Chlorin e6: A Promising Photosensitizer in Photo-Based Cancer Nanomedicine

Synergistic action of combining photodynamic therapy with immunotherapy for eradicating solid tumors in animal models: A systematic review

Malignancies maintain a high rate of mortality worldwide each year, requiring the development of novel therapeutic platforms. Immunotherapy approaches are considered a revolutionary treatment for overcoming malignancies. Photodynamic therapy (PDT) has attracted significant attention in various cancer types. Recent progress in cancer therapies has underscored the potential of combining PDT with immunotherapy. This approach can improve therapeutic outcomes by directly eliminating tumor cells and boosting immune responses for sustained anti-tumor effects in the whole body. This study aims to determine the relative efficacy of combining PDT with immunotherapy compared to PDT alone. Following the PRISMA guidance, an extensive literature review was conducted utilizing Scopus, Web of Science, and PubMed to identify high-quality preclinical studies exploring various aspects of PDT combined with immunotherapy. The adopted PICO framework included studies with rigorous experimental designs and relevant outcomes. The present review reveals the characteristics of tumor models, delivery systems, photosensitizers, and immunotherapy approaches. Key findings indicate that the combined PDT-immunotherapy approach shows promise in treating multiple tumors according to their size, therapeutic biomarkers, and inhibition of distant tumors. Finally, this integrated therapeutic strategy holds significant promise for advancing cancer treatment paradigms by potentiating each treatment efficacy; however, its clinical utility requires careful consideration of the associated challenges.

808 nm Light-Triggered Cyanine-Decorated Iridium(III) Complexes for Antibacterial Photodynamic Therapy in Deep-Tissue

Acute bacterial skin and skin structure infections (ABSSSIs) pose significant global health challenges, exacerbated by rising antibiotic resistance. Antibacterial photodynamic therapy (APDT) has emerged as a promising strategy to combat these infections by utilizing a photosensitizer (PS) that generates reactive oxygen species (ROS) upon light activation. However, the limited tissue penetration of conventional organic PSs, which primarily absorb in the UV-vis spectra, has hindered their therapeutic potential for deeper infections. Herein, we introduce a novel iridium(III)-cyanine complex (Ir-cy) with strong near-infrared (NIR) absorption at 814 nm (up to 101 nm red-shifted from previous reports), specifically designed to enhance tissue penetration for APDT. Under 808 nm laser irradiation, Ir-cy demonstrated a substantial ROS generation capacity, achieving approximately 70% reduction in Staphylococcus aureus (S. aureus) colonies at a depth of 7.2 mm within a simulated tissue model. Comprehensive in vitro and in vivo evaluations further confirmed its potent antibacterial efficacy against S. aureus while maintaining excellent biocompatibility. These findings highlight the potential of Ir-cy as a highly effective NIR-active PS, paving the way for advanced therapeutic strategies targeting deep-tissue ABSSSIs through optimized APDT.

Nanoparticles for Photodynamic Therapy of Breast Cancer: A Review of Recent Studies

Photodynamic therapy (PDT) is a therapeutic method based on the interaction between light and a photosensitizer. Supported by nanoparticles, this method represents a promising interdisciplinary approach for the treatment of many diseases. This article reviews the latest 2024 developments in the design and applications of nanoparticles dedicated to stand-alone PDT of breast cancer. Strategies to improve therapeutic efficacy by enhancing reactive oxygen species (ROS) production, precise delivery of photosensitizers and their stabilization in the systemic circulation are discussed, among others. Results from preclinical studies indicate significant improvements in therapeutic efficacy, including inhibition of tumor growth, reduction in metastasis and improvement of the immune microenvironment. The potential of these technologies to expand PDT applications in medicine and the need for further clinical trials to confirm their safety and efficacy are highlighted.

Multiprobe Photoproximity Labeling of the EGFR Interactome in Glioblastoma Using Red-Light

Photocatalytic proximity labeling has emerged as a valuable technique for studying interactions between biomolecules in a cellular context, providing precise spatiotemporal control over protein labeling. One significant advantage of these methods is their modularity, allowing the use of a single photocatalyst with different reactive probes to expand interactome coverage and capture diverse protein interactions. Despite these advances, fewer methods have been developed using red-light excitation, limiting the use of photoproximity labeling in more complex media such as tissues and animal models. Herein, we develop a platform for proximity labeling under red-light excitation, utilizing a single catalyst and two distinct probe types. We first design a carbene based labeling system that utilizes sulfonium diazo probes. This system is successfully applied on A549 cells to capture the interactome of epidermal growth factor receptor (EGFR) using a Cetuximab-Chlorin e6 conjugate. Benchmarking against established techniques indicates that this approach performs comparably to leading carbene-based proximity labeling methods. Next, we leverage the strong singlet oxygen generation (SOG) ability of Chlorin e6 to establish an alternative labeling system using aniline and hydrazide probes. EGFR directed chemoproteomics experiments reveal significant overlap with the carbene system, with the carbene approach capturing a subset of interactions identified by the SOG system. Finally, we deploy our approach for the characterization of EGFR in resected human glioblastoma (GBM) tissue samples removed from distinct locations in the same tumor, representing the tumor's infiltrating edge and its viable center, identifying several GBM specific interacting proteins that may serve as a launch point for future therapeutic campaigns.

Deep-Red and Ultrafast Photocatalytic Proximity Labeling Empowered In Situ Dissection of Tumor-Immune Interactions in Primary Tissues

Immunotherapy efficacy in solid tumors varies greatly, influenced by the tumor microenvironment (TME) and the dynamic tumor-immune interactions within it. Decoding these interactions in situ with minimal interference with native tissue architecture and delicate immune responses is critical for understanding tumor progression and optimizing therapeutic strategies. Here, we introduce CAT-Tissue, a novel deep-red photocatalytic proximity labeling method that enables ultrafast, high-resolution profiling of tumor-immune interactions in primary tissues. By leveraging nanobody-Chlorin e6 as the photocatalyst and biotin-aniline as the probe, CAT-Tissue enabled the rapid and comprehensive detection of various tumor-immune interactions in both coculture systems and primary tumor sections. Coupled with bulk RNA-sequencing, CAT-Tissue revealed distinct gene expression patterns between tumor-neighboring and tumor-distal lymphocytes, highlighting the recognition and immune responses of tumor-neighboring CD8+ T cells, which exhibited activated, effector, and exhausted phenotypes. By leveraging a deep-red photocatalytic proximity cell labeling strategy with excellent tissue penetration and biocompatibility, CAT-Tissue offers a nongenetically encoded platform with high sensitivity and spatiotemporal controllability for rapid profiling tumor-immune interactions within complex tissue environments in situ, which may advance our understanding of tumor immunology and guide the development of more effective immunotherapies.

A nano drug delivery system loading drugs and chlorin e6 separately to achieve photodynamic-chemo combination therapy

AIM

To develop a new drug delivery system (DDS) that can load chemotherapy agents and photosensitizer chlorin e6 (Ce6) onto the pores and surfaces of mesoporous silica nanoparticle (MSN) separately.

METHODS

Doxorubicin (DOX) was loaded into the pores of MSNs. Then, polyethyleneimine (PEI) was used to coat the surface of MSN to protect DOX, and then manganese dioxide (MnO2) nanoparticles were loaded through adding potassium permanganate (KMnO4) to bind with Ce6. Finally, polydopamine (PDA) was coated and coupled with hyaluronic acid (HA).

RESULTS

The synthesized versatile nanoparticle was pH-sensitive and exhibited positive photodynamic therapy (PDT) performance. Besides, it could be observed that the nanoparticles were efficiently taken up by tumor cells through confocal laser scanning microscopy (CLSM) and flow cytometry. Additionally, in vitro experiments suggested that the nanoparticles had pleasing toxicity to various tumor cells and equally positive therapeutic effect when curcumin replaced DOX.

CONCLUSION

Our work suggests that the nanoparticles designed by our strategy have satisfactory combination therapy performance and can enable more chemotherapy drugs to be used in photodynamic-chemo combination therapy.

Bioorthogonal reaction-mediated photosensitizer-peptide conjugate anchoring on cell membranes for enhanced photodynamic therapy

Photodynamic therapy (PDT), utilizing a photosensitizer (PS) to induce tumor cell death, is an effective modality for cancer treatment. PS-peptide conjugates have recently demonstrated remarkable antitumor potential in preclinical trials. However, the limited cell membrane binding affinity and rapid systemic clearance have hindered their transition to clinical applications. To address these challenges, we investigated whether in vivo covalent chemistry could enhance tumor accumulation and potentiate antitumor efficacy. Specifically, we synthesized a PS-peptide conjugate termed P-DBCO-Ce6, with chlorin e6 (Ce6) and dibenzocyclooctyne (DBCO) conjugated to a negatively charged short peptide. By employing metabolic glycoengineering and bioorthogonal reactions, P-DBCO-Ce6 achieves covalent bonding to the cell membrane, enabling prolonged retention of the PS on the cell surface and the in situ generation of reactive oxygen species (ROS) on cell membranes to kill tumor cells. In vivo studies demonstrated a 3.3-fold increase in tumor accumulation of the PS through bioorthogonal reactions compared to the control group, confirming that click chemistry can effectively enhance PS tumor accumulation. This approach allows for the effective elimination of tumors with a single treatment. The improved efficiency of this strategy provides new insights into the design of PDT systems for potential clinical applications.

