-tumor immune responses, including tumor antigen presentation by dendritic cells. Meanwhile, CAT@CaCO3 NPs-induced immunosupportive TME also promoted the polarization of the M2 tumor-associated macrophages to the M1 phenotype, further enhancing tumor antigen presentation. Consequently, T cell-mediated anti-tumor responses were activated, the efficacy of which was further boosted by aPD-1 immune checkpoint blockade. Our study demonstrated that local treatment of CAT@CaCO3 NPs and aPD-1 combination can effectively evoke local and systemic anti-tumor immune responses, inhibiting the growth of treated tumors and distant diseases.

Activable Photodynamic DNA Probe with an "AND" Logic Gate for Precision Skin Cancer Therapy

Photodynamic therapy (PDT) has emerged as a promising approach for squamous cell carcinoma treatment but hindered by tumor hypoxia, acquired resistance, phototoxicity, and so on. To address these issues, we developed a smart strategy utilizing activable photosensitizers delivered by an aptamer-functionalized DNA probe (ADP). The ADP incorporated an AS1411 aptamer for tumor targeting and a linear antisense oligonucleotide (ASO) for recognition of Survivin mRNA. In the absence of the target, PDT remained quenched, thereby avoiding phototoxicity during circulation and nonselective distribution. With the aid of the aptamer, ADP achieved selective targeting of tumors. Upon internalization, ADP targeted recognized Survivin mRNA, triggering PDT activation, and releasing ASO to down-regulate Survivin expression and reverse tumor resistance. Consequently, the activable photosensitizers exhibited an "AND" logic gate, combining tumor-targeting delivery and tumor-related gene activation, thus enhancing its specificity. Additionally, the incorporation of hemin into the ADP provided catalase activity, converting tumor-abundant H2O2 into O2, thereby ameliorating tumor hypoxia. The resulting functionalized G-quadruplex/hemin-DNA probe complex demonstrated targeted delivery and activation, minimized side effects, and enhanced PDT efficacy in both xenograft tumor-bearing mice and patient-derived xenograft models. This study offers a unique and promising platform for efficient and safe PDT, thus holding great potential for future clinical translation and improved cancer therapy.

Current Advances in Photodynamic Therapy (PDT) and the Future Potential of PDT-Combinatorial Cancer Therapies

Photodynamic therapy (PDT) is a two-stage treatment that implies the use of light energy, oxygen, and light-activated compounds (photosensitizers) to elicit cancerous and precancerous cell death after light activation (phototoxicity). The biophysical, bioengineering aspects and its combinations with other strategies are highlighted in this review, both conceptually and as they are currently applied clinically. We further explore the recent advancements of PDT with the use of nanotechnology, including quantum dots as innovative photosensitizers or energy donors as well as the combination of PDT with radiotherapy and immunotherapy as future promising cancer treatments. Finally, we emphasize the potential significance of organoids as physiologically relevant models for PDT.

Recent Advances in the HPPH-Based Third-Generation Photodynamic Agents in Biomedical Applications

Photodynamic therapy has emerged as a recognized anti-tumor treatment involving three fundamental elements: photosensitizers, light, and reactive oxygen species. Enhancing the effectiveness of photosensitizers remains the primary avenue for improving the biological therapeutic outcomes of PDT. Through three generations of development, HPPH is a 2-(1-hexyloxyethyl)-2-devinyl derivative of pyropheophorbide-α, representing a second-generation photosensitizer already undergoing clinical trials for various tumors. The evolution toward third-generation photosensitizers based on HPPH involves structural modifications for multimodal applications and the combination of multifunctional compounds, leading to improved imaging localization and superior anti-tumor effects. While research into third-generation HPPH is beneficial for advancing PDT treatment, equal attention should also be directed toward the other two essential elements and personalized diagnosis and treatment methodologies.

Controllable Star Cationic Poly(Disulfide)s Achieve Genetically Cascade Catalytic Therapy by Delivering Bifunctional Fusion Plasmids

The absence of effective delivery vectors and suitable multifunctional plasmids limits cancer gene therapy development. The star cationic poly(disulfide)s with β-cyclodextrin cores (termed β-CD-g-PSSn ) for caveolae-mediated endocytosis are designed and prepared via mild and controllable disulfide exchange polymerization for high-efficacy cancer therapy. Then, β-CD-g-PSSn /pDNA complexes are transported to the Golgi apparatus and endoplasmic reticulum. Disulfides in β-CD-g-PSSn vectors are degraded by glutathione in tumor cells, which not only promotes intracellular pDNA release but also reduces in vitro and in vivo toxicity. One bifunctional fusion plasmid pCATKR, which expresses catalase (CAT) fused to KillerRed (KR) (CATKR) in the same target cell, is also proposed for genetically cascade catalytic therapy. When compared with pCAT-KR (plasmid expressing CAT and KR separately in the same cell), delivered pCATKR decomposes hydrogen peroxide, alleviates tumor hypoxia more effectively, generates stronger reactive oxygen species (ROS) capabilities under moderate irradiation, and leads to robust antitumor cascade photodynamic effects. These impressive results are attributed to fusion protein design, which shortens the distance between CAT and KR catalytic centers and leads to improved ROS production efficiency. This work provides a promising strategy by delivering a catalytic cascade functional plasmid via a high-performance vector with biodegradable and caveolae-mediated endocytosis characteristics.

