Photodynamic therapy of cancer. Basic principles and applications

Photophysics and photochemistry of a prospective light-activated anticancer dirhodium complex

Dirhodium complexes Rh(II,II) with organic ligands are known to demonstrate light-induced cytotoxicity, combining both oxygen-dependent (like in the case of photodynamic therapy, PDT) and oxygen-independent (like in the case of photo-activated chemotherapy, PACT) anticancer activity. Photophysics and photochemistry of the previously reported light-activated anticancer dirhodium complex cis-[Rh2(μ-O2CCH3)2(dppn)2](O2CCH3)2 (dppn = benzo[i]dipyrido[3,2-a:2',3'-c]phenazine) were studied by means of several stationary (UV spectroscopy and capillary electrophoresis) and time-resolved (laser flash photolysis, ultrafast TA spectroscopy and direct singlet oxygen detection) methods. The only observed photochemical reaction is photoaquation with the release of an acetate ligand; its quantum yield is low (0.026%). The quantum yields of singlet oxygen formation in different solvents (D2O, CH3CN, and CD3OD) lie in the range (2-8)%, which is consistent with the presumably oxygen-independent pathway of light-induced cell-damage reported in the literature. Complicated behavior of intermediate absorption in the time interval from 100 fs to 20 μs was interpreted by "ladder" transitions between excited states of different nature, 1IL* → 3IL* → 3MLCT* → 3MC*. The lifetime of the longest-living excited state 3MC* is 6.2 μs. Estimations show that the oxygen-independent light-induced cytotoxic effect could be provided even without preliminary binding of the complex to the substrate.

Research progress of co-delivery nanoparticle drug delivery systems in non-small cell lung cancer: A review

Non-small cell lung cancer (NSCLC), as the most commonly diagnosed type of lung cancer, has long been a major focus for cancer drug researchers. Traditional chemotherapy has shown significant efficacy in patients initially diagnosed with NSCLC; however, with the emergence of drug resistance and notable toxic side effects, conventional and single-agent chemotherapy can no longer meet the treatment needs of patients. Nanomedicine systems have gained widespread attention among scholars due to their unique advantages, such as particle size, stable in vivo circulation, and multifunctional carrier materials. However, most single-drug delivery systems fail to meet the treatment expectations for NSCLC patients, prompting the active development of co-delivery nanomedicine systems in preclinical NSCLC research. These systems can utilize surface-modified carriers to co-deliver drugs, genes, photosensitizers, or sonosensitizers with different mechanisms of action. This approach not only achieves the synergistic effects of multiple drugs, multiple pathways, and the combination of chemotherapy with photodynamic/sonodynamic therapy but also, through the encapsulation of inorganic materials, allows for more controllable drug release under external forces such as magnetic fields. This further amplifies the synergistic effects between the drugs, and the results of these studies are significantly superior to those of single-drug treatments. In conclusion, this review summarizes the delivery strategies and the extended use of inorganic materials in the co-delivery of nanoparticles for NSCLC research in recent years, with the hope of providing reference for researchers' drug design strategies.

Protoporphyrin IX-Derived Ruthenium(II) Complexes for Photodynamic Therapy in Gastric Cancer Cells

In recent years, photodynamic therapy (PDT) has emerged as a promising alternative to classical chemotherapy for treating cancer. PDT is based on a nontoxic prodrug called photosensitizer (PS) activated by light at the desired location. Upon irradiation, the PS reacts with the oxygen present in the tumor, producing cytotoxic reactive oxygen species (ROS). Compounds with highly conjugated π-bond systems, such as porphyrins and chlorins, have proven to be excellent light scavengers, and introducing a metal atom in their structure improved the generation of ROS. In this work, a series of tetrapyrrole-ruthenium(II) complexes derived from protoporphyrin IX and the commercial drug verteporfin were designed as photosensitizers for PDT. The complexes were almost nontoxic on human gastric cancer cells under dark conditions, revealing remarkable cytotoxicity upon irradiation with light. The ruthenium atom in the central cavity of the chlorin ligand allowed combined mechanisms in photodynamic therapy, as both singlet oxygen and superoxide radicals were detected. Additionally, one complex produced large amounts of singlet oxygen under hypoxic conditions. Biological assays demonstrated that the ruthenium derivatives caused cell death through a caspase 3 mediated apoptotic pathway and via CHOP, an endoplasmic reticulum stress-inducible transcription factor involved in apoptosis and growth arrest.

Recent Progress of Molecular Design in Organic Type I Photosensitizers

Photodynamic therapy (PDT) represents a high-efficient and non-invasive therapeutic modality for current and future tumor treatments, drawing extensive attention in the fields of antitumor drug and clinical phototherapy. In recent years, the photosensitizer (PS) market and PDT clinical applications have expanded to address various cancers and skin diseases. However, hypoxic environment within tumors poses a substantial challenge to the therapeutic capability of reactive oxygen species-dependent PDT. Consequently, researches have increasingly focus from the type II to type I PDT mechanism, which relies on radical production with less or no oxygen dependence. Despite significant progress in the development of type I PSs, a holistic understanding regarding the design principles for these molecules remains elusive. Specifically, electron transfer-mediated type I PDT are extensively studied in recent years but is insufficiently addressed in existing reviews. This review systematically summarizes recent advancements in the molecular design rationales of organic type I PSs, categorizing them into three key fundamental strategies: modulating PS charge distribution, singlet oxygen forbidden via low triplet excited state, and accelerating PS radical formation via inducing electron transfer. This review aims to offer valuable insights for the future type I PS design and the advancement of anti-hypoxia PDT.

A carnitine-based BODIPY photosensitizer

Organelle-selective photodynamic therapy (PDT) has emerged as a promising approach to enhance the precision and efficacy of cancer treatment by targeting key cellular structures. In this study, we report the design of a novel carnitine-based BODIPY photosensitizer, probe 1, which retains mitochondrial selectivity while acting as both a fluorescent probe and a potent photosensitizer. Building on our previously developed mitochondria-targeting probe (R)-BCT-2, which is transported into the mitochondrial matrix by the inner membrane protein carnitine-acylcarnitine translocase (CAC), probe 1 incorporates two bromine atoms that enhance intersystem crossing, leading to a singlet oxygen quantum yield of ∼80%, while retaining sufficient fluorescence for effective cell staining in fluorescence microscopy. Theoretical calculations indicate that the carnitine moiety distorts chromophore planarity, reducing oscillator strength but enhancing spin-orbit coupling, which, together with the extended triplet lifetime, contributes to increased phototoxicity. Probe 1 co-localizes in both mitochondria and, to a lesser extent, in lysosomes, and this dual targeting may synergistically enhance phototoxic activity by amplifying cellular stress responses. Importantly, probe 1 demonstrated high phototoxicity upon green light irradiation, with IC50 values of 52 nm under normoxia and 117 nm under hypoxia, while remaining non-cytotoxic in the dark. These results suggest that probe 1 is a promising candidate for organelle-targeted PDT, particularly in hypoxic tumor environments where its dual organelle targeting could enhance therapeutic efficacy.

Bismuth doped carbon nanospheres conjugated to boronated porphyrins for photodynamic therapy

Novel 4- (5,10,15)-tris-boronphenyl-20-(4-formylphenoxy) porphyrin (complex 1) and its Zn-metalated derivative (complex 2) were synthesized and conjugated to bismuth doped carbon nanospheres (BiCNS) through non-covalent bonds (π-π). The conjugation of BiCNS to porphyrin complexes enhanced the singlet oxygen production of porphyrin complexes, as it was observed that porphyrin complex 1 gave a singlet oxygen quantum yield (Φ∆) value of 0.17 and complex 2 gave Φ∆ of 0.23, and upon conjugation with BiCNS the Ф∆ values increased to 0.52 and 0.67, respectively. Photodynamic therapy (PDT) studies were performed against MDA-MB-231 breast cancer cell line using these complexes and their conjugates and it was observed that BiCNS conjugates resulted in enhanced PDT activity when compared to CNS conjugates. Conjugates 2-CNS, and 2-BiCNS at the concentration of 100 µg/mL they resulted with cell viabilities of 28.43 and 26.82 %, respectively.

