Photodynamic therapy

Far-red light-triggered cargo release from liposomes b ound to a photosensitizer-cellulose nanofiber hydrogel

In our research we used the anionic nanofibrillar cellulose (ANFC) as a platform for far-red light-induced release of cargo from liposomes. In contrast to previous works, where photosensitizers are usually in the liposomal bilayers, we used a cellulose-binding dye. Our phthalocyanine derivative has been shown to bind very strongly to cellulose and cellulose nanofiber hydrogels, allowing us to place it outside of the liposomes. Both the sensitizer and cationic liposomes bind strongly to the ANFC after mixing, making the system easy to fabricate. Upon light activation, the photosensitizer generates reactive oxygen species (ROS) within the ANFC hydrogel, where the reactive oxygen species oxidize unsaturated lipids in the liposomal membrane, which makes the liposomes more permeable, resulting in on-demand cargo release. We were able to achieve ca. 70 % release of model hydrophilic cargo molecule calcein from the hydrogels with a relatively low dose of light (262 J/cm2) while employing the straightforward fabrication techniques. Our system was remarkably responsive to the far-red light (730 nm), enabling deep tissue penetration. Therefore, this very promising novel cellulose-immobilized photosensitizer liposomal platform could be used as a controlled drug delivery system, which can have applications in externally activated coatings or implants.

Towards efficient Ir(III) anticancer photodynamic therapy agents by extending π-conjugation on N^N ligands

In this work we disclose a new family of biscyclometallated Ir(III) complexes of the general formula [Ir(C^N)2(N^N)]Cl (IrL1-IrL5), where HC^N is 1-phenyl-β-carboline and N^N ligands (L1-L5) are different diimine ligands that differ from each other in the number of aromatic rings fused to the bipyridine scaffold. The photophysical properties of IrL1-IrL5 were thoroughly studied, and theoretical calculations were performed for a deeper comprehension of the respective variations along the series. All complexes exhibited high photostability under blue light irradiation. An increase in the number of aromatic rings led to a reduction in the HOMO-LUMO band gap causing a red-shift in the absorbance bands. Although all the complexes generated singlet oxygen (1O2) in aerated aqueous solutions through a photocatalytic process, IrL5 was by far the most efficient photosensitizer. Consequently, IrL5 was highly active in the photocatalytic oxidation of NADH. The formation of aggregates in DMSO at a high concentration (25 mM) was confirmed using different techniques, but was proved to be negligible in the concentration range of biological experiments. Moreover, ICP-MS studies proved that the cellular uptake of IrL2 and IrL3 is much better relative to that of IrL1, IrL4 and IrL5. The antiproliferative activity of IrL1-IrL5 was investigated in the dark and under blue light irradiation against different cancer cell lines. Complexes IrL1-IrL4 were found to be cytotoxic under dark conditions, while IrL5 turned out to be weakly cytotoxic. Despite the low cellular uptake of IrL5, this derivative exhibited a high increase of cytotoxicity upon blue light irradiation resulting in photocytotoxicity indexes (PI) up to 38. IrL1-IrL4 showed lower photocytotoxicity indexes ranging from 1.3 to 17.0. Haemolytic experiments corroborated the compatibility of our complexes with red blood cells. Confocal microscopy studies proved their accumulation in mitochondria, leading to mitochondrial membrane depolarization, and ruled out their localization in lysosomes. Overall, the mitochondria-targeted activity of IrL5, which inhibits considerably the viability of cancer cells upon blue light irradiation, allows us to outline this PS as a new alternative to traditional chemotherapeutic agents.

Multifunctional nano-in-micro delivery systems for targeted therapy in fundus neovascularization diseases

Fundus neovascularization diseases are a series of blinding eye diseases that seriously impair vision worldwide. Currently, the means of treating these diseases in clinical practice are continuously evolving and have rapidly revolutionized treatment opinions. However, key issues such as inadequate treatment effectiveness, high rates of recurrence, and poor patient compliance still need to be urgently addressed. Multifunctional nanomedicine can specifically respond to both endogenous and exogenous microenvironments, effectively deliver drugs to specific targets and participate in activities such as biological imaging and the detection of small molecules. Nano-in-micro (NIM) delivery systems such as metal, metal oxide and up-conversion nanoparticles (NPs), quantum dots, and carbon materials, have shown certain advantages in overcoming the presence of physiological barriers within the eyeball and are widely used in the treatment of ophthalmic diseases. Few studies, however, have evaluated the efficacy of NIM delivery systems in treating fundus neovascular diseases (FNDs). The present study describes the main clinical treatment strategies and the adverse events associated with the treatment of FNDs with NIM delivery systems and summarizes the anatomical obstacles that must be overcome. In this review, we wish to highlight the principle of intraocular microenvironment normalization, aiming to provide a more rational approach for designing new NIM delivery systems to treat specific FNDs.

Hemin enhances the 5-aminolevulinic acid-photodynamic therapy effect through the changes of cellular iron homeostasis

BACKGROUND

Photodynamic therapy (PDT) has been utilized as a promising alternative cancer treatment due to its minimum invasiveness over the years. Exogenous 5-aminolevulinic acid (ALA) triggers protoporphyrin IX (PpIX) accumulation, which happens in cancer cells. However, certain types of cancer exhibit reduced effectiveness in the PpIX accumulation mechanism. This study aimed to determine the effect of ALA-PDT combination with hemin on gastric carcinoma TMK-1 cells.

METHODS

This study utilized TMK-1 gastric cancer cell line to evaluate PpIX, ROS, and Fe2+ accumulation following the administration of ALA, hemin, and a combination of ALA and hemin PDT. We also evaluate the mRNA expressions related to iron homeostasis and treatment impacts on cell viability.

RESULTS

The co-addition of ALA and hemin PDT for 4 hours of treatment resulted in a significant decrease in cell viability by up to 18%. While ALA-PDT enhanced PpIX metabolism, the addition of hemin influenced both the production of reactive oxygen species (ROS) and cellular iron homeostasis by inducing Fe2+ accumulation and affecting mRNA levels of IRP, Tfr1, Ferritin, NFS1, and SDHB.

CONCLUSION

These findings suggest that the addition of ALA and hemin enhances phototoxicity in TMK-1 cells. The combination of ALA and hemin with PDT induces cell death, evidenced by increased cytotoxicity properties such as PpIX and ROS, along with significant changes in TMK-1 gastric cancer iron homeostasis. Therefore, the combination of ALA and hemin could be one of the alternatives in photodynamic therapy for cancer in the future.

Temoporfin-Conjugated PEGylated Poly(N,N-dimethylacrylamide)-Coated Upconversion Colloid for NIR-Induced Photodynamic Therapy of Pancreatic Cancer

Photodynamic therapy (PDT) has the potential to cure pancreatic cancer with minimal side effects. Visible wavelengths are primarily used to activate hydrophobic photosensitizers, but in clinical practice, these wavelengths do not sufficiently penetrate deeper localized tumor cells. In this work, NaYF4:Yb3+,Er3+,Fe2+ upconversion nanoparticles (UCNPs) were coated with polymer and labeled with meta-tetra(hydroxyphenyl)chlorin (mTHPC; temoporfin) to enable near-infrared light (NIR)-triggered PDT of pancreatic cancer. The coating consisted of alendronate-terminated poly[N,N-dimethylacrylamide-co-2-aminoethylacrylamide]-graft-poly(ethylene glycol) [P(DMA-AEM)-PEG-Ale] to ensure the chemical and colloidal stability of the particles in aqueous physiological fluids, thereby also improving the therapeutic efficacy. The designed particles were well tolerated by the human pancreatic adenocarcinoma cell lines CAPAN-2, PANC-1, and PA-TU-8902. After intratumoral injection of mTHPC-conjugated polymer-coated UCNPs and subsequent exposure to 980 nm NIR light, excellent PDT efficacy was achieved in tumor-bearing mice.

Helical BODIPY Dyes as Heavy-Atom-Free Triplet Photosensitizers for Photodynamic Therapy of Cancer

Despite of having many advantages over the popular cancer therapies, photodynamic therapy still is not widely acceptable for clinical applications. Scarcity of efficient triplet photosensitizers (PSs) is one of the main bottlenecks for this. Although numerous heavy atom attached PSs are developed as PDT agents, but these are not suitable for clinical applications due to several reasons. Thus, development of heavy-atom-free organic PSs is urgently required. In this context, development of new type of helical BODIPYs as PSs for PDT is discussed. BODIPYs have rich photophysical properties and structural helicity further enhances their triplet conversion rates. This new concept of structural helicity to enhance the triplet conversion of BODIPYs is discussed with reported helical BODIPYs. Helical geometries of these dyes are checked by X-ray crystallography studies and their high triplet conversions as compared to planar BODIPYs are also confirmed. Importantly, these dyes have high triplet lifetimes and are capable of generating high singlet oxygens even in hypoxia condition as compared to conventional heavy atom attached BODIPYs. All these make the helical BODIPYs excellent candidates as PDT agents. Finally, their successful applications as PDT agents in killing of various types of cancer cells are also discussed. The results are encouraging which indicate that helical BODIPYs could be next generation heavy-atom-free PSs for PDT applications.