Multifunctional protein-based self-assembled nanoplatform: overcoming hypoxic tumor microenvironment for enhanced imaging-guided photodynamic therapy

Photodynamic therapy (PDT) has emerged as a promising modality for cancer treatment, but its efficacy is often limited by tumour hypoxia. Here, we report the development of a novel protein-based, self-assembled nanoplatform, CAT-I-BODIPY NPs (CIB NPs), to address this limitation. We first design and synthesize an I-BODIPY photosensitizer based on the heavy atom effect and modification of the electron-donating group, which exhibits excellent capabilities in generating reactive oxygen species and enabling near-infrared (NIR) fluorescence imaging. The incorporation of an oxygen-producing enzyme, catalase (CAT), within these nanoassemblies enables in situ oxygen generation to counteract hypoxic constraints. Controllable self-assembly by multiple supramolecular interactions into highly ordered architecture not only guarantees CAT's catalytic activity but also leads to excellent NIR fluorescence imaging ability and enhanced PDT efficacy. Notably, the visualization of optimal accumulation of CIB NPs within tumour sites 18 h post-injection offers precise PDT application guidance. Both in vitro and in vivo studies corroborate the remarkable anti-tumour efficacy of CIB NPs under NIR illumination, providing a significant advancement in PDT. The favourable biosafety profile of CIB NPs further emphasizes their potential for clinical application in hypoxic tumour therapy.

Controllable Regulation of Ag2 S Quantum-Dot-Mediated Protein Nanoassemblies for Imaging-Guided Synergistic PDT/PTT/Chemotherapy against Hypoxic Tumor

The combination of phototherapy and chemotherapy holds great potential for cancer treatment, while hypoxia in tumor as well as unexpected drug release largely restricts anticancer therapy. Inspired by the natural intelligence, herein, for the first time, a "bottom-up" protein self-assembly strategy mediated by near-infrared (NIR) quantum dots (QDs) with multicharged electrostatic interactions is presented to develop a tumor microenvironment (TME)-responsive theranostic nanoplatform for imaging-guided synergistic photodynamic therapy (PDT)/photothermal therapy (PTT)/chemotherapy. Catalase (CAT) possesses diverse surface charge distribution under different pH conditions. After modification by chlorin e6 (Ce6), the formulated CAT-Ce6 with patchy negative charges can be assembled with NIR Ag2 S QDs by regulating their electrostatic interactions, allowing for effective incorporation of specific anticancer drug oxaliplatin (Oxa). Such Ag2 S@CAT-Ce6@Oxa nanosystems are able to visualize nanoparticle (NP) accumulation to guide subsequent phototherapy, together with significant alleviation of tumor hypoxia to further enhance PDT. Moreover, the acidic TME triggers controllable disassembly through weakening the CAT surface charge to disrupt electrostatic interactions, allowing for sustained drug release. Both in vitro and in vivo results demonstrate remarkable inhibition of colorectal tumor growth with a synergistic effect. Overall, this multicharged electrostatic protein self-assembly strategy provides a versatile platform for realizing TME-specific theranostics with high efficiency and safety, promising for clinical translation.

Transdermal Delivery of Photosensitizer-Catalase Conjugate by Fluorinated Polyethylenimine for Enhanced Topical Photodynamic Therapy of Bacterial Infections

Pathogenic bacteria induce subcutaneous infections pose serious threats to global public health. Recently, photodynamic therapy (PDT) has been proposed as a non-invasive approach for anti-microbial treatment without the risk to induce drug resistance. However, due to the hypoxic environment of most anaerobiont-infected sites, the therapeutic efficacy of oxygen consuming PDT has been limited. Herein, a transdermal delivery system is reported to allow effective delivery of photosensitizers into infected skin for PDT treatment of skin infections by bacteria. Considering the overproduction of hydrogen peroxide (H2 O2 ) in the abscess area, catalase (CAT), an enzyme that triggers H2 O2 decomposition to generate O2 , is conjugated with chlorine e6 (Ce6) to form a photosensitizer conjugate (Ce6-CAT) as an enhanced PDT agent against Staphylococcus Aureus. After screening a series of fluorinated low molecular weight polyethylenimine (F-PEI) with different fluorination degrees, the optimized F-PEI formulation is identified with the best transdermal delivery ability system. Upon mixing, the formed Ce6-CAT@F-PEI nanocomplex shows effective transdermal penetration after being applied to the skin surface. With light exposure of the infected skin, highly effective in vivo anti-bacterial PDT therapeutic effect with Ce6-CAT@F-PEI is observed. This work proposes a transdermal PDT therapeutic nanomedicine particularly promising for the anti-bacterial treatment of skin infections.

Cancer Cell Membrane-Enveloped Dexamethasone Normalizes the Tumor Microenvironment and Enhances Gynecologic Cancer Chemotherapy

The aberrant tumor microenvironment (TME), especially immature and leaky vessels, prevents the penetration and accumulation of chemotherapeutics and results in the failure of chemotherapy to treat gynecologic cancer. Herein, dexamethasone (Dex), a glucocorticoid steroid used to moderate tumor extracellular matrix and normalize vessels, was enclosed within a biocompatible material known as poly(lactic-co-glycolic acid) (PLGA), and the obtained Dex@PLGA was further coated with a mouse cervical cancer cell membrane (CM). The formulated Dex@PLGA-CM nanoparticles showed efficient extravascular diffusion within the tumor owing to the homologous targeting abilities inherited from the source cancer cells. The Dex@PLGA-CM nanoparticles greatly reshaped the TME, enhancing the penetration of Doxil and thus markedly improving the therapeutic effect of this drug against cervical cancers. Excitingly, the Dex@PLGA-CM nanoparticles coated with mouse ovarian cancer cell membranes also promoted Doxil-mediated chemotherapy effects in metastatic ovarian cancer when administered intraperitoneally. This work presents an effective nanomedicine for the efficient modification of the TME to enhance the effects of gynecologic cancer chemotherapy.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