Dual Pathways of Photorelease Carbon Monoxide via Photosensitization for Tumor Treatment

Carbon monoxide (CO) gas therapy, as an emerging therapeutic strategy, is promising in tumor treatment. However, the development of a red or near-infrared light-driven efficient CO release strategy is still challenging due to the limited physicochemical characteristics of the photoactivated carbon monoxide-releasing molecules (photoCORMs). Here, we discovered a novel photorelease CO mechanism that involved dual pathways of CO release via photosensitization. Specifically, the photosensitizer Chlorin e6 (Ce6) sensitized oxygen to produce singlet oxygen (1O2) and oxidized photoCORM Mn2(CO)10 to release CO in an air-saturated solvent under red light (655 nm, 50 mW/cm2) irradiation. Furthermore, Ce6 and Mn2(CO)10 could undergo multistep photochemical reactions to release CO, as well as the degradation of the photosensitizer Ce6 in an oxygen-depleted solution. As a proof of concept, we demonstrated the feasibility and tumor inhibition of this CO release strategy both in vitro and in vivo. These results provide a robust platform for the development of new approaches to CO-mediated modulation of signaling pathways and further facilitate the practical use of gas therapeutic methods in tumor therapy in vivo.

Hypericum Perforatum-Derived Exosomes-Like Nanovesicles: A Novel Natural Photosensitizer for Effective Tumor Photodynamic Therapy

Background

Natural photosensitizers hold potential for photodynamic therapy (PDT) but are often limited by poor visible light absorption. Plant-derived exosome-like nanovesicles offer an innovative platform for enhancing photosensitizer performance.

Methods

Hypericum perforatum-derived nanovesicles (HPDENs) were characterized using electron microscopy, dynamic light scattering, and proteomic and miRNA sequencing. High-performance liquid chromatography confirmed hypericin content. PDT efficacy was assessed in vitro and in vivo.

Results

HPDENs exhibited robust photosensitizing properties, generating reactive oxygen species (ROS) through both Type I and Type II pathways upon light activation. In vitro, HPDENs showed light dose-dependent cytotoxicity against human melanoma cells, characterized by elevated ROS production and apoptosis induction. In vivo, HPDEN-mediated PDT significantly suppressed tumor growth and induced extensive tumor necrosis, with no observable toxicity to major organs.

Conclusion

HPDENs represent a novel plant-derived photosensitizer with dual ROS generation pathways and significant therapeutic efficacy, providing a promising platform for enhancing photodynamic therapy.

Chlorin e6: a promising photosensitizer of anti-tumor and anti-inflammatory effects in PDT

Photodynamic therapy (PDT) involves the activation of photosensitizers (PSs) by visible laser light at the target site to catalyze the production of reactive oxygen species, resulting in tumor cell death and blood vessel closure. The efficacy of PDT depends on the PSs, the amount of oxygen, and the intensity of the excitation laser. PSs have been extensively researched, and great efforts have been made to develop an ideal photosensitizer. Chlorin-e6 is an FDA-approved second-generation PSs that has attracted widespread research interest in the medical field, especially with respect to antitumor and anti-inflammatory activity. Chlorin-e6 possesses the advantages of a large absorption coefficient, high strength, low residue in the body, and relatively high safety and thus has promising application prospects. Here we review the use of chlorin-e6 in PDT and discuss the prospects of further development of this technology.

An esophageal stent integrated with wireless battery-free movable photodynamic-therapy unit for targeted tumor treatment

Esophageal cancer is the eighth most common cancer worldwide and the sixth leading cause of cancer-related deaths. In this study, we propose a novel esophageal stent equipped with a wireless, battery-free, and movable photodynamic therapy (PDT) unit designed to treat esophageal tumors with flexibility, precision, and real-time control. This system integrates a PDT unit and an electrochemical pneumatic soft actuator into a conventional esophageal stent. Each module incorporates a piezoelectric transducer capable of receiving external ultrasound to power the respective module. These transducers selectively respond to different external ultrasound frequencies, enabling independent operation without mutual interference. The therapy module provides a light source for PDT, inducing the production of cytotoxic reactive oxygen species (ROS) in tumor cells and promoting apoptosis. The pneumatic actuator based on electrochemical principles plays a critical role in controlling the position of the PDT light source, enabling the movement of the therapy module up to 200 mm within 15 min. This allows real-time control to maintain the light source near the tumor, ensuring precise and targeted treatment. The system can wirelessly and in real-time control the PDT light source's position via external ultrasound, offering a novel approach for treating esophageal cancer patients according to the need of tumor's progression.

Ex Vivo Biosafety and Efficacy Assessment of Advanced Chlorin e6 Nanoemulsions as a Drug Delivery System for Photodynamic Antitumoral Application

The photosensitizer (PS) in the Photodynamic Therapy (PDT) field represents a key factor, being directly connected to the therapeutic efficacy of the process. Chlorin e6 is a second-generation photosensitizer, approved by the FDA with the most desired clinical properties for PDT applications, presenting high reactive oxygen species (ROS) generation and proven anticancer properties. However, hydrophobicity is a major limitation, leading to poor biodistribution. To overcome this condition, the present work developed an up-to-date nanoemulsion incorporating Ce6 in a new nanosystem (Ce6/NE). A comprehensive study of physicochemical properties, stability, fluorescence characteristics, the in vitro release profile, in vivo and ex vivo biocompatibility, and ex vivo efficacy was established. The nanoemulsions showed the desired particle size and stability over six months, with no spectroscopic or photophysical alterations. Uptake studies demonstrated the internalization of the Ce6/NE in monolayers, with biocompatibility at the lowest concentrations. The HET-CAM assay, however, revealed a higher biocompatibility range, also indicating Ce6/NE's potential for cancer treatment through antiangiogenic studies. These findings highlight the use of a new promising photosensitizer for PDT modulated with nanotechnology that promotes low toxicity, higher bioavailability, and site-specific delivery.

Self-Assembly Nanomedicine Initiating Cancer-Immunity Cycle with Cascade Reactions for Boosted Immunotherapy

Immune checkpoint blockade (ICB) therapy has been extensively integrated into cancer clinical management. However, its overall response rate is limited due to the stagnating cancer-immunity cycle (CIC) caused by the immunosuppressive tumor microenvironment (TME). Here, a multi-pronged nanomedicine, defined as LCCS, was constructed by the self-assembly of lactate oxidase, catalase, chlorin e6, and sorafenib. Through cascade reactions, LCCS effectively reprogrammed the TME and re-initiated the CIC by depleting lactate, alleviating hypoxia, inducing immunogenic cell death, and normalizing tumor vessels. Immunological analyses indicated that treatment with LCCS decreased the infiltration of immunosuppressive cells while increasing the recruitment of immune effector cells in tumors. Leveraging the effective operation of the CIC, LCCS improved the efficacy of ICB therapy to inhibit breast cancer, and effectively induced the elimination of colorectal cancer and long-term immune memory. Therefore, multifunctional nanomedicines targeting CIC hold great potential for applications in cancer immunotherapy.

Chlorin e6-Loaded Nanostructured Lipid Carriers Targeted by Angiopep-2: Advancing Photodynamic Therapy in Glioblastoma

Glioblastoma (GBM) is a highly aggressive brain tumor known for its resistance to standard treatments. Despite surgery being a primary option, it often leads to incomplete removal and high recurrence rates. Photodynamic therapy (PDT) holds promise as an adjunctive treatment, but safety concerns and the need for high-power lasers have limited its widespread use. This research addresses these challenges by introducing a novel PDT approach, using chlorin e6 (Ce6) enclosed in nanostructured lipid carriers (Ang-Ce6-NLCs) and targeted to GBM with the angiopep-2 peptide. Remarkably, a single 5-min irradiation session with LEDs at 660 nm and low power density (10 mW cm- 2) proves effective against GBM, while reducing safety risks associated with high-power lasers. Encapsulation improves Ce6 stability and performance in physiological environments, while angiopep-2 targeting enhances delivery to GBM cells, maximizing treatment efficacy and minimizing off-target effects. The findings demonstrate that Ang-Ce6-NLCs-mediated PDT brings about a significant reduction in GBM cell viability, increases oxidative stress, reduces tumor migration, and enhances apoptosis. Overall, such treatment holds potential as a safe and efficient intraoperative removal of GBM infiltrating cells that cannot be reached by surgery, using low-power LED light to minimize harm to surrounding healthy tissue while maximizing tumor treatment.