Photoactivated Rose Bengal Triggers Phospholipid Hydroperoxidation and Late Apoptosis in Colorectal Cancer Cells

Rose Bengal (RB) is a promising photosensitizer (PS) for photodynamic therapy (PDT), but its application to colorectal carcinoma remains largely unexplored. Herein, we employ in vitro assays to demonstrate that incorporation of RB has substantial phototoxicity against Caco-2 cells, with more than 80% reduction in cell viability for 24 h incubation with 5 × 10-6 mol/L RB followed by irradiation. In contrast, RB had minimal toxicity without irradiation. The mechanisms of RB action were further elucidated using confocal fluorescence microscopy, Langmuir monolayers as cell membrane models, and flow cytometry to determine the cell death pathways. Flow cytometry revealed that the primary mode of cell death was late apoptosis. RB incorporation affected Caco-2 plasma membrane morphology under light irradiation, and membrane interactions were confirmed using Langmuir monolayers of Caco-2 lipid extracts. Incorporation of RB into the monolayers shifted the pressure-area isotherms toward larger molecular areas, especially at low surface pressures and increasing RB concentrations (1, 10, and 25 × 10-6 mol/L). RB adsorption also caused a decrease in the in-plane elasticity (Cs1-) of the Caco-2 monolayers, with a large increase in monolayer flexibility as RB concentration increased. According to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), the anionic RB interacted electrostatically with positively charged phospholipid groups. Moreover, the changes in surface area observed in the monolayers upon RB incorporation and irradiation could be attributed to hydroperoxidation reactions triggered by the generation of singlet oxygen (1O2). These findings indicate that RB may be used as a PS in the PDT of colorectal cancer, providing detailed insights into its mechanism of action and phototoxicity.

5-Aminolaevulinic Acid-Mediated Photodynamic Therapy Combined with Tirapazamine Enhances Efficacy in Ovarian Cancer

Objectives: Ovarian cancer is a common gynaecological malignancy. Photodynamic therapy (PDT) mediated by 5-aminolaevulinic acid (5-ALA-PDT) is widely used in clinical practice. However, hypoxia may impact the efficacy of this treatment. In the present study, we combined the bioreductively active drug tirapazamine (TPZ) with PDT to explore its potential in enhancing ovarian cancer cell death. Methods: A cell counting kit-8 assay was used to determine cytotoxicity under different intervention conditions. The distribution of protoporphyrin IX, a metabolite of 5-ALA, was observed using in vivo fluorescence imaging. The effect of the combined treatment was assessed by measuring changes in tumour size following the corresponding interventions and by haematoxylin and eosin staining of tumour tissues. Immunohistochemical staining was used to detect the expression levels of relevant proteins. Results: TPZ exhibited no cytotoxicity under normoxic conditions but was activated under hypoxic conditions, inducing cytotoxic effects that were enhanced when combined with PDT. Over time, protoporphyrin IX achieved systemic distribution, and high drug concentrations were maintained within the tumour. The combination therapy suppressed tumour growth, and pathological staining showed that necrotic tumour areas were significantly enlarged after treatment. The enhanced therapeutic effect may be attributable to the inhibition of the hypoxia-inducible factor-1α/vascular endothelial growth factor axis and PI3K/Akt/mTOR pathway. Conclusions: 5-ALA-PDT combined with TPZ can overcome both the hypoxic state of ovarian cancer tissues and the increased hypoxia induced by PDT, thereby inhibiting tumour growth.

Preparation of aggregation-free ZnPc-doped nanophotosensitizers for highly efficient photodynamic therapy

Zinc phthalocyanine (ZnPc), a promising second-generation photosensitizer, suffers from decreased quantum yield of singlet oxygen due to poor water solubility and prone-to-aggregation nature in both physiological environment and solid matrix. To address this issue, in this work we reported a simple ligand-assisted reprecipitation method to prepare aggregation-free ZnPc-doped nanoparticles (NPs). Specifically, a short-chain ligand hexylamine was introduced to coordinate with ZnPc during reprecipitation, so that to alleviate ZnPc aggregation in the polymeric nanomatrix. As a consequence, the as-prepared ZnPc-loaded NPs with an optimal loading content of 4 wt.% acquired a high singlet oxygen quantum yield (ΦΔ) of 0.5, which was comparable to that of ZnPc monomer (ΦΔ= 0.55). Moreover, 10 wt.% ZnPc-loaded NPs could still retain a singlet oxygen quantum yield of 0.38. Taking advantage of the aggregation-free nano-photosensitizers (NPSs), efficient photodynamic therapy effect was achieved on HeLa cells upon 660 nm photo-irradiation with an ultra-low light dose (1.8 J cm-2). This study not only presented a high efficient ZnPc-based NPS, but also proposed a new strategy to reduce the aggregation of metal complex in solid matrix through ligand coordination.

Reactive oxygen species switcher via MnO2-coated Prussian blue loaded hyaluronic acid methacrylate hydrogel microspheres for local anti-tumor treatment

ROS-induced therapy can eradicate breast tumors when combined with thermal ablation, but excessive ROS also threatens peritumoral tissue with inflammation. To eradicate tumors and avoid inflammatory sequela, it is necessary to generate ROS in treatment stage and scavenge ROS in prognostic stage. However, it is a great challenge to reverse ROS in different stages. Herein, the "ROS switcher" of MnO2-coated Prussian blue (PM) is loaded in hyaluronic acid methacrylate (HAMA) hydrogel microspheres, combining ROS generation by Mn-mediated Fenton-like reaction, and ROS scavenging by Fe3+/2+ electron transfer. Firstly, it is ROS generator that oxidatively damages biomacromolecules in residual tumors, then it is ROS scavenger that reduces pro-inflammatory cytokines and oxidation stress in peritumoral skin. Glucose oxidase is immobilized in HAMA microspheres to enhance ROS supply by catalyzing glucose into H2O2, degrading MnO2 into Mn2+, and providing H2O2 for a Fenton-like reaction. After MnO2 degradation, Prussian blue is gradually exposed and scavenges ROS, thus defending oxidative skin damage and alleviating ROS-stimulated inflammation. In vitro results indicate that the microsphere supplied sustained ROS for up to 5 days, and H2O2-degraded PM (0.2 mg mL-1) scavenged 500 μM H2O2. In vivo results confirm that 4/6 breast tumors were eradicated while pro-inflammatory cytokines were significantly reduced with ROS level in peri-tumoral skin. In summary, ROS switcher is developed by Mn-mediated nano-shell peeling and achieves tumor eradication and post-operative skin repair after thermal ablation of the breast tumor.

Impact of the hydrophilic-lipophilic balance of free-base and Zn(II) tricationic pyridiniumporphyrins and irradiation wavelength in PDT against the melanoma cell lines

The amphiphilic and asymmetric structure of porphyrins, when used as photosensitizers (PSs) for photodynamic therapy (PDT), has been shown through numerous previous studies to be a very important property that facilitates their entry into cells, which improves their efficiency in PDT. In this work, two groups of cationic AB3 pyridiniumporphyrins, free-base and chelated with Zn(II), both substituted with alkyl chains of various lengths, were studied in PDT on melanoma cell lines. The aim was to investigate the impact of hydrophilic-lipophilic balance and Zn(II) chelation, and the importance of matching the irradiation wavelength to the optical properties of the PS on in vitro PDT efficiency. Therefore, spectroscopic studies, singlet oxygen production and lipophilicity as well as cellular uptake, localization and cytotoxicity studies of the two series of porphyrins were performed. In both series of porphyrins, the longest alkyl chain (17 C-atoms long) enables the greatest internalization of the PS. Chelation with Zn(II) resulted in better physicochemical properties, but slower cellular internalization. As expected, free-base porphyrins were more PDT efficient than their Zn(II) complexes after 30-min photoactivation by low-fluence (2 mW/cm2) red light (643 nm). However the use of orange light (606 nm) with the same fluence rate was more suitable for Zn(II) porphyrins and resulted in similar overall toxicity to their free-base analogues with similar lipophilicity. Although the highest phototoxicity was achieved with the PSs carrying the longest alkyl chain, TMPyP3-C13H27 and Zn(II)-TMPyP3-C13H27 proved to be the most promising candidates for use in PDT as they exhibit high phototoxicity, but also greater selectivity towards melanoma cell lines (MeWo and A375) compared to fibroblasts (HDF).