Photodynamic therapy (PDT), with its advantages of high targeting, minimally invasive, and low toxicity side effects, has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment (TME) presents hypoxia due to the low oxygen (O2 ) supply caused by abnormal vascularization in neoplastic tissues and high O2 consumption induced by the rapid proliferation of tumor cells. The efficacy of oxygen-consumping PDT can be hampered by a hypoxic TME. To address this problem, researchers have been developing advanced nanoplatforms and strategies to enhance the therapeutic effect of PDT in tumor treatment. This review summarizes recent advanced PDT therapeutic strategies to against the hypoxic TME, thus enhancing PDT efficacy, including increasing O2 content in TME through delivering O2 to the tumors and in situ generations of O2 ; decreasing the O2 consumption during PDT by design of type I photosensitizers. Moreover, recent synergistically combined therapy of PDT and other therapeutic methods such as chemotherapy, photothermal therapy, immunotherapy, and gas therapy is accounted for by addressing the challenging problems of mono PDT in hypoxic environments, including tumor resistance, proliferation, and metastasis. Finally, perspectives of the opportunities and challenges of PDT in future clinical research and translations are provided.

M1 Macrophage-Biomimetic Targeted Nanoparticles Containing Oxygen Self-Supplied Enzyme for Enhancing the Chemotherapy

Tumor hypoxia is considered one of the key causes of the ineffectiveness of various strategies for cancer treatment, and the non-specific effects of chemotherapy drugs on tumor treatment often lead to systemic toxicity. Thus, we designed M1 macrophage-biomimetic-targeted nanoparticles (DOX/CAT@PLGA-M1) which contain oxygen self-supplied enzyme (catalase, CAT) and chemo-therapeutic drug (doxorubicin, DOX). The particle size of DOX/CAT@PLGA-M1 was 202.32 ± 2.27 nm (PDI < 0.3). DOX/CAT@PLGA-M1 exhibited a characteristic core-shell bilayer membrane structure. The CAT activity of DOX/CAT@PLGA-M1 was 1000 (U/mL), which indicated that the formation of NPs did not significantly affect its enzymatic activity. And in vitro drug release showed that the cumulative release rate of DOX/CAT@PLGA-M1 was enhanced from 26.93% to 50.10% in the release medium of hydrogen peroxide, which was attributed to the reaction of CAT in the NPs. DOX/CAT@PLGA-M1 displayed a significantly higher uptake in 4T1 cells, because VCAM-1 in tumor cells interacted with specific integrin (α4 and β1), and thereby achieved tumor sites. And the tumor volume of the DOX/CAT@PLGA-M1 group was significantly reduced (0.22 cm3), which further proved the active targeting effect of the M1 macrophage membrane. Above all, a novel multifunctional nano-therapy was developed which improved tumor hypoxia and obtained tumor targeting activity.

Hyaluronic acid coated nano-particles for H2O2-elevation augmented photo-/chemodynamic therapy

In recent years, the association of chemodynamic therapy (CDT) with photodynamic therapy (PDT) has attracted much attention due to their mutually reinforced property. Nevertheless, how to further strengthen their performance is still a big challenge. Given the PDT/CDT therapeutic mechanism, the H2O2 amount might affect their final performance. Thus, in this paper, our synthesized pH-responsive Fenton agents (ferrocene-cinnamaldehyde conjugates, Fc-CA) were encapsulated in hyaluronic acid (HA) coated porphyrin-based MOF to obtain supramolecular nano-particles (Fc-CA-PCN-HA). After the CD44-receptor mediated internalization, the released Fc-CA could further dissociate in the acidic pH micro-environment. The released CA can activate the NADPH oxidase to elevate the H2O2 amount which could be preferable to produce more ·OH through Fenton reaction for cancer cells apoptosis. Additionally, O2 was also generated in the CDT which could alleviate tumor hypoxia condition and be provided as the reactant for PDT to produce more 1O2. Thus, given the excellent cascade reactions induced therapeutic performance of Fc-CA-PCN-HA in vitro and in vivo, the H2O2-elevation strategy might further enhance the PDT/CDT outcomes.

Mitochondria-Targeting Upconversion Nanoparticles@MOF for Multiple-Enhanced Photodynamic Therapy in Hypoxic Tumor

The effect of photodynamic therapy (PDT) is severely limited by tumor hypoxia and the short half-life of reactive oxygen species (ROS). Herein, we constructed a near-infrared (NIR) light-regulated PDT nanoplatform (TPP-UCNPs@MOF-Pt) consisting of an upconversion nanoparticle (UCNP) core and porphyrin-based metal-organic framework (MOF) shell with platinum nanoparticles (PtNPs) and a mitochondria-targeting triphenylphosphine (TPP) group on the surface. TPP-UCNPs@MOF-Pt could effectively relieve the tumor hypoxia by converting intracellular H₂O₂ to oxygen (O₂) and elevated the ROS level to enhance PDT efficacy under NIR light irradiation. In addition, the mitochondria-targeting TPP-UCNPs@MOF-Pt was localized on the mitochondria, leading to severe depolarization of the mitochondrial membrane and activation of the apoptotic pathway, further amplifying the therapeutic efficacy. In vitro and in vivo experiments demonstrated that the greatly enhanced photodynamic therapeutic efficacy of TPP-UCNPs@MOF-Pt was achieved by combining relief of tumor hypoxia with mitochondrial targeting and NIR activation. This study provides a promising strategy for construction of an MOF-based multifunctional nanoplatform to address the current limitations of PDT treatment for hypoxic tumors.

