Mesenchymal Stem Cell Membrane-Coated TPCS2a-Loaded Nanoparticles for Breast Cancer Photodynamic Therapy

Despite substantial improvements in breast cancer (BC) treatment there is still an urgent need to find alternative treatment options to improve the outcomes for patients with advanced-stage disease. Photodynamic therapy (PDT) is gaining a lot of attention as a BC therapeutic option because of its selectivity and low off-target effects. However, the hydrophobicity of photosensitizers (PSs) impairs their solubility and limits the circulation in the bloodstream, thus representing a major challenge. The use of polymeric nanoparticles (NPs) to encapsulate the PS may represent a valuable strategy to overcome these issues. Herein, we developed a novel biomimetic PDT nanoplatform (NPs) based on a polymeric core of poly(lactic-co-glycolic)acid (PLGA) loaded with the PS meso-tetraphenylchlorin disulfonate (TPCS_2a). TPCS_2a@NPs of 98.89 ± 18.56 nm with an encapsulation efficiency percentage (EE%) of 81.9 ± 7.92% were obtained and coated with mesenchymal stem cells-derived plasma membranes (mMSCs) (mMSC-TPCS_2a@NPs, size of 139.31 ± 12.94 nm). The mMSC coating armed NPs with biomimetic features to impart long circulation times and tumor-homing capabilities. In vitro, biomimetic mMSC-TPCS_2a@NPs showed a decrease in macrophage uptake of 54% to 70%, depending on the conditions applied, as compared to uncoated TPCS_2a@NPs. Both NP formulations efficiently accumulated in MCF7 and MDA-MB-231 BC cells, while the uptake was significantly lower in normal breast epithelial MCF10A cells with respect to tumor cells. Moreover, encapsulation of TPCS_2a in mMSC-TPCS_2a@NPs effectively prevents its aggregation, ensuring efficient singlet oxygen (¹O₂) production after red light irradiation, which resulted in a considerable in vitro anticancer effect in both BC cell monolayers (IC₅₀ < 0.15 µM) and three-dimensional spheroids.

Overview of Nanoparticle-Based Approaches for the Combination of Photodynamic Therapy (PDT) and Chemotherapy at the Preclinical Stage

Simple Summary

The present review represents the outstanding and promising recent literature reports (2017–2022) on nanoparticle-based formulations developed for anticancer therapy with photodynamic therapy (PDT), photosensitizers, and chemotherapeutics. Besides brief descriptions of chemotherapeutics’ classification and of PDT mechanisms and limitations, several examples of nanosystems endowed with different responsiveness (e.g., acidic pH and reactive oxygen species) and peculiarity (e.g., tumor oxygenation capacity, active tumor targeting, and biomimetic features) are described, and for each drug combination, in vitro and in vivo results on preclinical cancer models are reported.

Abstract

The widespread diffusion of photodynamic therapy (PDT) as a clinical treatment for solid tumors is mainly limited by the patient’s adverse reaction (skin photosensivity), insufficient light penetration in deeply seated neoplastic lesions, unfavorable photosensitizers (PSs) biodistribution, and photokilling efficiency due to PS aggregation in biological environments. Despite this, recent preclinical studies reported on successful combinatorial regimes of PSs with chemotherapeutics obtained through the drugs encapsulation in multifunctional nanometric delivery systems. The aim of the present review deals with the punctual description of several nanosystems designed not only with the objective of co-transporting a PS and a chemodrug for combination therapy, but also with the goal of improving the therapeutic efficacy by facing the main critical issues of both therapies (side effects, scarce tumor oxygenation and light penetration, premature drug clearance, unspecific biodistribution, etc.). Therefore, particular attention is paid to the description of bio-responsive drugs and nanoparticles (NPs), targeted nanosystems, biomimetic approaches, and upconverting NPs, including analyzing the therapeutic efficacy of the proposed photo-chemotherapeutic regimens in in vitro and in vivo cancer models.

Gold-based nanoparticles realize photothermal and photodynamic synergistic treatment of liver cancer and improve the anaerobic tumor microenvironment under near-infrared light

In order to solve the different pains caused by traditional cancer treatment methods such as surgical treatment, the nano-drug delivery system provides new ideas for cancer treatment. In this paper, a novel anti-tumor therapy nanoparticle, P(AAm-co-AN)-AuNRs@CeO2-Ce6(PA/Ce6), is prepared, which provides a novel idea for liver cancer treatment. The CeO2-coated gold nanorods were grafted onto the surface of the temperature-sensitive polymer P(AAm-co-AN)-CTPD. The photosensitizer Ce6 is loaded on the surface of the nanoparticles and the polymer layer. CeO2 can effectively alleviate the tumor anaerobic microenvironment, and under 808 nm near-infrared (NIR) excitation, the gold nanorods achieve photothermal conversion to induce local heating, which leads to the phase transition of the polymer layer and realizes a controllable release mechanism. In addition, 660 nm NIR light can effectively induce Ce6 to produce singlet oxygen, thereby effectively killing cancer cells. Under the 808 nm laser irradiation within 600 s, the PA/Ce6 solution can heat up to about 60°C, which was enough to ablate both cancer cells and tumor tissues. When the temperature was 50°C, the cumulative release rate of Ce6 was 95.31%. Under the 808 nm laser irradiation, oxygen production capacity of PA/Ce6 was higher and can effectively reduce the content of hydrogen peroxide in cancer cells. Compared to free Ce6, the reactive oxygen species-mediated fluorescence of PA/Ce6 nanoparticles was greater. The cell viability and migration of HepG2 cells were decreased after the 660 and 880 nm lasers were irradiated at the same time. The cancer cells were further inhibited, showing a good in vitro anti-tumor effect. PA-DOX showed the best tumor growth inhibitory effect under NIR laser irradiation and had no acute toxicity in vivo. Due to the existence of AuNRs, nanoparticles had high-efficiency photothermal conversion ability to achieve photothermal therapy. Ce6 can generate singlet oxygen under the excitation of 660 nm laser to realize photodynamic therapy. The experimental results also showed that PA/Ce6 can effectively decompose hydrogen peroxide under laser irradiation, aiming to effectively alleviate the anaerobic microenvironment of tumors. These indicate that PA/Ce6 plays a promising role for hepatocellular carcinoma treatment.