The application of photodynamic therapy in recurrent genital herpes

BACKGROUND

Frequently, recurrence of genital herpes imposes significant physical and psychological burdens on patients, and existing treatments are often ineffective in preventing recurrence. Previous studies have indicated that photodynamic therapy (PDT) showed promising outcomes in the treatment of labial herpes simplex virus (HSV) infections; however, its efficacy for genital herpes remained unclear.

METHOD

The study screened patients with genital herpes at Daping Hospital from July 2020 to May 2024. Patients were divided into two groups based on whether they received PDT treatment. Over a one-year follow-up period, patients' healing time and recurrence rates were compared between the two groups. The cumulative incidence of recurrence and restricted mean survival time (RMST) were used to assess outcomes. Propensity score matching (PSM) was employed to minimize bias.

RESULT

A total of 41 patients enrolled in our study, with 8 (19.5 %) received PDT. The non-PDT group exhibited a slower skin lesion healing time, averaging at 7.2 days compared to 5.4 days in the PDT group. A significant difference was observed in the cumulative incidence of recurrence between the PDT and non-PDT groups (37.5 % versus 71.4 %) after PSM. The RMST in the PDT group was 9.94 days, compared to 5.13 days in the non-PDT group before PSM, and 4.14 after PSM.

CONCLUSION

Our study demonstrated that the PDT effectively reduced lesion recovery time and delayed recurrences of genital herpes. We recommend considering PDT as a potential treatment option for patients with recurrent genital herpes.

A simple hydrogen peroxide-activatable Bodipy for tumor imaging and type I/II photodynamic therapy

Tumor microenvironment-activatable photosensitizers have gained significant attention for cancer theranostics. Considering the hypoxic environment of solid tumors, activatable phototheranostic agents with type I PDT are desired to obtain improved cancer treatment efficiency. Herein, we report a simple, effective and multifunctional Bodipy photosensitizer for tumor imaging and type I/II photodynamic therapy. The photosensitizer featuring a methylphenylboronic acid pinacol ester group at the meso-position of Bodipy specifically responds to tumor-abundant H2O2. Its photophysical properties were characterized using steady-state and time-resolved transient optical spectroscopies. The fluorescence (ΦF = 0.09%) and singlet oxygen efficacy (ΦΔ = 10.2%) of the Bodipy units were suppressed in the caged dyads but significantly enhanced (ΦF = 0.72%, ΦΔ = 20.3%) upon H2O2 activation. Fluorescence emission spectroscopy and continuous wave electron paramagnetic resonance (EPR) spectroscopy confirmed that the Bodipy photosensitizer generates reactive oxygen species (ROS) via both electron transfer-mediated type I and energy transfer-mediated type II mechanisms. In vitro experiments demonstrated rapid internalization into tumor cells, enhanced brightness stimulated by tumor microenvironments, and tumor cell death (phototoxicity, IC50 = 0.5 μM). In vivo fluorescence imaging indicated preferential accumulation of this Bodipy photosensitizer in tumor sites, followed by decaging by tumor-abundant H2O2, further elevating the signal-to-background ratio (SBR) of imaging. Besides outstanding performance in tumor imaging, a prominent inhibition of tumor growth was observed. Given its simple molecular skeleton, this Bodipy photosensitizer is a competitive candidate for cancer theranostics.

Light-activated hypoxia-sensitive biomimetic decoy efficiently cascading photodynamic-chemo therapy for breast cancer

The hypoxic microenvironment within the tumor microenvironment of breast cancer imposes a challenge in overcoming chemotherapy resistance. In this investigation, we designed a novel strategy utilizing a light-controlled cascade targeting nanomedicine specifically tailored for enhanced immune therapy of breast cancer. Albumin nanoparticle was achieved by crosslinking, followed by loading TPZ and Ce6, and subsequent modification to enable selective binding with CD44 hyaluronic acid to form nanomedicine. Encouragingly, it was demonstrated the remarkable ability of the nanomedicine to effectively internalize into cellular entities, thereby inducing apoptosis in 4T1 cells efficiently in vitro when exposed to light irradiation. In vivo assessments showcased the exceptional aptitude of the nanomedicine not only for preferential accumulation within tumor tissues, but also for substantial suppression of tumor growth. Immune mechanisms have shown that nanomedicine treatment promoted the maturation of DCs in vivo, enhanced the proportion of CD8+ T cells in the spleen and tumor, and simultaneously upregulated the ratio of M1 macrophages favorable for anti-tumor effects. These outcomes collectively advance a fresh perspective for the clinical breast cancer therapy.

Photodynamic therapy with curcumin and near-infrared radiation as an antitumor strategy to glioblastoma cells

Glioblastoma is a malignant neoplasm that develops in the central nervous system and is characterized by high rates of cell proliferation and invasion, presenting resistance to treatments and a poor prognosis. Photodynamic therapy (PDT) is a therapeutic modality that can be applied in oncological cases and stands out for being less invasive. Photosensitizers (PS) of natural origin gained prominence in PDT. Curcumin (CUR) is a natural compound that has been used in PDT, considered a promising PS. In this work, we evaluated the effects of PDT-mediated CUR and near-infrared radiation (NIR) in glioblastoma cells. Through trypan blue exclusion analysis, we chose the concentration of 5 μM of CUR and the dose of 2 J/cm2 of NIR that showed better responses in reducing the viable cell number in the C6 cell line and did not show cytotoxic/cytostatic effects in the HaCat cell line. Our results show that there is a positive interaction between CUR and NIR as a PDT model since there was an increase in ROS levels, a decrease in cell proliferation, increase in cytotoxicity with cell death by autophagy and necrosis, in addition to the presence of oxidative damage to proteins. These results suggest that the use of CUR and NIR is a promising strategy for the antitumor application of PDT.

Quantification of cellular phototoxicity of organelle stains by the dynamics of microtubule polymerization

Being able to quantify the phototoxicity of dyes and drugs in live cells allows biologists to better understand cell responses to exogenous stimuli during imaging. This capability further helps to design fluorescent labels with lower phototoxicity and drugs with better efficacy. Conventional ways to evaluate cellular phototoxicity rely on late-stage measurements of individual or different populations of cells. Here, we developed a quantitative method using intracellular microtubule polymerization as a rapid and sensitive marker to quantify early-stage phototoxicity. Implementing this method, we assessed the photosensitization induced by organelle dyes illuminated with different excitation wavelengths. Notably, fluorescent markers targeting mitochondria, nuclei, and endoplasmic reticulum exhibited diverse levels of phototoxicity. Furthermore, leveraging a real-time precision opto-control technology allowed us to evaluate the synergistic effect of light and dyes on specific organelles. Studies in hypoxia revealed enhanced phototoxicity of Mito-Tracker Red CMXRos that is not correlated with the generation of reactive oxygen species but a different deleterious pathway in low oxygen conditions.

Advances in two-photon absorption photodynamic therapy of glioma based on porphyrin-based metal-organicframework composites

Gliomas of the brain are characterised by high aggressiveness, high postoperative recurrence rate, high morbidity and mortality, posing a great challenge to clinical treatment. Traditional treatments include surgery, radiotherapy and chemotherapy; they also have significant associated side effects, leading to difficulties in tumour resection and recurrence. Photodynamic therapy has been shown to be a promising new strategy to help treat malignant tumours of the brain. It irradiates the tumour site at a specific wavelength to activate a photosensitiser, which selectively accumulates at the tumour site, triggering a photochemical reaction that destroys the tumour cells. It has the advantages of being minimally invasive, highly targeted and with few adverse reactions, and is expected to be well used in anti-tumour therapy. However, the therapeutic effect of traditional PDT is limited by the weak tissue penetration ability of photosensitiser, hypoxia and immunosuppression in the tumour microenvironment. This paper reviews the current research status on the therapeutic principle of photodynamic therapy in glioma and the mechanism of tumour cell injury, and also analyses the advantages and disadvantages of the current application in glioma treatment, and clarifies the analysis of ideas to improve the tissue penetration ability of photosensitizers. It aims to provide a feasible direction for the improvement of photodynamic therapy for glioma and a reference for the clinical treatment of deep brain tumours.