Mild-Temperature Responsive Nanocatalyst for Controlled Drug Release and Enhanced Catalytic Therapy

Owing to the advantages of the in situ production of toxic agents through catalytic reactions, nanocatalytic therapy has arisen as a highly potential strategy for cancer therapeutics in recent years. However, the insufficient amount of endogenous hydrogen peroxide (H₂O₂) in the tumor microenvironment commonly limits their catalytic efficacy. Here, we employed carbon vesicle nanoparticles (CV NPs) with high near-infrared (NIR, 808 nm) photothermal conversion efficiency as carriers. Ultrafine platinum iron alloy nanoparticles (PtFe NPs) were grown in situ on the CV NPs, where the highly porous nature of the resultant CV@PtFe NPs was employed to encapsulate a drug, β-lapachone (La), and phase-change material (PCM). As a multifunctional nanocatalyst CV@PtFe/(La-PCM) NPs can exhibit a NIR-triggered photothermal effect and activate cellular heat shock response, which upregulates the downstream NQO1 via HSP70/NQO1 axis to facilitate bio-reduction of the concurrently melted and released La. Moreover, sufficient oxygen (O₂) is supplied by CV@PtFe/(La-PCM) NPs catalyzed at the tumor site to reinforce the La cyclic reaction with abundant H₂O₂ generation. This promotes the bimetallic PtFe-based nanocatalysis, which breaks H₂O₂ down into highly toxic hydroxyl radicals (•OH) for catalytic therapy. Our results show that this multifunctional nanocatalyst can be used as a versatile synergistic therapeutic agent with NIR-enhanced nanocatalytic tumor therapy by tumor-specific H₂O₂ amplification and mild-temperature photothermal therapy, which holds promising potential for targeted cancer treatment. STATEMENT OF SIGNIFICANCE: We present a multifunctional nanoplatform with mild-temperature responsive nanocatalyst for controlled drug release and enhanced catalytic therapy. This work aimed at not only reduce the damage to normal tissues caused by photothermal therapy, but also improves the efficiency of nanocatalytic therapy by stimulating endogenous H₂O₂ production through photothermal heat. In vitro and in vivo confirmed that CV@PtFe/(La-PCM) NPs exhibited powerful and overall antitumor effects. This formulation may provide an alternative strategy for the development of the mild- photothermal enhanced nanocatalytic therapy effect in solid tumor.

Developmental synergism in the management of oral potentially malignant disorders

Oral potentially malignant disorders (OPMDs) are associated with an increased risk of occurrence of cancers of the oral cavity or lips. The unifying theme of OPMDs is their potential risk for cancer development. Therefore, the primary objective of the management should be to prevent carcinogenesis. Beyond diagnosis, current strategies for the management of OPMDs predominantly include non-surgical and surgical interventions and a "watch-and-see" approach, such as disease monitoring or surveillance, and preventive strategies. Though no optimal clinical treatment has gained universal approval for reducing or preventing malignant development of OPMDs. Therefore, an urgent need exits for improved treatment properties and effective predictive markers for OPMDs treatment. This review aims to outline recent synergism regarding to the management of OPMDs. Developing new technologies and improved application parameters to promote the treatment efficacy and a novel management prescription approach to OPMDs are proposed.

Photodynamic therapy: Innovative approaches for antibacterial and anticancer treatments

Photodynamic therapy is an alternative treatment mainly for cancer but also for bacterial infections. This treatment dates back to 1900 when a German medical school graduate Oscar Raab found a photodynamic effect while doing research for his doctoral dissertation with Professor Hermann von Tappeiner. Unexpectedly, Raab revealed that the toxicity of acridine on paramecium depends on the intensity of light in his laboratory. Photodynamic therapy is therefore based on the administration of a photosensitizer with subsequent light irradiation within the absorption maxima of this substance followed by reactive oxygen species formation and finally cell death. Although this treatment is not a novelty, there is an endeavor for various modifications to the therapy. For example, selectivity and efficiency of the photosensitizer, as well as irradiation with various types of light sources are still being modified to improve final results of the photodynamic therapy. The main aim of this review is to summarize anticancer and antibacterial modifications, namely various compounds, approaches, and techniques, to enhance the effectiveness of photodynamic therapy.

Oxygen-independent alkyl radical nanogenerator enhances breast cancer therapy

The hypoxic microenvironment of breast cancer substantially reduces oxygen-dependent free radical generation. Overexpression of glutathione (GSH) in tumor cells mitigates the impact of free radical generation. In this study, we designed and developed an oxygen-independent alkyl radical nanogenerator (copper monosulfide/2,2'-azabis(2-imidazoline) dihydrochloride@bovine serum albumin; CuS/AIPH@BSA) with spatiotemporally controlled properties and GSH consumption to enhance breast cancer therapy. We encapsulated the alkyl radical initiator, AIPH, in hollow mesoporous CuS nanoparticles with photothermal conversion effect and enveloped them in BSA. AIPH was released and decomposed to generate alkyl radicals in hypoxic breast cancer with the photothermal conversion effect of CuS under near-infrared laser irradiation. CuS consumed high GSH levels in tumor cells because it could form complex with GSH and thereby enhanced free radical treatment. In vivo and in vitro assays demonstrated the anti-tumor efficacy of the rationally designed free-radical nanogenerator in hypoxic microenvironment of breast cancer without showing systemic toxicity.