A Novel Approach for Bladder Cancer Treatment: Nanoparticles as a Drug Delivery System

Bladder cancer represents one of the most prevalent malignant neoplasms of the urinary tract. In the Asian context, it represents the eighth most common cancer in males. In 2022, there were approximately 613,791 individuals diagnosed with bladder cancer worldwide. Despite the availability of efficacious treatments for the two principal forms of bladder cancer, namely non-invasive and invasive bladder cancer, the high incidence of recurrence following treatment and the suboptimal outcomes observed in patients with high-grade and advanced disease represent significant concerns in the management of bladder cancer at this juncture. Nanoparticles have gained attention for their excellent properties, including stable physical properties, a porous structure that can be loaded with a variety of substances, and so on. The in-depth research on nanoparticles has led to their emergence as a new class of nanoparticles for combination therapy, due to their advantageous properties. These include the extension of the drug release window, the enhancement of drug bioavailability, the improvement of drug targeting ability, the reduction of local and systemic toxicity, and the simultaneous delivery of multiple drugs for combination therapy. As a result, nanoparticles have become a novel agent of the drug delivery system. The advent of nanoparticles has provided a new impetus for the development of non-surgical treatments for bladder cancer, including chemotherapy, immunotherapy, gene therapy and phototherapy. The unique properties of nanoparticles have facilitated the combination of diverse non-surgical therapeutic modalities, enhancing their overall efficacy. This review examines the recent advancements in the use of nanoparticles in non-surgical bladder cancer treatments, encompassing aspects such as delivery, therapeutic efficacy, and the associated toxicity of nanoparticles, as well as the challenges encountered in clinical applications.

FDA-Approved Hydrogel-Mediated In Situ Sonodynamic and Chemotherapeutic Therapy for Pancreatic Cancer

Background: Albumin-bound paclitaxel (nab-PTX) nanoparticles have been proven effective in treating advanced pancreatic cancer. However, the clinical application of nab-PTX nanoparticles is often associated with suboptimal outcomes and severe side effects due to its non-specific distribution and rapid clearance. This study aims to develop a novel nanoplatform that integrates sonodynamic therapy (SDT) and chemotherapy to enhance treatment efficacy and reduce systemic side effects. Methods: Bovine serum albumin (BSA) was conjugated with chlorin e6 and paclitaxel (PTX) to form stable nanoparticles (NPs). These NPs were then incorporated into a biodegradable poly(lactic-co-glycolic acid)-b-polyethylene glycol-b-poly(lactic-co-glycolic acid) hydrogel for targeted drug delivery. The system's stability and drug release profile were analyzed, followed by in vitro studies to evaluate cellular uptake and cancer cell killing efficacy. In vivo evaluation was performed using pancreatic cancer xenograft models, with intratumoral injection of the drug-loaded hydrogel. Results: The developed hydrogel system demonstrated enhanced stability and sustained release of PTX. In vitro analyses revealed significant cellular uptake and synergistic cancer cell killing effects through combined SDT and chemotherapy. In vivo studies showed prolonged intratumoral retention of the drug and remarkable inhibition of tumor growth. Conclusions: This novel nanoplatform offers a promising approach for improving pancreatic cancer treatment by enhancing intratumoral drug retention and minimizing systemic side effects. The synergistic effects of SDT and chemotherapy demonstrate the potential of this strategy in achieving better therapeutic outcomes.

Unveiling therapeutic avenues targeting xCT in head and neck cancer

Head and neck cancer (HNC) remains a major global health burden, prompting the need for innovative therapeutic strategies. This review examines the role of the cystine/glutamate antiporter (xCT) in HNC, specifically focusing on how xCT contributes to cancer progression through mechanisms such as redox imbalance, ferroptosis, and treatment resistance. The central questions addressed include how xCT dysregulation affects tumor biology and the potential for targeting xCT to enhance treatment outcomes. We explore recent developments in xCT-targeted current and emerging therapies, including xCT inhibitors and novel treatment modalities, and their role in addressing therapeutic challenges. This review aims to provide a comprehensive analysis of xCT as a therapeutic target and to outline future directions for research and clinical application.

Reactive Oxygen Species-Sensitive Nanophotosensitizers Composed of Buthionine Sulfoximine-Conjugated Chitosan Oligosaccharide for Enhanced Photodynamic Treatment of Cancer Cells

The efficacy of photodynamic therapy (PDT) based on traditional photosensitizers is generally limited by the cellular redox homeostasis system due to the reactive oxygen species (ROS) scavenging effect of glutathione (GSH). In this study, buthionine sulfoximine (BSO), a GSH inhibitor, was conjugated with the amine group of chitosan oligosaccharide (COS) using a thioketal linker (COSthBSO) to liberate BSO and chlorine e6 (Ce6) under oxidative stress, and then, Ce6-COSthBSO NP (Ce6-COSthBSO NP), fabricated by a dialysis procedure, showed an accelerated release rate of BSO and Ce6 by the addition of hydrogen peroxide, indicating that nanophotosensitizers have ROS sensitivity. In the in vitro cell culture study using HCT116 colon carcinoma cells, a combination of BSO and Ce6 efficiently suppressed the intracellular GSH and increased ROS production compared to the sole treatment of Ce6. In particular, Ce6-COSthBSO NP showed higher efficacy in the suppression of GSH levels and ROS production compared to the free Ce6 and Ce6/BSO combination. These results were due to the fact that Ce6-COSthBSO NP was efficiently delivered to the intracellular region, suppressed intracellular GSH levels, and elevated ROS levels. The in vivo animal tumor xenograft study demonstrated Ce6-COSthBSO NP being efficiently delivered to the tumor tissue, i.e., the fluorescence intensity in the tumor tissue was higher than those of other organs. The combination of Ce6 and BSO efficiently suppressed tumor growth compared to the sole treatment of Ce6, indicating that BSO might efficiently suppress GSH levels and increase ROS levels in the tumor microenvironment. Specifically, Ce6-COSthBSO NP showed the strongest performance in inhibition of tumor growth than those of Ce6 or the CE6/BSO combination, indicating that they were efficiently delivered to tumor tissue, increased ROS levels, and then efficiently inhibited tumor growth. We suggest that COSthBSO nanophotosensitizers are promising candidates for PDT treatment of cancer cells.

Multifunctional gold nanoparticles for cancer theranostics

The diagnosis and treatment of cancer can often be challenging requiring more attractive options. Some types of cancers are more aggressive than others and symptoms for many cancers are subtle, especially in the early stages. Nanotechnology provides high sensitivity, specificity and multimodal capability for cancer detection, treatment and monitoring. In particular, metal nanoparticles (NPs) such as gold nanoparticles (AuNPs) are attractive nanosystems for researchers interested in bioimaging and therapy. The size, shape and surface of AuNPs can be modified for improving targeting and accumulation in cancer cells, for example through introduction of ligands and surface charge. The interactions of AuNPs with electromagnetic radiation (e.g., visible-near-infrared, X-rays) can be used for photothermal therapy and radiation therapy, through heat generated from light absorption and emission of Auger electrons, respectively. The subsequent expansion and high X-ray attenuation from AuNPs can be used for enhancing contrast for tumor detection (e.g., using photoacoustic, computed tomography imaging). Multi-functionality can be further extended through covalent/non-covalent functionalization, for loading additional imaging/therapeutic molecules for combination therapy and multimodal imaging. In order to cover the important aspects for designing and using AuNPs for cancer theranostics, this review focuses on the synthesis, functionalization and characterization methods that are important for AuNPs, and presents their unique properties and different applications in cancer theranostics.

Combined use of 5-ALA-induced protoporphyrin IX and chlorin e6 for fluorescence diagnostics and photodynamic therapy of skin tumors

Different types of photosensitizers (PSs) have different dynamics and intensities of accumulation, depending on the type of tumor or different areas within the same tumor. This determines the effectiveness of fluorescence diagnostics and photodynamic therapy (PDT). This paper studies the processes of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) and chlorin e6 (Ce6) accumulation in the central and border zones of a tumor after combined administration of two PSs into the patient's body. Fluorescence diagnostic methods have shown that sublingual administration of 5-ALA leads to the more intense accumulation of PpIX in a tumor compared to oral administration. Differences have been identified in the dynamics of 5-ALA-induced PpIX and Ce6 accumulation in the central and border zones of the tumor, as well as normal tissues. Ce6 accumulates mainly in the central zone of the tumor while PpIX accumulates in the border zone of the tumor. All patients with combined PDT experienced complete therapeutic pathomorphosis and relapse-free observation.

