A type I and type II chemical biology toolbox to overcome the hypoxic tumour microenvironment for photodynamic therapy

Photodynamic therapy (PDT) is a minimally invasive therapeutic modality employed for the treatment of various types of cancers, localized infections, and other diseases. Upon illumination, the photo-excited photosensitizer generates singlet oxygen and other reactive species, thereby inducing cytotoxicity in the target cells. The hypoxic tumour microenvironment (TME), however, poses a limitation on the supply of oxygen in tumour tissues. Moreover, under such conditions, tumour metastasis and drug resistance frequently occur, further compromising the efficacy of PDT in combating tumours. Traditionally, type I photosensitizers with lower oxygen consumption demonstrate significant potential in overcoming hypoxic environments and play a crucial role in determining the therapeutic efficacy of PDT because type I photosensitizers can generate highly cytotoxic free radicals. In comparison, type II photosensitizers exhibit high oxygen dependence. The rate of reactive oxygen species (ROS) generation in the type II process is significantly higher than that in the type I process. Thus, the efficiency and selectivity of PDT depend on the properties of the photosensitizer. Here, the recent development and application of type I and type II photosensitizers, mainly in the past year, are summarized. The design methods, electronic structures, photophysical properties, lipophilic properties, electric charge, and other molecular characteristics of these photosensitizers are discussed in detail. These modifications alter the microstructure of photosensitizers and directly impact the results of PDT. The main content of this paper will have a positive promoting and inspiring effect on the future development of PDT.

Black Titania Janus Mesoporous Nanomotor for Enhanced Tumor Penetration and Near-Infrared Light-Triggered Photodynamic Therapy

Thanks to their excellent photoelectric characteristics to generate cytotoxic reactive oxygen species (ROS) under the light-activation process, TiO2 nanomaterials have shown significant potential in photodynamic therapy (PDT) for solid tumors. Nevertheless, the limited penetration depth of TiO2-based photosensitizers and excitation sources (UV/visible light) for PDT remains a formidable challenge when confronted with complex tumor microenvironments (TMEs). Here, we present a H2O2-driven black TiO2 mesoporous nanomotor with near-infrared (NIR) light absorption capability and autonomous navigation ability, which effectively enhances solid tumor penetration in NIR light-triggered PDT. The nanomotor was rationally designed and fabricated based on the Janus mesoporous nanostructure, which consists of a NIR light-responsive black TiO2 nanosphere and an enzyme-modified periodic mesoporous organosilica (PMO) nanorod that wraps around the TiO2 nanosphere. The overexpressed H2O2 can drive the nanomotor in the TME under catalysis of catalase in the PMO domain. By precisely controlling the ratio of TiO2 and PMO compartments in the Janus nanostructure, TiO2&PMO nanomotors can achieve optimal self-propulsive directionality and velocity, enhancing cellular uptake and facilitating deep tumor penetration. Additionally, by the decomposition of endogenous H2O2 within solid tumors, these nanomotors can continuously supply oxygen to enable highly efficient ROS production under the NIR photocatalysis of black TiO2, leading to intensified PDT effects and effective tumor inhibition.

Automatic segmentation of lysosomes and analysis of intracellular pH with Radachlorin photosensitizer and FLIM

We report application of the fluorescence lifetime imaging microscopy (FLIM) for analysis of distributions of intracellular acidity using a chlorin-e6 based photosensitizer Radachlorin. An almost two-fold increase of the photosensitizer fluorescence lifetime in alkaline microenvironments as compared to acidic ones allowed for clear distinguishing between acidic and alkaline intracellular structures. Clusterization of a phasor plot calculated from fits of the FLIM raw data by two Gaussian distributions provided accurate automatic segmentation of lysosomes featuring acidic contents. The approach was validated in colocalization experiments with LysoTracker fluorescence in living cells of four established lines. The dependence of photosensitizer fluorescence lifetime on microenvironment acidity allowed for estimation of pH inside the cells, except for the nuclei, where photosensitizer does not penetrate. The developed method is promising for combined application of the photosensitizer for both photodynamic treatment and diagnostics.