Recent Progress in Carrier-Free Nanomedicine for Tumor Phototherapy

Safe and effective strategies are urgently needed to fight against the life-threatening diseases of various cancers. However, traditional therapeutic modalities, such as radiotherapy, chemotherapy and surgery, exhibit suboptimal efficacy for malignant tumors owing to the serious side effects, drug resistance and even relapse. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are emerging therapeutic strategies for localized tumor inhibition, which can produce a large amount of reactive oxygen species (ROS) or elevate the temperature to initiate cell death by non-invasive irradiation. In consideration of the poor bioavailability of phototherapy agents (PTAs), lots of drug delivery systems have been developed to enhance the tumor targeted delivery. Nevertheless, the carriers of drug delivery systems inevitably bring biosafety concerns on account of their metabolism, degradation, and accumulation. Of note, carrier-free nanomedicine attracts great attention for clinical translation with synergistic antitumor effect, which is characterized by high drug loading, simplified synthetic method and good biocompatibility. In this review, the latest advances of phototherapy with various carrier-free nanomedicines are summarized, which may provide a new paradigm for the future development of nanomedicine and tumor precision therapy.

Deciphering the catalytic mechanism of superoxide dismutase activity of carbon dot nanozyme

Nanozymes with superoxide dismutase (SOD)-like activity have attracted increasing interest due to their ability to scavenge superoxide anion, the origin of most reactive oxygen species in vivo. However, SOD nanozymes reported thus far have yet to approach the activity of natural enzymes. Here, we report a carbon dot (C-dot) SOD nanozyme with a catalytic activity of over 10,000 U/mg, comparable to that of natural enzymes. Through selected chemical modifications and theoretical calculations, we show that the SOD-like activity of C-dots relies on the hydroxyl and carboxyl groups for binding superoxide anions and the carbonyl groups conjugated with the π-system for electron transfer. Moreover, C-dot SOD nanozymes exhibit intrinsic targeting ability to oxidation-damaged cells and effectively protect neuron cells in the ischemic stroke male mice model. Together, our study sheds light on the structure-activity relationship of C-dot SOD nanozymes, and demonstrates their potential for treating of oxidation stress related diseases.

Nanoengineered hydrogels as 3D biomimetic extracellular matrix with injectable and sustained delivery capability for cartilage regeneration

The regeneration of articular cartilage remains a great challenge due to the difficulty in effectively enhancing spontaneous healing. Recently, the combination of implanted stem cells, suitable biomaterials and bioactive molecules has attracted attention for tissue regeneration. In this study, a novel injectable nanocomposite was rationally designed as a sustained release platform for enhanced cartilage regeneration through integration of a chitosan-based hydrogel, articular cartilage stem cells (ACSCs) and mesoporous SiO₂ nanoparticles loaded with anhydroicaritin (AHI). The biocompatible engineered nanocomposite acting as a novel 3D biomimetic extracellular matrix exhibited a remarkable sustained release effect due to the synergistic regulation of the organic hydrogel framework and mesopore channels of inorganic mSiO₂ nanoparticles (mSiO₂ NPs). Histological assessment and biomechanical tests showed that the nanocomposites exhibited superior performance in inducing ACSCs proliferation and differentiation in vitro and promoting extracellular matrix (ECM) production and cartilage regeneration in vivo. Such a novel multifunctional biocompatible platform was demonstrated to significantly enhance cartilage regeneration based on the sustained release of AHI, an efficient bioactive natural small molecule for ACSCs chondrogenesis, within the hybrid matrix of hydrogel and mSiO₂ NPs. Hence, the injectable nanocomposite holds great promise for use as a 3D biomimetic extracellular matrix for tissue regeneration in clinical diagnostics.

•

The anhydroicaritin (AHI) was identified as a bioactive factor for promoting cartilage repair.

•

The hydrogel was designed to achieve sustained AHI release and optimize the microenvironment of cartilage defect sites.

•

The hydrogel exhibited superior advantages for chondrogenic differentiation and cartilage regeneration.

•

The hydrogel holds a great promise for use as functional scaffold for tissue and organ regeneration in the future.

Nanoparticle-Based Combination Therapy for Ovarian Cancer

Ovarian cancer is one of the most common malignant tumors in gynecology with a high incidence. Combination therapy, eg, administration of paclitaxel followed by a platinum anticancer drug is recommended to treat ovarian cancer due to its advantages in, eg, reducing side effects and reversing (multi)drug-resistance compared to single treatment. However, the benefits of combination therapy are often compromised. In chemo and chemo/gene combinations, co-deposition of the combined therapeutics in the tumor cells is required, which is difficult to achieve due to dramatic pharmacokinetic differences between combinational agents in free forms. Moreover, some undesired properties such as the low-water solubility of chemodrugs and the difficulty of cellular internalization of gene therapeutics also hinder the therapeutic potential. Delivery of dual or multiple agents by nanoparticles provides opportunities to tackle these limits. Nanoparticles encapsulate hydrophobic drug(s) to yield aqueous dispersions facilitating its administration and/or to accommodate hydrophilic genes facilitating its access to cells. Moreover, nanoparticle-based therapeutics can not only improve drug properties (eg, in vivo stability) and ensure the same drug disposition behavior with controlled drug ratios but also can minimize drug exposure of the normal tissues and increase drug co-accumulation at targeted tissues via passive and/or active targeting strategies. Herein, this work summarizes nanoparticle-based combination therapies, mainly including anticancer drug-based combinations and chemo/gene combinations, and emphasizes the advantageous outcomes of nanocarriers in the combination treatment of ovarian cancer. In addition, we also review mechanisms of synergetic effects resulting from different combinations.