A Spatiotemporally Controlled Gene-Regulation Strategy for Combined Tumor Therapy Based on Upconversion Hybrid Nanosystem

The lack of precise spatiotemporal gene modulation and therapy impedes progress in medical applications. Herein, a 980 nm near-infrared (NIR) light-controlled nanoplatform, namely URMT, is developed, which can allow spatiotemporally controlled photodynamic therapy and trigger the enzyme-activated gene expression regulation in tumors. URMT is constructed by engineering an enzyme-activatable antisense oligonucleotide, which combined with an upconversion nanoparticle (UCNP)-based photodynamic nanosystem, followed by the surface functionalization of triphenylphosphine (TPP), a mitochondria-targeting ligand. URMT allows for the 980 nm NIR light-activated generation of reactive oxygen species, which can induce the translocation of a DNA repair enzyme (namely apurinic/apyrimidinic endonuclease 1, APE1) from the nucleus to mitochondria. APE1 can recognize the basic apurinic/apyrimidinic (AP) sites in DNA double-strands and perform cleavage, thereby releasing the functional single-strands for gene regulation. Overall, an augmented antitumor effect is observed due to NIR light-controlled mitochondrial damage and enzyme-activated gene regulation. Altogether, the approach reported in this study offers high spatiotemporal precision and shows the potential to achieve precise and specific gene regulation for targeted tumor treatment.

Hepatoma-Targeting and ROS-Responsive Polymeric Micelle-Based Chemotherapy Combined with Photodynamic Therapy for Hepatoma Treatment

Background

The combination of nanoplatform-based chemotherapy and photodynamic therapy (PDT) is a promising way to treat cancer. Celastrol (Cela) exhibits highly effective anti-hepatoma activity with low water solubility, poor bioavailability, non-tumor targeting, and toxic side effects. The combination of Cela-based chemotherapy and PDT via hepatoma-targeting and reactive oxygen species (ROS)-responsive polymeric micelles (PMs) could solve the application problem of Cela and further enhance antitumor efficacy.

Methods

In this study, Cela and photosensitizer chlorin e6 (Ce6) co-loaded glycyrrhetinic acid-modified carboxymethyl chitosan-thioketal-rhein (GCTR) PMs (Cela/Ce6/GCTR PMs) were prepared and characterized. The safety, ROS-sensitive drug release, and intracellular ROS production were evaluated. Furthermore, the in vitro anti-hepatoma effect and cellular uptaken in HepG2 and BEL-7402 cells, and in vivo pharmacokinetic, tissue distribution, and antitumor efficacy of Cela/Ce6/GCTR PMs in H22 tumor-bearing mice were then investigated.

Results

Cela/Ce6/GCTR PMs were successfully prepared with nanometer-scale particle size, favorable drug loading capacity, and encapsulation efficiency. Cela/Ce6/GCTR PMs exhibited a strong safety profile and better hemocompatibility, exhibiting less damage to normal tissues. Compared with Cela-loaded GCTR PMs, the ROS-responsiveness of Cela/Ce6/GCTR PMs was increased, and the release of Cela was accelerated after combination with PDT. Cela/Ce6/GCTR PMs can efficiently target liver tumor cells by uptake and have a high cell-killing effect in response to ROS. The combination of GCTR PM-based chemotherapy and PDT resulted in increased bioavailability of Cela and Ce6, improved liver tumor targeting, and better anti-hepatoma effects in vivo.

Conclusion

Hepatoma-targeting and ROS-responsive GCTR PMs co-loaded with Cela and Ce6 combined with PDT exhibited improved primary hepatic carcinoma therapeutic effects with lower toxicity to normal tissues, overcoming the limitations of monotherapy and providing new strategies for tumor treatment.

Supramolecular self-sensitized dual-drug nanoassemblies potentiating chemo-photodynamic therapy for effective cancer treatment

Chemo-photodynamic synergistic therapy (CPST) holds tremendous promise for treating cancers. Unfortunately, existing CPST applications suffer from complex synthetic procedures, low drug co-loading efficiency, and carrier-related toxicity. To address these issues, we have developed a supramolecular carrier-free self-sensitized nanoassemblies by co-assembling podophyllotoxin (PTOX) and chlorin e6 (Ce6) to enhance CPST efficiency against tumors. The nanoassemblies show stable co-assembly performance in simulative vivo neural environment (∼150 nm), with high co-loading ability for PTOX (72.2 wt%) and Ce6 (27.8 wt%). In vivo, the nanoassemblies demonstrate a remarkable ability to accumulate at tumor sites by leveraging the enhanced permeability and retention (EPR) effect. The disintegration of nanoassemblies following photosensitizer bioactivation triggered by the acidic tumor environment effectively resolves the challenge of aggregation-caused quenching (ACQ) effect. Upon exposure to external light stimulation, the disintegrated nanoassemblies not only illuminate cancer cells synergistically but also exert a more potent antitumor effect when compared with PTOX and Ce6 administered alone. This self-sensitized strategy represents a significant step forward in CPST, offering a unique co-delivery paradigm for clinic cancer treatment.

Reactive Oxygen Species-Regulated Conjugates Based on Poly(jasmine) Lactone for Simultaneous Delivery of Doxorubicin and Docetaxel

In cancer therapy, it is essential to selectively release cytotoxic agents into the tumor to prevent the adverse effects associated with anticancer drugs. Thus, in this study, a stimuli-sensitive polymer-drug conjugate was synthesized for selective drug release. Doxorubicin (DOX) and docetaxel (DTX) were conjugated onto novel poly(jasmine lactone) based copolymer via a thioketal (TK) linker. In addition, a photosensitizer (chlorin e6) was attached to the polymer, which served as a reactive oxygen species generator to cleave the TK linker. The conjugate is readily self-assembled into micelles less than 100 nm in size. Micelles demonstrate a notable increase in their ability to cause cell death when exposed to near-infrared (NIR) light on MDA-MB-231 breast cancer cells. The increase in cytotoxicity is higher than that observed with the combination of free DOX and DTX. The accumulation of DOX in the nucleus after release from the micelles (laser irradiation) was also confirmed by confocal microscopy. In the absence of light, micelles did not show any toxicity while the free drugs were found toxic irrespective of the light exposure. The obtained results suggest the targeted drug delivery potential of micelles regulated by the external stimuli, i.e., NIR light.

Design of a nanozyme-based magnetic nanoplatform to enhance photodynamic therapy and immunotherapy

The tumor microenvironment, particularly the hypoxic property and glutathione (GSH) overexpression, substantially inhibits the efficacy of cancer therapy. In this article, we present the design of a magnetic nanoplatform (MNPT) comprised of a photosensitizer (Ce6) and an iron oxide (Fe3O4)/manganese oxide (MnO2) composite nanozyme. Reactive oxygen species (ROS), such as singlet oxygen (1O2) radicals produced by light irradiation and hydroxyl radicals (·OH) produced by catalysis, are therapeutic species. These therapeutic substances stimulate cell apoptosis by increasing oxidative stress. This apoptosis then triggers the immunological response, which combines photodynamic therapy and T-cell-mediated immunotherapy to treat cancer. Furthermore, MNPT can be utilized as a contrast agent in magnetic resonance and fluorescence dual-modality imaging to give real-time tracking and feedback on treatment.

A Fe2O3/CNx cascade nanoreactor with dual-enzyme-mimetic activities for cancer hypoxia relief to amplify chemo/photodynamic therapy

Reactive oxygen species (ROS)-mediated therapeutic strategies, including chemodynamic therapy (CDT), photodynamic therapy (PDT), and their combination, are effective for treating cancer. Developing a nanoreactor with combined functions of catalase (CAT) and peroxidase (POD) that can simultaneously convert excess H2O2 in tumors into O2 required for type II PDT and hydroxyl radicals (•OH) for CDT can help achieve combined therapy. Here, we reported on a safe Fe2O3/CNx nanoreactor with dual enzyme simulated activity, in which CNx sheet was the carrier and reducing agent to convert Fe2O3 to Fe2+. After modified by MgO2 and photosensitizer Ce6, MgO2-Fe2O3/CNx-Ce6 (MFCC) platform integrated multiple functions, including photosensitizer delivery, compensated H2O2 continuous supply, relieve of hypoxia, generation of •OH and consumption of GSH into a single formulation. Under 660 nm irradiation for 4 min, MFCC actives more ROS to conduct PDT/CDT, leading to the remarkable reduced survival rate of breast cancer cells to 14 %. Due to the enhanced permeability and retention (EPR) effect, MFCC can retain and accumulate at the tumor site of mice for a longer period that inhibit the expression of tumor angiogenic factors, suppress tumor neovascularization, and suppress the proliferation and growth of tumor cells.

A toolbox for enzymatic modification of nucleic acids with photosensitizers for photodynamic therapy

Photodynamic therapy (PDT) is an approved cancer treatment modality. Despite its high efficiency, PDT is limited in terms of specificity and by the poor solubility of the rather lipophilic photosensitizers (PSs). In order to alleviate these limitations, PSs can be conjugated to oligonucleotides. However, most conjugation methods often involve complex organic synthesis and result in the appendage of single modifications at the 3'/5' termini of oligonucleotides. Here, we have investigated the possibility of bioconjugating a range of known PSs by polymerase-mediated synthesis. We have prepared a range of modified nucleoside triphosphates by different conjugation methods and investigated the substrate tolerance of these nucleotides for template-dependent and -independent DNA polymerases. This method represents a mild and versatile approach for the conjugation of single or multiple PSs onto oligonucleotides and can be useful to further improve the efficiency of the PDT treatment.