Long-term outcomes of PDT for centrally-located early lung cancers with tumor diameters > 2.0 cm

BACKGROUND

Photodynamic therapy (PDT) is used for the treatment of centrally-located early lung cancers (CLELCs) and is recommended for tumors ≤ 1.0 cm in diameter. We previously reported that PDT using talaporfin sodium, second-generation photosensitizer, for tumors > 1.0 cm but ≤ 2.0 cm in diameter was able to achieve a therapeutic outcome comparable to that of tumors with a diameter of ≤ 1.0 cm. However, the effectiveness of PDT using talaporfin sodium for tumors > 2.0 cm in diameter remains unclear. We conducted a retrospective analysis of cases in which PDT was performed for flat-type CLELCs with tumor diameters of > 2.0 cm.

METHODS

We retrospectively analyzed seven cases (eight lesions) with tumor diameters > 2.0 cm and no evidence of extracartilaginous invasion or lymph node metastasis.

RESULTS

All the patients underwent multiple PDT sessions. The PDT treatment results over the study period were partial response in one case (14.3 %), stable disease (SD) in three cases (42.9 %), and progressive disease (PD) in three cases (42.9 %). At the time of writing this report, five of seven cases (71.4 %) are still undergoing treatment. The duration of SD-the time from the start of treatment until the criteria for PD were met (SD or better maintained)-ranged from 7 to 52 months (mean, 25.3 months).

CONCLUSIONS

"Maintenance PDT" for CLELCs > 2.0 cm in diameter has the potential to inhibit tumor progression in the long term while maintaining quality of life, rather than simply aiming only for a quick radical cure.

In vitro modeling of recurrent Dermatofibrosarcoma Protuberans: Assessment of 5-aminolevulinic acid photodynamic therapy efficacy

BACKGROUND

Dermatofibrosarcoma Protuberans (DFSP) is a rare, low-grade malignant tumor of the dermis with a high recurrence rate post-surgery. Current treatments, including surgery, radiotherapy, and targeted therapy, have limitations. Photodynamic therapy (PDT) with 5-aminolevulinic acid (5-ALA) is a promising non-invasive approach, but its efficacy in DFSP treatment remains underexplored.

METHODS

This study aimed to evaluate the anti-tumor efficacy of 5-ALA PDT using an in vitro model derived from a recurrent DFSP patient. The cells were treated with varying concentrations of 5-ALA and exposed to red light, followed by assessments of cell viability, proliferation, apoptosis, migration, invasion, angiogenesis, and expression of DFSP-related genes and proteins.

RESULTS

5-ALA PDT significantly reduced DFSP cell viability in a dose-dependent manner and induced apoptosis. It also effectively inhibited cell proliferation, migration, and invasion, as well as suppressed angiogenic activity in conditioned media. Furthermore, 5-ALA PDT downregulated the expression of COL1A1 and PDGFRB, key genes in DFSP pathogenesis.

CONCLUSIONS

The findings provide the first evidence of 5-ALA PDT's in vitro anti-tumor efficacy against DFSP, suggesting its potential as a novel therapeutic approach for DFSP. Further studies are warranted to explore the clinical utility of 5-ALA PDT in preventing DFSP recurrence.

Evaluation of the therapeutic effects of Photodynamic Therapy in vulvar lichen sclerosus and impact on patient quality of life and sexual funtion

BACKGROUND

Vulvar lichen sclerosus (VLS) is often associated with irritable symptoms of itching, burning pain and can lead to scarring, architectural changes and sexual dysfunction as well as a decline in quality of life.The etiology of the disease is unknown. This study sought to assess the therapeutic effects of Photodynamic Therapy (PDT) in VLS, and improvment of patient quality of life and sexual funtion.

METHODS

From January 2022 to April 2023, a total of 65 patients with vulvar sclerosi (VLS) were treated with PDT in our hospital. All 65 patients were divided into two groups: early-stage group and late-stage group. The Cattaneo scoring method, the Dermatology Life Quality Index (DLQI) and the Female Sexual Function Index (FSFI) scores were used to evaluate the clinical effectiveness of the treatment on patients' symptoms and clincal signs, quality of life as well as sexual function before and at 6-month after treatment.

RESULTS

The total effective rate of early-stage patients was significantly greater than that of late-stage patients at 6-month after PDT treatment (90.91% [40/44] vs 76.19% [16/21], p <0.05). At 6-month follow-up, the symptoms and clinical signs of patients in early-stage group were significantly improved compared with baseline, the average scores of itching, skin elasticity, whitening and lesion range were significantly lower than the scores before treatment (p <0.05). In late-stage group, The decrease in scores of itching, whitening and lesion range at the 6-months follow-up is significant(p <0.05), but skin elasticity (p=0.0625). On post-treatment follow-up examination, FSFI score was seen to have significantly improved in early-stage patients(from a median score of 17.45 to 21.1, p<0.05); DLQI also significantly improved after treatment (from a median score of 7 to 4, p<0.05). In late stage patients, The DLQI score improved significantly after treatment (from a median score of 18 to 15, p<0.05). However, the improvement in sexual function is not statistically significant (pre-treatment: median=10.55, post-treatment: median=10, p=0.1865).

CONCLUSION

Photodynamic therapy can effectively improve most symptoms and clinical signs, as well as quality of life of patients with VLS, especially for earlly stage patients. Moreover, improvement in sexual function is observed in early stage patients after PDT treatment. This study suggests that early and timely PDT treatment are recommended to achieve better results.

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

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

Upregulation of iNOS/NO in Cancer Cells That Survive a Photodynamic Challenge: Role of No in Accelerated Cell Migration and Invasion

Anti-tumor photodynamic therapy (PDT) is a unique modality that employs a photosensitizer (PS), PS-exciting light, and O2 to generate cytotoxic oxidants. For various reasons, not all malignant cells in any given tumor will succumb to a PDT challenge. Previous studies by the authors revealed that nitric oxide (NO) from inducible NO synthase (iNOS/NOS2) plays a key role in tumor cell resistance and also stimulation of migratory/invasive aggressiveness of surviving cells. iNOS was the only NOS isoform implicated in these effects. Significantly, NO from stress-upregulated iNOS was much more important in this regard than NO from preexisting enzymes. Greater NO-dependent resistance, migration, and invasion was observed with at least three different cancer cell lines, and this was attenuated by iNOS activity inhibitors, NO scavengers, or an iNOS transcriptional inhibitor. NO diffusing from PDT-targeted cells also stimulated migration/invasion potency of non-targeted bystander cells. Unless counteracted by appropriate measures, all these effects could seriously compromise clinical PDT efficacy. Here, we will review specific examples of these negative side effects of PDT and how they might be suppressed by adjuvants such as NO scavengers or inhibitors of iNOS activity or expression.

Spin-Restricted Descriptions of Singlet Oxygen Reactions from XMS-CASPT2 Benchmarks

Reactions of singlet oxygen are numerous, some of which are desired but many are unwanted. Therefore, the ability to correctly predict and interpret this reactivity for complex molecular systems is essential to our understanding of singlet oxygen reactions. DFT is widely used for predicting many reactions but is not suited to degenerate electronic structures; application to isolated singlet oxygen often uses the spin-unrestricted formalism, which results in severe spin contamination. In this work, we demonstrate that spin-restricted DFT can correctly describe the reaction pathway for four prototypical singlet oxygen reactions. By careful benchmarking with XMS-CASPT2, we show that, from the first transition state onward, the degeneracy of the 1Δg state is broken due to differing interactions of the (degenerate) π* orbitals with the organic substrate; this result is well replicated with DFT. These findings demonstrate the utility of using spin-restricted DFT to explore reactions, opening the way to confidently use this computationally efficient method for molecular systems of medium to large organic molecules.

A series of potent BODIPY photosensitisers featuring tellurophene motifs at boron

This article describes the synthesis and photophysical properties of a series of BODIPY photosensitisers that feature tellurophene motifs appended at the boron centre. These compounds were obtained via nucleophilic substitution of various F-BODIPYs with lithiated tellurophene. The synthetic scope, photophysical characteristics and photosensitisation properties are discussed. Structural modifications around the BODIPY core resulted in an eight-fold improvement in light IC50 values compared to previous designs.