O2-Supplying Nanozymes Alleviate Hypoxia and Deplete Lactate to Eliminate Tumors and Activate Antitumor Immunity

Direct hypoxia alleviation and lactate depletion in the tumor microenvironment (TME) are promising for effective cancer therapy but still very challenging. To address this challenge, the current research directly reshapes the TME for inhibiting tumor growth and activating the antitumor immunity using a drug-free nanozyme. Herein, the acid-sensitive nanozymes were constructed based on peroxidized layered double hydroxide nanoparticles for O₂ self-supply and self-boosted lactate depletion. The coloading of partially cross-linked catalase and lactate oxidase enabled the acid-sensitive nanozymes to promote three reactions, that is, (1) H₂O₂ generation from MgO₂ hydrolysis (30% at pH 7.4 vs 63% at pH 6.0 in 8 h); (2) O₂ generation from H₂O₂ (12% at pH 7.4 vs 21% at pH 6.0 in 2 h); and (3) lactate depletion by in situ generated O₂ (50% under hypoxia vs 75% under normoxia in 24 h in vitro) in parallel or tandem. These promoted reactions together efficiently induced colon cancer cell apoptosis under the hypoxic conditions, significantly inhibited tumor growth (>95%), and suppressed distant tumor growth upon seven administrations in every 3 days and moreover transformed the immunosuppressive tumor into "hot" one in the colon tumor-bearing mouse model. This is the first example for a nanozyme that supplies sufficient O₂ for hypoxia relief and lactate depletion, thus providing a new insight into drug-free nanomaterial-mediated TME-targeted cancer therapy.

Metabolic reprogramming mediated PD-L1 depression and hypoxia reversion to reactivate tumor therapy

As a promising cancer treatment, photodynamic therapy (PDT) still achieved limited clinical success due to the severe hypoxia and programmed death ligand-1 (PD-L1) over-expressed immunosuppression tumor microenvironment. At present, few methods have been proven to solve these two defects simply and effectively by a single drug or nano-system simultaneously. To ameliorate this situation, we designed and constructed MB@Bu@MnO₂ nanoparticles with two-step oxygen regulation ability and PD-1/PD-L1 axis cascade-disruption capacity via a biomineralization method. In such a nanosystem, manganese dioxide albumin (MnO₂@Alb) was used as the drug carrier, Butformin (Bu) as mitochondria-associated oxidative phosphorylation (OXPHOS) disruption agent with PD-L1 depression and oxygen reversion ability, and methylene blue (MB) as PDT drug with programmed cell death protein 1 (PD-1) inhibition capacity. Owing to the tumor-responsive capacity of MB@Bu@MnO₂ nanoparticles, Bu and MB were selectively delivered and released in tumors. Then, the tumor hypoxia was dramatically reversed by Bu inhibited oxygen consumption, and MnO₂ improved oxygen generation. Following this, the reactive oxygen species (ROS) generation was enhanced by MB@Bu@MnO₂ nanoparticles mediated PDT owing to the reversed tumor hypoxia. Furthermore, the immunosuppression microenvironment was also obviously reversed by MB@Bu@MnO₂ nanoparticles enhanced immunogenic cell death (ICD) and PD-1/PD-L1 axis cascade-disruption, which then enhanced T cell infiltration and improved its tumor cell killing ability. Finally, the growth of solid tumors was significantly depressed by MB@Bu@MnO₂ nanoparticles mediated PDT. All in all, this well-designed nanosystem could solve the defects of traditional PDT via PD-1/PD-L1 axis dual disruption and reversing tumor hypoxia by two-step oxygen regulation.

Cascade two-stage tumor re-oxygenation and immune re-sensitization mediated by self-assembled albumin-sorafenib nanoparticles for enhanced photodynamic immunotherapy

As a promising modality for cancer therapy, photodynamic therapy (PDT) still acquired limited success in clinical nowadays due to the extremely serious hypoxia and immunosuppression tumor microenvironment. To ameliorate such a situation, we rationally designed and prepared cascade two-stage re-oxygenation and immune re-sensitization BSA-MHI148@SRF nanoparticles via hydrophilic and hydrophobic self-assembly strategy by using near-infrared photodynamic dye MHI148 chemically modified bovine serum albumin (BSA-MHI148) and multi-kinase inhibitor Sorafenib (SRF) as a novel tumor oxygen and immune microenvironment regulation drug. Benefiting from the accumulation of SRF in tumors, BSA-MHI148@SRF nanoparticles dramatically enhanced the PDT efficacy by promoting cascade two-stage tumor re-oxygenation mechanisms: (i) SRF decreased tumor oxygen consumption via inhibiting mitochondria respiratory. (ii) SRF increased the oxygen supply via inducing tumor vessel normalization. Meanwhile, the immunosuppression micro-environment was also obviously reversed by two-stage immune re-sensitization as follows: (i) Enhanced immunogenic cell death (ICD) production amplified by BSA-MHI148@SRF induced reactive oxygen species (ROS) generation enhanced T cell infiltration and improve its tumor cell killing ability. (ii) BSA-MHI148@SRF amplified tumor vessel normalization by VEGF inhibition also obviously reversed the tumor immune-suppression microenvironment. Finally, the growth of solid tumors was significantly depressed by such well-designed BSA-MHI148@SRF nanoparticles, which could be potential for clinical cancer therapy.