PLGA-based nanocarriers for combined delivery of colchicine and purpurin 18 in cancer therapy: Multimodal approach employing cancer cell spheroids

Improving the anticancer efficacy of chemotherapeutic drugs and photosensitizers requires innovative multifunctional nanoplatforms. This study introduces a chemo- and phototherapeutic drug delivery system (DDS) based on poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs), both PEGylated and non-PEGylated, with a mean size of 200 ± 75 nm. Colchicine (Colch) and purpurin18 (P18) were co-encapsulated into these NPs, and their in vitro drug release profiles were investigated. The anticancer potential of these systems was evaluated across various cell lines (i.e., CaCo-2, PC-3, MCF-7, and MRC-5 cells), demonstrating enhanced NP uptake by cancer cells compared to free drugs. Co-administration of Colch and P18 in 2D and 3D cell line models exhibited a synergistic effect, harnessing both chemotherapeutic and photodynamic effects, leading to higher cancer cell elimination efficacy. This newly developed multifunctional DDS presents a promising platform for combined chemo- and photodynamic therapy in cancer treatment.

The Remarkable Anti-Breast Cancer Efficacy and Anti-Metastasis by Multifunctional Nanoparticles Co-Loading Squamocin, R848 and IR 780

Background

Breast cancer is a heterogeneous disease globally accounting for approximately 1 million new cases annually. Chemotherapy remains the main therapeutic option, but the antitumor efficacy needs to be improved.

Methods

Two multifunctional nanoparticles were developed in this paper using oleic acid and mPEG2k-PCL2k as the drug carriers. Squamocin (Squ) was employed as a chemotherapeutic agent. Resiquimod (R848) or ginsenoside Rh2 was co-encapsulated in the nanoparticles to remold the immunosuppressive tumor microenvironment, and IR780 was coloaded as a photosensitizer to realize photothermal therapy.

Results

The obtained Squ-R848-IR780 nanoparticles and Squ-Rh2-IR780 nanoparticles were uniformly spherical and approximately (162.200 ± 2.800) nm and (157.300 ± 1.1590) nm, respectively, in average diameter, with good encapsulation efficiency (above 85% for each drug), excellent stability in various physiological media and high photothermal conversion efficiency (24.10% and 22.58%, respectively). After intravenous administration, both nanoparticles quickly accumulated in the tumor and effectively enhanced the local temperature of the tumor to over 45 °C when irradiated by an 808 nm laser. At a low dose of 0.1 mg/kg, Squ nanoparticles treatment alone displayed a tumor inhibition rate of 55.28%, pulmonary metastasis inhibition rate of 59.47% and a mean survival time of 38 days, which were all higher than those of PTX injection (8 mg/kg) (43.64%, 25 days and 37.25%), indicating that Squ was a potent and effective antitumor agent. Both multifunctional nanoparticles, Squ-Rh2-IR780 nanoparticles and Squ-R848-IR780 nanoparticles, demonstrated even better therapeutic efficacy, with tumor inhibition rates of 90.02% and 97.28%, pulmonary metastasis inhibition rates of 95.42% and 98.09, and mean survival times of 46 days and 52 days, respectively.

Conclusion

The multifunctional nanoparticles coloaded with squamocin, R848 and IR 780 achieved extraordinary therapeutic efficacy and excellent antimetastasis activity and are thus promising in the future treatment of breast tumors and probably other tumors.

Two-Photon Photodegradation of E3 Ubiquitin Ligase Cereblon by a Ru(II) Complex: Inducing Ferroptosis in Cisplatin-Resistant Tumor Cells

Using photodynamic therapy (PDT) to trigger nonconventional cell death pathways has provided a new scheme for highly efficient and non-side effects to drug-resistant cancer therapies. Nonetheless, the unclear targets of available photosensitizers leave the manner of PDT-induced tumor cell death relatively unpredictable. Herein, we developed a novel Ru(II)-based photosensitizer, Ru-Poma. Possessing the E3 ubiquitin ligase CRBN-targeting moiety and high singlet oxygen yield of 0.96, Ru-Poma was demonstrated to specifically photodegrade endogenous CRBN, increase lipid peroxide, downregulate GPX4 and GAPDH expression, and consequently induce ferroptosis in cisplatin-resistant cancerous cells. Furthermore, with the deep penetration of two-photon excitation, Ru-Poma achieved drug-resistant circumvention in a 3D tumor cell model. Thus, we describe the first sample of the CRBN-targeting Ru(II) complex active in PDT.

Superior Drug Delivery Performance of Multifunctional Bilosomes: Innovative Strategy to Kill Skin Cancer Cells for Nanomedicine Application

Purpose

Numerous failures in melanoma treatment as a highly aggressive form of skin cancer with an unfavorable prognosis and excessive resistance to conventional therapies are prompting an urgent search for more effective therapeutic tools. Consequently, to increase the treatment efficiency and to reduce the side effects of traditional administration ways, herein, it has become crucial to combine photodynamic therapy as a promising therapeutic approach with the selectivity and biocompatibility of a novel colloidal transdermal nanoplatform for effective delivery of hybrid cargo with synergistic effects on melanoma cells.