Exploiting G-Quadruplex-DNA Damage as a Tool to Quantify Singlet Oxygen Production

G-Quadruplexes (G4s) are highly dynamic and polymorphic nucleic acid structures that can adopt a variety of conformations. When exposed to oxidative conditions, more specifically singlet oxygen, the guanosine nucleobases can be oxidized, which in turn can affect the conformation and folding of the G4. Based on this peculiar phenomenon, it is rationalized that G4s can serve as quantification sensors for the production of singlet oxygen. Here, a method for determining the quantum yield of singlet oxygen generation for visible as well as UV-light excited photosensitizers, using a short G4 DNA sequence, readily available from common DNA companies, as a biological and water-soluble probe, is presented.

Studies related to the enhanced the effect of 5-aminolevulinic acid-based photodynamic therapy combined with tirapazamine

OBJECTIVE

5-aminolevulinic acid (5-ALA) is a precursor of the photosensitizer Protoporphyrin IX (PpIX) and photodynamic therapy (PDT) with 5-ALA has been used in clinical practice. However, tumor cellular hypoxia severely affects the efficiency of photodynamic therapy. In this study, photodynamic therapy was combined with tirapazamine to investigate the effects of the combined intervention and the related mechanisms it may involve.

METHODS

Colony formation assays were used to demonstrate cell proliferation. Transwell assays were performed to observe the effect on cell invasion and metastasis after the corresponding intervention. DCFH-DA probe was used to detect the reactive oxygen species content. Flow cytometry was used to detect the effects of the interventions on apoptosis and cell cycle. The relevant pathways that may be involved are explored by examining the expression levels of the relevant proteins and genes.

RESULTS

Colony formation assays indicated that the combined intervention inhibited cell proliferation. Transwell assays demonstrated that PDT combined with TPZ effectively inhibited tumor cell invasion and metastasis. In addition, fluorescence intensity generated by DCFH-DA oxidation was detected indicating that the combined intervention increased the formation of reactive oxygen species. Flow cytometry clearly showed that the combination of PDT and TPZ further increased apoptosis and cell cycle arrest. The results of western blotting and qRT-PCR experiments confirmed that the combination therapy inhibited HIF-1α/VEGF axis and the PI3K/Akt/mTOR pathway activation.

CONCLUSION

5-ALA-PDT combined with TPZ can inhibit cell proliferation, increase apoptosis, and inhibit the PI3K/Akt/mTOR pathway, thus inhibiting tumor growth and metastasis and improving anti-cancer effects.

Nanozyme Decorated Metal-Organic Framework Nanosheet for Enhanced Photodynamic Therapy Against Hypoxic Tumor

INTRODUCTION

Photodynamic therapy (PDT) has attracted increasing attention in the clinical treatment of epidermal and luminal tumors. However, the PDT efficacy in practice is severely impeded by tumor hypoxia and the adverse factors associated with hydrophobic photosensitizers (PSs), including low delivery capacity, poor photoactivity and limited ROS diffusion. In this study, Pt nanozymes decorated two-dimensional (2D) porphyrin metal-organic framework (MOF) nanosheets (PMOF@HA) were fabricated and investigated to conquer the obstacles of PDT against hypoxic tumors.

MATERIALS AND METHODS

PMOF@HA was synthesized by the coordination of transition metal iron (Zr4+) and PS (TCPP), in situ generation of Pt nanozyme and surface modification with hyaluronic acid (HA). The abilities of hypoxic relief and ROS generation were evaluated by detecting the changes of O2 and 1O2 concentration. The cellular uptake was investigated using flow cytometry and confocal laser scanning microscopy. The SMMC-7721 cells and the subcutaneous tumor-bearing mice were used to demonstrate the PDT efficacy of PMOF@HA in vitro and in vivo, respectively.

RESULTS

Benefiting from the 2D structure and inherent properties of MOF materials, the prepared PMOF@HA could not only serve as nano-PS with high PS loading but also ensure the rational distance between PS molecules to avoid aggregation-induced quenching, enhance the photosensitive activity and promote the rapid diffusion of generated radical oxide species (ROS). Meanwhile, Pt nanozymes with catalase-like activity effectively catalyzed intratumoral overproduced H2O2 into O2 to alleviate tumor hypoxia. Additionally, PMOF@HA, with the help of externally coated HA, significantly improved the stability and increased the cell uptake by CD44 overexpressed tumor cells to strengthen O2 self-supply and PDT efficacy.

CONCLUSION

This study provided a new strategy of integrating 2D porphyrin MOF nanosheets with nanozymes to conquer the obstacles of PDT against hypoxic tumors.

An intelligent NIR-IIb-responsive lanthanide@metal-organic framework core-shell nanocatalyst for combined deep-tumor therapy

The ground-breaking combination of photodynamic therapy (PDT) and photothermal therapy (PTT) has attracted much attention in medical fields as an effective method for fighting cancer. However, evidence suggests that the therapy efficiency is still limited by shallow light penetration depth and poor photosensitizer loading capacity. Herein, we constructed an upconversion nanoparticle@Zr-based metal-organic framework@indocyanine green molecule (UCNPs@ZrMOF@ICG) nanocomposite to integrate 1532 nm light-triggered PDT and 808 nm light-mediated PTT. NaLnF4 nanoparticles are designed to emit upconversion luminescence (UCL) under 1532 nm laser excitation, which is consistent with the absorption spectra of the ZrMOF. Benefiting from the excellent energy transfer efficiency, the ZrMOF can absorb visible light from the UCNPs and then catalyze O2 into 1O2 for deep tissue PDT. To achieve combination therapy, the clinically approved ICG nanocomposite was introduced as a photothermal agent for PTT under 808 nm laser irradiation, and the photothermal conversion efficiency was calculated to be ∼28%. The designed nanosystems facilitate efficient deep-tissue tumor treatment by integrating PDT with PTT. Ultimately, this study creates a multifunctional nanocomposite by combining 1532 nm light-triggered deep tissue PDT and near-infrared (NIR) light-driven PTT for personalized cancer therapy.

Tumor oxygen microenvironment-tailored electron transfer-type photosensitizers for precise cancer therapy

The oxygen level in a tumor typically exhibits complex characteristics, ranging from mild hypoxia to moderate and even severe hypoxia. This poses significant challenges for the efficacy of photodynamic therapy, where oxygen is an essential element. Herein, we propose a novel therapeutic strategy and develop a series of lipid droplet-targeting photosensitive dyes (Ser-TPAs), i.e., in situ synergistic activation of two different electron transfer-type reactions. Based on this strategy, Ser-TPAs can synergistically generate O2˙- and nitrogen radicals regardless of the oxygen content, which results in a sustained high concentration of strongly oxidizing substances in the lipid droplets of cancer cells. As such, Ser-TPAs exhibited inhibitory activity against tumor growth in vivo, resulting in a significant reduction in tumor volume (V experimental group : V control group ≈ 0.07). This strategy offers a conceptual framework for the design of innovative photosensitive dyes that are suitable for cancer therapy in complex oxygen environments.