A Nanozyme-Immobilized Hydrogel with Endogenous ROS-Scavenging and Oxygen Generation Abilities for Significantly Promoting Oxidative Diabetic Wound Healing

Non-healing wound is a common complication of diabetic patients associated with high morbidity and mortality. Engineered therapeutic hydrogels have enviable advantages in tissue regeneration, however, they are suboptimal for the healing of diabetic wounds characterized by reactive oxygen species (ROS) accumulation and chronic hypoxia. Here, a unique biological metabolism-inspired hydrogel, for ameliorating this hostile diabetic microenvironment, is presented. Consisting of natural polymers (hydrazide modified hyaluronic acid and aldehyde modified hyaluronic acid) and a metal-organic frameworks derived catalase-mimic nanozyme (ε-polylysine coated mesoporous manganese cobalt oxide), the engineered nanozyme-reinforced hydrogels can not only capture the endogenous elevated ROS in diabetic wounds, but also synergistically produce oxygen through the ROS-driven oxygen production ability. These fascinating properties of hydrogels protect skin cells (e.g., keratinocytes, fibroblasts, and vascular endothelial cells) from ROS and hypoxia-mediated death and proliferation inhibition. Diabetic wounds treated with the nanozyme-reinforced hydrogels highlight the potential of inducing the macrophages polarization from pro-inflammatory phenotype (M1) to anti-inflammatory subtype (M2). The hydrogel dressings demonstrate a prominently accelerated healing rate as shown by alleviating the excessive inflammatory, inducing efficiently proliferation, re-epithelialization, collagen deposition, and neovascularization. This work provides an effective strategy based on nanozyme-reinforced hydrogel as a ROS-driven oxygenerator for enhancing diabetic wound healing.

Post-Remedial Oxygen Supply: A New Perspective on Photodynamic Therapy to Suppress Tumor Metastasis

Photodynamic therapy (PDT) holds great promise in tumor therapy due to high safety, efficacy, and specificity. However, the risk of increased metastasis in hypoxic tumors after oxygen-dependent PDT remains underestimated. Here, we propose a post-PDT oxygen supply (POS) strategy to reduce the risk of metastasis. Herein, biocompatible and tumor-targeting Ce6@BSA and PFC@BSA nanoparticles were constructed for PDT and POS in a 4T1-orthotropic breast cancer model. PDT with Ce6@BSA nanoparticles increased tumor metastasis via the HIF-1α signaling pathway, whereas POS significantly reduced the PDT-triggered metastasis by blocking this pathway. Furthermore, POS, with clinical protocols and an FDA-approved photosensitizer (hypericin), and oxygen inhalation reduced PDT-induced metastasis. Our study findings indicate that PDT may increase the risk of tumor metastasis and that POS may solve this problem. POS can reduce the metastasis resulting not only from PDT but also from other oxygen-dependent treatments such as radiotherapy and sonodynamic therapy.

A Microneedle Patch with Self-Oxygenation and Glutathione Depletion for Repeatable Photodynamic Therapy

Photodynamic therapy (PDT) has attained extensive attention as a noninvasive tumor treatment modality. However, the hypoxia in solid tumors, skin phototoxicity of "always on" photosensitizers (PSs), and abundant supply of glutathione (GSH) in cancer cells severely hampered the clinical applications of PDT. Herein, a self-oxygenation nanoplatform (denoted as CZCH) with GSH depletion ability was encapsulated into the hyaluronic acid microneedle patch (MN-CZCH) to simultaneously improve the biosafety and therapeutic efficacy of PDT. The Cu²⁺-doped porous zeolitic imidazolate framework incorporated with catalase (CAT) is capable of efficiently loading PS 2-(1-hexyloxyethyl)-2-divinylpyropheophorbic-a (HPPH). The CZCH intermingled MN patch (MN-CZCH) could effectively penetrate the stratum corneum, topically transport HPPH to the target tumor site, achieve a long tumor retention time, and enhance the efficacy of PDT via the simultaneously synergistic effect of CAT-catalyzed self-supplying O₂ and Cu²⁺-mediated GSH depletion. Using traceable fluorescence (FL) imaging of the released HPPH from CZCH, the FL imaging-guided repeatable PDT can be achieved for enhanced antitumor efficacy. As a result, the MN-CZCH patch exhibited excellent therapeutic efficacy against melanoma with minimal toxicity, which has promising potential for cancer theranostics.