Methods

The self-assembled bilosomes, co-stabilized with L-α-phosphatidylcholine, sodium cholate, Pluronic® P123, and cholesterol, were designated, and the stability of colloidal vesicles was studied using dynamic and electrophoretic light scattering, also provided in cell culture medium (Dulbecco's Modified Eagle's Medium). The hybrid compounds - a classical photosensitizer (Methylene Blue) along with a complementary natural polyphenolic agent (curcumin), were successfully co-loaded, as confirmed by UV-Vis, ATR-FTIR, and fluorescent spectroscopies. The biocompatibility and usefulness of the polymer functionalized bilosome with loaded double cargo were demonstrated in vitro cyto- and phototoxicity experiments using normal keratinocytes and melanoma cancer cells.

Results

The in vitro bioimaging and immunofluorescence study upon human skin epithelial (A375) and malignant (Me45) melanoma cell lines established the protective effect of the PEGylated bilosome surface. This effect was confirmed in cytotoxicity experiments, also determined on human cutaneous (HaCaT) keratinocytes. The flow cytometry experiments indicated the enhanced uptake of the encapsulated hybrid cargo compared to the non-loaded MB and CUR molecules, as well as a selectivity of the obtained nanocarriers upon tumor cell lines. The phyto-photodynamic action provided 24h-post irradiation revealed a more significant influence of the nanoplatform on Me45 cells in contrast to the A375 cell line, causing the cell viability rate below 20% of the control.

Conclusion

As a result, we established an innovative and effective strategy for potential metastatic melanoma treatment through the synergism of phyto-photodynamic therapy and novel bilosomal-origin nanophotosensitizers.

GSH-Responsive Liposomes with Heat Shock Protein Regulatory Ability for Efficient Photodynamic/Photothermal Combined Therapy of Tumors

Phototherapy, represented by photodynamic therapy (PDT) and photothermal therapy (PTT), has great potential in tumor treatment. However, the presence of antioxidant glutathione (GSH) and the heat shock proteins (HSPs) expression caused by high temperature can weaken the effects of PDT and PTT. Here, a multifunctional nanocomplex BT&GA@CL is constructed to realize enhanced synergistic PDT/PTT. Cinnamaldehyde liposomes (CLs) formed by cinnamaldehyde dimer self-assembly were loaded with in gambogic acid (GA) and an aggregation-induced emission molecule BT to obtain BT&GA@CL. As a drug carrier, CL can consume glutathione (GSH) and release drugs responsively. The released BT aggregates can simultaneously act as both a photothermal agent and photosensitizer to achieve PDT and PTT under 660 nm laser irradiation. Specifically, GA as an HSP90 inhibitor can attenuate PTT-induced HSP90 protein expression, thereby weakening the tolerance of tumor cells to high temperatures and enhancing PTT. Such a multifunctional nanocomplex simultaneously modulates the content of GSH and HSP90 in tumor cells, thus enhancing both PDT and PTT, ultimately achieving the goal of efficient combined tumor suppression.

"Three Musketeers" Enhances Photodynamic Effects by Reducing Tumor Reactive Oxygen Species Resistance

Photodynamic therapy (PDT) based on upconversion nanoparticles (UCNPs) has been widely used in the treatment of a variety of tumors. Compared with other therapeutic methods, this treatment has the advantages of high efficiency, strong penetration, and controllable treatment range. PDT kills tumors by generating a large amount of reactive oxygen species (ROS), which causes oxidative stress in the tumor. However, this killing effect is significantly inhibited by the tumor's own resistance to ROS. This is because tumors can either deplete ROS by high concentration of glutathione (GSH) or stimulate autophagy to eliminate ROS-generated damage. Furthermore, the tumor can also consume ROS through the lactic acid metabolic pathway, ultimately hindering therapeutic progress. To address this conundrum, we developed a UCNP-based nanocomposite for enhanced PDT by reducing tumor ROS resistance. First, Ce6-doped SiO2 encapsulated UCNPs to ensure the efficient energy transfer between UCNPs and Ce6. Then, the biodegradable tetrasulfide bond-bridged mesoporous organosilicon (MON) was coated on the outer layer to load chloroquine (CQ) and α-cyano4-hydroxycinnamic acid (CHCA). Finally, hyaluronic acid was utilized to modify the nanomaterials to realize an active-targeting ability. The obtained final product was abbreviated as UCNPs@MON@CQ/CHCA@HA. Under 980 nm laser irradiation, upconverted red light from UCNPs excited Ce6 to produce a large amount of singlet oxygen (1O2), thus achieving efficient PDT. The loaded CQ and CHCA in MON achieved multichannel enhancement of PDT. Specifically, CQ blocked the autophagy process of tumor cells, and CHCA inhibited the uptake of lactic acid by tumor cells. In addition, the coated MON consumed a high level of intracellular GSH. In this way, these three functions complemented each other, just as the "three musketeers" punctured ROS resistance in tumors from multiple angles, and both in vitro and in vivo experiments had demonstrated the elevated PDT efficacy of nanomaterials.