Cationic Axial Ligand Effects on Sulfur-Substituted Subphthalocyanines

Herein, we report the synthesis of sulfur-substituted boron(III) subphthalocyanines (SubPcs) with cationic axial ligands. Subphthalocyanines were synthesized by a condensation reaction using the corresponding phthalonitriles and boron trichloride as a template. An aminoalkyl group was introduced on the central boron atom; this process was followed by N-methylation to introduce a cationic axial ligand. The peripheral sulfur groups shifted the Q band of SubPcs to a longer wavelength. The cationic axial ligands increased the polarity and enhanced the hydrophilicity of SubPcs. The effect of axial ligands on absorption and fluorescence properties is generally small. However, a further red shift was observed by introducing cationic axial ligands into the sulfur-substituted SubPcs. This change is similar to that in sulfur-substituted silicon(IV) phthalocyanines. The unique effect of the cationic axial ligand was extensively investigated by theoretical calculations and electrochemistry. In particular, the precise oxidation potential was determined using ionization potential measurements. Thus, the results of the present study provide a novel strategy for developing functional dyes and pigments based on SubPcs.

HOMO-LUMO photosensitization analyses of coronene-cytosine complexes

Photosensitization analyses of models of (–HC = CH–)n assisted coronene-cytosine complexes assigned by Cor-n-Cyt; n varying by 0, 1, 2, and 3, were investigated in this work by performing density functional theory (DFT) calculations. The investigated models were optimized and chemical descriptors were evaluated. To achieve the goal of this work, energy levels of the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) were evaluated to reach the absorption energy requirement for innovating photosensitizer (PS) compounds. The models indicated that the complex formations could help the structures to participate in interactions easier than the singular models, in which HOMO-LUMO descriptors indicated lower required absorption energy for them to increase their safety for human health level. The required absorption energies of complexes with n = 0, 1, and 2, were in ultraviolet (UV) region whereas that of complex with n = 3 was moved to visible region. In this regard, the idea of new PS compounds innovation was examined here to introduce Cor-n-Cyt complexes for possible applications in photodynamic therapy (PDT).

Hybrid Inorganic-Organic Core-Shell Nanodrug Systems in Targeted Photodynamic Therapy of Cancer

Hybrid inorganic-organic core-shell nanoparticles (CSNPs) are an emerging paradigm of nanodrug carriers in the targeted photodynamic therapy (TPDT) of cancer. Typically, metallic cores and organic polymer shells are used due to their submicron sizes and high surface to volume ratio of the metallic nanoparticles (NPs), combined with enhances solubility, stability, and absorption sites of the organic polymer shell. As such, the high loading capacity of therapeutic agents such as cancer specific ligands and photosensitizer (PS) agents is achieved with desired colloidal stability, drug circulation, and subcellular localization of the PS agents at the cancer site. This review highlights the synthesis methods, characterization techniques, and applications of hybrid inorganic-organic CSNPs as loading platforms of therapeutic agents for use in TPDT. In addition, cell death pathways and the mechanisms of action that hybrid inorganic-organic core-shell nanodrug systems follow in TPDT are also reviewed. Nanodrug systems with cancer specific properties are able to localize within the solid tumor through the enhanced permeability effect (EPR) and bind with affinity to receptors on the cancer cell surfaces, thus improving the efficacy of short-lived cytotoxic singlet oxygen. This ability by nanodrug systems together with their mechanism of action during cell death forms the core basis of this review and will be discussed with an overview of successful strategies that have been reported in the literature.

Coordination Complexes as a New Generation Photosensitizer for Photodynamic Anticancer Therapy

Photodynamic therapy (PDT) has become an alternative to standard cancer treatment methods such as surgery, chemotherapy and radiotherapy. The uniqueness of this method relies on the possibility of using various photosensitizers (PS) that absorb and convert light emission in radical oxygen-derived species (ROS). They can be present alone or in the presence of other compounds such as metal organic frameworks (MOFs), non-tubules or polymers. The interaction between DNA and metal-based complexes plays a key role in the development of new anti-cancer drugs. The use of coordination compounds in PDT has a significant impact on the amount ROS generated, quantum emission efficiency (Φem) and phototoxic index (PI). In this review, we will attempt to systematically review the recent literature and analyze the coordination complexes used as PS in PDT. Finally, we compared the anticancer activities of individual coordination complexes and discuss future perspectives. So far, only a few articles link so many transition metal ion coordination complexes of varying degrees of oxidation, which is why this review is needed by the scientific community to further expand this field worldwide. Additionally, it serves as a convenient collection of important, up-to-date information.