Photodynamic Therapy: A Novel Approach for Head and Neck Cancer Treatment with Focusing on Oral Cavity

Oral cancers, specifically oral squamous cell carcinoma (OSCC), pose a significant global health challenge, with high incidence and mortality rates. Conventional treatments such as surgery, radiotherapy, and chemotherapy have limited effectiveness and can result in adverse reactions. However, as an alternative, photodynamic therapy (PDT) has emerged as a promising option for treating oral cancers. PDT involves using photosensitizing agents in conjunction with specific light to target and destroy cancer cells selectively. The photosensitizers accumulate in the cancer cells and generate reactive oxygen species (ROS) upon exposure to the activating light, leading to cellular damage and ultimately cell death. PDT offers several advantages, including its non-invasive nature, absence of known long-term side effects when administered correctly, and cost-effectiveness. It can be employed as a primary treatment for early-stage oral cancers or in combination with other therapies for more advanced cases. Nonetheless, it is important to note that PDT is most effective for superficial or localized cancers and may not be suitable for larger or deeply infiltrating tumors. Light sensitivity and temporary side effects may occur but can be managed with appropriate care. Ongoing research endeavors aim to expand the applications of PDT and develop novel photosensitizers to further enhance its efficacy in oral cancer treatment. This review aims to evaluate the effectiveness of PDT in treating oral cancers by analyzing a combination of preclinical and clinical studies.

Immunometabolism of ferroptosis in the tumor microenvironment

Ferroptosis is an iron-dependent form of cell death that results from excess lipid peroxidation in cellular membranes. Within the last decade, physiological and pathological roles for ferroptosis have been uncovered in autoimmune diseases, inflammatory conditions, infection, and cancer biology. Excitingly, cancer cell metabolism may be targeted to induce death by ferroptosis in cancers that are resistant to other forms of cell death. Ferroptosis sensitivity is regulated by oxidative stress, lipid metabolism, and iron metabolism, which are all influenced by the tumor microenvironment (TME). Whereas some cancer cell types have been shown to adapt to these stressors, it is not clear how immune cells regulate their sensitivities to ferroptosis. In this review, we discuss the mechanisms of ferroptosis sensitivity in different immune cell subsets, how ferroptosis influences which immune cells infiltrate the TME, and how these interactions can determine epithelial-to-mesenchymal transition (EMT) and metastasis. While much focus has been placed on inducing ferroptosis in cancer cells, these are important considerations for how ferroptosis-modulating strategies impact anti-tumor immunity. From this perspective, we also discuss some promising immunotherapies in the field of ferroptosis and the challenges associated with targeting ferroptosis in specific immune cell populations.

Multifunctional Nanosystem for Dual Anti-Inflammatory and Antibacterial Photodynamic Therapy in Infectious Diabetic Wounds

Infectious diabetic wounds present a substantial challenge, characterized by inflammation, infection, and delayed wound healing, leading to elevated morbidity and mortality rates. In this work, we developed a multifunctional lipid nanoemulsion containing quercetin, chlorine e6, and rosemary oil (QCRLNEs) for dual anti-inflammatory and antibacterial photodynamic therapy (APDT) for treating infectious diabetic wounds. The QCRLNEs exhibited spherical morphology with a size of 51 nm with enhanced encapsulation efficiency, skin permeation, and localized delivery at the infected wound site. QCRLNEs with NIR irradiation have shown excellent wound closure and antimicrobial properties in vitro, mitigating the nonselective cytotoxic behavior of PDT. Also, excellent biocompatibility and anti-inflammatory and wound healing responses were observed in zebrafish models. The infected wound healing properties in S. aureus-infected diabetic rat models indicated re-epithelization and collagen deposition with no signs of inflammation. This multifaceted approach using QCRLNEs with NIR irradiation holds great promise for effectively combating oxidative stress and bacterial infections commonly associated with infected diabetic wounds, facilitating enhanced wound healing and improved clinical outcomes.

Photothermal/photodynamic synergistic antibacterial study of MOF nanoplatform with SnFe2O4 as the core

Drug-resistant bacterial infections cause significant harm to public life, health, and property. Biofilm is characterized by overexpression of glutathione (GSH), hypoxia, and slight acidity, which is one of the main factors for the formation of bacterial resistance. Traditional antibiotic therapy gradually loses its efficacy against multi-drug-resistant (MDR) bacteria. Therefore, synergistic therapy, which regulates the biofilm microenvironment, is a promising strategy. A multifunctional nanoplatform, SnFe2O4-PBA/Ce6@ZIF-8 (SBC@ZIF-8), in which tin ferrite (SnFe2O4, denoted as SFO) as the core, loaded with 3-aminobenzeneboronic acid (PBA) and dihydroporphyrin e6 (Ce6), and finally coated with zeolite imidazole salt skeleton 8 (ZIF-8). The platform has a synergistic photothermal therapy (PTT)/photodynamic therapy (PDT) effect, which can effectively remove overexpressed GSH by glutathione peroxidase-like activity, reduce the antioxidant capacity of biofilm, and enhance PDT. The platform had excellent photothermal performance (photothermal conversion efficiency was 55.7 %) and photothermal stability. The inhibition rate of two MDR bacteria was more than 96 %, and the biofilm clearance rate was more than 90 % (150 μg/mL). In the animal model of MDR S. aureus infected wound, after 100 μL SBC@ZIF-8+NIR (150 μg/mL) treatment, the wound area of mice was reduced by 95 % and nearly healed. The serum biochemical indexes and H&E staining results were within the normal range, indicating that the platform could promote wound healing and had good biosafety. In this study, we designed and synthesized multifunctional nanoplatforms with good anti-drug-resistant bacteria effect and elucidated the molecular mechanism of its anti-drug-resistant bacteria. It lays a foundation for clinical application in treating wound infection and promoting wound healing.

Self-Assembled PD-L1 Downregulator to Boost Photodynamic Activated Tumor Immunotherapy Through CDK5 Inhibition

The immunosuppressive characteristics and acquired immune resistance can restrain the therapy-initiated anti-tumor immunity. In this work, an antibody free programmed death receptor ligand 1 (PD-L1) downregulator (designated as CeSe) is fabricated to boost photodynamic activated immunotherapy through cyclin-dependent kinase 5 (CDK5) inhibition. Among which, FDA approved photosensitizer of chlorin e6 (Ce6) and preclinical available CDK5 inhibitor of seliciclib (Se) are utilized to prepare the nanomedicine of CeSe through self-assembly technique without drug excipient. Nanoscale CeSe exhibits an increased stability and drug delivery efficiency, contributing to intracellular production of reactive oxygen species (ROS) for robust photodynamic therapy (PDT). The PDT of CeSe can not only suppress the primary tumor growth, but also induce the immunogenic cell death (ICD) to release tumor associated antigens. More importantly, the CDK5 inhibition by CeSe can downregulate PD-L1 to re-activate the systemic anti-tumor immunity by decreasing the tumor immune escape and therapy-induced acquired immune resistance. This work provides an antibody free strategy to activate systemic immune response for metastatic tumor treatment, which may accelerate the development of translational nanomedicine with sophisticated mechanism.

Dual-molecular targeting nanomedicine upregulates synergistic therapeutic efficacy in preclinical hepatoma models

Advanced hepatocellular carcinoma (HCC) is one of the most challenging cancers because of its heterogeneous and aggressive nature, precluding the use of curative treatments. Sorafenib (SOR) is the first approved molecular targeting agent against the mitogen-activated protein kinase (MAPK) pathway for the noncurative therapy of advanced HCC; yet, any clinically meaningful benefits from the treatment remain modest, and are accompanied by significant side effects. Here, we hypothesized that using a nanomedicine platform to co-deliver SOR with another molecular targeting drug, metformin (MET), could tackle these issues. A micelle self-assembled with amphiphilic polypeptide methoxy poly(ethylene glycol)-block-poly(L-phenylalanine-co-l-glutamic acid) (mPEG-b-P(LP-co-LG)) (PM) was therefore designed for combinational delivery of two molecular targeted drugs, SOR and MET, to hepatomas. Compared with free drugs, the proposed, dual drug-loaded micelle (PM/SOR+MET) enhanced the drugs' half-life in the bloodstream and drug accumulation at the tumor site, thereby inhibiting tumor growth effectively in the preclinical subcutaneous, orthotopic and patient-derived xenograft hepatoma models without causing significant systemic and organ toxicity. Collectively, these findings demonstrate an effective dual-targeting nanomedicine strategy for treating advanced HCC, which may have a translational potential for cancer therapeutics. STATEMENT OF SIGNIFICANCE: Treatment of advanced hepatocellular carcinoma (HCC) remains a formidable challenge due to its aggressive nature and the limitations inherent to current therapies. Despite advancements in molecular targeted therapies, such as Sorafenib (SOR), their modest clinical benefits coupled with significant adverse effects underscore the urgent need for more efficacious and less toxic treatment modalities. Our research presents a new nanomedicine platform that synergistically combines SOR with metformin within a specialized diblock polypeptide micelle, aiming to enhance therapeutic efficacy while reducing systemic toxicity. This innovative approach not only exhibits marked antitumor efficacy across multiple HCC models but also significantly reduces the toxicity associated with current treatments. Our dual-molecular targeting approach unveils a promising nanomedicine strategy for the molecular treatment of advanced HCC, potentially offering more effective and safer treatment alternatives with significant translational potential.