Screening Antibacterial Photodynamic Effect of Monascus Red Yeast Rice (Hong-Qu) and Mycelium Extracts

The fungus Monascus is a well-known source of secondary metabolites with interesting pharmaceutical and nutraceutical applications. In particular, Monascus pigments possess a wide range of biological activities (e.g. antimicrobial, antioxidant, anti-inflammatory or antitumoral). To broaden the scope of their possible application, this study focused on testing Monascus pigment extracts as potential photosensitizing agents efficient in antimicrobial photodynamic therapy (aPDT) against bacteria. For this purpose, eight different extracts of secondary metabolites from the liquid- and solid-state fermentation of Monascus purpureus DBM 4360 and Monascus sp. DBM 4361 were tested against Gram-positive and Gram-negative model bacteria, Bacillus subtilis and Escherichia coli and further screened for ESKAPE pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. To the bacterial culture, increasing concentration of extracts was added and it was found that all extracts showed varying antimicrobial activity against Gram-positive bacteria in dark, which was further increased after irradiation. Gram-negative bacteria were tolerant to the extracts' exposure in the dark but sensitivity to almost all extracts that occurred after irradiation. The Monascus sp. DBM 4361 extracts seemed to be the best potential candidate for aPDT against Gram-positive bacteria, being efficient at low doses, i.e. the lowest total concentration of Monascus pigments exhibiting aPDT effect was 3.92 ± 1.36 mg/L for E. coli. Our results indicate that Monascus spp., forming monascuspiloin as the major yellow pigment and not-forming mycotoxin citrinin, is a promising source of antimicrobials and photoantimicrobials.

Photodynamically Tumor Vessel Destruction Amplified Tumor Targeting of Nanoparticles for Efficient Chemotherapy

Efficient tumor-targeted drug delivery is still a challenging and currently unbreakable bottleneck in chemotherapy for tumors. Nanomedicines based on passive or active targeting strategy have not yet achieved convincing chemotherapeutic benefits in the clinic due to the tumor heterogeneity. Inspired by the efficient inflammatory-cell recruitment to acute clots, we constructed a two-component nanosystem, which is composed of an RGD-modified pyropheophorbide-a (Ppa) micelle (PPRM) that mediates the tumor vascular-targeted photodynamic reaction to activate local coagulation and subsequently transmits the coagulation signals to the circulating clot-targeted CREKA peptide-modified camptothecin (CPT)-loaded nanodiscs (CCNDs) for amplifying tumor targeting. PPRM could effectively bind with the tumor vasculature and induce sufficient local thrombus by a photodynamic reaction. Local photodynamic reaction-induced tumor target amplification greatly increased the tumor accumulation of CCND by 4.2 times, thus significantly enhancing the chemotherapeutic efficacy in the 4T1 breast tumor model. In other words, this study provides a powerful platform to amplify tumor-specific drug delivery by taking advantage of the efficient crosstalk between the PPRM-activated coagulation cascade and clot-targeted CCND.

Self-Adaptive Photodynamic-to-Photothermal Switch for Smart Antitumor Photoimmunotherapy

Photodynamic therapy (PDT) and photothermal therapy (PTT) possess different merits in cancer phototherapy, but the tumor microenvironment becomes unfavorable during the phototheranostic progress. Herein, we report a self-adaptive cyanine derivative Cy5-TPA with the PDT-dominated state to PTT-dominated state autoswitch feature for enhanced photoimmunotherapy. The incorporation of rotatable triphenylamine (TPA) moiety renders Cy5-TPA with the temperature or intramolecular-motion regulated photoactivities, which shows preferable reactive oxygen species (ROS) generation at lower temperature while stronger photothermal conversion at higher ones. Such a promising feature permits the in situ switch from PDT-dominated state to PTT-dominated state along with intratumoral temperature increase during laser irradiation, which also works in line with the concurrently reduced intratumoral oxygen level, exhibiting a self-adaptive phototherapeutic behavior to maximize the phototherapeutic antitumor outcome. Most importantly, the self-adaptive PDT-dominated state to PTT-dominated state switch also facilitates the sequential generation and release of damage-associated molecular patterns during immunogenic cell death (ICD). Hence, Cy5-TPA demonstrates excellent photoimmunotherapy performance in ICD induction, dendritic cell maturation, and T cell activation for tumor eradication and metastasis inhibition.