Enhanced systemic antitumor efficacy of PD-1/PD-L1 blockade with immunological response induced by photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) is an antitumor therapy and has traditionally been regarded as a localized therapy in itself. However, recent reports have shown that it not only exerts a direct cytotoxic effect on cancer cells but also enhances body's tumor immunity. We hypothesized that the immunological response induced by PDT could potentially enhance the efficacy of programmed death-1 (PD-1) / programmed death-ligand 1 (PD-L1) blockade.

METHODS

The cytotoxic effects of PDT on colon 26 cells were investigated in vitro using the WST assay. We investigated whether the antitumor effect of anti-PD-1 antibodies could be amplified by the addition of PDT. We performed combination therapy by randomly allocating tumor-bearing mice to four treatment groups: control, anti-PD-1 antibodies, PDT, and a combination of anti-PD-1 antibodies and PDT. To analyze the tumor microenvironment after treatment, the tumors were resected and pathologically evaluated.

RESULTS

The viability rate of colon 26 cells decreased proportionally with the laser dose. In vivo experiments for combined PDT and anti-PD-1 antibody treatment, combination therapy showed an enhanced antitumor effect compared with the control. Immunohistochemical findings of the tumor microenvironment 10 days after PDT indicated that the number of CD8+ cells, the area of Iba-1+ cells and the area expressing PD-L1 were significantly higher in tumors treated with combination therapy than in tumors treated with anti-PD-1 antibody alone, PDT alone, or the control.

CONCLUSIONS

PDT increased immune cell infiltration into the tumor microenvironment. The immunological response induced by PDT may enhance the efficacy of PD-1/PD-L1 blockade.

Methods for assessing and removing non-specific photoimmunotherapy damage in patient-derived tumor cell culture models

Tumor-targeted, activatable photoimmunotherapy (taPIT) has been shown to selectively destroy tumor in a metastatic mouse model. However, the photoimmunoconjugate (PIC) used for taPIT includes a small fraction of non-covalently associated (free) benzoporphyrin derivative (BPD), which leads to non-specific killing in vitro. Here, we report a new treatment protocol for patient-derived primary tumor cell cultures ultrasensitive to BPD photodynamic therapy (BPD-PDT). Based on free BPD efflux dynamics, the updated in vitro taPIT protocol precludes non-specific BPD-PDT by silencing the effect of free BPD. Following incubation with PIC, incubating cells with PIC-free medium allows time for expulsion of free BPD whereas BPD covalently bound to PIC fragments is retained. Administration of the light dose after the intracellular free BPD drops below the threshold for inducing cell death helps to mitigate non-specific damage. In this study, we tested two primary ovarian tumor cell lines that are intrinsically chemoresistant, yet ultrasensitive to BPD-PDT such that small amounts of free BPD (a few percent of the total BPD dose) lead to potent induction of cell death upon irradiation. The modifications in the protocol suggested here improve in vitro taPIT experiments that lack in vivo mechanisms of free BPD clearance (i.e., lymph and blood flow).

Low-cost, 3D printed irradiation system for in vitro photodynamic therapy experiments

The development of a suitable irradiation setup is essential for in vitro experiments in photodynamic therapy (PDT). While various irradiation systems have been developed for PDT, only a few offer practical and high-quality setups for precise and reproducible results in cell culture experiments. This report introduces a cost-effective illumination setup designed for in vitro photodynamic treatments. The setup consists of a commercially available light-emitting diode (LED) lamp, a cooling unit, and a specially designed 3D-printed enclosure to accommodate a multiwell plate insert. The LED lamp is versatile, supporting various irradiation wavelengths and adjustable illumination fields, ensuring consistent and reliable performance. The study evaluates the setup through various parameters, including photon flux density, illumination uniformity, photon distribution across the multiwell plate, and temperature changes during irradiation. In addition, the effectiveness of the LED-based illumination system is tested by treating mouse mammary breast carcinoma cells (4T1) with Rose Bengal and LED irradiation at around 525 nm. The resulting IC50 of 5.2 ± 0.9 μM and a minimum media temperature change of ca. 1.2°C indicate a highly promising LED-based setup that offers a cost-effective and technically feasible solution for achieving consistent, reproducible, and uniform irradiation, enhancing research capabilities and potential applications.

Cetuximab-Toxin Conjugate and NPe6 with Light Enhanced Cytotoxic Effects in Head and Neck Squamous Cell Carcinoma In Vitro

BACKGROUND

Photodynamic therapy (PDT) is a cancer-targeted treatment that uses a photosensitizer (PS) and irradiation of a specific wavelength to exert cytotoxic effects. To enhance the antitumor effect against head and neck squamous cell carcinoma (HNSCC), we developed a new phototherapy, intelligent targeted antibody phototherapy (iTAP). This treatment uses a combination of immunotoxin (IT) and a PS for PDT and light irradiation. In our prior study, we demonstrated that an immunotoxin (IT) consisting of an anti-ROBO1 antibody conjugated to saporin, when used in combination with the photosensitizer (PS) disulfonated aluminum phthalocyanine (AlPcS2a) and irradiated with light at the appropriate wavelength, resulted in increased cytotoxicity against head and neck squamous cell carcinoma (HNSCC) cells. ROBO1 is a receptor known to be involved in the progression of cancer. In this study, we newly investigate the iTAP targeting epidermal growth factor receptor (EGFR) which is widely used as a therapeutic target for HNSCC.

METHODS

We checked the expression of EGFR in HNSCC cell lines, SAS, HO-1-u-1, Sa3, and HSQ-89. We analyzed the cytotoxicity of saporin-conjugated anti-EGFR antibody (cetuximab) (IT-Cmab), mono-L-aspartyl chlorin e6 (NPe6, talaporfin sodium), and light (664 nm) irradiation (i.e., iTAP) in SAS, HO-1-u-1, Sa3, and HSQ-89 cells.

RESULTS

EGFR was expressed highly in Sa3, moderately in HO-1-u-1, SAS, and nearly not in HSQ-89. Cmab alone or IT-Cmab alone did not show cytotoxic effects in Sa3, HO-1-u-1, and HSQ-89 cells, which have moderate or low expression levels of EGFR protein. However, the iTAP method enhanced the cytotoxicity of IT-Cmab by the photodynamic effect in Sa3 and HO-1-u-1 cells, which have moderate levels of EGFR expression.

CONCLUSION

Our study is the first to report on the iTAP method using IT-Cmab and NPe6 for HNSCC. The cytotoxic effects are enhanced in cell lines with moderate levels of EGFR protein expression, but not in nonexpressing cell lines, which is expected to expand the range of therapeutic windows and potentially reduce complications.

Donor-Acceptor Modulating of Ionic AIE Photosensitizers for Enhanced ROS Generation and NIR-II Emission

Photosensitizers (PSs) with aggregation-induced emission (AIE) characteristics are competitive candidates for bioimaging and therapeutic applications. However, their short emission wavelength and nonspecific organelle targeting hinder their therapeutic effectiveness. Herein, a donor-acceptor modulation approach is reported to construct a series of ionic AIE photosensitizers with enhanced photodynamic therapy (PDT) outcomes and fluorescent emission in the second near-infrared (NIR-II) window. By employing dithieno[3,2-b:2',3'-d]pyrrole (DTP) and indolium (In) as the strong donor and acceptor, respectively, the compound DTP-In exhibits a substantial redshift in absorption and fluorescent emission reach to NIR-II region. The reduced energy gap between singlet and triplet states in DTP-In also increases the reactive oxygen species (ROS) generation rate. Further, DTP-In can self-assemble in aqueous solutions, forming positively charged nanoaggregates, which are superior to conventional encapsulated nanoparticles in cellular uptake and mitochondrial targeting. Consequently, DTP-In aggregates show efficient photodynamic ablation of 4T1 cancer cells and outstanding tumor theranostic in vivo under 660 nm laser irradiation. This work highlights the potential of molecular engineering of donor-acceptor AIE PSs with multiple functionalities, thereby facilitating the development of more effective strategies for cancer therapy.