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

BACKGROUND

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

PURPOSE

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

METHODS

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

RESULTS

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

Self-Reporting Conjugated Polymer Nanoparticles for Superoxide Generation and Detection

Conjugated polymer nanoparticles (CPNs or Pdots) have become increasingly popular fluorophores for multimodal applications that combine imaging with phototherapeutic effects. Reports of CPNs in photodynamic therapy applications typically focus on their ability to generate singlet oxygen. Alternatively, CPN excited states can interact with oxygen to form superoxide radical anion and a CPN-based hole polaron, both of which can have deleterious effects on fluorescence properties. Here, we demonstrate that CPNs prepared from the common conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1',3}-thiadiazole)] (PFBT, also known as F8BT) generate superoxide upon irradiation. We use the same CPNs to detect superoxide by doping them with a superoxide-responsive hydrocyanine dye developed by Murthy and co-workers. Superoxide induces off-to-on fluorescence switching by converting quenching hydrocyanine dyes to fluorescent cyanine dyes that act as fluorescence resonance energy transfer (FRET) acceptors for PFBT chromophores. Amplified FRET from the multichromophoric CPNs yields fluorescence signal intensities that are nearly 50 times greater than when the dye is excited directly or over 100 times greater when signal readout is from the CPN channel. The dye loading level governs the maximum amount of superoxide that induces a change in fluorescence properties and also influences the rate of superoxide generation by furnishing competitive excited state deactivation pathways. These results suggest that CPNs can be used to deliver superoxide in applications in which it is desirable and provide a caution for fluorescence-based CPN applications in which superoxide can damage fluorophores.

The therapeutic efficacy of 5-ALA based photodynamic therapy and chemotherapy combination in triple negative breast cancer cells

Triple negative breast cancer (TNBC) is one of the subtypes of breast cancer characterized by a heterogeneous and aggressive nature. Photodynamic therapy (PDT) has drawn significant attention in cancer treatment. However, solubility of photosensitizer, penetration problems into a target tissue and insufficient oxygen concentration limit the effectiveness of PDT. To overcome these limitations and to reduce the side effects of chemotherapy, combination treatment modalities play an essential role in cancer treatment. In this study, we aimed to investigate the combination efficacy of cisplatin-based chemotherapy and 5-Aminolevulinic acid (5-ALA)/PDT in TNBC cells and healthy breast cells in vitro. To determine the effect of the combination effects of cisplatin and 5-ALA/PDT on TNBC cells, two treatment protocols (simultaneous and sequential combination therapy) were evaluated compared with cisplatin and 5-ALA/PDT monotherapy and WST-1, Annexin V assay, acridine orange (AO) and mitochondrial staining were performed. Our findings showed that MDA-MB-231 TNBC cell viability was significantly decreased following simultaneous combination treatment compared to cisplatin and 5-ALA/PDT monotherapy. Additionally, simultaneous combination treatment was more effective than sequential combination treatment. The simultaneous combination treatment of 2.5 µM cisplatin and 5-ALA/PDT at 6 J/cm2 and 9 J/cm2 induced 46.78% and 53.6% total apoptotic death, respectively in TNBC cells compared with monotherapies (cisplatin (37.88%) and 5-ALA/PDT (6 J/cm2: 31.48% and 9 J/cm2: 37.78%). Additionally, cisplatin and 5-ALA/PDT combination treatment resulted in nuclear fragmentation and mitochondrial damage due to apoptosis. Our results suggest that cisplatin and 5-ALA/PDT simultaneous combination therapy could be a promising new alternative strategy for treating TNBC. However, further studies are required to assess the underlying molecular mechanisms of cisplatin and 5-ALA/PDT combination treatment at the molecular level.

Enhanced biosafety, anticancer and antibacterial photodynamic activities using silver-pyropheophorbide-a nanoconjugates

Aim: A study of the enhancement of photodynamic activities of pyropheophorbide-a using PG-Ag-PPa nanoconjugates.Materials & methods: The nanoconjugates were formulated from silver nanoparticles and PPa via amide linkage, then characterized, and their photodynamic activities were examined.Results: The nanoconjugates displayed a higher rate of reactive oxygen species generation, commendable cellular uptake by Eca-109 cancer cells, higher photocytotoxicity toward the cancer cells and better bio-safety. They revealed strong antibacterial activity against Escherichia coli following internal reactive oxygen species generation and membrane disintegration. The in vivo anticancer studies confirmed higher cytotoxicity of the nanoconjugates toward cancer cells and better safety than PPa.Conclusion: Therefore, PG-Ag-PPa nanoconjugates could be considered potential nano photosensitizers for photodynamic therapy of tumors and bacterial infection with good bio-safety.

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.

Research progress of fullerenes and their derivatives in the field of PDT

In contemporary studies, the predominant utilization of C60 derivatives pertains to their role as photosensitizers or agents that scavenge free radicals. The intriguing coexistence of these divergent functionalities has prompted extensive investigation into water-soluble fullerenes. The photodynamic properties of these compounds find practical applications in DNA cleavage, antitumor interventions, and antibacterial endeavors. Consequently, photodynamic therapy is progressively emerging as a pivotal therapeutic modality within the biomedical domain, owing to its notable levels of safety and efficacy. The essential components of photodynamic therapy encompass light of the suitable wavelength, oxygen, and a photosensitizer, wherein the reactive oxygen species generated by the photosensitizer play a pivotal role in the therapeutic mechanism. The remarkable ability of fullerenes to generate singlet oxygen has garnered significant attention from scholars worldwide. Nevertheless, the limited permeability of fullerenes across cell membranes owing to their low water solubility necessitates their modification to enhance their efficacy and utilization. This paper reviews the applications of fullerene derivatives as photosensitizers in antitumor and antibacterial fields for the recent years.

Carbon dots as a novel photosensitizer for photodynamic therapy of cancer and bacterial infectious diseases: recent advances

Carbon dots (CDs) are novel carbon-based nanomaterials that have been used as photosensitizer-mediated photodynamic therapy (PDT) in recent years due to their good photosensitizing activity. Photosensitizers (PSs) are main components of PDT that can produce large amounts of reactive oxygen species (ROS) when stimulated by light source, which have the advantages of low drug resistance and high therapeutic efficiency. CDs can generate ROS efficiently under irradiation and therefore have been extensively studied in disease local phototherapy. In tumor therapy, CDs can be used as PSs or PS carriers to participate in PDT and play an extremely important role. In bacterial infectious diseases, CDs exhibit high bactericidal activity as CDs are effective in disrupting bacterial cell membranes leading to bacterial death upon photoactivation. We focus on recent advances in the therapy of cancer and bacteria with CDs, and also briefly summarize the mechanisms and requirements for PSs in PDT of cancer, bacteria and other diseases. We also discuss the role CDs play in combination therapy and the potential for future applications against other pathogens.

Assessing the Effects of Curcumin and 450 nm Photodynamic Therapy on Oxidative Metabolism and Cell Cycle in Head and Neck Squamous Cell Carcinoma: An In Vitro Study

Oral cancer is the 16th most common malignant tumor worldwide. The risk of recurrence and mortality is high, and the survival rate is low over the following five years. Recent studies have shown that curcumin causes apoptosis in tumor cells by affecting FoF1-ATP synthase (ATP synthase) activity, which, in turn, hinders cell energy production, leading to a loss of cell viability. Additionally, irradiation of curcumin within cells can intensify its detrimental effects on cancer cell viability and proliferation (photodynamic therapy). We treated the OHSU-974 cell line, a model for human head and neck squamous cell carcinoma (HNSCC), and primary human fibroblasts. The treatment involved a 1 h exposure of cells to 0.1, 1.0, and 10 μM curcumin, followed or not by irradiation or the addition of the same concentration of pre-irradiated curcumin. Both instances involved a diode laser with a wavelength of 450 nm (0.25 W, 15 J, 60 s, 1 cm2, continuous wave mode). The treatment with non-irradiated 1 and 10 µM curcumin caused ATP synthase inhibition and a consequent reduction in the oxygen consumption rate (OCR) and the ATP/AMP ratio, which was associated with a decrement in lipid peroxidation accumulation and a slight increase in glutathione reductase and catalase activity. By contrast, 60 s curcumin irradiation with 0.25 W-450 nm caused a further oxidative phosphorylation (OxPhos) metabolism impairment that induced an uncoupling between respiration and energy production, leading to increased oxidative damage, a cellular growth and viability reduction, and a cell cycle block in the G1 phase. These effects appeared to be more evident when the curcumin was irradiated after cell incubation. Since cells belonging to the HNSCC microenvironment support tumor development, curcumin's effects have been analyzed on primary human fibroblasts, and a decrease in cell energy status has been observed with both irradiated and non-irradiated curcumin and an increase in oxidative lipid damage and a slowing of cell growth were observed when the curcumin was irradiated before or after cellular administration. Thus, although curcumin displays an anti-cancer role on OHSU-974 in its native form, photoactivation seems to enhance its effects, making it effective even at low dosages.