Oxygen Self-Supplied Perfluorocarbon-Modified Micelles for Enhanced Cancer Photodynamic Therapy and Ferroptosis

Photodynamic therapy (PDT) and ferroptosis show significant potential in tumor treatment. However, their therapeutic efficacy is often hindered by the oxygen-deficient tumor microenvironment and the challenges associated with efficient intracellular drug delivery into tumor cells. Toward this end, this work synthesized perfluorocarbon (PFC)-modified Pluronic F127 (PFC-F127), and then exploits it as a carrier for codelivery of photosensitizer Chlorin e6 (Ce6) and the ferroptosis promoter sorafenib (Sor), yielding an oxygen self-supplying nanoplatform denoted as Ce6-Sor@PFC-F127. The PFCs on the surface of the micelle play a crucial role in efficiently solubilizing and delivering oxygen as well as increasing the hydrophobicity of the micelle surface, giving rise to enhanced endocytosis by cancer cells. The incorporation of an oxygen-carrying moiety into the micelles enhances the therapeutic impact of PDT and ferroptosis, leading to amplified endocytosis and cytotoxicity of tumor cells. Hypotonic saline technology was developed to enhance the cargo encapsulation efficiency. Notably, in a murine tumor model, Ce6-Sor@PFC-F127 effectively inhibited tumor growth through the combined use of oxygen-enhanced PDT and ferroptosis. Taken together, this work underscores the promising potential of Ce6-Sor@PFC-F127 as a multifunctional therapeutic nanoplatform for the codelivery of multiple cargos such as oxygen, photosensitizers, and ferroptosis inducers.

Ionic Liquid Pretreatment Enhances Skin Penetration of 5-Aminolevulinic Acid: A Promising Scheme for Photodynamic Therapy for Acne Vulgaris

Acne vulgaris is one of the most prevalent skin disorders; it affects up to 85% of adolescents and often persists into adulthood. Topical 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) provides an alternative treatment for acne; however, its efficacy is greatly undermined by the limited skin permeability of ALA. Herein, biocompatible ionic liquids (ILs) based on aliphatic acid/choline were employed to enhance the dermal delivery of ALA, thereby improving the efficacy of PDT. In addition to the one-step delivery of ALA by utilizing ILs as carriers, a two-step strategy of pretreating the skin with blank ILs, followed by the administration of free ALA, was employed to test the IL-facilitated dermal delivery of ALA in vitro. The cumulative permeation of ALA through the excised rat skin after IL pretreatment was significantly greater than that in the untreated group, the 20% dimethyl sulfoxide (DMSO) penetration enhancer group, and the one-step group. The penetration efficiency was influenced by formulation and treatment factors, including the type of IL, pretreatment duration, water content in the ILs, and concentration of ALA. In rats, IL pretreatment facilitated faster, greater, and deeper ALA-induced protoporphyrin IX (PpIX) accumulation. Moreover, the IL pretreatment regimen significantly improved the efficacy of ALA-based PDT against acne vulgaris in a rat ear model. The model IL choline citrate ([Ch]3[Cit]1) had a moderate effect on the skin barrier. Trans-epidermal water loss could be recovered 1 h after IL treatment, but no irritation to the rat skin was detected after 7 days of consecutive treatment. It was concluded that biocompatible IL pretreatment enhances the penetration of ALA and thus facilitates the transformation of PpIX and improves the efficacy of PDT against acne vulgaris.

Hybrid Sono-Photodynamic Combination Therapy Mediated by Water-Soluble Gallium Phthalocyanine Enhances the Cytotoxic Effect against Breast Cancer Cell Lines