Probing the Interactions of Porphyrins with Macromolecules Using NMR Spectroscopy Techniques

Porphyrinic compounds are widespread in nature and play key roles in biological processes such as oxygen transport in blood, enzymatic redox reactions or photosynthesis. In addition, both naturally derived as well as synthetic porphyrinic compounds are extensively explored for biomedical and technical applications such as photodynamic therapy (PDT) or photovoltaic systems, respectively. Their unique electronic structures and photophysical properties make this class of compounds so interesting for the multiple functions encountered. It is therefore not surprising that optical methods are typically the prevalent analytical tool applied in characterization and processes involving porphyrinic compounds. However, a wealth of complementary information can be obtained from NMR spectroscopic techniques. Based on the advantage of providing structural and dynamic information with atomic resolution simultaneously, NMR spectroscopy is a powerful method for studying molecular interactions between porphyrinic compounds and macromolecules. Such interactions are of special interest in medical applications of porphyrinic photosensitizers that are mostly combined with macromolecular carrier systems. The macromolecular surrounding typically stabilizes the encapsulated drug and may also modify its physical properties. Moreover, the interaction with macromolecular physiological components needs to be explored to understand and control mechanisms of action and therapeutic efficacy. This review focuses on such non-covalent interactions of porphyrinic drugs with synthetic polymers as well as with biomolecules such as phospholipids or proteins. A brief introduction into various NMR spectroscopic techniques is given including chemical shift perturbation methods, NOE enhancement spectroscopy, relaxation time measurements and diffusion-ordered spectroscopy. How these NMR tools are used to address porphyrin-macromolecule interactions with respect to their function in biomedical applications is the central point of the current review.

DNA photocleavage and melanoma cells cytotoxicity induced by a meso-tetra-ruthenated porphyrin under visible light irradiation

Porphyrins are used as photosensitizing agents in photodynamic therapy (PDT) for several pathologies. Here we demonstrate the DNA photocleavage and cytotoxicity properties of a free-base meso-tetra-ruthenated porphyrin (H₂RuTPyP) in purified DNA samples and in a melanoma cell line, respectively. Cytotoxicity of H₂RuTPyP was investigated by the tetrazolium dye (MTT) colorimetric assay and its genotoxic potential by direct plasmid DNA photocleavage after incubation with specific DNA repair enzymes. H₂RuTPyP porphyrin efficiently induced DNA damage at the lower concentration of 5.0 μM, whereas it induced complete DNA degradation at 15 μM. The addition of different scavengers for reactive oxygen species (ROS) during the visible light exposures did not decrease the DNA damage formation, suggesting a hydrolytic mechanism for the induction of DNA breaks. Also, H₂RuTPyP exhibited a much higher cytotoxicity in melanoma cells in comparison to a keratinocyte cell line. The detection of intracellular reactive oxygen species (ROS) produced by H₂RuTPyP through the DCF-DA assay also suggests that ROS have a minor role in the induction of cytotoxicity. Therefore, H₂RuTPyP seems to be a very effective photosensitizer, representing a promising alternative for the development of new skin cancer treatments using PDT process.

Porphyrin Derivative Nanoformulations for Therapy and Antiparasitic Agents

Porphyrins and analogous macrocycles exhibit interesting photochemical, catalytic, and luminescence properties demonstrating high potential in the treatment of several diseases. Among them can be highlighted the possibility of application in photodynamic therapy and antimicrobial/antiparasitic PDT, for example, of malaria parasite. However, the low efficiency generally associated with their low solubility in water and bioavailability have precluded biomedical applications. Nanotechnology can provide efficient strategies to enhance bioavailability and incorporate targeted delivery properties to conventional pharmaceuticals, enhancing the effectiveness and reducing the toxicity, thus improving the adhesion to the treatment. In this way, those limitations can be overcome by using two main strategies: (1) Incorporation of hydrophilic substituents into the macrocycle ring while controlling the interaction with biological systems and (2) by including them in nanocarriers and delivery nanosystems. This review will focus on antiparasitic drugs based on porphyrin derivatives developed according to these two strategies, considering their vast and increasing applications befitting the multiple roles of these compounds in nature.

Enhanced Cellular Uptake and Photodynamic Effect with Amphiphilic Fluorinated Porphyrins: The Role of Sulfoester Groups and the Nature of Reactive Oxygen Species

A class of amphiphilic photosensitizers for photodynamic therapy (PDT) was developed. Sulfonate esters of modified porphyrins bearing-F substituents in the ortho positions of the phenyl rings have adequate properties for PDT, including absorption in the red, increased cellular uptake, favorable intracellular localization, low cytotoxicity, and high phototoxicity against A549 (human lung adenocarcinoma) and CT26 (murine colon carcinoma) cells. Moreover, the role of type I and type II photochemical processes was assessed by fluorescent probes specific for various reactive oxygen species (ROS). The photodynamic effect is improved not only by enhanced cellular uptake but also by the high generation of both singlet oxygen and oxygen-centered radicals. All of the presented results support the idea that the rational design of photosensitizers for PDT can be further improved by better understanding the determinants affecting its therapeutic efficiency and explain how smart structural modifications can make them suitable photosensitizers for application in PDT.

