Glutathione depletion and dual-model oxygen balance disruption for photodynamic therapy enhancement

Phototherapy in cancer treatment: strategies and challenges

Phototherapy has emerged as a promising modality in cancer treatment, garnering considerable attention for its minimal side effects, exceptional spatial selectivity, and optimal preservation of normal tissue function. This innovative approach primarily encompasses three distinct paradigms: Photodynamic Therapy (PDT), Photothermal Therapy (PTT), and Photoimmunotherapy (PIT). Each of these modalities exerts its antitumor effects through unique mechanisms-specifically, the generation of reactive oxygen species (ROS), heat, and immune responses, respectively. However, significant challenges impede the advancement and clinical application of phototherapy. These include inadequate ROS production rates, subpar photothermal conversion efficiency, difficulties in tumor targeting, and unfavorable physicochemical properties inherent to traditional phototherapeutic agents (PTs). Additionally, the hypoxic microenvironment typical of tumors complicates therapeutic efficacy due to limited agent penetration in deep-seated lesions. To address these limitations, ongoing research is fervently exploring innovative solutions. The unique advantages offered by nano-PTs and nanocarrier systems aim to enhance traditional approaches' effectiveness. Strategies such as generating oxygen in situ within tumors or inhibiting mitochondrial respiration while targeting the HIF-1α pathway may alleviate tumor hypoxia. Moreover, utilizing self-luminescent materials, near-infrared excitation sources, non-photoactivated sensitizers, and wireless light delivery systems can improve light penetration. Furthermore, integrating immunoadjuvants and modulating immunosuppressive cell populations while deploying immune checkpoint inhibitors holds promise for enhancing immunogenic cell death through PIT. This review seeks to elucidate the fundamental principles and biological implications of phototherapy while discussing dominant mechanisms and advanced strategies designed to overcome existing challenges-ultimately illuminating pathways for future research aimed at amplifying this intervention's therapeutic efficacy.

Metal-Organic Frameworks (MOFs): Classification, Synthesis, Modification, and Biomedical Applications

Metal-organic frameworks (MOFs) are a new variety of solid crystalline porous functional materials. As an extension of inorganic porous materials, it has made important progress in preparation and application. MOFs are widely used in various fields such as gas adsorption storage, drug delivery, sensing, and biological imaging due to their high specific surface area, porosity, adjustable pore size, abundant active sites, and functional modification by introducing groups. In this paper, the types of MOFs are classified, and the synthesis methods and functional modification mechanisms of MOFs materials are summarized. Finally, the application prospects and challenges of metal-organic framework materials in the biomedical field are discussed, hoping to promote their application in multidisciplinary fields.

Recent Advances in Strategies for Addressing Hypoxia in Tumor Photodynamic Therapy

Photodynamic therapy (PDT) is a treatment modality that uses light to target tumors and minimize damage to normal tissues. It offers advantages including high spatiotemporal selectivity, low side effects, and maximal preservation of tissue functions. However, the PDT efficiency is severely impeded by the hypoxic feature of tumors. Moreover, hypoxia may promote tumor metastasis and tumor resistance to multiple therapies. Therefore, addressing tumor hypoxia to improve PDT efficacy has been the focus of antitumor treatment, and research on this theme is continuously emerging. In this review, we summarize state-of-the-art advances in strategies for overcoming hypoxia in tumor PDTs, categorizing them into oxygen-independent phototherapy, oxygen-economizing PDT, and oxygen-supplementing PDT. Moreover, we highlight strategies possessing intriguing advantages such as exceedingly high PDT efficiency and high novelty, analyze the strengths and shortcomings of different methods, and envision the opportunities and challenges for future research.

Phototherapy and multimodal imaging of cancers based on perfluorocarbon nanomaterials

Phototherapy, such as photodynamic therapy (PDT) and photothermal therapy (PTT), possesses unique characteristics of non-invasiveness and minimal side effects in cancer treatment, compared with conventional therapies. However, the ubiquitous tumor hypoxia microenvironments could severely reduce the efficacy of oxygen-consuming phototherapies. Perfluorocarbon (PFC) nanomaterials have shown great practical value in carrying and transporting oxygen, which makes them promising agents to overcome tumor hypoxia and extend reactive oxygen species (ROS) lifetime to improve the efficacy of phototherapy. In this review, we summarize the latest advances in PFC-based PDT and PTT, and combined multimodal imaging technologies in various cancer types, aiming to facilitate their application-oriented clinical translation in the future.