Gold nanoparticles-mediated photothermal and photodynamic therapies for cancer

Cancer remains one of the major causes of death globally, with one out of every six deaths attributed to the disease. The impact of cancer is felt on psychological, physical, and financial levels, affecting individuals, communities, and healthcare institutions. Conventional cancer treatments have many challenges and inadequacies. Nanomedicine, however, presents a promising solution by not only overcoming these problems but also offering the advantage of combined therapy for treatment-resistant cancers. Nanoparticles specifically engineered for use in nanomedicine can be efficiently targeted to cancer cells through a combination of active and passive techniques, leading to superior tumor-specific accumulation, enhanced drug availability, and reduced systemic toxicity. Among various nanoparticle formulations designed for cancer treatment, gold nanoparticles have gained prominence in the field of nanomedicine due to their photothermal, photodynamic, and immunologic effects without the need for photosensitizers or immunotherapeutic agents. To date, there is no comprehensive literature review that focuses on the photothermal, photodynamic, and immunologic effects of gold nanoparticles. In this review, significant attention has been devoted to examining the parameters pertaining to the structure of gold nanoparticles and laser characteristics, which play a crucial role in influencing the efficacy of photothermal therapy (PTT) and photodynamic therapy (PDT). Moreover, this article provides insights into the success of PTT and PDT mediated by gold nanoparticles in primary cancer treatment, as well as the immunological effects of PTT and PDT on metastasis and recurrence, providing a promising strategy for cancer therapy. In summary, gold nanoparticles, with their unique properties, have the potential for clinical application in various cancer therapies, including the treatment of primary cancer, recurrence and metastasis.

Growing Trend to Adopt Speckle Variance Optical Coherence Tomography for Biological Tissue Assessments in Pre-Clinical Applications

Speckle patterns are a generic feature in coherent imaging techniques like optical coherence tomography (OCT). Although speckles are granular like noise texture, which degrades the image, they carry information that can be benefited by processing and thereby furnishing crucial information of sample structures, which can serve to provide significant important structural details of samples in in vivo longitudinal pre-clinical monitoring and assessments. Since the motions of tissue molecules are indicated through speckle patterns, speckle variance OCT (SV-OCT) can be well-utilized for quantitative assessments of speckle variance (SV) in biological tissues. SV-OCT has been acknowledged as a promising method for mapping microvasculature in transverse-directional blood vessels with high resolution in micrometers in both the transverse and depth directions. The fundamental scope of this article reviews the state-of-the-art and clinical benefits of SV-OCT to assess biological tissues for pre-clinical applications. In particular, focus on precise quantifications of in vivo vascular response, therapy assessments, and real-time temporal vascular effects of SV-OCT are primarily emphasized. Finally, SV-OCT-incorporating pre-clinical techniques with high potential are presented for future biomedical applications.

Enhancing Phototoxicity in Human Colorectal Tumor Cells Through Nanoarchitectonics for Synergistic Photothermal and Photodynamic Therapies

Phototherapies are promising for noninvasive treatment of aggressive tumors, especially when combining heat induction and oxidative processes. Herein, we show enhanced phototoxicity of gold shell-isolated nanorods conjugated with toluidine blue-O (AuSHINRs@TBO) against human colorectal tumor cells (Caco-2) with synergic effects of photothermal (PTT) and photodynamic therapies (PDT). Mitochondrial metabolic activity tests (MTT) performed on Caco-2 cell cultures indicated a photothermal effect from AuSHINRs owing to enhanced light absorption from the localized surface plasmon resonance (LSPR). The phototoxicity against Caco-2 cells was further increased with AuSHINRs@TBO where oxidative processes, such as hydroperoxidation, were also present, leading to a cell viability reduction from 85.5 to 39.0%. The molecular-level mechanisms responsible for these effects were investigated on bioinspired tumor membranes using Langmuir monolayers of Caco-2 lipid extract. Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) revealed that the AuSHINRs@TBO incorporation is due to attractive electrostatic interactions with negatively charged groups of the Caco-2 lipid extract, resulting in the expansion of surface pressure isotherms. Upon irradiation, Caco-2 lipid extract monolayers containing AuSHINRs@TBO (1:1 v/v) exhibited ca. 1.0% increase in surface area. This is attributed to the generation of reactive oxygen species (ROS) and their interaction with Caco-2 lipid extract monolayers, leading to hydroperoxide formation. The oxidative effects are facilitated by AuSHINRs@TBO penetration into the polar groups of the extract, allowing oxidative reactions with carbon chain unsaturations. These mechanisms are consistent with findings from confocal fluorescence microscopy, where the Caco-2 plasma membrane was the primary site of the cell death induction process.

Triphenylphosphonium-functionalized dimeric BODIPY-based nanoparticles for mitochondria-targeting photodynamic therapy

The dimerization of boron dipyrromethene (BODIPY) moieties is an appealing molecular design approach for developing heavy-atom-free triplet photosensitizers (PSs). However, BODIPY dimer-based PSs generally lack target specificity, which limits their clinical use for photodynamic therapy. This study reports the synthesis of two mitochondria-targeting triphenylphosphonium (TPP)-functionalized meso-β directly linked BODIPY dimers (BTPP and BeTPP). Both BODIPY dimers exhibited solvent-polarity-dependent singlet oxygen (1O2) quantum yields, with maximum values of 0.84 and 0.55 for BTPP and BeTPP, respectively, in tetrahydrofuran. The compact orthogonal geometry of the BODIPY dimers facilitated the generation of triplet excited states via photoinduced charge separation (CS) and subsequent spin-orbit charge-transfer intersystem crossing (SOCT-ISC) processes and their rates were dependent on the energetic configuration between the frontier molecular orbitals of the two BODIPY subunits. The as-synthesized compounds were amphiphilic and hence formed stable nanoparticles (∼36 nm in diameter) in aqueous solutions, with a zeta potential of ∼33 mV beneficial for mitochondrial targeting. In vitro experiments with MCF-7 and HeLa cancer cells indicated the effective localization of BTPP and BeTPP within cancer-cell mitochondria. Under light irradiation, BTPP and BeTPP exhibited robust photo-induced therapeutic effects in both cell lines, with half-maximal inhibitory concentration (IC50) values of ∼30 and ∼55 nM, respectively.

Iridium(III) complexes decorated with silicane-modified rhodamine: near-infrared light-initiated photosensitizers for efficient deep-tissue penetration photodynamic therapy

Meeting the demand for efficient photosensitizers in photodynamic therapy (PDT), a series of iridium(III) complexes decorated with silicane-modified rhodamine (Si-rhodamine) was meticulously designed and synthesized. These complexes demonstrate exceptional PDT potential owing to their strong absorption in the near-infrared (NIR) spectrum, particularly responsive to 808 nm laser stimulation. This feature is pivotal, enabling deep-penetration laser excitation and overcoming depth-related challenges in clinical PDT applications. The molecular structures of these complexes allow for reliable tuning of singlet oxygen generation with NIR excitation, through modification of the cyclometalating ligand. Notably, one of the complexes (4) exhibits a remarkable ROS quantum yield of 0.69. In vivo results underscore the efficacy of 4, showcasing significant tumor regression at depths of up to 8.4 mm. This study introduces a promising paradigm for designing photosensitizers capable of harnessing NIR light effectively for deep PDT applications.

Investigation of the Nanoparticulation Method and Cell-Killing Effect following the Mitochondrial Delivery of Hydrophobic Porphyrin-Based Photosensitizers

Photodynamic therapy is expected to be a less invasive treatment, and strategies for targeting mitochondria, the main sources of singlet oxygen, are attracting attention to increase the efficacy of photodynamic therapy and reduce its side effects. To date, we have succeeded in encapsulating the photosensitizer rTPA into MITO-Porter (MP), a mitochondria-targeted Drug Delivery System (DDS), aimed at mitochondrial delivery of the photosensitizer while maintaining its activity. In this study, we report the results of our studies to alleviate rTPA aggregation in an effort to improve drug efficacy and assess the usefulness of modifying the rTPA side chain to improve the mitochondrial retention of MITO-Porter, which exhibits high therapeutic efficacy. Conventional rTPA with anionic side chains and two rTPA analogs with side chains that were converted to neutral or cationic side chains were encapsulated into MITO-Porter. Low-MP (MITO-Porter with Low Drug/Lipid) exhibited high drug efficacy for all three types of rTPA, and in Low-MP, charged rTPA-encapsulated MP exhibited high drug efficacy. The cellular uptake and mitochondrial translocation capacities were similar for all particles, suggesting that differences in aggregation rates during the incorporation of rTPA into MITO-Porter resulted in differences in drug efficacy.