Monitoring of optical properties of tumors during laser plasmon photothermal therapy

We studied grafted tumors obtained by subcutaneous implantation of kidney cancer cells into male white rats. Gold nanorods with a plasmon resonance of about 800 nm were injected intratumorally for photothermal heating. Experimental irradiation of tumors was carried out percutaneously using a near-infrared diode laser. Changes in the optical properties of the studied tissues in the spectral range 350-2200 nm under plasmonic photothermal therapy (PPT) were studied. Analysis of the observed changes in the absorption bands of water and hemoglobin made it possible to estimate the depth of thermal damage to the tumor. A significant decrease in absorption peaks was observed in the spectrum of the upper peripheral part and especially the tumor capsule. The obtained changes in the optical properties of tissues under laser irradiation can be used to optimize laboratory and clinical PPT procedures.

Three-dimensional printing of the human lung pleural cavity model for PDT malignant mesothelioma

OBJECTIVE

The primary aim was to investigate emerging 3D printing and optical acquisition technologies to refine and enhance photodynamic therapy (PDT) dosimetry in the management of malignant pleural mesothelioma (MPM).

MATERIALS AND METHODS

A rigorous digital reconstruction of the pleural lung cavity was conducted utilizing 3D printing and optical scanning methodologies. These reconstructions were systematically assessed against CT-derived data to ascertain their accuracy in representing critical anatomic features and post-resection topographical variations.

RESULTS

The resulting reconstructions excelled in their anatomical precision, proving instrumental translation for precise dosimetry calculations for PDT. Validation against CT data confirmed the utility of these models not only for enhancing therapeutic planning but also as critical tools for educational and calibration purposes.

CONCLUSION

The research outlined a successful protocol for the precise calculation of light distribution within the complex environment of the pleural cavity, marking a substantive advance in the application of PDT for MPM. This work holds significant promise for individualizing patient care, minimizing collateral radiation exposure, and improving the overall efficiency of MPM treatments.

Comparative response to PDT with methyl-aminolevulinate and temoporfin in cutaneous and oral squamous cell carcinoma cells

Cutaneous and Head and Neck squamous cell carcinoma (CSCC, HNSCC) are among the most prevalent cancers. Both types of cancer can be treated with photodynamic therapy (PDT) by using the photosensitizer Temoporfin in HNSCC and the prodrug methyl-aminolevulinate (MAL) in CSCC. However, PDT is not always effective. Therefore, it is mandatory to correctly approach the therapy according to the characteristics of the tumour cells. For this reason, we have used cell lines of CSCC (A431 and SCC13) and HNSCC (HN5 and SCC9). The results obtained indicated that the better response to MAL-PDT was related to its localization in the plasma membrane (A431 and HN5 cells). However, with Temoporfin all cell lines showed lysosome localization, even the most sensitive ones (HN5). The expression of mesenchymal markers and migratory capacity was greater in HNSCC lines compared to CSCC, but no correlation with PDT response was observed. The translocation to the nucleus of β-catenin and GSK3β and the activation of NF-κβ is related to the poor response to PDT in the HNSCC lines. Therefore, we propose that intracellular localization of GSK3β could be a good marker of response to PDT in HNSCC. Although the molecular mechanism of response to PDT needs further elucidation, this work shows that the most MAL-resistant line of CSCC is more sensitive to Temoporfin.

Natural Compounds in Non-Melanoma Skin Cancer: Prevention and Treatment

The elevated occurrence of non-melanoma skin cancer (NMSC) and the adverse effects associated with available treatments adversely impact the quality of life in multiple dimensions. In connection with this, there is a necessity for alternative approaches characterized by increased tolerance and lower side effects. Natural compounds could be employed due to their safety profile and effectiveness for inflammatory and neoplastic skin diseases. These anti-cancer drugs are often derived from natural sources such as marine, zoonotic, and botanical origins. Natural compounds should exhibit anti-carcinogenic actions through various pathways, influencing apoptosis potentiation, cell proliferation inhibition, and metastasis suppression. This review provides an overview of natural compounds used in cancer chemotherapies, chemoprevention, and promotion of skin regeneration, including polyphenolic compounds, flavonoids, vitamins, alkaloids, terpenoids, isothiocyanates, cannabinoids, carotenoids, and ceramides.

Advancing Cancer Treatment: Enhanced Combination Therapy through Functionalized Porous Nanoparticles

Cancer remains a major global health challenge, necessitating the development of innovative treatment strategies. This review focuses on the functionalization of porous nanoparticles for combination therapy, a promising approach to enhance cancer treatment efficacy while mitigating the limitations associated with conventional methods. Combination therapy, integrating multiple treatment modalities such as chemotherapy, phototherapy, immunotherapy, and others, has emerged as an effective strategy to address the shortcomings of individual treatments. The unique properties of mesoporous silica nanoparticles (MSN) and other porous materials, like nanoparticles coated with mesoporous silica (NP@MS), metal-organic frameworks (MOF), mesoporous platinum nanoparticles (mesoPt), and carbon dots (CDs), are being explored for drug solubility, bioavailability, targeted delivery, and controlled drug release. Recent advancements in the functionalization of mesoporous nanoparticles with ligands, biomaterials, and polymers are reviewed here, highlighting their role in enhancing the efficacy of combination therapy. Various research has demonstrated the effectiveness of these nanoparticles in co-delivering drugs and photosensitizers, achieving targeted delivery, and responding to multiple stimuli for controlled drug release. This review introduces the synthesis and functionalization methods of these porous nanoparticles, along with their applications in combination therapy.

Quantification of cellular phototoxicity of organelle stains by the dynamics of microtubule polymerization

Being able to quantify the phototoxicity of dyes and drugs in live cells allows biologists to better understand cell responses to exogenous stimuli during imaging. This capability further helps to design fluorescent labels with lower phototoxicity and drugs with better efficacy. Conventional ways to evaluate cellular phototoxicity rely on late-stage measurements of individual or different populations of cells. Here, we developed a quantitative method using intracellular microtubule polymerization as a rapid and sensitive marker to quantify early-stage phototoxicity. Implementing this method, we assessed the photosensitization induced by organelle dyes illuminated with different excitation wavelengths. Notably, fluorescent markers targeting mitochondria, nuclei, and endoplasmic reticulum exhibited diverse levels of phototoxicity. Furthermore, leveraging a real-time precision opto-control technology allowed us to evaluate the synergistic effect of light and dyes on specific organelles. Studies in hypoxia revealed enhanced phototoxicity of Mito-Tracker Red CMXRos that is not correlated with the generation of reactive oxygen species but a different deleterious pathway in low oxygen conditions.

Teaser

Microtubule dynamics in live cells allow quantification of cellular phototoxicity of fluorescent dyes in various conditions.

Enhancement of cytotoxic effects with ALA-PDT on treatment of radioresistant cancer cells

Radiation therapy is a lower invasive local treatment than surgery and is selected as a primary treatment for solid tumors. However, when some cancer cells obtain radiotherapy tolerance, cytotoxicity of radiotherapy for cancer cells is attenuated. Photodynamic therapy (PDT) is a non-invasive cancer therapy combined with photosensitizers and laser irradiation with an appropriate wavelength. PDT is carried out for recurrent esophageal cancer patients after radiation chemotherapy and is an effective treatment for radiation-resistant tumors. However, it is not clear why PDT is effective against radioresistant cancers. In this study, we attempted to clear this mechanism using X-ray resistant cancer cells. X-ray resistant cells produce high amounts of mitochondria-derived ROS, which enhanced nuclear translocation of NF-κB, resulting in increased NO production. Moreover, the expression of PEPT1 that imports 5-aminolevulinic acid, the precursor of photosensitizers, was upregulated in X-ray resistant cancer cells. This was accompanied by an increase in intracellular 5-aminolevulinic acid-derived porphyrin accumulation, resulting in enhancement of PDT-induced cytotoxicity. Therefore, effective accumulation of photosensitizers induced by ROS and NO may achieve PDT after radiation therapy and PDT could be a promising treatment for radioresistant cancer cells.