Advances in nanomaterials for photodynamic therapy applications: Status and challenges

Photodynamic therapy (PDT), as a non-invasive therapeutic modality that is alternative to radiotherapy and chemotherapy, is extensively investigated for cancer treatments. Although conventional organic photosensitizers (PSs) are still widely used and have achieved great progresses in PDT, the disadvantages such as hydrophobicity, poor stability within PDT environment and low cell/tissue specificity largely limit their clinical applications. Consequently, nano-agents with promising physicochemical and optical properties have emerged as an attractive alternative to overcome these drawbacks of traditional PSs. Herein, the up-to-date advances in the fabrication and fascinating applications of various nanomaterials in PDT have been summarized, including various types of nanoparticles, carbon-based nanomaterials, and two-dimensional nanomaterials, etc. In addition, the current challenges for the clinical use of PDT, and the corresponding strategies to address these issues, as well as future perspectives on further improvement of PDT have also been discussed.

CD44 Targeting Mediated by Polymeric Nanoparticles and Combination of Chlorine TPCS2a-PDT and Docetaxel-Chemotherapy for Efficient Killing of Breast Differentiated and Stem Cancer Cells In Vitro

The presence of rare but highly tumorigenic cancer stem cells (CSCs) within the tumors is recognized as one of the major reasons of failure of conventional chemotherapies, mainly attributed to the development of drug resistance and increasing metastatic potential. Here, we propose a therapeutic strategy based on the simultaneous delivery of docetaxel (DTX) and the photosensitizer meso-tetraphenyl chlorine disulfonate (TPCS2a) using hyaluronic acid (HA) coated polymeric nanoparticles (HA-NPs) for the targeting and killing of CD44 over-expressing breast cancer (BC) cells, both differentiated and CSCs (CD44high/CD24low population), thus combining chemotherapy and photodynamic therapy (PDT). Using the CD44high MDA-MB-231 and the CD44low MCF-7 cells, we demonstrated the occurrence of CD44-mediated uptake of HA-NPs both in monolayers and mammosphere cultures enriched in CSCs. Cell treatments showed that combination therapy using co-loaded NPs (HA@DTX/TPCS2a-NPs) had superior efficacy over monotherapies (HA@DTX-NPs or HA@TPCS2a-NPs) in reducing the self-renewal capacity, measured as mammosphere formation efficiency, and in eradicating the CSC population evaluated with aldehyde dehydrogenase activity assay and CD44/CD24 immunostaining. In summary, these in vitro studies demonstrated for the first time the potential of the combination of DTX-chemotherapy and TPCS2a-PDT for killing CSCs using properly designed NPs.

Synthesis of new water soluble silicon phthalocyanine substituted by linker sulfur atom and photophysicochemical studies for photodynamic therapy

In this work, 5-(trifluoromethyl)-2-thiopyridine substituted SiPc (1) and its quaternized derivative (2) were synthesized, and the effect of the linker sulfur atom on silicon phthalocyanines has been investigated for the first time in the literature. Both of the complexes have been characterized by standard spectroscopy methods. The complexes have good solubility in organic solvents and showed monomeric tendencies in all studied solvents. Only complex 2 had some aggregation in water because of solvent effects, as expected. In order to determine the therapeutic effect for cancer treatment, photophysicochemical properties were investigated in DMSO, DMF, toluene and water (for complex 2). The synthesized complexes were found to have about 3.5 times higher singlet oxygen quantum yields than the yields of unsubstituted SiPcCl2 ([Formula: see text] = 0.15 (in DMSO), 0.12 (in DMF), 0.10 (in toluene)) because of the effects of bulky axial groups.

Glycosylated porphyrin-cucurbituril conjugate for photodynamic inactivation of bacteria and doxorubicin carriage for anticancer drug delivery

Porphyrin derivatives are highly attractive in the construction of multifunctional molecular platforms with interesting properties and applications. In this regard, we report here the use of a multifunctional porphyrin-based molecular platform as a photosensitizer for photodynamic therapy and as a drug carrier. This molecular platform was constructed by conjugating a host molecule, cucurbit[7]uril to a triglycosylated tetraphenyl porphyrin and serves very efficiently as a photosensitizer in the inactivation of both gram-negative (Escherichia coli, E. coli) and gram-positive bacteria (Bacillus subtilis, B. subtilis) and growth inhibition of cancer cells as well as a doxorubicin (DOX) carrier for chemo-photodynamic dual cancer therapy. Another remarkable feature of this photosensitizer is that it shows negligible cytotoxicity in the dark.

Photodynamic activity of Sn(IV) meso-tetraacenaphthylporphyrin and its methyl-β-cyclodextrin inclusion complexes on MCF-7 breast cancer cells

A novel Sn(IV) meso-tetraacenaphthylporphyrin (SnTAcP) has been synthesized and characterized. SnTAcP was complexed with methyl-[Formula: see text]-cyclodextrin (m[Formula: see text]-CD), a nanocarrier that enhances water solubility, and the complexes were evaluated as PDT agents using MCF-7 breast cancer cells. A relatively low singlet oxygen quantum yield value of 0.36 was obtained in DMF, and the lowest energy Q band lies at 608 nm on the edge of the therapeutic window. SnTAcP was found to be non-toxic in the dark and phototoxic towards MCF-7 breast cancer cells with a half-maximal inhibitory concentration (IC[Formula: see text] value of 11 ± 1.1 [Formula: see text]g · mL[Formula: see text] after 30 min of irradiation with a 625 nm Thorlabs LED that provides a dose of 432 J · cm[Formula: see text]. A higher IC[Formula: see text] value of 21 ± 1.1 [Formula: see text]g · mL-1 was obtained for the m[Formula: see text]-CD inclusion complex of SnTAcP.