Perfluorocarbon nanomaterials for photodynamic therapy

Photodynamic therapy (PDT) is a treatment modality in which a photosensitizer is irradiated with light, producing reactive oxygen species, often via energy transfer with oxygen. As it is common for tumors to be hypoxic, methods to deliver photosensitizer and oxygen are desirable. One such approach is the use of perfluorocarbons, molecules in which all C-H bonds are replaced with C-F bonds, to co-deliver oxygen because of the high solubility of gases in perfluorocarbons. This review highlights the benefits and limitations of several fluorinated nanomaterial architectures for use in PDT.

Mitochondria-targeted and ultrasound-responsive nanoparticles for oxygen and nitric oxide codelivery to reverse immunosuppression and enhance sonodynamic therapy for immune activation

Background: Sonodynamic therapy (SDT) is a promising strategy to inhibit tumor growth and activate antitumor immune responses for immunotherapy. However, the hypoxic and immunosuppressive tumor microenvironment limits its therapeutic efficacy and suppresses immune response. Methods: In this study, mitochondria-targeted and ultrasound-responsive nanoparticles were developed to co-deliver oxygen (O2) and nitric oxide (NO) to enhance SDT and immune response. This system (PIH-NO) was constructed with a human serum albumin-based NO donor (HSA-NO) to encapsulate perfluorodecalin (FDC) and the sonosensitizer (IR780). In vitro, the burst release of O2 and NO with US treatment to generate reactive oxygen species (ROS), the mitochondria targeting properties and mitochondrial dysfunction were evaluated in tumor cells. Moreover, in vivo, tumor accumulation, therapeutic efficacy, the immunosuppressive tumor microenvironment, immunogenic cell death, and immune activation after PIH-NO treatment were also studied in 4T1 tumor bearing mice. Results: PIH-NO could accumulate in the mitochondria and relive hypoxia. After US irradiation, O2 and NO displayed burst release to enhance SDT, generated strongly oxidizing peroxynitrite anions, and led to mitochondrial dysfunction. The release of NO increased blood perfusion and enhanced the accumulation of the formed nanoparticles. Owing to O2 and NO release with US, PIH-NO enhanced SDT to inhibit tumor growth and amplify immunogenic cell death in vitro and in vivo. Additionally, PIH-NO promoted the maturation of dendritic cells and increased the number of infiltrating immune cells. More importantly, PIH-NO polarized M2 macrophages into M1 phenotype and depleted myeloid-derived suppressor cells to reverse immunosuppression and enhance immune response. Conclusion: Our findings provide a simple strategy to co-deliver O2 and NO to enhance SDT and reverse immunosuppression, leading to an increase in the immune response for cancer immunotherapy.

IR780-based nanomaterials for cancer imaging and therapy

IR780, a small molecule with a strong optical property and excellent photoconversion efficiency following near infrared (NIR) irradiation, has attracted increasing attention in the field of cancer treatment and imaging. This review is focused on different IR780-based nanoplatforms and the application of IR780-based nanomaterials for cancer bioimaging and therapy. Thus, this review summarizes the overall aspects of IR780-based nanomaterials that positively impact cancer biomedical applications.

Functionalized g-C3N4 nanosheets for potential use in magnetic resonance imaging-guided sonodynamic and nitric oxide combination therapy

The oxygen consumption-induced hypoxia and the high concentration of glutathione in tumor microenvironment limit the treatment outcomes of sonodynamic therapy (SDT). SDT needs to be combined with other treatment modalities to achieve the desired therapeutic efficiency. In this study, an oxidized g-C₃N₄ (OCN) nanosheet-based theranostic nanoplatform is developed for sonodynamic and nitric oxide (NO) combination therapy of cancer. The OCN nanosheets are successively modified with amino-terminated 6-armed polyethylene glycol, chlorin e6, and Gd³⁺ ions, and then the as-prepared OCN-PEG-(Ce6-Gd³⁺) nanosheets are loaded with the NO donor N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine (BNN6). Upon ultrasound (US) irradiation, the OCN-PEG-(Ce6-Gd³⁺)/BNN6 nanocomposite can induce the generation of reactive oxygen species (ROS) and simultaneously release NO molecules to effectively kill the cancer cells, thereby significantly suppressing the tumor growth. Moreover, a good in vivo T₁-weighted magnetic resonance imaging (MRI) contrast effect is achieved after intravenous injection of OCN-PEG-(Ce6-Gd³⁺)/BNN6 due to remarkably enhanced contrast performance of the nanocomposite. Therefore, the OCN-PEG-(Ce6-Gd³⁺)/BNN6 formulation can serve as a promising theranostic agent for MRI-guided sonodynamic-NO combination therapy.