Photodynamic Therapy in the Treatment of Cancer-The Selection of Synthetic Photosensitizers

Photodynamic therapy (PDT) is a promising cancer treatment method that uses photosensitizing (PS) compounds to selectively destroy tumor cells using laser light. This review discusses the main advantages of PDT, such as its low invasiveness, minimal systemic toxicity and low risk of complications. Special attention is paid to photosensitizers obtained by chemical synthesis. Three generations of photosensitizers are presented, starting with the first, based on porphyrins, through the second generation, including modified porphyrins, chlorins, 5-aminolevulinic acid (ALA) and its derivative hexyl aminolevulinate (HAL), to the third generation, which is based on the use of nanotechnology to increase the selectivity of therapy. In addition, current research trends are highlighted, including the search for new photosensitizers that can overcome the limitations of existing therapies, such as heavy-atom-free nonporphyrinoid photosensitizers, antibody-drug conjugates (ADCs) or photosensitizers with a near-infrared (NIR) absorption peak. Finally, the prospects for the development of PDTs are presented, taking into account advances in nanotechnology and biomedical engineering. The references include both older and newer works. In many cases, when writing about a given group of first- or second-generation photosensitizers, older publications are used because the properties of the compounds described therein have not changed over the years. Moreover, older articles provide information that serves as an introduction to a given group of drugs.

Peptide nanocarriers co-delivering an antisense oligonucleotide and photosensitizer elicit synergistic cytotoxicity

Combination therapies demand co-delivery platforms with efficient entrapment of distinct payloads and specific delivery to cells and possibly organelles. Herein, we introduce the combination of two therapeutic modalities, gene and photodynamic therapy, in a purely peptidic platform. The simultaneous formation and cargo loading of the multi-micellar platform is governed by self-assembly at the nanoscale. The multi-micellar architecture of the nanocarrier and the positive charge of its constituent micelles offer controlled dual loading capacity with distinct locations for a hydrophobic photosensitizer (PS) and negatively charged antisense oligonucleotides (ASOs). Moreover, the nuclear localization signal (NLS) sequence built-in the peptide targets PS + ASO-loaded nanocarriers to the nucleus. Breast cancer cells treated with nanocarriers demonstrated photo-triggered enhancement of radical oxygen species (ROS) associated with increased cell death. Besides, delivery of ASO payloads resulted in up to 90 % knockdown of Bcl-2, an inhibitor of apoptosis that is overexpressed in more than half of all human cancers. Simultaneous delivery of PS and ASO elicited synergistic apoptosis to an extent that could not be reached by singly loaded nanocarriers or the free form of the drugs. Both, the distinct location of loaded compounds that prevents them from interfering with each other, and the highly efficient cellular delivery support the great potential of this versatile peptide platform in combination therapy.

Preventing High Fat Diet-Induced Obesity and Related Hepatic Steatosis by Chlorin e6-Mediated Photodynamic Therapy

Obesity and its associated hepatic steatosis have become a global concern, posing numerous health hazards. Photodynamic therapy (PDT) is a unique approach that promotes anti-obesity by releasing intracellular fat. Chlorin e6 (Ce6)-PDT was tested for its anti-obesity properties in male ovariectomized (OVX) beagle dogs, as well as male C57BL/6 and Balb/c mice. The 12 OVX beagles were randomly assigned to one of four groups: high-fat diet (HFD) only, Ce6 only, Ce6 + 10 min of light-emitting diode light (LED) treatment, and Ce6 + 15 min of light treatment. We assessed several parameters, such as body weight, adipose tissue morphology, serum biochemistry, and body fat content analysis by computed tomography (CT) scan in HFD-fed beagle dogs. At the end of the study period, dogs that were treated for 35 days with Ce6 and exposed to LED irradiation (660 nm) either for 10 min (Ce6 + 10 min of light) or for 15 min (Ce6 + 15 min of light) had decreased body weight, including visceral and subcutaneous fats, lower aspartate transaminase (AST)/alanine transaminase (ALT) ratios, and a reduction in the area of individual adipocytes with a concomitant increase in the number of adipocytes. Furthermore, C57BL/6 male mice following an HFD diet were effectively treated by Ce6-PDT treatment through a reduction in weight gain and fat accumulation. Meanwhile, Ce6-PDT attenuated hepatocyte steatosis by decreasing the epididymal adipose tissue and balloon degeneration in hepatocytes in HFD-fed Balb/c mice. Taken together, our results support the idea that Ce6-PDT is a promising therapeutic strategy for the recovery of obesity and obesity-related hepatic steatosis.

Photodynamic effect of vascular-targeted polyphenol nanoparticles on Endothelial cells

BACKGROUND

Port wine stains (PWS) are vascular malformations, and photodynamic therapy (PDT) is a promising treatment. Emerging drug delivery methods employ nanoparticles (NPs) to enhance drug permeability and retention in diseased blood vessels and improve drug bioavailability. (-) -epigallocatechin-3-gallate glycine (EGCG) has anti-angiogenetic effects and boosts photodynamic therapy. Chlorin e6 (Ce6) is capable of efficiently producing singlet oxygen, rendering it a very promising photosensitizer for utilization in nanomedicine.

MATERIAL AND METHODS

EGCG-Ce6-NPs were synthesized and characterized using various techniques. The photodynamic effects of EGCG-Ce6-NPs on endothelial cells were evaluated. The compatibility and toxicity of the nanoparticle was tested using the CCK-8 assay. The intracellular uptake of the nanoparticle was observed using an inverted fluorescence microscope, and the intracellular fluorescence intensity was detected using flow cytometry. The ROS generation and apoptosis induced by EGCG-Ce6-NPs was observed using confocal laser scanning microscopy and flow cytometry respectively.

RESULTS

EGCG-Ce6-NPs exhibited stability, spherical shape of uniform size while reducing the particle diameter, low polydisperse profile and retaining the ability to effectively generate singlet oxygen. These characteristics suggest promising potential for enhancing drug permeability and retention. Additionally, EGCG-Ce6-NPs demonstrated good compatibility with endothelial cells and enhanced intracellular uptake of Ce6. Furthermore, EGCG-Ce6-NPs increased activation efficiency, induced significant toxicity, more reactive oxygen species, and a higher rate of late apoptosis after laser irradiation.

CONCLUSION

This in vitro study showed the potentials EGCG-Ce6-NPs for the destruction of endothelial cells in vasculature.

Chlorin e6-Conjugated Mesoporous Titania Nanorods as Potential Nanoplatform for Photo-Chemotherapy

Photodynamic therapy (PDT) has developed as an efficient strategy for cancer treatment. PDT involves the production of reactive oxygen species (ROS) by light irradiation after activating a photosensitizer (PS) in the presence of O2. PS-coupled nanomaterials offer additional advantages, as they can merge the effects of PDT with conventional enabling-combined photo-chemotherapeutics effects. In this work, mesoporous titania nanorods were surface-immobilized with Chlorin e6 (Ce6) conjugated through 3-(aminopropyl)-trimethoxysilane as a coupling agent. The mesoporous nanorods act as nano vehicles for doxorubicin delivery, and the Ce6 provides a visible light-responsive production of ROS to induce PDT. The nanomaterials were characterized by XRD, DRS, FTIR, TGA, N2 adsorption-desorption isotherms at 77 K, and TEM. The obtained materials were tested for their singlet oxygen and hydroxyl radical generation capacity using fluorescence assays. In vitro cell viability experiments with HeLa cells showed that the prepared materials are not cytotoxic in the dark, and that they exhibit photodynamic activity when irradiated with LED light (150 W m-2). Drug-loading experiments with doxorubicin (DOX) as a model chemotherapeutic drug showed that the nanostructures efficiently encapsulated DOX. The DOX-nanomaterial formulations show chemo-cytotoxic effects on Hela cells. Combined photo-chemotoxicity experiments show enhanced effects on HeLa cell viability, indicating that the conjugated nanorods are promising for use in combined therapy driven by LED light irradiation.