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

Mitochondria-targeted porphyrin-based photosensitizers containing triphenylphosphonium cations showing efficient in vitro photodynamic therapy effects

Subcellular organelle-targeted photosensitizers have recently reported to be effective photodynamic therapy (PDT) agents. In this work, three porphyrin-derived photosensitizers, containing one, two or four triphenylphosphonium targeting groups, were synthesized and characterized by NMR, HRMS, UV-vis and fluorescence spectroscopy. These photosensitizers showed similar photophysical properties to classical porphyrins and exhibited excellent [Formula: see text]O[Formula: see text] quantum yields in acetonitrile. Subcellular colocalization indicated that all three photosensitizers specifically stain the mitochondria of HeLa cells. Photosensitizer mito-dp, containing two triphenylphosphonium cations was found to be the most uptaken by cells and exhibited the best PDT effect with an effective phototoxicity (IC[Formula: see text] (light) [Formula: see text] 12.4 nM), suggestive of a higher practicable potential of mitochondria-targeted PDT agents in cancer therapy.

Enhancement of PDT-cytotoxicity via ROS induced by indomethacin in metastatic breast cancer

Breast cancer is one of the most common types of cancers prevalent in women. Several types of breast cancers can easily metastasize to bone and cause disease complications such as hypercalcemia and pathologic fracture, thus compromising the quality of life of people affected by it. Bisphosphonate drugs are often used for the treatment of bone metastasis to suppress osteoclastic bone resorption. However, bisphosphonate has adverse effects on the gastrointestinal tract and kidneys and also induces osteonecrosis of the jaw. Photodynamic therapy (PDT) is an alternative cancer treatment approach with minimal invasiveness. It is a combination treatment that uses photosensitizers, which accumulate in tumor cells, followed by laser irradiation. We previously reported that the cellular incorporation of 5-aminolevulinic acid (5-ALA), which was a precursor of protoporphyrin IX (PpIX), was regulated by reactive oxygen species derived from mitochondria (mitROS). In this study, we investigated the incorporation of 5-ALA, accumulation of PpIX, and subsequent effects on cell viability after laser irradiation of two different breast cancer cell lines with different metastaticites. The highly metastatic breast cancer cell line 4T1E/M3 showed a significant increase in ROS production after treatment with indomethacin (IND). In addition, IND treatment enhanced the cellular uptake of 5-ALA via PEPT1 upregulation in 4T1E/M3, but not in the non-metastatic cell line. Overall, metastatic breast cancer is likely to be sensitive to ROS and activate signaling pathways associated with 5-ALA transportation, suggesting that ALA-PDT could be an effective treatment with low invasiveness for metastatic breast cancer.

Dual function of lectins — new perspectives in targeted photodynamic therapy

Porphyrins and phthalocyanines are photosensitizers (PS) that are used in clinical imaging, detection of cancer cells and are particularly applied in photodynamic therapy (PDT). Many scientists have been focused on the design of different porphyrin compounds. However, similar to other anti-cancer agents, they cannot selectively recognize tumor tissues. Scientists are seeking new methods to overcome this problem and to find appropriate targeted delivery strategies. Plant lectins are especially suitable molecules for such targeting as they preferentially recognize specific antigens on the glycosylated cancer cells. This review will give more detailed information about the dual function of lectins and their interactions with PSs, which is a new perspective in targeted PDT. The implications and potential applications of such studies will also be discussed.

Effect of PVP formulation on the in vitro photodynamic efficiency of a photosensitizing phthalocyanine

The administration of photosensitizers and their biocompatibility is crucial to the success of photodynamic therapy treatment. Amongst the various strategies developed to administer photosensitizers of low water-solubility, the use of polyvinylpyrrolidone (PVP), an FDA-approved food additive, is emerging as extremely promising. Its effect on photodynamic outcome was compared to more classical formulation in DMSO and direct solubilization in water. The tetrakis (2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-Zn(II) phthalocyanine chosen as the model photosensitizer for this study proved to be a powerful photosensitizer. Even if slightly less efficient than DMSO formulation, PVP formulation proved to work very well, with submicromolar IC50 and IC90 values against MDA-MB-231 human cancer cells.

Binding of Gold(III) Porphyrin by the Pro-metastatic Regulatory Protein Human Galectin-3

Gold(III) porphyrin presents an attractive alternative to the use of, for example, cisplatin in chemotherapy. However, approaches that allow to selectively target cancer cells are highly sought. Many plant and mammalian lectins have been shown to bind oligosaccharide sequences of the aberrant glycosylation pattern found on cancerous tumors. For example human galectin-3, of the galectin family specific for β-galactoside, is overexpressed in the extracellular matrix of tumorigenous and metastatic tissues. We searched for non-carbohydrate ligands for galectin-3 that can guide a cytotoxic drug to the cancer cells by maintaining its affinity for tumor associated carbohydrate antigens. Previous findings showed that zinc tetrasulfonatophenylporphyrin can bind galectin-3 with sub-micromolar affinity without disturbing lactose binding. Gold(III) porphyrin is not only cytotoxic to cancer cells, it knows also a potential application as photosensitiser in photodynamic therapy. We investigated the binding of gold(III) porphyrin to galectin-3 using different biophysical interaction techniques and demonstrated a low micromolar affinity of human galectin-3 for the cytotoxic compound. Co-crystallization attempts in order to understand the binding mode of gold porphyrin to galectin-3 failed, but molecular docking emphasized a highly populated secondary binding site that does not hinder lactose or Thomsen Friendenreich disaccharide binding. This suggests that gold(III) porphyrin might significantly enhance its concentration and delivery to cancer cells by binding to human galectin-3 that keeps its orientation towards tumor associated carbohydrate antigens.