Ruthenium(II) polypyridyl complexes as emerging photosensitisers for antibacterial photodynamic therapy

Photodynamic therapy (PDT) has recently emerged as a potential valuable alternative to treat microbial infections. In PDT, singlet oxygen is generated in the presence of photosensitisers and oxygen under light irradiation of a specific wavelength, causing cytotoxic damage to bacteria. This review highlights different generations of photosensitisers and the common characteristics of ideal photosensitisers. It also focuses on the emergence of ruthenium and more specifically on Ru(II) polypyridyl complexes as metal-based photosensitisers used in antimicrobial photodynamic therapy (aPDT). Their photochemical and photophysical properties as well as structures are discussed while relating them to their phototoxicity. The use of Ru(II) complexes with recent advancements such as nanoformulations, combinatory therapy and photothermal therapy to improve on previous shortcomings of the complexes are outlined. Future perspectives of these complexes used in two-photon PDT, photoacoustic imaging and sonotherapy are also discussed. This review covers the literature published from 2017 to 2023.

Lectins as a promising therapeutic agent for breast cancer: A review

Efficient treatment of cancer has been a subject of research by scientists for many years. Current treatments for cancer, such as radiotherapy, chemotherapy and surgery have been used in traditional combination therapy, but they have major setbacks like non-specificity, non-responsiveness in certain cancer types towards treatment, tumor recurrence, etc. Epidemiological data has shown that breast cancer accounts for 14% of cancer cases occurring in Indian women. In recent years, scientists have started to focus on the use of natural compounds like lectins obtained from various sources to counter the side effects of traditional therapy. Lectins like Sambucus nigra Agglutinin, Maackia amurensis lectin, Okra lectins, Haliclona caerulea lectin, Sclerotium rolfsii lectin, etc., have been discovered to have both diagnostic and therapeutic potential for breast cancer patients. Lectins have been found to have inhibitory effects on various cancer cell activities such as neo-angiogenesis, causing cell cycle arrest at the G1 phase, and inducing apoptosis. The major idea behind the use of lectins in cancer diagnostics and therapeutics is their capability to bind to glycosylated proteins that are expressed on the cell surface. This review focuses on an exploration of the roles of post-translational modification in cancer cells, especially glycosylation, and the potential of lectins in cancer diagnosis and therapeutics.

Photodynamic Therapy and Immunological View in Gastrointestinal Tumors

Gastrointestinal cancers are a specific group of oncological diseases in which the location and nature of growth are of key importance for clinical symptoms and prognosis. At the same time, as research shows, they pose a serious threat to a patient's life, especially at an advanced stage of development. The type of therapy used depends on the anatomical location of the cancer, its type, and the degree of progression. One of the modern forms of therapy used to treat gastrointestinal cancers is PDT, which has been approved for the treatment of esophageal cancer in the United States. Despite the increasingly rapid clinical use of this treatment method, the exact immunological mechanisms it induces in cancer cells has not yet been fully elucidated. This article presents a review of the current understanding of the mode of action of photodynamic therapy on cells of various gastrointestinal cancers with an emphasis on colorectal cancer. The types of cell death induced by PDT include apoptosis, necrosis, and pyroptosis. Anticancer effects are also a result of the destruction of tumor vasculature and activation of the immune system. Many reports exist that concern the mechanism of apoptosis induction, of which the mitochondrial pathway is most often emphasized. Photodynamic therapy may also have a beneficial effect on such aspects of cancer as the ability to develop metastases or contribute to reducing resistance to known pharmacological agents.

Exploring a Mitochondria Targeting, Dinuclear Cyclometalated Iridium (III) Complex for Image-Guided Photodynamic Therapy in Triple-Negative Breast Cancer Cells

Photodynamic therapy (PDT) has emerged as an efficient and noninvasive treatment approach utilizing laser-triggered photosensitizers for combating cancer. Within this rapidly advancing field, iridium-based photosensitizers with their dual functionality as both imaging probes and PDT agents exhibit a potential for precise and targeted therapeutic interventions. However, most reported classes of Ir(III)-based photosensitizers comprise mononuclear iridium(III), with very few examples of dinuclear systems. Exploring the full potential of iridium-based dinuclear systems for PDT applications remains a challenge. Herein, we report a dinuclear Ir(III) complex (IRDI) along with a structurally similar monomer complex (IRMO) having 2-(2,4-difluorophenyl)pyridine and 4'-methyl-2,2'-bipyridine ligands. The comparative investigation of the mononuclear and dinuclear Ir(III) complexes showed similar absorption profiles, but the dinuclear derivative IRDI exhibited a higher photoluminescence quantum yield (Φp) of 0.70 compared to that of IRMO (Φp = 0.47). Further, IRDI showed a higher singlet oxygen generation quantum yield (Φs) of 0.49 compared to IRMO (Φs = 0.28), signifying the enhanced potential of the dinuclear derivative for image-guided photodynamic therapy. In vitro assessments indicate that IRDI shows efficient cellular uptake and significant photocytotoxicity in the triple-negative breast cancer cell line MDA-MB-231. In addition, the presence of a dual positive charge on the dinuclear system facilitates the inherent mitochondria-targeting ability without the need for a specific targeting group. Subcellular singlet oxygen generation by IRDI was confirmed using Si-DMA, and light-activated cellular apoptosis via ROS-mediated PDT was verified through various live-dead assays performed in the presence and absence of the singlet oxygen scavenger NaN3. Further, the mechanism of cell death was elucidated by an annexin V-FITC/PI flow cytometric assay and by investigating the cytochrome c release from mitochondria using Western blot analysis. Thus, the dinuclear complex designed to enhance spin-orbit coupling with minimal excitonic coupling represents a promising strategy for efficient image-guided PDT using iridium complexes.

2D Materials for Combination Therapy to Address Challenges in the Treatment of Cancer

2D materials exhibit a variety of characteristics that make them appealing platforms for cancer treatment such as high drug loading capacity and photothermal and photodynamic properties. A key advantage of 2D material platforms for oncological applications is the ability to harness multiple modalities including drug delivery, photothermal therapy, photodynamic therapy, chemodynamic therapy, gene delivery, and immunotherapy approaches for improved efficacy. In this review, a comparison of the unique properties of different classes of 2D materials that enable their usage as platforms for multimodal therapy is provided. Further, the benefits and drawbacks of different platforms are also highlighted. Finally, current challenges and emerging opportunities for future development of 2D materials to further enable combination therapy and translation from the bench to clinical oncology applications are discussed.

HER2-specific liposomes loaded with proteinaceous BRET pair as a promising tool for targeted self-excited photodynamic therapy

Photodynamic therapy (PDT) for deep-seated tumors is still challenging due to the limited penetration of visible light through tissues. To resolve this limitation, systems based on bioluminescence resonance energy transfer (BRET), that do not require an external light source are proposed. Herein, for BRET-activated PDT we developed proteinaceous BRET-pair consisting of luciferase NanoLuc, which acts as energy donor upon addition of luciferase specific substrate furimazine, and phototoxic protein SOPP3 as a photosensitizer. We have shown that hybrid protein NanoLuc-SOPP3 is an excellent BRET pair with BRET ratio of 1.12. Targeted delivery of NanoLuc-SOPP3 BRET pair via tumor-specific small liposomes (∼100 nm) to tumors overexpressing the HER2-receptor (human epidermal growth factor receptor 2) was demonstrated in vitro and in vivo. The proposed BRET-activated system has been shown to significantly suppress tumor growth in a model of subcutaneous and, more importantly, deep-seated tumor model. Taking into account the in vivo efficiency of proposed BRET-activated system, we believe that it has great potential for depth-independent PDT and can significantly broaden the application of PDT in the clinic.

Cancer Metabolism as a Therapeutic Target and Review of Interventions

Cancer is amenable to low-cost treatments, given that it has a significant metabolic component, which can be affected through diet and lifestyle change at minimal cost. The Warburg hypothesis states that cancer cells have an altered cell metabolism towards anaerobic glycolysis. Given this metabolic reprogramming in cancer cells, it is possible to target cancers metabolically by depriving them of glucose. In addition to dietary and lifestyle modifications which work on tumors metabolically, there are a panoply of nutritional supplements and repurposed drugs associated with cancer prevention and better treatment outcomes. These interventions and their evidentiary basis are covered in the latter half of this review to guide future cancer treatment.