Spatiotemporally-controlled hydrophobic drug delivery via photosensitizer-driven assembly-disassembly for enhanced triple-negative breast cancer treatment

Therapeutic approaches for triple-negative breast cancer (TNBC) have been continuously advancing, but inadequate control over release behavior, insufficient tumor selectivity, and limited drug availability continue to impede therapeutic outcomes in nanodrug systems. In this study, we propose a general hydrophobic antineoplastic delivery system, termed spatiotemporally-controlled hydrophobic antineoplastic delivery system (SCHADS) for enhanced TNBC treatment. The key feature of SCHADS is the formation of metastable photosensitive-antineoplastic complexes (PACs) through the self-assembly of hydrophobic drugs driven by photosensitive molecules. With the further decoration of tumor-targeting peptides coupled with the EPR effect, the PACs tend to accumulate in the tumor site tremendously, promoting drug delivery efficiency. Meanwhile, the disassembly behavior of the metastable PACs could be driven by light on demand to achieve in situ drug release, thus promoting chemotherapeutics availability. Furthermore, the abundant ROS generated by the photosensitizer could effectively kill tumor cells, ultimately realizing an effective combination of photodynamic and chemotherapeutic therapy. As an exemplary presentation, chlorin e6 has been chosen to drive the formation of PACs with the system xc- inhibitor sorafenib. Compared with pure drug treatment, the PACs with the above-described preponderances exhibit superior therapeutic effects both in vitro and in vivo and circumvent the side effects due to off-target. By manipulating the laser irradiation, the PACs-treated cell death mechanism could be dynamically regulated, thus providing the potential to remedy intrinsic/acquired resistance of tumor. Collectively, this SCHADS achieves spatio-temporal control of the drug that greatly enhances the availability of anticarcinogen and realizes synergistic antitumor effect in TNBC treatment, even ultimately being extended to the treatment of other types of tumors.

A Bioinspired Immunostimulatory System for Inducing Powerful Antitumor Immune Function by Directly Causing Plasma Membrane Rupture

The Gasdermin protein is a membrane disruptor that can mediate immunogenic pyroptosis and elicit anti-tumor immune function. However, cancer cells downregulate Gasdermin and develop membrane repair mechanisms to resist pyroptosis. Therefore, an artificial membrane disruptor (AMD) that can directly mediate membrane rupture in pyroptosis-deficient cells and induce antitumor immune responses in a controllable manner will be valuable in preclinical and clinical research. A micron-scale Ce6-based AMD that can directly induce plasma membrane rupture (PMR) in gasdermin-deficient tumor cells is established. Micron-scale AMDs localize Ce6 specifically to the plasma membrane without labeling other organelles. Compared to free Ce6 molecules, the use of AMDs results in a higher degree of specificity for the plasma membrane. Due to this specificity, AMDs mediate fast and irreversible PMR under 660 nm red light. Furthermore, the AMDs are capable of inducing programmed cell death and lytic cell death in a catalytic manner, demonstrating that the amount of Ce6 used by AMDs is only one-fifth of that used by Ce6 alone when inducing 80% of cancer cell death. In vivo, the AMDs show specificity for tumor targeting and penetration, suggesting that light-driven programmed cell death is specific to tumors. AMDs are applied to antitumor therapy in gasdermin-deficient tumors, resulting in efficient tumor elimination with minimal damage to major organs when combined with anti-PD-1 therapy. Tumor regression is correlated with PMR-mediated inflammation and T-cell-based immune responses. This study provides new insights for designing bioinspired membrane disruptors for PMR and mediating anti-tumor immunotherapy. Additionally, AMD is a dependable tool for examining the immunogenicity of PMR both in vitro and in vivo.

Natural-product-based, carrier-free, noncovalent nanoparticles for tumor chemo-photodynamic combination therapy

Cancer, with its diversity, heterogeneity, and complexity, is a significant contributor to global morbidity, disability, and mortality, highlighting the necessity for transformative treatment approaches. Photodynamic therapy (PDT) has aroused continuous interest as a viable alternative to conventional cancer treatments that encounter drug resistance. Nanotechnology has brought new advances in medicine and has shown great potential in drug delivery and cancer treatment. For precise and efficient therapeutic utilization of such a tumor therapeutic approach with high spatiotemporal selectivity and minimal invasiveness, the carrier-free noncovalent nanoparticles (NPs) based on chemo-photodynamic combination therapy is essential. Utilizing natural products as the foundation for nanodrug development offers unparalleled advantages, including exceptional pharmacological activity, easy functionalization/modification, and well biocompatibility. The natural-product-based, carrier-free, noncovalent NPs revealed excellent synergistic anticancer activity in comparison with free photosensitizers and free bioactive natural products, representing an alternative and favorable combination therapeutic avenue to improve therapeutic efficacy. Herein, a comprehensive summary of current strategies and representative application examples of carrier-free noncovalent NPs in the past decade based on natural products (such as paclitaxel, 10-hydroxycamptothecin, doxorubicin, etoposide, combretastatin A4, epigallocatechin gallate, and curcumin) for tumor chemo-photodynamic combination therapy. We highlight the insightful design and synthesis of the smart carrier-free NPs that aim to enhance PDT efficacy. Meanwhile, we discuss the future challenges and potential opportunities associated with these NPs to provide new enlightenment, spur innovative ideas, and facilitate PDT-mediated clinical transformation.

Melanin-Ce6-loaded polydopamine nanoparticles-based enhanced phototherapy for B16 melanoma cancer cells

Melanoma is one of the most aggressive and lethal types of cancer owing to its metastatic propensity and chemoresistance property. An alternative therapeutic option is photodynamic and photothermal therapies (PDT/PTT), which employ near-infrared (NIR) light to generate heat and reactive oxygen species (ROS). As per previous reports, Melanin (Mel), and its synthetic analogs (i.e. polydopamine nanoparticles) can induce NIR light-mediated heat energy, thereby selectively targeting and ameliorating cancer cells. Similarly, chlorin e6 (Ce6) also has high ROS generation ability and antitumor activity against various types of cancer. Based on this tenet, In the current study, we have encapsulated Mel-Ce6 in a polydopamine (PDA) nanocarrier (MCP NPs) synthesized by the oxidation polymerization method. The hydrodynamic diameter of the synthesized spherical MCP NPs was 139 ± 10 nm. The MCP NPs, upon irradiation with NIR 690 nm laser for 6 min, showed photothermal efficacy of more than 50 °C. Moreover, the red fluorescence in the MCP NPs due to Ce6 can be leveraged for diagnostic purposes. Further, the MCP NPs exhibited considerable biocompatibility with the L929 cell line and exerted nearly 70% ROS-mediated cytotoxicity on the B16 melanoma cell line after the laser irradiation. Thus, the prepared MCP NPs could be a promising theranostic agent for treating the B16 melanoma cancer.

Nanoassemblies of heptamethine cyanine dye-initiated poly(amino acid) enhance ROS generation for effective antitumour phototherapy

Phototherapy shows great potential for pinpoint tumour treatment. Heptamethine cyanine dyes like IR783 have high potential as agents for antitumour phototherapy due to their inherent tumour targeting ability, though their effectiveness in vivo is unsatisfactory for clinical translation. To overcome this limitation, we present an innovative strategy involving IR783-based polymeric nanoassemblies that improve the dye's performance as an antitumoural photosensitizer. In the formulation, IR783 is modified with cysteamine and used to initiate the ring-opening polymerization (ROP) of the N-carboxyanhydride of benzyl-L-aspartate (BLA), resulting in IR783-installed poly(BLA). Compared to free IR783, the IR783 dye in the polymer adopts a twisted molecular conformation and tuned electron orbital distribution, remarkably enhancing its optical properties. In aqueous environments, the polymers spontaneously assemble into nanostructures with 60 nm diameter, showcasing surface-exposed IR783 dyes that function as ligands for cancer cell and mitochondria targeting. Moreover, the nanoassemblies stabilized the dyes and enhanced the generation of reactive oxygen species (ROS) upon laser irradiation. Thus, in murine tumor models, a single injection of the nanoassemblies with laser irradiation significantly inhibits tumour growth with no detectable off-target toxicity. These findings highlight the potential for improving the performance of heptamethine cyanine dyes in antitumor phototherapy through nano-enabled strategies.