Vascular targeted photodynamic therapy: A review of the efforts towards molecular targeting of tumor vasculature

The therapeutic value of vascular targeted photodynamic therapy (VTP) for cancer has already been recognized in the clinic: TOOKAD® has been clinically approved in Europe and Israel for treatment of men with low-risk prostate cancer. When light is applied shortly after intravenous administration of the photosensitizer, the damage is primarily done to the vasculature. This results in vessel constriction, blood flow stasis, and thrombus formation. Subsequently, the tumor is killed due to oxygen and nutrient deprivation. To further increase treatment specificity and to reduce undesired side effects such as damaging to the surrounding healthy tissues, efforts have been made to selectively target the PS to the tumor vasculature, an approach named molecular targeted VTP (molVTP). Several receptors have already been explored for this approach, namely CD13, CD276, Extra domains of fibronectin (A, B), Integrin αvβ3, Neuropilin-1, Nucleolin, PDGFRβ, tissue factor, and VEGFR-2, which are overexpressed on tumor vasculature. Preclinical studies have shown promising results, further encouraging the investigation and future application of molVTP, to improve selectivity and efficacy of cancer treatment. This strategy will hopefully lead to even more selective treatments for many cancer patients.

Evaluation of polyvinylpyrrolidone and block copolymer micelle encapsulation of serine chlorin e6 and chlorin e4 on their reactivity towards albumin and transferrin and their cell uptake

Encapsulation of porphyrinic photosensitizers (PSs) into polymeric carriers plays an important role in enhancing their efficiency as drugs in photodynamic therapy (PDT). Porphyrin aggregation and low solubility as well as the preservation of the advantageous photophysical properties pose a challenge on the design of efficient PS-carrier systems. Block copolymer micelles (BCMs) and polyvinylpyrrolidone (PVP) are promising drug delivery vehicles for physical entrapment of PSs. BCMs exhibit enhanced dynamics as compared to the less flexible PVP network. In the current work the question is addressed how these different dynamics affect PS encapsulation, release from the carrier, reaction with serum proteins, and cellular uptake. The porphyrinic compounds serine-amide of chlorin e6 (SerCE) and chlorin e4 (CE4) were used as model PSs with different lipophilicity and aggregation properties. ¹H NMR and fluorescence spectroscopy were applied to study their interactions with PVP and BCMs consisting of Kolliphor P188 (KP). Both chlorins were well encapsulated by the carriers and had improved photophysical properties. Compared to SerCE, the more lipophilic CE4 exhibited stronger hydrophobic interactions with the BCM core, stabilizing the system and preventing exchange with the surrounding medium as was shown by NMR NOESY and DOSY experiments. PVP and BCMs protected the encapsulated chlorins against interaction with human transferrin (Tf). However, SerCE and CE4 were released from BCMs in favor of binding to human serum albumin (HSA) while PVP prevented interaction with HSA. Fluorescence spectroscopic studies revealed that HSA binds to the surface of PVP forming a protein corona. PVP and BCMs reduced cellular uptake of the chlorins. However, encapsulation into BCMs resulted in more efficient cell internalization for CE4 than for SerCE. HSA significantly lowered both, free and carrier-mediated cell uptake for CE4 and SerCE. In conclusion, PVP appears as the more universal delivery system covering a broad range of host molecules with respect to polarity, whereas BCMs require a higher drug-carrier compatibility. Poorly soluble hydrophobic PSs benefit stronger from BCM-type carriers due to enhanced bioavailability through disaggregation and solubilization allowing for more efficient cell uptake. In addition, increased PS-carrier hydrophobic interactions have a stabilizing effect. For more hydrophilic PSs, the main advantage of polymeric carriers like PVP or poloxamer micelles lies in their protection during the transport through the bloodstream. HSA binding plays an important role for drug release and cell uptake in carrier-mediated delivery to the target tissue.

Photodynamic therapy of intradermal metastatic breast cancer (literature review)

In recent years, an increase in the incidence of breast cancer has been observed throughout the world, and in 20% of cases, with the development of intradermal metastases. The possibilities of surgical and radiation treatment of intradermal breast metastases are quite limited, and the effectiveness of polychemotherapy using standard regimens does not exceed 22–27%, while the period of remission, in general, is only 2–3 months. Photodynamic therapy (PDT) is a promising treatment for intradermal metastases of breast cancer. The experience of using PDT in this nosology is quite limited, but the results show its high efficiency and safety. Thus, several Russian studies are devoted to assessing the effectiveness of PDT of intradermal breast metastases with Photolon, a chlorin series photosensitizer. According to the authors, the therapeutic effect was achieved in 85–97% of patients (the percentage of patients with full and partial effect was 73–85%). Studies on the effectiveness of PDT in patients with the same nosology using the Photosens photosensitizer show a slightly lower effectiveness – the therapeutic effect was achieved in 81.8% of cases, while the proportion of patients with full and partial effect was only about 50%. Several studies have been carried out abroad on models of metastatic breast cancer using new photosensitizers (e.g. sodium sinoporphyrin) and new combined PDT regimens (e.g. adjuvant PDT with fluorouracil or Capecitabine). The obtained results demonstrate the promise of new approaches: PDT with sodium sinoporphyrin inhibited the growth of both the tumor itself and its metastases; the use of adjuvant regimens led to an increase in the tumor cells differentiation in the animal model, the cessation of tumor and metastatic foci growth.