A tumor targeted antifouling upconversion nanoplatform for fluorescence imaging and precise photodynamic therapy triggered by NIR laser

Photodynamic therapy (PDT) has been considered as a promising treatment in the biomedical field because of low toxicity to normal tissues and minor trauma area. However, the PDT effect of materials is greatly affected by many factors, such as nonspecific adsorption and poor light penetration, etc. In this work, an intelligent nano platform has been constructed based on upconversion nanoparticles (UCNPs) loaded with a large amount of photosensitizers Ce6, which could specifically light up tumor tissues and stimulate the production of reactive oxygen species (ROS) under 980 nm near-infrared (NIR) irradiation, exhibiting a conspicuous imaging and therapeutic effect of PDT treatment for deep tumors. An excellent anti-fouling performance in complex biological substrate was obtained upon the judicious introduction of anti-fouling peptide, which also contributed to the improved PDT efficiency. In addition, the specificity of nanoplatform to malignant breast cancer cells was realized by modification of polypeptide targeting for HER2. This anti-fouling nanoplatform provided an original paradigm for the development of fluorescence imaging and PDT for deep tumor tissue with high targeting and therapeutic efficacy, promising to be used in the early therapy of malignant breast cancer specifically.

Cancer phototherapy with nano-bacteria biohybrids

The utilization of light for therapeutic interventions, also known as phototherapy, has been extensively employed in the treatment of a wide range of illnesses, including cancer. Despite the benefits of its non-invasive nature, phototherapy still faces challenges pertaining to the delivery of phototherapeutic agents, phototoxicity, and light delivery. The incorporation of nanomaterials and bacteria in phototherapy has emerged as a promising approach that leverages the unique properties of each component. The resulting nano-bacteria biohybrids exhibit enhanced therapeutic efficacy when compared to either component individually. In this review, we summarize and discuss the various strategies for assembling nano-bacteria biohybrids and their applications in phototherapy. We provide a comprehensive overview of the properties and functionalities of nanomaterials and cells in the biohybrids. Notably, we highlight the roles of bacteria beyond their function as drug vehicles, particularly their capacity to produce bioactive molecules. Despite being in its early stage, the integration of photoelectric nanomaterials and genetically engineered bacteria holds promise as an effective biosystem for antitumor phototherapy. The utilization of nano-bacteria biohybrids in phototherapy is a promising avenue for future investigation, with the potential to enhance treatment outcomes for cancer patients.

Efficacy of Green Synthesized Nanoparticles in Photodynamic Therapy: A Therapeutic Approach

Cancer is a complex and diverse disease characterized by the uncontrolled growth of abnormal cells in the body. It poses a significant global public health challenge and remains a leading cause of death. The rise in cancer cases and deaths is a significant worry, emphasizing the immediate need for increased awareness, prevention, and treatment measures. Photodynamic therapy (PDT) has emerged as a potential treatment for various types of cancer, including skin, lung, bladder, and oesophageal cancer. A key advantage of PDT is its ability to selectively target cancer cells while sparing normal cells. This is achieved by preferentially accumulating photosensitizing agents (PS) in cancer cells and precisely directing light activation to the tumour site. Consequently, PDT reduces the risk of harming surrounding healthy cells, which is a common drawback of conventional therapies such as chemotherapy and radiation therapy. The use of medicinal plants for therapeutic purposes has a long history dating back thousands of years and continues to be an integral part of healthcare in many cultures worldwide. Plant extracts and phytochemicals have demonstrated the ability to enhance the effectiveness of PDT by increasing the production of reactive oxygen species (ROS) and promoting apoptosis (cell death) in cancer cells. This natural approach capitalizes on the eco-friendly nature of plant-based photoactive compounds, offering valuable insights for future research. Nanotechnology has also played a pivotal role in medical advancements, particularly in the development of targeted drug delivery systems. Therefore, this review explores the potential of utilizing photosensitizing phytochemicals derived from medicinal plants as a viable source for PDT in the treatment of cancer. The integration of green photodynamic therapy with plant-based compounds holds promise for novel treatment alternatives for various chronic illnesses. By harnessing the scientific potential of plant-based compounds for PDT, we can pave the way for innovative and sustainable treatment strategies.

Photodynamic Therapy: From the Basics to the Current Progress of N-Heterocyclic-Bearing Dyes as Effective Photosensitizers

Photodynamic therapy, an alternative that has gained weight and popularity compared to current conventional therapies in the treatment of cancer, is a minimally invasive therapeutic strategy that generally results from the simultaneous action of three factors: a molecule with high sensitivity to light, the photosensitizer, molecular oxygen in the triplet state, and light energy. There is much to be said about each of these three elements; however, the efficacy of the photosensitizer is the most determining factor for the success of this therapeutic modality. Porphyrins, chlorins, phthalocyanines, boron-dipyrromethenes, and cyanines are some of the N-heterocycle-bearing dyes' classes with high biological promise. In this review, a concise approach is taken to these and other families of potential photosensitizers and the molecular modifications that have recently appeared in the literature within the scope of their photodynamic application, as well as how these compounds and their formulations may eventually overcome the deficiencies of the molecules currently clinically used and revolutionize the therapies to eradicate or delay the growth of tumor cells.

The Distinctive Features behind the Aggressiveness of Oral and Cutaneous Squamous Cell Carcinomas

Squamous cell carcinomas arise from stratified squamous epithelia. Here, a comparative analysis based on recent studies defining the genetic alterations and composition of the stroma of oral and cutaneous squamous cell carcinomas (OSCC and CSCC, respectively) was performed. Both carcinomas share some but not all histological and genetic features. This review was focused on how mutations in tumor suppressor genes and protooncogenes cooperate to determine the differentiation, aggressiveness, and metastatic potential of OSCC and CSCC. In fact, driver mutations in tumor suppressor genes are more frequently observed in OSCC than CSCC. These include mutations in TP53 (encoding pP53 protein), CDKN2A (encoding cyclin dependent kinase inhibitor 2A), FAT1 (encoding FAT atypical cadherin 1), and KMT2D (encoding lysine methyltransferase 2D), with the exception of NOTCH (encoding Notch receptor 1), whose mutation frequency is lower in OSCC compared to CSCC. Finally, we describe the differential composition of the tumor microenvironment and how this influences the aggressiveness of each tumor type. Although both OSCC and CSCC tumors are highly infiltrated by immune cells, high levels of tumor-infiltrating lymphocytes (TILs) have been more frequently reported as predictors of better outcomes in OSCC than CSCC. In conclusion, OSCC and CSCC partially share genetic alterations and possess different causal factors triggering their development. The tumor microenvironment plays a key role determining the outcome of the disease.

A red light-triggered chemical tool for sequence-specific alkylation of G-quadruplex and I-motif DNA

The importance of non-canonical DNA structures such as G-quadruplexes (G4) and intercalating-motifs (iMs) in the fine regulation of a variety of cellular processes has been recently demonstrated. As the crucial roles of these structures are being unravelled, it is becoming more and more important to develop tools that allow targeting these structures with the highest possible specificity. While targeting methodologies have been reported for G4s, this is not the case for iMs, as evidenced by the limited number of specific ligands able to bind the latter and the total absence of selective alkylating agents for their covalent targeting. Furthermore, strategies for the sequence-specific covalent targeting of G4s and iMs have not been reported thus far. Herein, we describe a simple methodology to achieve sequence-specific covalent targeting of G4 and iM DNA structures based on the combination of (i) a peptide nucleic acid (PNA) recognizing a specific sequence of interest, (ii) a pro-reactive moiety enabling a controlled alkylation reaction, and (iii) a G4 or iM ligand orienting the alkylating warhead to the reactive residues. This multi-component system allows for the targeting of specific G4 or iM sequences of interest in the presence of competing DNA sequences and under biologically relevant conditions.