Enhancing cancer immunotherapy with photodynamic therapy and nanoparticle: making tumor microenvironment hotter to make immunotherapeutic work better

Cancer immunotherapy has made tremendous advancements in treating various malignancies. The biggest hurdle to successful immunotherapy would be the immunosuppressive tumor microenvironment (TME) and low immunogenicity of cancer cells. To make immunotherapy successful, the 'cold' TME must be converted to 'hot' immunostimulatory status to activate residual host immune responses. To this end, the immunosuppressive equilibrium in TME should be broken, and immunogenic cancer cell death ought to be induced to stimulate tumor-killing immune cells appropriately. Photodynamic therapy (PDT) is an efficient way of inducing immunogenic cell death (ICD) of cancer cells and disrupting immune-restrictive tumor tissues. PDT would trigger a chain reaction that would make the TME 'hot' and have ICD-induced tumor antigens presented to immune cells. In principle, the strategic combination of PDT and immunotherapy would synergize to enhance therapeutic outcomes in many intractable tumors. Novel technologies employing nanocarriers were developed to deliver photosensitizers and immunotherapeutic to TME efficiently. New-generation nanomedicines have been developed for PDT immunotherapy in recent years, which will accelerate clinical applications.

Tracking the cellular uptake and phototoxicity of Ru(ii)-polypyridyl-1,8-naphthalimide Tröger's base conjugates

Ruthenium(ii) complexes are attracting significant research attention as a promising class of photosensitizers (PSs) in photodynamic therapy (PDT). Having previously reported the synthesis of two novel Ru(ii)-polypyridyl-1,8-naphthalimide Tröger's base compounds 1 and 2 with interesting photophysical properties, where the emission from either the Ru(ii) polypyridyl centres or the naphthalimide moieties could be used to monitor binding to nucleic acids, we sought to use these compounds to investigate further and in more detail their biological profiling, which included unravelling their mechanism of cellular uptake, cellular trafficking and cellular responses to photoexcitation. Here we demonstrate that these compounds undergo rapid time dependent uptake in HeLa cells that involved energy dependent, caveolae and lipid raft-dependent mediated endocytosis, as demonstrated by confocal imaging, and transmission and scanning electron microscopy. Following endocytosis, both compounds were shown to localise to mostly lysosomal and Golgi apparatus compartments with some accumulation in mitochondria but no localisation was found to the nucleus. Upon photoactivation, the compounds increased ROS production and induced ROS-dependent apoptotic cell death. The photo-activated compounds subsequently induced DNA damage and altered tubulin, but not actin structures, which was likely to be an indirect effect of ROS production and induced apoptosis. Furthermore, by changing the concentration of the compounds or the laser used to illuminate the cells, the mechanism of cell death could be changed from apoptosis to necrosis. This is the first detailed biological study of Ru(ii)-polypyridyl Tröger's bases and clearly suggests caveolae-dependent endocytosis is responsible for cell uptake - this may also explain the lack of nuclear uptake for these compounds and similar results observed for other Ru(ii)-polypyridyl complexes. These conjugates are potential candidates for further development as PDT agents and may also be useful in mechanistic studies on cell uptake and trafficking.

Design of AsLOV2 domain as a carrier of light-induced dissociable FMN photosensitizer

Flavin mononucleotide (FMN) is a highly efficient photosensitizer (PS) yielding singlet oxygen (1 O2 ). However, its 1 O2 production efficiency significantly decreases upon isoalloxazine ring encapsulation into the protein matrix in genetically encoded photosensitizers (GEPS). Reducing isoalloxazine ring interactions with surrounding amino acids by protein engineering may increase 1 O2 production efficiency GEPS, but at the same time weakened native FMN-protein interactions may cause undesirable FMN dissociation. Here, in contrast, we intentionally induce the FMN release by light-triggered sulfur oxidation of strategically placed cysteines (oxidation-prone amino acids) in the isoalloxazine-binding site due to significantly increased volume of the cysteinyl side residue(s). As a proof of concept, in three variants of the LOV2 domain of Avena sativa (AsLOV2), namely V416C, T418C, and V416C/T418C, the effective 1 O2 production strongly correlated with the efficiency of irradiation-induced FMN dissociation (wild type (WT) < V416C < T418C < V416C/T418C). This alternative approach enables us: (i) to overcome the low 1 O2 production efficiency of flavin-based GEPSs without affecting native isoalloxazine ring-protein interactions and (ii) to utilize AsLOV2, due to its inherent binding propensity to FMN, as a PS vehicle, which is released at a target by light irradiation.

Tools of clinical Photodynamic Therapy (PDT): A Mini Compendium

Unlike surgical instruments and endoscopic equipment, Photodynamic Therapy (PDT) devices are not readily available or accessible to the clinicians who may like to add this form of treatment modality for selected patients and on an ad hock basis. There is in fact a vacuum in finding the "tools" of PDT for those clinicians who are not part of a "Centre" with a built-in knowledge base and contacts for manufacturers. In this compendium the Yorkshire Laser Centre /YLC in the UK, (the Project of the Moghissi Laser Trust - (Charity number 326689) requested three experienced clinicians (RA, ZH, KM) to produce essential information on the use of and equipment for PDT in the clinic. The YLC also sponsored a researcher (ID) to search and compile a detailed but non-exhaustive list of approved photosensitizing agents, pharmaceutical companies, light sources and laser manufacturers with appropriate delivery devices for PDT. Thus, this Mini -Compendium is the end result of what is hoped to be a useful adjunct for practitioners, scientists and students of PDT.

Strategies for the Nuclear Delivery of Metal Complexes to Cancer Cells

The nucleus is an essential organelle for the function of cells. It holds most of the genetic material and plays a crucial role in the regulation of cell growth and proliferation. Since many antitumoral therapies target nucleic acids to induce cell death, tumor-specific nuclear drug delivery could potentiate therapeutic effects and prevent potential off-target side effects on healthy tissue. Due to their great structural variety, good biocompatibility, and unique physico-chemical properties, organometallic complexes and other metal-based compounds have sparked great interest as promising anticancer agents. In this review, strategies for specific nuclear delivery of metal complexes are summarized and discussed to highlight crucial parameters to consider for the design of new metal complexes as anticancer drug candidates. Moreover, the existing opportunities and challenges of tumor-specific, nucleus-targeting metal complexes are emphasized to outline some new perspectives and help in the design of new cancer treatments.

Photoinactivation by UVA radiation and visible light of Candida auris compared to other fungi

In addition to the rising number of patients affected by viruses and bacteria, the number of fungal infections has also been rising over the years. Due to the increase in resistance to various antimycotics, investigations into further disinfection options are important. In this study, two yeasts (Candida auris and Saccharomyces cerevisiae) and a mold (Cladosporium cladosporioides) were irradiated at 365, 400, and 450 nm individually. The resulting log 1 reduction doses were determined and compared with other studies. Furthermore, fluorescence measurements of C. auris were performed to detect possible involved photosensitizers. A roughly exponential photoinactivation was observed for all three fungi and all irradiation wavelengths with higher D90 doses for longer wavelengths. The determined log 1 reduction doses of C. auris and S. cerevisiae converged with increasing wavelength. However, S. cerevisiae was more photosensitive than C. auris for all irradiation wavelengths and is therefore not a suitable C. auris surrogate for photoinactivation experiments. For the mold C. cladosporioides, much higher D90 doses were determined than for both yeasts. Concerning potential photosensitizers, flavins and various porphyrins were detected by fluorescence measurements. By excitation at 365 nm, another, so far unreported fluorophore and potential photosensitizer was also observed. Based on its fluorescence spectrum, we assume it to be thiamine.Graphic abstract.

Comparison of red and green light for treating non-muscle invasive bladder cancer in rats using singlet oxygen-cleavable prodrugs with PPIX-PDT

It has been 30 years since Photofrin-PDT was approved for the treatment of bladder cancer in Canada. However, Photofrin-PDT failed to gain popularity due to bladder complications. The PDT with red light and IV-administered Photofrin could permanently damage the bladder muscle. We have been developing a new combination strategy of PpIX-PDT with singlet oxygen-cleavable prodrugs for NMIBC with minimal side effects, avoiding damage to the bladder muscle layer. PpIX can be excited by either green (532 nm) or red (635 nm) light. Red light could be more efficacious in vivo due to its deeper tissue penetration than green light. Since HAL preferentially produces PpIX in tumors, we hypothesized that illuminating PpIX with red light might spare the muscle layer. PpIX-PDT was used to compare green and red laser efficacy in vitro and in vivo. The IC50 of in vitro PpIX-PDT was 18 mW/cm2 with the red laser and 22 mW/cm2 with the green laser. The in vivo efficacy of the red laser with 50, 75, and 100 mW total dose was similar to the same dose of green laser in reducing tumor volume. Combining PpIX-PDT with prodrugs methyl-linked mitomycin C (Mt-L-MMC) and rhodamine-linked SN-38 (Rh-L-SN-38) significantly improved efficacy (tumor volume comparison). PpIX-PDT or PpIX-PDT + prodrug combination did not cause muscle damage in histological analysis. Overall, a combination of PpIX-PDT and prodrug with 635 nm laser is promising for non-muscle invasive bladder cancer treatment.