Tailored porphyrin–gold nanoparticles for biomedical applications

In this review we present an updated survey of the main synthesis methods of gold nanoparticles (AuNPs) in order to obtain various tailored nanosystems for biomedical imaging. The synthesis approach significantly impacts on the AuNPs properties such as surface chemistry, biocompatibility and cytotoxicity. In recent years, nanomedicine emphasized the development of functionalized AuNPs for biomedical imaging. AuNPs are a good option for used as delivery photosensitizer agents for PDT of cancer. For example, the complex formed from AuNPs functionalized with PEGylate porphyrins presents several advantages in the medical field such as a better use in photodynamic therapy because of high triplet states and singlet oxygen quantum yield efficiency of porphyrin molecules.

Porphyrinoid-based photosensitizers for diagnostic and therapeutic applications: An update

Porphyrin-based molecules are actively studied as dual function theranostics: fluorescence-based imaging for diagnostics and fluorescence-guided therapeutic treatment of cancers. The intrinsic fluorescent and photodynamic properties of the bimodal molecules allows for these theranostic approaches. Several porphyrinoids bearing both hydrophilic and/or hydrophobic units at their periphery have been developed for the aforementioned applications, but better tumor selectivity and high efficacy to destroy tumor cells is always a key setback for their use. Another issue related to their effective clinical use is that, most of these chromophores form aggregates under physiological conditions. Nanomaterials that are known to possess incredible properties that cannot be achieved from their bulk systems can serve as carriers for these chromophores. Porphyrinoids, when conjugated with nanomaterials, can be enabled to perform as multifunctional nanomedicine devices. The integrated properties of these porphyrinoid-nanomaterial conjugated systems make them useful for selective drug delivery, theranostic capabilities, and multimodal bioimaging. This review highlights the use of porphyrins, chlorins, bacteriochlorins, phthalocyanines and naphthalocyanines as well as their multifunctional nanodevices in various biomedical theranostic platforms.

Hydrogels: soft matters in photomedicine

Photodynamic therapy (PDT), a shining beacon in the realm of photomedicine, is a non-invasive technique that utilizes dye-based photosensitizers (PSs) in conjunction with light and oxygen to produce reactive oxygen species to combat malignant tissues and infectious microorganisms. Yet, for PDT to become a common, routine therapy, it is still necessary to overcome limitations such as photosensitizer solubility, long-term side effects (e.g., photosensitivity) and to develop safe, biocompatible and target-specific formulations. Polymer based drug delivery platforms are an effective strategy for the delivery of PSs for PDT applications. Among them, hydrogels and 3D polymer scaffolds with the ability to swell in aqueous media have been deeply investigated. Particularly, hydrogel-based formulations present real potential to fulfill all requirements of an ideal PDT platform by overcoming the solubility issues, while improving the selectivity and targeting drawbacks of the PSs alone. In this perspective, we summarize the use of hydrogels as carrier systems of PSs to enhance the effectiveness of PDT against infections and cancer. Their potential in environmental and biomedical applications, such as tissue engineering photoremediation and photochemistry, is also discussed.

Keratin nanoparticles co-delivering Docetaxel and Chlorin e6 promote synergic interaction between chemo- and photo-dynamic therapies

The combination of chemotherapy and photodynamic therapy (PDT) is considered a valuable strategy for increasing therapeutic response in cancer treatment, and the re-formulation of pharmaceuticals in biocompatible nanoparticles (NPs) is particularly appealing for the possibility of co-loading drugs exerting cytotoxicity by different mechanisms, with the aim to produce synergic effects. We report the in-water synthesis of a novel keratin-based nanoformulation for the co-delivery of the antimitotic Docetaxel (DTX) and the photosensitizer Chlorin e6 (Ce6). The drug-induced aggregation method allowed the formation of monodisperse NPs (DTX/Ce6-KNPs) with an average diameter of 133 nm and loaded with a drug ratio of 1:1.8 of Ce6 vs DTX. The efficacy of DTX/Ce6-KNPs was investigated in vitro in monolayers and spheroids of DTX-sensitive HeLa (HeLa-P) and DTX-resistant HeLa (HeLa-R) cells. In monolayers, the cytotoxic effects of DTX/Ce6-KNPs toward HeLa-P cells were comparable to those induced by free DTX + Ce6, while in HeLa-R cells the drug co-loading in KNPs produced synergic interaction between chemotherapy and PDT. Moreover, as respect to monotherapies, DTX/Ce6-KNPs induced stronger cytotoxicity to both HeLa-P and HeLa-R multicellular spheroids and reduced their volumes up to 50%. Overall, the results suggest that KNPs are very promising systems for the co-delivery of chemotherapeutics and PSs, favoring synergic interactions between PDT and chemotherapy.