Breast cancer is a life-threatening disease that is gaining increasing importance due to its rising incidence, highlighting the need for novel treatment methods with the least disadvantages. Recently, scientists have focused on developing therapeutic treatment modalities for effective cancer treatment. In contrast to conventional cancer treatment methods such as immunotherapy, surgery, chemotherapy, or radiotherapy, photodynamic therapy (PDT) is gaining prominence. Besides, sonodynamic treatment (SDT) is a noninvasive therapeutic approach that uses ultrasound to induce high tissue penetration. In both methods, sensitizers are activated to generate cytotoxic reactive oxygen species such as •OH and 1O2. In particular, the combined use of hybrid and complementary treatment methods has become an important modality in cancer treatment in recent years. Sono-photodynamic therapy (SPDT), which is an important method applied in combination with PDT and SDT, has started to be preferred in terms of reducing potential side effects compared to monotherapy. One of the most important types of sensitizers used in PDT and SDT is known as phthalocyanines (Pcs). Motivated by these facts, this research presents the sono-photochemical, in vitro cytotoxicity, and theoretical evaluation of water-soluble gallium phthalocyanine (GaPc). The results indicate that the quantum yield of the generation of singlet oxygen increased in sono-photochemical studies (ΦΔ = 0.94), compared to photochemical studies (ΦΔ = 0.72). In vitro analyses revealed that GaPc did not exhibit significant cytotoxic effects at the specified varying concentration doses (1-20 μM). Furthermore, GaPc-mediated SPDT triggered cell death by inducing reactive oxygen species formation in the breast cancer cell line (MCF-7). The interaction mechanism of the GaPc with EGFR and VEGFR2 target proteins, which are critical regulators of metastasis, proliferation, and angiogenesis, was investigated by molecular docking simulation. GaPc has effective binding affinities against target proteins, and this affinity was found to be the highest against VEGFR2. Molecular docking results showed a good correlation with the obtained biological results. Eventually, this molecular building of the efficient water-soluble phthalocyanine-based sensitizer is a potential therapeutic for PDT, SDT, and SPDT applications.

In Vitro Synergistic Photodynamic, Photothermal, Chemodynamic, and Starvation Therapy Performance of Chlorin e6 Immobilized, Polydopamine-Coated Hollow, Porous Ceria-Based, Hypoxia-Tolerant Nanozymes Carrying a Cascade System

A synergistic therapy agent (STA) with photothermal, photodynamic, chemodynamic, and starvation therapy (PTT, PDT, CDT, and ST) functions was developed. Hollow, mesoporous, and nearly uniform CeO2 nanoparticles (H-CeO2 NPs) were synthesized using a staged shape templating sol-gel protocol. Chlorin e6 (Ce6) was adsorbed onto H-CeO2 NPs, and a thin polydopamine (PDA) layer was formed on Ce6-adsorbed H-CeO2 NPs. Glucose oxidase (GOx) was bound onto PDA-coated Ce6-adsorbed H-CeO2 NPs to obtain the targeted STA (H-CeO2@Ce6@PDA@GOx NPs). A reversible photothermal conversion behavior with the temperature elevations up to 34 °C was observed by NIR laser irradiation at 808 nm. A cascade enzyme system based on immobilized GOx and intrinsic catalase-like activity of H-CeO2 NPs was rendered on STA for enhancing the effectiveness of PDT by elevation of ROS generation and alleviation of hypoxia in a tumor microenvironment. Glucose-mediated generation of highly toxic hydroxyl radicals (·OH) was evaluated for CDT. The effectiveness of PDT on glioblastoma T98G cells was markedly enhanced by O2 generation started by the decomposition of glucose. A similar increase in cell death was also observed when ST and CDT functions were enhanced by photothermal action. The viability of T98G cells decreased to 10.6% by in vitro synergistic action including ST, CDT, PDT, and PTT without using any antitumor agent.

Supramolecular Nanoparticles of Histone and Hyaluronic Acid for Co-Delivery of siRNA and Photosensitizer In Vitro

Small interfering RNA (siRNA) has significant potential as a treatment for cancer by targeting specific genes or molecular pathways involved in cancer development and progression. The addition of siRNA to other therapeutic strategies, like photodynamic therapy (PDT), can enhance the anticancer effects, providing synergistic benefits. Nevertheless, the effective delivery of siRNA into target cells remains an obstacle in cancer therapy. Herein, supramolecular nanoparticles were fabricated via the co-assembly of natural histone and hyaluronic acid for the co-delivery of HMGB1-siRNA and the photosensitizer chlorin e6 (Ce6) into the MCF-7 cell. The produced siRNA-Ce6 nanoparticles (siRNA-Ce6 NPs) have a spherical morphology and exhibit uniform distribution. In vitro experiments demonstrate that the siRNA-Ce6 NPs display good biocompatibility, enhanced cellular uptake, and improved cytotoxicity. These outcomes indicate that the nanoparticles constructed by the co-assembly of histone and hyaluronic acid hold enormous promise as a means of siRNA and photosensitizer co-delivery towards synergetic therapy.