Nanomaterials for light-mediated therapeutics in deep tissue

Light-mediated therapeutics, including photodynamic therapy, photothermal therapy and light-triggered drug delivery, have been widely studied due to their high specificity and effective therapy. However, conventional light-mediated therapies usually depend on the activation of light-sensitive molecules with UV or visible light, which have poor penetration in biological tissues. Over the past decade, efforts have been made to engineer nanosystems that can generate luminescence through excitation with near-infrared (NIR) light, ultrasound or X-ray. Certain nanosystems can even carry out light-mediated therapy through chemiluminescence, eliminating the need for external activation. Compared to UV or visible light, these 4 excitation modes penetrate more deeply into biological tissues, triggering light-mediated therapy in deeper tissues. In this review, we systematically report the design and mechanisms of different luminescent nanosystems excited by the 4 excitation sources, methods to enhance the generated luminescence, and recent applications of such nanosystems in deep tissue light-mediated therapeutics.

Photodynamic Therapy and Cardiovascular Diseases

Cardiovascular diseases are the third most common cause of death in the world. The most common are heart attacks and stroke. Cardiovascular diseases are a global problem monitored by many centers, including the World Health Organization (WHO). Atherosclerosis is one aspect that significantly influences the development and management of cardiovascular diseases. Photodynamic therapy (PDT) is one of the therapeutic methods used for various types of inflammatory, cancerous and non-cancer diseases. Currently, it is not practiced very often in the field of cardiology. It is most often practiced and tested experimentally under in vitro experimental conditions. In clinical practice, the use of PDT is still rare. The aim of this review was to characterize the effectiveness of PDT in the treatment of cardiovascular diseases. Additionally, the most frequently used photosensitizers in cardiology are summarized.

Mitochondrial targeting improves the selectivity of singlet-oxygen cleavable prodrugs in NMIBC treatment

Mitochondria play an essential role in cancer treatment by providing apoptotic signals. Hexyl aminolevulinate, an FDA-approved diagnosis for non-muscle invasive bladder cancer, induces the production of protoporphyrin IX (PpIX) preferentially by mitochondria in cancer cells. Photosensitizer PpIX upon illumination can release active chemotherapy drugs from singlet oxygen-activatable prodrugs. Prodrugs placed close enough to PpIX formed in mitochondria can improve the antitumor efficiency of PpIX-PDT. The preferred uptake of prodrugs by cancer cells and tumors can further enhance the selective damage of cancer cells over non-cancer cells and surrounding normal tissues. Mitochondriotropic prodrugs of anticancer drugs, such as paclitaxel and SN-38, were synthesized using rhodamine, a mitochondrial-targeting moiety. In vitro, the mitochondrial targeting helped achieve preferential cellular uptake in cancer cells. In RT112 cells (human bladder cancer cells), intracellular prodrug concentrations were 2-3 times higher than the intracellular prodrug concentrations in BdEC cells (human bladder epithelial cells), after 2 h incubation. In an orthotopic rat bladder tumor model, mitochondria-targeted prodrugs achieved as much as 34 times higher prodrug diffusion in the tumor area compared to the nontumor bladder area. Overall, mitochondria targeting made prodrugs more effective in targeting cancer cells and tumors over non-tumor areas, thereby reducing nonspecific toxicity.

Combined Photosensitive Gene Therapy Effective Against Triple-Negative Breast Cancer in Mice Model

Introduction

Tumor hypoxia and invasion present significant challenges for the efficacy of photodynamic therapy (PDT) in triple-negative breast cancer (TNBC). This study developed a mitochondrial targeting strategy that combined PDT and gene therapy to promote each other and address the challenges.

Methods

The positively charged amphiphilic material triphenylphosphine-tocopherol polyethylene glycol succinate (TPP-TPGS, TPS) and the photosensitizer chloride e6 (Ce6) formed TPS@Ce6 nanoparticles (NPs) by hydrophobic interaction. They electrostatically condensed microRNA-34a (miR-34a) to form stable TPS@Ce6/miRNA NPs.

Results

Firstly, Ce6 disrupted the lysosomal membrane, followed by successful delivery of miR-34a by TPS@Ce6/miRNA NPs. Meanwhile, miR-34a reduced ROS depletion and further enhanced the effectiveness of PDT. Consequently, the mutual promotion between PDT and gene therapy led to enhanced anti-tumor effects. Furthermore, the TPS@Ce6/miRNA NPs promoted apoptosis by down-regulating Caspase-3 and inhibited tumor cell migration and invasion by down-regulating N-Cadherin. In addition, in vitro and in vivo experiments demonstrated that the TPS@Ce6/miRNA NPs achieved excellent anti-tumor effects. These findings highlighted the enhanced anticancer effects and reduced migration of tumor cells through the synergistic effects of PDT and gene therapy.

Conclusion

Taken together, the targeted co-delivery of Ce6 and miR-34a will facilitate the application of photodynamic and genic nanomedicine in the treatment of aggressive tumors, particularly TNBC.

A photo-degradable BODIPY-modified Ru(II) photosensitizer for safe and efficient PDT under both normoxic and hypoxic conditions

Photodynamic therapy (PDT) is promising for cancer treatment but still suffers from some limitations. For instance, PDT based on 1O2 generation (in a type-II mechanism) is heavily dependent on high oxygen concentrations and will be significantly depressed in hypoxic tumors. In addition, the residual photosensitizers after PDT treatment may cause severe side-effects under light irradiation. To solve these problems, herein a BODIPY (boron dipyrromethene)-modified Ru(II) complex [Ru(dip)2(tpy-BODIPY)]2+ (complex 1, dip = 4,7-diphenyl-1,10-phenanthroline, tpy = 2,2':6',2''-terpyridine) was designed and synthesized. Complex 1 exhibited both high singlet oxygen quantum yield (Φ = 0.7 in CH3CN) and excellent superoxide radical (O2˙-) generation, and thus demonstrated efficient PDT activity under both normoxic and hypoxic conditions. Moreover, complex 1 is photo-degradable in water, and greatly loses its ROS generation ability after PDT treatment. These novel properties of complex 1 make it promising for efficient PDT under both normoxic and hypoxic conditions with reduced side-effects.

Effect of photodynamic therapy mediated by hematoporphyrin derivatives on small cell lung cancer H446 cells and bronchial epithelial BEAS-2B cells

To investigate the effects of photodynamic therapy (PDT) mediated by hematoporphyrin derivatives (HPD) on the proliferation of small cell lung cancer H446 cells and bronchial epithelial BEAS-2B cells. H446 cells and BEAS-2B cells were cultured in vitro with different concentrations of HPD(0, 5, 10, 12, 15, 20 μg/mL) for 4 h, and then irradiated with 630 nm laser with different energy densities (0, 25, 50, 75, 100 mW/cm2). Cell viability of H446 cells and BEAS-2B cells were detected by CCK8 assay. The cell apoptosis was observed with Annexin V-FTTC/PI double staining and Hoechst 33258. The RT-PCR examination was applied to detect the transcriptional changes of the mRNA of Bax、Bcl-2, and Caspase-9. The results of CCK8 showed that when the HPD was 15 μg/mL and the laser power density reached 50 mW/cm2, the cell viability was significantly decreased compared with the black control group. Hoechst 33258 staining showed that with the increase of HPD concentration, the cell density was reduced, and apoptotic cells increased. Flow cytometry assay revealed that the apoptotic rates of the HPD-PDT group of H446 cells and BEAS-2B cells were significantly different from those of the blank control group. The RT-PCR examination showed that the expression levels of Bax and Caspase-9 mRNA in the HPD-PDT group were up-regulated, while the expression levels of Bcl-2 mRNA were down-regulated significantly. HPD-PDT can inhibit H446 cells and BEAS-2B cells growth. The mechanism may be related to up-regulating the expression levels of Bax and Caspase-9 mRNA and down-regulating the expression levels of Bcl-2 mRNA.

Current Photodynamic Therapy for Glioma Treatment: An Update

Research on the development of photodynamic therapy for the treatment of brain tumors has shown promise in the treatment of this highly aggressive form of brain cancer. Analysis of both in vivo studies and clinical studies shows that photodynamic therapy can provide significant benefits, such as an improved median rate of survival. The use of photodynamic therapy is characterized by relatively few side effects, which is a significant advantage compared to conventional treatment methods such as often-used brain tumor surgery, advanced radiotherapy, and classic chemotherapy. Continued research in this area could bring significant advances, influencing future standards of treatment for this difficult and deadly disease.