Effect of intermittency factor on singlet oxygen and PGE2 formation in azulene-mediated photodynamic therapy: A preliminary study

In photodynamic therapy, intermittent irradiation modes that incorporate an interval between pulses are believed to decrease the effect of hypoxia by permitting an interval of re-oxygenation. The effect of the irradiation intermittency factor (the ratio of the irradiation pulse time to the total irradiation time) on singlet oxygen formation and inflammatory cytokine production was examined using azulene as a photosensitizer. Effects of difference intermittency factor on singlet oxygen formation and inflammatory cytokine were examined. Azulene solutions (1/10 μM) were irradiated with a 638-nm 500 mW diode laser in fractionation (intermittency factor of 5 or 9) or continuous mode using 50 mW/cm² at 4 or 8 J/cm². Singlet oxygen measurement was performed using a dimethyl anthracene probe. Peripheral blood mononuclear cells (PBMC) were stimulated by 10 ng/ml rhTNF-α for 6 h, before addition of 1 and 10 μM azulene solutions and irradiation. PGE₂ measurement was undertaken using a human PGE₂ ELISA kit. Kruskal-Wallis with Dunn Bonferroni test was used for statistical analyses at p < 0.05.Irradiation of 1 μM azulene+4 J/cm²+intermittency factor of 9 increased singlet oxygen 3-fold (p < 0.0001). Irradiation of 10 μM azulene at either 4 J/cm²+intermittency of 9 or 8 J/cm²+intermittency factor of 5 reduced PGE₂ expression in PBMCs to non-inflamed levels. Thus, at 50 mW/cm², 10 μM azulene-mediated photodynamic therapy with a high intermittency factor and a low energy density generated sufficient singlet oxygen to suppress PGE₂ in Inflamed PBMCs.

•

Different intermittency factors can stimulate ROS formation differently.

•

Relative high intermittency factor with azulene induces high ROS formation.

•

Relative high intermittency factor with low energy density inhibits PGE₂ production.

•

Azulene-based photodynamic therapy suppresses inflammation.

Thiolated hyaluronic acid and catalase-enhanced CD44-targeting and oxygen self-supplying nanoplatforms with photothermal/photodynamic effects against hypoxic breast cancer cells

Photothermal and photodynamic therapies (PTT/PDT) have been widely accepted as noninvasive therapeutic methods for cancer treatment. However, tumor hypoxia and insufficient delivery of photoactive compounds to cancer cells can reduce the efficacy of phototherapy. Herein, we first synthesized thiolated hyaluronic acid (THA) and then conjugated it with catalase (CAT) onto chlorin e6 (Ce6)-adsorbed small gold nanorods (Ce6@sAuNRs) with near-infrared (NIR)/visible light activated photothermal/photodynamic effects. The conjugation of THA and CAT on Ce6@sAuNRs resulted in a red-shift of the longitudinal LSPR absorption band of sAuNRs up to 1000 nm and maintained the excellent enzymatic activity of catalase. Modification of Ce6@sAuNRs with THA resulted in efficient internalization of the nanocomposite into MCF-7/ADR multidrug-resistant (MDR) breast cancer cells (CD44+), thereby significantly enhancing the intracellular accumulation of the photosensitizer Ce6. CAT endows Ce6@sAuNRs with self-supporting oxygen production, which enables them to efficiently generate singlet oxygen (¹O₂) under 660 nm laser irradiation and enhances the photodynamic effect against hypoxic breast cancer cells. The results highlight the prospect of this novel multi-functional nanoplatform integrating active biological macromolecules (THA and CAT) into photosensitizer/photothermal gold nanocomposites in overcoming the limitations of hypoxic MDR breast cancer cell treatment.

Cell Membrane Camouflaged Metal Oxide-Black Phosphorus Biomimetic Nanocomplex Enhances Photo-chemo-dynamic Ferroptosis

Despite the availability of various treatment options, the inherent complexity of tumors significantly impairs therapeutic efficacy. Recently, combination treatments exhibited great anticancer potential due to low cross-resistance and good therapeutic additivity. Herein, a photoactive metal oxide-black phosphorus biomimetic nanocomplex (photophage) is developed for improving the antitumor combination of ferroptosis and photodynamic therapy (PDT). The photophage is composed of M1 macrophage membrane camouflaged MnO2 and Fe3O4 nanoparticles anchored black phosphorus nanosheets (BPNs), which together trigger a synergistic antitumor action. Fe3O4 acts as an iron source to activate Fenton-reaction-dependent ferroptosis, which can be further strengthened by BPN-mediated PDT. Besides the original antitumor effects, PDT also generates reactive oxygen species to enhance lipid peroxidation and glutathione depletion, which in turn reinforce ferroptosis and PDT efficacy. Importantly, MnO2 can in situ generate oxygen to relieve tumor hypoxia and consequently leverage cell behaviors to improve therapeutic responses. Particularly, M1 macrophage membrane modification endows the photophage with good tumor targeting capability and tumor penetration, which promote synergistic ferroptosis and PDT to destroy tumors while reducing systemic side effects, resulting in the prolonged survival of tumor-bearing mice. Therefore, we present a biomimetic nanoplatform for overcoming tumor barriers and advancing tumor-targeted treatment.

Hypoxia responsive phytonanotheranostics: A novel paradigm towards fighting cancer

Hypoxia enhances tumor aggressiveness, thereby reducing the efficacy of anticancer therapies. Phytomedicine, which is nowadays considered as the new panacea owing to its dynamic physiological properties, is often plagued by shortcomings. Incorporating these wonder drugs in nanoparticles (phytonanomedicine) for hypoxia therapy is a new prospect in the direction of cancer management. Similarly, the concept of phytonanotheranostics for the precise tumor lesion detection and treatment monitoring in the hypoxic scenario is going on a rampant speed. In the same line, smart nanoparticles which step in for "on-demand" drug release based on internal or external stimuli are also being explored as a new tool for cancer management. However, studies regarding these smart and tailor-made nanotheranostics in the hypoxic tumor microenvironment are very limited. The present review is an attempt to collate these smart stimuli-responsive phytonanotherapeutics in one place for initiating future research in this upcoming field for better cancer treatment.