Photoactivated Formation of an Extravascular Dynamic Hydrogel as an Intelligent Blood Flow Regulator to Reprogram the Immunogenic Landscape

Long-term tumor starvation may be a potential strategy to elevate the antitumor immune response by depriving nutrients. However, combining long-term starvation therapy with immunotherapy often yields limited efficacy due to the blockage of immune cell migration pathways. Herein, an intelligent blood flow regulator (BFR) is first established through photoactivated in situ formation of the extravascular dynamic hydrogel to compress blood vessels, which can induce long-term tumor starvation to elicit metabolic stress in tumor cells without affecting immune cell migration pathways. By leveraging methacrylate-modified nanophotosensitizers (HMMAN) and biodegradable gelatin methacrylate (GelMA), the developed extravascular hydrogel dynamically regulates blood flow via enzymatic degradation. Additionally, aPD-L1 loaded into HMMAN continuously blocks immune checkpoints. Systematic in vivo experiments demonstrate that the combination of immune checkpoint blockade (ICB) and BFR-induced metabolic stress (BIMS) significantly delays the progression of Lewis lung and breast cancers by reshaping the tumor immunogenic landscape and enhancing antitumor immune responses.

Light-Driven Mitochondrion-to-Nucleus DNA Cascade Fluorescence Imaging and Enhanced Cancer Cell Photoablation

Nucleic acids are mainly found in the mitochondria and nuclei of cells. Detecting nucleic acids in the mitochondrion and nucleus in cascade mode is crucial for understanding diverse biological processes. This study introduces a novel nucleic acid-based fluorescent styrene dye (SPP) that exhibits light-driven cascade migration from the mitochondrion to the nucleus. By introducing N-arylpyridine on one side of the styrene dye skeleton and a bis(2-ethylsulfanyl-ethy)-amino unit on the other side, we found that SPP exhibits excellent DNA specificity (16-fold, FDNA/Ffree) and a stronger binding force to nuclear DNA (-5.09 kcal/mol) than to mitochondrial DNA (-2.59 kcal/mol). SPP initially accumulates in the mitochondrion and then migrates to the nucleus within 10 s under light irradiation. By tracking the damage to nucleic acids in apoptotic cells, SPP allows the successful visualization of the differences between apoptosis and ferroptosis. Finally, a triphenylamine segment with photodynamic effects was incorporated into SPP to form a photosensitizer (MTPA-SPP), which targets the mitochondria for photosensitization and then migrates to the nucleus under light irradiation for enhanced photodynamic cancer cell treatment. This innovative nucleic acid-based fluorescent molecule with light-triggered mitochondrion-to-nucleus migration ability provides a feasible approach for the in situ identification of nucleic acids, monitoring of subcellular physiological events, and efficient photodynamic therapy.

Double-layer hollow mesoporous silica nanoparticles for ultrasound-guided photodynamic treatment

Cervical carcinoma persists as a major global public health burden. While conventional therapeutic modalities inevitably cause ablation of adjacent non-tumorous tissues, photodynamic therapy (PDT) offers a targeted cytotoxic strategy through a photosensitizing agent (PS). However, the hydrophobicity and lack of selective accumulation of promising PS compounds such as zinc(II) phthalocyanine (ZnPc) impedes their clinical translation as standalone agents. The present study sought to incorporate ZnPc within double-layer hollow mesoporous silica nanoparticles (DHMSN) as nanocarriers to enhance aqueous dispersibility and tumor specificity. Owing to their compartmentalized design, the hollow mesoporous silica nanoparticles (HMSN) demonstrated enhanced ultrasonic imaging contrast. Combined with the vaporization of the perfluorocarbon perfluoropentane (PFP), the HMSN-encapsulated ZnPc enabled real-time ultrasound monitoring of PDT treatment.In vivo, the innate thermal energy induced vaporization of the DHMSN-carried PFP to significantly amplify ultrasound signals from the tumor site. Results demonstrated biocompatibility, efficient PFP microbubble generation, and robust photocatalytic activity. Collectively, this investigation establishes ultrasound-guided PDT utilizing multi-layer HMSN as a targeted therapeutic strategy for cervical malignancies with mitigated toxicity.

Anion-π+ AIEgens for Fluorescence Imaging and Photodynamic Therapy

Fluorescence imaging-guided photodynamic therapy (PDT) has attracted extensive attention due to its potential of real-time monitoring the lesion locations and visualizing the treatment process with high sensitivity and resolution. Aggregation-induced emission luminogens (AIEgens) show enhanced fluorescence and reactive oxygen species (ROS) generation after cellular uptake, giving them significant advantages in bioimaging and PDT applications. However, most AIEgens are unfavorable for the application in organisms due to their severe hydrophobicity. Anion-π+ type AIEgens carry intrinsic charges that can effectively alleviate their hydrophobicity and improve their binding capability to cells, which is expected to enhance the bioimaging quality and PDT performance. This concept summarizes the applications of anion-π+ type AIEgens in fluorescence imaging, fluorescence imaging-guided photodynamic anticancer and antimicrobial therapy in recent years, hoping to provide some new ideas for the construction of robust photosensitizers. Finally, the current problems and future challenges of anion-π+ AIEgens are discussed.