Therapeutic strategies based on non-ionizing radiation to prevent venous neointimal hyperplasia: the relevance for stenosed arteriovenous fistula, and the role of vascular compliance

We have reviewed the development and current status of therapies based on exposure to non-ionizing radiation (with a photon energy less than 10 eV) aimed at suppressing the venous neointimal hyperplasia, and consequentially at avoiding stenosis in arteriovenous grafts. Due to the drawbacks associated with the medical use of ionizing radiation, prominently the radiation-induced cardiovascular disease, the availability of procedures using non-ionizing radiation is becoming a noteworthy objective for the current research. Further, the focus of the review was the use of such procedures for improving the vascular access function and assuring the clinical success of arteriovenous fistulae in hemodialysis patients. Following a brief discussion of the physical principles underlying radiotherapy, the current methods based on non-ionizing radiation, either in use or under development, were described in detail. There are currently five such techniques, including photodynamic therapy (PDT), far-infrared therapy, photochemical tissue passivation (PTP), Alucent vascular scaffolding, and adventitial photocrosslinking. The last three are contingent on the mechanical stiffening achievable by the exogenous photochemical crosslinking of tissular collagen, a process that leads to the decrease of venous compliance. As there are conflicting opinions on the role of compliance mismatch between arterial and venous conduits in a graft, this aspect was also considered in our review.

A design strategy of pure Type-I thiadiazolo[3,4-g]quinoxaline-based photosensitizers for photodynamic therapy

Most photosensitizers (PSs) for photodynamic therapy (PDT) can generate singlet oxygen through transferring energy with oxygen, called Type-II PSs. However, the microenvironment of solid tumor is usually anoxic. Type-I PSs can generate reactive oxygen species (ROS) through transferring electron to substrate, showing more efficient in PDT. But pure Type-I PSs are very rare. The relationship between PSs' chemical structure and Type-I mechanism has not been explicitly stated. In this study, two thiadiazolo [3,4-g]quinoxaline (TQ) PSs (PsCBz-1 and PsCBz-2) are synthesized through introducing carbazole groups to the 4,9-position of TQ backbone. Comparing with their prototype PS, 4,9-dibrominated TQ (TQs-4), the introduction of carbazole groups reverses the reaction mechanism of PSs from pure Type-II to pure Type-I. Excitingly, the water-dispersible nanoparticles (NPs) of PsCBz-1 can achieve strong phototoxicity in vitro under both normoxia and hypoxia through Type-I mechanism. In addition, PsCBz-1 NPs also exhibits remarkable PDT antitumor effect in vivo. This study provides a feasible design strategy for pure Type-I PSs.

Photodynamic Therapy for Eye, Ear, Laryngeal Area, and Nasal and Oral Cavity Diseases: A Review

Photodynamic therapy (PDT) has emerged as a promising modality for the treatment of various diseases. This non-invasive approach utilizes photosensitizing agents and light to selectively target and destroy abnormal cells, providing a valuable alternative to traditional treatments. Research studies have explored the application of PDT in different areas of the head. Research is focusing on a growing number of new developments and treatments for cancer. One of these methods is PDT. Photodynamic therapy is now a revolutionary, progressive method of cancer therapy. A very important feature of PDT is that cells cannot become immune to singlet oxygen. With this therapy, patients can avoid lengthy and costly surgeries. PDT therapy is referred to as a safe and highly selective therapy. These studies collectively highlight the potential of PDT as a valuable therapeutic option in treating the head area. As research in this field progresses, PDT may become increasingly integrated into the clinical management of these conditions, offering a balance between effectiveness and minimal invasiveness.

Lysosome-targeted Aza-BODIPY photosensitizers for anti-cancer photodynamic therapy

Developing effective near-infrared (NIR) photosensitizers (PSs) has been an attractive goal of photodynamic therapy (PDT) for cancer treatment. In this study, we synthesized N, N-diethylaminomethylphenyl-containing Aza-BODIPY photosensitizers and comprehensively investigated their photophysical/photochemical properties, as well as cell-based and animal-based anti-tumor studies. Among them, BDP 1 has strong NIR absorption at 680 nm and higher singlet oxygen yield in PBS which showed favorable pH-activatable and lysosome-targeting ability. BDP 1 could be easily taken up by tumor cells and showed negligible dark activity (IC50 > 50 μM), however strong phototoxicity upon exposure to light irradiation. The acceptable fluorescence emission from BDP 1 allowed convenient in vivo fluorescence imaging for organ distribution studies in mice. After PDT treatment with upon single time PDT treatment at the beginning using relatively low light dose (54 J/ cm2), BDP 1 (2 mg/kg, 0.1 mL) was found to have strong efficacy to inhibit tumor growth and even to ablate off tumor without causing body weight loss. Therefore, pH-activatable and lysosome-targeted PS may become an effective way to develop potent PDT agent.

Combining near infrared fluorescence and laser speckle imaging with optical tissue clearing for in vivo transcranial monitoring of cerebral blood vessels damaged by photodynamic nanoformulation

In vivo near infrared (NIR) fluorescence imaging and laser speckle contrast imaging (LSCI) are emerging optical bioimaging modalities, which can provide information on blood vessels morphology, volume and the blood flow velocity. Optical tissue clearing (OTC) technique addresses a light scattering problem in optical bioimaging, which is imperative for the transcranial brain imaging. Herein, we report an approach combining NIR fluorescence and LSC microscopy imaging with OTC. A liposomal nanoformulation comprising NIR fluorescent dye ICG and photosensitizer BPD was synthesized and injected intravenously into mouse with OTC treated skull. Transcranial excitation of BPD in nanoliposomes resulted in the localized, irradiation dose dependent photodynamic damage of the brain blood vessels, which was manifested both in NIR fluorescence and LSC transcranial imaging, revealing changes in the vessels morphology, volume and the blood flow rate. The developed approach allows for bimodal imaging guided, localized vascular PDT of cancer and other diseases.

Outcome of curcumin-based photodynamic therapy in endodontic microsurgery: A case report

INTRODUCTION

Persistent apical periodontitis after root canal treatment may require surgical retreatment when non-surgical options are ineffective or impractical due to anatomical challenges or iatrogenic errors. Endodontic microsurgery (EMS) is a precise technique that aims to overcome extraradicular biofilm and root morphology issues. Photodynamic therapy (PDT) is an emerging supplementary disinfection approach that utilizes a photosensitizer agent and light to eliminate microorganisms through oxidative reactions.

REPORT

A 60-year-old male with persistent apical periodontitis in a left maxillary first molar underwent non-surgical root canal retreatment followed by surgical reintervention due to anatomical complexities. During surgery, PDT was performed using a novel curcumin-based photosensitizer agent. After the procedure, the tooth was retrofilled with bioceramic cement, and photobiomodulation was applied to enhance tissue healing. One year post-surgery, the patient exhibited complete periradicular repair and remained asymptomatic.

DISCUSSION

EMS is considered a last resort to salvage an endodontically treated tooth and has shown moderate success rates. PDT has demonstrated promise in improving periapical healing and reducing microorganisms. In this case, curcumin, diluted with 2 % chlorhexidine gel, served as an effective photosensitizer agent with antimicrobial properties. Moreover, performing photobiomodulation aided in cell recovery and reduced postoperative discomfort.

CONCLUSION

The proposed EMS treatment protocol with PDT using curcumin yielded positive outcomes in this case report. Further randomized clinical trials are necessary to assess the efficacy of this approach in EMS. Additionally, further research on curcumin-based photosensitizer agents encapsulated in nanoparticles and enhanced antimicrobial agents is recommended to refine this treatment protocol for routine use.

A Review of Phototoxic Plants, Their Phototoxic Metabolites, and Possible Developments as Photosensitizers

This study provides a comprehensive overview of the current knowledge regarding phototoxic terrestrial plants and their phototoxic and photosensitizing metabolites. Within the 435,000 land plant species, only around 250 vascular plants have been documented as phototoxic or implicated in phototoxic occurrences in humans and animals. This work compiles a comprehensive catalog of these phototoxic plant species, organized alphabetically based on their taxonomic family. The dataset encompasses meticulous details including taxonomy, geographical distribution, vernacular names, and information on the nature and structure of their phototoxic and photosensitizing molecule(s). Subsequently, this study undertook an in-depth investigation into phototoxic molecules, resulting in the compilation of a comprehensive and up-to-date list of phytochemicals exhibiting phototoxic or photosensitizing activity synthesized by terrestrial plants. For each identified molecule, an extensive review was conducted, encompassing discussions on its phototoxic activity, chemical family, occurrence in plant families or species, distribution within different plant tissues and organs, as well as the biogeographical locations of the producer species worldwide. The analysis also includes a thorough discussion on the potential use of these molecules for the development of new photosensitizers that could be used in topical or injectable formulations for antimicrobial and anticancer phototherapy as well as manufacturing of photoactive devices.