Targeted Delivery of Catalase and Photosensitizer Ce6 by a Tumor-Specific Aptamer Is Effective against Bladder Cancer In Vivo

Photodynamic therapy (PDT) is often applied in a clinical setting to treat bladder cancer. However, current photosensitizers report drawbacks such as low efficacy, low selectivity, and numerous side effects, which have limited the clinical values of PDT for bladder cancer. Previously, we developed the first bladder cancer-specific aptamer that can selectively bind to and be internalized by bladder tumor cells versus normal uroepithelium cells. Here, we use an aptamer-based drug delivery system to deliver photosensitizer chlorine e6 (Ce6) into bladder tumor cells. In addition to Ce6, we also incorporate catalase into the drug complex to increase local oxygen levels in the tumor tissue. Compared with free Ce6, an aptamer-guided DNA nanotrain (NT) loaded with Ce6 and catalase (NT-Catalase-Ce6) can specifically recognize bladder cancer cells, produce oxygen locally, induce ROS in tumor cells, and cause mitochondrial apoptosis. In an orthotopic mouse model of bladder cancer, the intravesical instillation of NT-Catalase-Ce6 exhibits faster drug internalization and a longer drug retention time in tumor tissue compared with that in normal urothelium. Moreover, our modified PDT significantly inhibits tumor growth with fewer side effects such as cystitis than free Ce6. This aptamer-based photosensitizer delivery system can therefore improve the selectivity and efficacy and reduce the side effects of PDT treatment in mouse models of bladder cancer, bearing a great translational value for bladder cancer intravesical therapy.

Versatile chondroitin sulfate-based nanoplatform for chemo-photodynamic therapy against triple-negative breast cancer

Versatile nanoplatform equipped with chemo-photodynamic therapeutic attributes play an important role in improving the effectiveness of tumor treatments. Herein, we developed multifunctional nanoparticles based on chondroitin sulfate A (CSA) for the targeted delivery of chlorin e6 (Ce6) and doxorubicin (DOX), in a combined chemo-photodynamic therapy against triple-negative breast cancer. CSA was chosen for its hydrophilic properties and its affinity to CD44 receptor-overexpressed tumor cells. The CSA-ss-Ce6 (CSSC) conjugate was synthesized utilizing a disulfide linker. Subsequently, DOX-loaded CSSC (CSSC-D) nanoparticles were fabricated, showcasing a nearly spherical shape with an average particle size of 267 nm. In the CSSC-D nanoparticles, the chemically attached Ce6 constituted 1.53 %, while the physically encapsulated DOX accounted for 8.11 %. Both CSSC-D and CSSC nanoparticles demonstrated a reduction-sensitive release of DOX or Ce6 in vitro. Under near-infrared (NIR) laser irradiation, CSSC-D showed the enhanced generation of reactive oxygen species (ROS), improving cytotoxic effects against triple-negative breast cancer 4T1 and MDA-MB-231 cells. Remarkably, the CSSC-D with NIR exhibited the most potent tumor growth inhibition in comparison to other groups in the 4T1-bearing Balb/c mice model. Overall, this CSSC-D nanoplatform shows significant promise as a powerful tool for a synergetic approach in chemo-photodynamic therapy in triple-negative breast cancer.

Detection of Arsenic(V) by Fluorescence Sensing Based on Chlorin e6-Copper Ion

The high toxicity of arsenic (As) can cause irreversible harm to the environment and human health. In this study, the chlorin e6 (Ce6), which emits fluorescence in the infrared region, was introduced as the luminescence center, and the addition of copper ion (Cu2+) and As(V) provoked a regular change in fluorescence at 652 nm, whereas that of As(III) was 665 nm, which was used to optionally detect Cu2+, arsenic (As(III), and As(V)). The limit of detection (LOD) values were 0.212 μM, 0.089 ppm, and 1.375 ppb for Cu2+, As(III), and As(V), respectively. The developed method can be used to determine Cu2+ and arsenic in water and soil with good sensitivity and selectivity. The 1:1 stoichiometry of Ce6 with Cu2+ was obtained from the Job plot that was developed from UV-visible spectra. The binding constants for Cu2+ and As(V) were established to be 1.248 × 105 M-1 and 2.35 × 1012 M-2, respectively, using B-H (Benesi-Hildebrand) plots. Fluorescence lifetimes, B-H plots, FT-IR, and 1H-NMR were used to postulate the mechanism of Cu2+ fluorescence quenching and As(V) fluorescence restoration and the interactions of the two ions with the Ce6 molecule.

Novel Carrier-Free Nanodrug Enhances Photodynamic Effects by Blocking the Autophagy Pathway and Synergistically Triggers Immunogenic Cell Death for the Efficient Treatment of Breast Cancer

Photosensitizers have been widely used to cause intratumoral generation of reactive oxygen species (ROS) for cancer therapy, but they are easily disturbed by the autophagy pathway, a self-protective mechanism by mitigating oxidative damage. Hereby, we reported a simple and effective strategy to construct a carrier-free nanodrug, Ce6@CQ namely, based on the self-assembly of the photosensitizer chlorin e6 (Ce6) and the autophagy inhibitor chloroquine (CQ). Specifically, Ce6@CQ avoided the unexpected toxicity caused by the regular nanocarrier and also ameliorated its stability in different conditions. Light-activated Ce6 generated cytotoxic ROS and elicited part of the immunogenic cell death (ICD). Moreover, CQ induced autophagy dysfunction, which hindered self-healing in tumor cells and enhanced photodynamic therapy (PDT) to exert a more potent killing effect and more efficient ICD. Also, Ce6@CQ could effectively accumulate in the xenograft breast tumor site in a mouse model through the enhanced permeability and retention (EPR) effect, and the growth of breast tumors was effectively inhibited by Ce6@CQ with light. Such a carrier-free nanodrug provided a new strategy to improve the efficacy of PDT via the suppression of autophagy to digest ROS-induced toxic substances.

Metal-based nanoparticles in cancer therapy: Exploring photodynamic therapy and its interplay with regulated cell death pathways

Photodynamic therapy (PDT) represents a non-invasive treatment strategy currently utilized in the clinical management of selected cancers and infections. This technique is predicated on the administration of a photosensitizer (PS) and subsequent irradiation with light of specific wavelengths, thereby generating reactive oxygen species (ROS) within targeted cells. The cellular effects of PDT are dependent on both the localization of the PS and the severity of ROS challenge, potentially leading to the stimulation of various cell death modalities. For many years, the concept of regulated cell death (RCD) triggered by photodynamic reactions predominantly encompassed apoptosis, necrosis, and autophagy. However, in recent decades, further explorations have unveiled additional cell death modalities, such as necroptosis, ferroptosis, cuproptosis, pyroptosis, parthanatos, and immunogenic cell death (ICD), which helps to achieve tumor cell elimination. Recently, nanoparticles (NPs) have demonstrated substantial advantages over traditional PSs and become important components of PDT, due to their improved physicochemical properties, such as enhanced solubility and superior specificity for targeted cells. This review aims to summarize recent advancements in the applications of different metal-based NPs as PSs or delivery systems for optimized PDT in cancer treatment. Furthermore, it mechanistically highlights the contribution of RCD pathways during PDT with metal NPs and how these forms of cell death can improve specific PDT regimens in cancer therapy.

Biomedical Application of Porphyrin-Based Amphiphiles and Their Self-Assembled Nanomaterials

Porphyrins have been vastly explored and applied in many cutting-edge fields with plenty of encouraging achievements because of their excellent properties. As important derivatives of porphyrins, porphyrin-based amphiphiles (PBAs) not only maintain the advanced properties of porphyrins (catalysis, imaging, and energy transfer) but also possess self-assembly and encapsulation capability in aqueous solution. Accordingly, PBAs and their self-assembles have had important roles in diagnosing and treating tumors and inflammation lesions in vivo, but not limited to these. In this article, we introduce the research progress of PBAs, including their constitution, structure design strategies, and performances in tumor and inflammation lesion diagnosis and treatments. On that basis, the defects of synthesized PBAs during their application and the possible effective strategies to overcome the limitations are also proposed. Finally, perspectives on PBAs exploration are updated based on our knowledge. We hope this review will bring researchers from various domains insights about PBAs.

Recent Innovations of Mesoporous Silica Nanoparticles Combined with Photodynamic Therapy for Improving Cancer Treatment

Cancer is a global health burden and is one of the leading causes of death. Photodynamic therapy (PDT) is considered an alternative approach to conventional cancer treatment. PDT utilizes a light-sensitive compound, photosensitizers (PSs), light irradiation, and molecular oxygen (O2). This generates cytotoxic reactive oxygen species (ROS), which can trigger necrosis and/ or apoptosis, leading to cancer cell death in the intended tissues. Classical photosensitizers impose limitations that hinder their clinical applications, such as long-term skin photosensitivity, hydrophobic nature, nonspecific targeting, and toxic cumulative effects. Thus, nanotechnology emerged as an unorthodox solution for improving the hydrophilicity and targeting efficiency of PSs. Among nanocarriers, mesoporous silica nanoparticles (MSNs) have gained increasing attention due to their high surface area, defined pore size and structure, ease of surface modification, stable aqueous dispersions, good biocompatibility, and optical transparency, which are vital for PDT. The advancement of integrated MSNs/PDT has led to an inspiring multimodal nanosystem for effectively treating malignancies. This review gives an overview of the main components and mechanisms of the PDT process, the effect of PDT on tumor cells, and the most recent studies that reported the benefits of incorporating PSs into silica nanoparticles and integration with PDT against different cancer cells.