An NIR-II-emitting type-I photosensitizer for efficient hypoxic tumor phototheranostics

A small molecule-based NIR-II type-I photosensitizer (IT-IC) with a strong push-pull effect and good planar π-conjugated structure was synthesized. The IT-IC NPs exhibited strong light absorption, outstanding NIR-II fluorescence emission, excellent photothermal conversion and efficient type-I/II ROS generation, showing encouraging therapeutic outcomes for hypoxic tumors.

Combined Ferritin Nanocarriers with ICG for Effective Phototherapy Against Breast Cancer

Introduction

Photodynamic Therapy (PDT) is a promising, minimally invasive treatment for cancer with high immunostimulatory potential, no reported drug resistance, and reduced side effects. Indocyanine Green (ICG) has been used as a photosensitizer (PS) for PDT, although its poor stability and low tumor-target specificity strongly limit its efficacy. To overcome these limitations, ICG can be formulated as a tumor-targeting nanoparticle (NP).

Methods

We nanoformulated ICG into recombinant heavy-ferritin nanocages (HFn-ICG). HFn has a specific interaction with transferrin receptor 1 (TfR1), which is overexpressed in most tumors, thus increasing HFn tumor tropism. First, we tested the properties of HFn-ICG as a PS upon irradiation with a continuous-wave diode laser. Then, we evaluated PDT efficacy in two breast cancer (BC) cell lines with different TfR1 expression levels. Finally, we measured the levels of intracellular endogenous heavy ferritin (H-Fn) after PDT treatment. In fact, it is known that cells undergoing ROS-induced autophagy, as in PDT, tend to increase their ferritin levels as a defence mechanism. By measuring intracellular H-Fn, we verified whether this interplay between internalized HFn and endogenous H-Fn could be used to maximize HFn uptake and PDT efficacy.

Results

We previously demonstrated that HFn-ICG stabilized ICG molecules and increased their delivery to the target site in vitro and in vivo for fluorescence guided surgery. Here, with the aim of using HFn-ICG for PDT, we showed that HFn-ICG improved treatment efficacy in BC cells, depending on their TfR1 expression. Our data revealed that endogenous H-Fn levels were increased after PDT treatment, suggesting that this defence reaction against oxidative stress could be used to enhance HFn-ICG uptake in cells, increasing treatment efficacy.

Conclusion

The strong PDT efficacy and peculiar Trojan horse-like mechanism, that we revealed for the first time in literature, confirmed the promising application of HFn-ICG in PDT.

Light-Triggered Nanozymes Remodel the Tumor Hypoxic and Immunosuppressive Microenvironment for Ferroptosis-Enhanced Antitumor Immunity

Cancer immunotherapy holds significant promise for addressing diverse malignancies. Nevertheless, its efficacy remains constrained by the intricate tumor immunosuppressive microenvironment. Herein, a light-triggered nanozyme Fe-TCPP-R848-PEG (Fe-MOF-RP) was designed for remodeling the immunosuppressive microenvironment. The Fe-TCPP-MOFs were utilized not only as a core catalysis component against tumor destruction but also as a biocompatible delivery vector of an immunologic agonist, improving its long circulation and tumor enrichment. Concurrently, it catalyzes the decomposition of H2O2 within the tumor, yielding oxygen to augment photodynamic therapy. The induced ferroptosis, in synergy with photodynamic therapy, prompts the liberation of tumor-associated antigens from tumor cells inducing immunogenic cell death. Phototriggered on-demand release of R848 agonists stimulated the maturation of dendritic cells and reverted the tumor-promoting M2 phenotypes into adoptive M1 macrophages, which further reshaped the tumor immunosuppressive microenvironment. Notably, the nanozyme effectively restrains well-established tumors, such as B16F10 melanoma. Moreover, it demonstrates a distal tumor-inhibiting effect upon in situ light treatment. What is more, in a lung metastasis model, it elicits robust immune memory, conferring enduring protection against tumor rechallenge. Our study presents a straightforward and broadly applicable strategy for crafting nanozymes with the potential to effectively thwart cancer recurrence and metastasis.