ALA-PDT promotes the death and contractile capacity of hypertrophic scar fibroblasts through inhibiting the TGF-β1/Smad2/3/4 signaling pathway

BACKGROUND

Hypertrophic scars, an abnormal wound-healing response to burn injuries, are characterized by massive fibroblast proliferation and excessive deposition of extracellular matrix and collagen. 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) is a promising therapy for hypertrophic scar, details of the mechanisms remain to be elucidated. In this study, we aimed to investigate the molecular mechanisms involved in ALA-PDT against hypertrophic scar fibroblasts.

METHODS

The morphologies of hypertrophic scar fibroblasts (HSFs) treated with ALA-PDT were observed under a light microscopy. The viability of HSFs was detected using the CCK-8 assay. HSFs-populated collagen gel contraction assays were conducted to examine the fibroblast contractility and the cytotoxicity of HSFs in 3D collagen tissues were observed using confocal microscopy. The effect of ALA-PDT on TGF-β1/Smad2/3/4 signaling pathway activation and effector gene expression were verified by immunoprecipitation, western blot and real-time quantitative PCR analysis.

RESULTS

We observed significant changes in cell morphology after ALA-PDT treatment of HSFs. As ALA concentration and light dose increased, the viability of HSFs significantly decreased. ALA-PDT can significantly alleviate the contractile capacity and promote the death of HSFs induced by TGF-β1 treatment in a three-dimensional collagen culture model. TGF-β1 treatment of HSFs can significantly induce phosphorylation of Smad2/3 (p-Smad2/3) in whole cells, as well as p-Smad2/3 and Smad4 proteins into the nucleus and increase the mRNA levels of collagen 1/3 and α-SMA. ALA-PDT hampers the TGF-β1-Smad2/3/4 signaling pathway activation by inducing K48-linked ubiquitination and degradation of Smad4.

CONCLUSIONS

Our results provide evidence that ALA-PDT can inhibit fibroblast contraction and promote cell death by inhibiting the activation of the TGF-β1 signaling pathway that mediates hypertrophic scar formation, which may be the basis for the efficacy of ALA-PDT in the treatment of hypertrophic scars.

Hydrophilic Biocompatible Fluorescent Organic Nanoparticles as Nanocarriers for Biosourced Photosensitizers for Photodynamic Therapy

Most photosensitizers of interest for photodynamic therapy-especially porphyrinoids and chlorins-are hydrophobic. To circumvent this difficulty, the use of nanocarriers is an attractive strategy. In this perspective, we have developed highly water-soluble and biocompatible fluorescent organic nanoparticles (FONPs) made from citric acid and diethyltriamine which are then activated by ethlynene diamine as nanoplatforms for efficient photosensitizers (PSs). Purpurin 18 (Pp18) was selected as a biosourced chlorin photosensitizer combining the efficient single oxygen generation ability and suitable absorption in the biological spectral window. The simple reaction of activated FONPs with Pp18, which contains a reactive anhydride ring, yielded nanoparticles containing both Pp18 and Cp6 derivatives. These functionalized nanoparticles combine solubility in water, high singlet oxygen generation quantum yield in aqueous media (0.72) and absorption both in the near UV region (FONPS) and in the visible region (Soret band approximately 420 nm as well as Q bands at 500 nm, 560 nm, 660 nm and 710 nm). The functionalized nanoparticles retain the blue fluorescence of FONPs when excited in the near UV region but also show deep-red or NIR fluorescence when excited in the visible absorption bands of the PSs (typically at 520 nm, 660 nm or 710 nm). Moreover, these nanoparticles behave as efficient photosensitizers inducing colorectal cancer cell (HCT116 and HT-29 cell lines) death upon illumination at 650 nm. Half maximal inhibitory concentration (IC50) values down to, respectively, 0.04 and 0.13 nmol/mL were observed showing the potential of FONPs[Cp6] for the PDT treatment of cancer. In conclusion, we have shown that these novel biocompatible nanoparticles, which can be elaborated from biosourced components, both show deep-red emission upon excitation in the red region and are able to produce singlet oxygen with high efficiency in aqueous environments. Moreover, they show high PDT efficiency on colorectal cancer cells upon excitation in the deep red region. As such, these functional organic nanoparticles hold promise both for PDT treatment and theranostics.

M1 macrophage-derived exosome for reprograming M2 macrophages and combining endogenous NO gas therapy with enhanced photodynamic synergistic therapy in colorectal cancer

Reprogramming immunosuppressive M2 macrophages into M1 macrophages in tumor site provides a new strategy for the immunotherapy of colorectal cancer. In this study, M1 macrophage-derived exosome nanoprobe (M1UC) with Ce6-loaded upconversion material is designed to enhance the photodynamic performance of Ce6 while reprogramming M2 macrophages at tumor site and producing NO gas for three-mode synergistic therapy. Under the excitation of near-infrared light at 808 nm, the probe can generate 660 nm up-conversion fluorescence, which enables the photosensitizer Ce6 to produce ROS efficiently. In addition, the probe leads the production of NO by nitric oxide synthase on exosomes. Confocal laser and flow cytometry results show that M1UC probe reprograms M2 macrophages into M1 macrophages with an efficiency of 95.12%. The cell experiments show that the apoptosis rate of the three-mode synergistic therapy group is 78.8%, and the therapeutic effect is significantly higher than those of the other single treatment groups. In vivo experiments results show that M1UC probes maximally gather at the tumor site after 12 h of intravenous injection in orthotopic colorectal cancer mice. After 808 nm laser irradiation, the survival rate of mice is 100% and the recurrence rate was 0 within 60 d, and the therapeutic effect is significantly higher than those of other single treatment groups, which is also confirmed by immunohistochemistry. This M1 macrophage-derived exosome nanoplatform which is based on the three modes of immunotherapy, gas therapy and photodynamic therapy, provides a new design idea for the diagnosis and treatment of deep tumors.

Photodynamic Therapy: Current Trends and Potential Future Role in the Treatment of Bladder Cancer

Bladder cancer (BC) is the 10th most common cancer in the world. The therapeutic spectrum of BC is broad and is constantly expanding. Despite the wide clinical use of photodynamic diagnosis (PTD) for BC, PDT has not been sufficiently investigated in the treatment landscape of BC. We performed an online search of the PubMed database using these keywords: photodynamic therapy, bladder cancer, urothelial carcinoma, in vivo, in vitro, cell line, animal model. Reviews, case reports, and articles devoted to photodynamic diagnostics and the photodynamic therapy of tumors other than urothelial carcinoma were excluded. Of a total of 695 publications, we selected 20 articles with clinical data, 34 articles on in vivo PDT, and 106 articles on in vitro data. The results presented in animal models highlight the potential use of PDT in the neoadjuvant or adjuvant setting to reduce local recurrence in the bladder and upper urinary tracts. Possible regimens include the combination of PDT with intravesical chemotherapy for improved local tumor control or the integration of vascular-targeted PDT in combination with modern systemic drugs in order to boost local response. We summarize available evidence on the preclinical and clinical application of PDT for urothelial carcinoma in order to explain the current trends and future perspectives.

Turning on Singlet Oxygen Generation by Outer-Sphere Microenvironment Modulation in Porphyrinic Covalent Organic Frameworks for Photocatalytic Oxidation

Singlet oxygen (1 O2 ) is ubiquitously involved in various photocatalytic oxidation reactions; however, efficient and selective production of 1 O2 is still challenging. Herein, we reported the synthesis of nickel porphyrin-based covalent organic frameworks (COFs) incorporating functional groups with different electron-donating/-withdrawing features on their pore walls. These functional groups established a dedicated outer-sphere microenvironment surrounding the Ni catalytic center that tunes the activity of the COFs for 1 O2 -mediated thioether oxidation. With the increase of the electron-donating ability of functional groups, the modulated outer-sphere microenvironment turns on the catalytic activity from a yield of nearly zero by the cyano group functionalized COF to an excellent yield of 98 % by the methoxy group functionalized one. Electronic property investigation and density-functional theory (DFT) calculations suggested that the distinct excitonic behaviors attributed to the diverse band energy levels and orbital compositions are responsible for the different activities. This study represents the first regulation of generating reactive oxygen species (ROS) based on the strategy of outer-sphere microenvironment modulation in COFs.