Synergy of hypoxia relief and heat shock protein inhibition for phototherapy enhancement

BACKGROUND

Phototherapy is a promising strategy for cancer therapy by reactive oxygen species (ROS) of photodynamic therapy (PDT) and hyperthermia of photothermal therapy (PTT). However, the therapeutic efficacy was restricted by tumor hypoxia and thermal resistance of increased expression of heat shock protein (Hsp). In this study, we developed albumin nanoparticles to combine hypoxia relief and heat shock protein inhibition to overcome these limitations for phototherapy enhancement.

RESULTS

Near-infrared photosensitizer (IR780) and gambogic acid (GA, Hsp90 inhibitor) were encapsulated into albumin nanoparticles via hydrophobic interaction, which was further deposited MnO2 on the surface to form IGM nanoparticles. Both in vitro and in vivo studies demonstrated that IGM could catalyze overexpress of hydrogen peroxide to relive hypoxic tumor microenvironment. With near infrared irradiation, the ROS generation was significantly increase for PDT enhancement. In addition, the release of GA was promoted by irradiation to bind with Hsp90, which could reduce cell tolerance to heat for PTT enhancement. As a result, IGM could achieve better antitumor efficacy with enhanced PDT and PTT.

CONCLUSION

This study develops a facile approach to co-deliver IR780 and GA with self-assembled albumin nanoparticles, which could relive hypoxia and suppress Hsp for clinical application of cancer phototherapy.

Dual-targeted 5-aminolevulinic acid derivatives with glutathione depletion function for enhanced photodynamic therapy

Photodynamic therapy (PDT) is a promising tumor therapy which utilizes reactive oxygen species (ROSs) to cause tumor cells death. 5-aminolevulinic acid (ALA) and two of its esters are FDA-approved photosensitizers. However, their clinical application suffers from their instability and lack of tumor selectivity. In addition, the overexpression of glutathione (GSH) in some tumor cells reduces the PDT efficiency due to the ROS-scavenging ability of GSH. In this work, we present three multifunctional ALA derivates with the characteristics of dual-targeting and GSH depletion to improve the therapeutic effect of ALA-based PDT. The general structure of these compounds consists of an ALA methyl ester (ALA-OMe) moiety that can metabolize to photosensitive protoporphyin IX (PpIX) inside the cells, a biotin group for targeting biotin receptor-positive tumor cells and a disulfide bond-based self-immolative linker which can be activated by GSH to liberate ALA-OMe. Simultaneously, the reaction between the disulfide bond and GSH also depletes intracellular GSH, causing tumor cells more vulnerable to ROSs. All three compounds exhibited high stability under physiological conditions. In vitro experiments demonstrated that the more lipophilic compounds 1 and 2 were much more efficient in inducing PpIX production in biotin receptor-overexpressed HeLa cells as compared with their parent compound (ALA-OMe). And the PpIX generation induced by compounds 1 and 2 was positively correlated with the overexpression of biotin receptor and GSH level in tumor cells. More importantly, the GSH depletion ability of them significantly increased their phototoxicity. Furthermore, in comparison with ALA-OMe, compound 2 showed much higher in vivo efficiency in PpIX production. All the results demonstrate that the combination strategy of dual-targeting and GSH depletion can be used to concurrently enhance the tumor-specificity and anti-tumor efficiency of ALA-based PDT. And this strategy may be used for designing other ALA-based photosensitizers with higher tumor-specificity and better therapeutic effects.

In vivo phototoxic effects of a tetraethyleneglycol-substituted Zn phthalocyanine in tumor bearing rats at an enzymatic level

TEG-Pc, a Zn(II) phthalocyanine tetra substituted in non-peripheral position by tetraethylene glycol chains, proved to have good efficiency during in vitro photodynamic experiments. Its in vivo phototoxic effects have been investigated in tumor-bearing Wistar albino rats at an enzymatic level. The evolution of different oxidative markers are reviewed 6 h after the treatment.