Effect of symmetry and metal nanoparticles on the photophysicochemical and photodynamic therapy properties of cinnamic acid zinc phthalocyanine

In this study, a novel asymmetric cinnamic acid zinc phthalocyanine (ZnPc, 1) containing three tert-butyl substituents is reported. The asymmetric ZnPc (1) is further linked to amino functionalized magnetic nanoparticles (AMNPs) (1-AMNPs) and to cysteine functionalized silver nanoparticles (cys-AgNPs) (1-cys-AgNPs) through an amide bond. 1-AMNPs and 1-cys-AgNPs improved the triplet and singlet oxygen quantum yields of complex 1, this was also observed with the previously reported 2-AMNPs when compared to 2 while 3-AMNPs yielded an unexpected decrease in triplet quantum yield as compared to 3. The silver nanoparticles (1-cys-AgNPs) had a better effect on improving the singlet oxygen quantum yield of complex 1 than the magnetic nanoparticles (1-AMNPs). The Pcs and conjugates recorded low cell cytotoxicity in the dark and high photocytotoxicity against MCF-7 cells in-vitro. MCF-7 cell viabilities of less than 50% were recorded at 80 μg/mL making the Pcs and conjugates under study potential candidates for use as photosensitizers in cancer therapy.

Porphyrinoids in photodynamic diagnosis and therapy of oral diseases

Photodynamic methods have found application not only in the treatment process as photodynamic therapy but also for the early detection of neoplastic lesions and tumors as photodynamic diagnosis. Early detection of the disease allows not only to avoid the patient’s lifetime risk but also significantly reduce the costs of anticancer therapy, which are increasing every year. There is a constant search for new and more effective photosensitizers which will provide safety in therapy while maintaining efficiency. This paper summarizes recent reports focused on the photodynamic diagnosis of oral cancers. Moreover, it shows methods of the photodynamic treatment of oral verrucous hyperplasia, erythroleukoplakia, and oral leukoplakia. The treatment of choice for these diseases is a surgical excision, which always leads to scar formation. Photodynamic therapy provides a new scar-less tool for the treatment.

Synthesis and investigation of phthalocyanine-biotin conjugates

An isothiocyanato-functionalized phthalocyanine (Pc) was synthesized in good yield from the corresponding amine-substituted Pc. This Pc reacted with ethanolamine, biotin hydrazine, and biotin diethylamine under mild conditions (room temperature in DMF or DMSO in the presence of TEA) to produce the corresponding thiourea products in 60-75% yields. All Pcs showed intense Q absorptions in DMF around 677 nm, emissions centered at 683 nm, and fluorescence quantum yields in the range 0.18-0.27. The Pcs were phototoxic to human carcinoma HEp2 cells (IC50 ~ 7 at 1.5 J/cm2) and localized in multiple organelles, including the lysosomes, Golgi and ER. One biotin-Pc conjugate was injected via tail vein into nude mice bearing HT-29 tumors and demonstrated selective localization in the tumor tissue.

Functional Polymer Nanocarriers for Photodynamic Therapy

Photodynamic therapy (PDT) is an appealing therapeutic modality in management of some solid tumors and other diseases for its minimal invasion and non-systemic toxicity. However, the hydrophobicity and non-selectivity of the photosensitizers, inherent serious hypoxia of tumor tissues and limited penetration depth of light restrict PDT further applications in clinic. Functional polymer nanoparticles can be used as a nanocarrier for accurate PDT. Here, we elucidate the mechanism and application of PDT in cancer treatments, and then review some strategies to administer the biodistribution and activation of photosensitizers (PSs) to ameliorate or utilize the tumor hypoxic microenvironment to enhance the photodynamic therapy effect.

Catch and Release Photosensitizers: Combining Dual-Action Ruthenium Complexes with Protease Inactivation for Targeting Invasive Cancers

Dual action agents containing a cysteine protease inhibitor and Ru-based photosensitizer for photodynamic therapy (PDT) were designed, synthesized, and validated in 2D culture and 3D functional imaging assays of triple-negative human breast cancer (TNBC). These combination agents deliver and release Ru-based PDT agents to tumor cells and cause cancer cell death upon irradiation with visible light, while at the same time inactivating cathespin B (CTSB), a cysteine protease strongly associated with invasive and metastatic behavior. In total five Ru-based complexes were synthesized with the formula [Ru(bpy)₂(1)](O₂CCF₃)₂ (3), where bpy = 2,2'-bipyridine and 1 = a bipyridine-based epoxysuccinyl inhibitor; [Ru(tpy)(NN)(2)](PF₆)₂, where tpy = terpiridine, 2 = a pyridine-based epoxysuccinyl inhibitor and NN = 2,2'-bipyridine (4); 6,6'-dimethyl-2,2'-bipyridine (5); benzo[ i]dipyrido[3,2- a:2',3'- c]phenazine (6); and 3,6-dimethylbenzo[ i]dipyrido[3,2- a:2',3'- c]phenazine (7). Compound 3 contains a [Ru(bpy)₃]²⁺ fluorophore and was designed to track the subcellular localization of the conjugates, whereas compounds 4-7 were designed to undergo either photoactivated ligand dissociation and/or singlet oxygen generation. Photochemical studies confirmed that complexes 5 and 7 undergo photoactivated ligand dissociation, whereas 6 and 7 generate singlet oxygen. Inhibitors 1-7 all potently and irreversibly inhibit CTSB. Compounds 4-7 were evaluated against MDA-MB-231 TNBC and MCF-10A breast epithelial cells in 2D and 3D culture for effects on proteolysis and cell viability under dark and light conditions. Collectively, these data reveal that 4-7 potently inhibit dye-quenched (DQ) collagen degradation, whereas only compound 7 causes efficient cell death under light conditions, consistent with its ability to release a Ru(II)-based photosensitizer and to also generate ¹O₂.

Synthesis of PSMA-targeted 131- and 152-substituted chlorin e6 derivatives and their biological properties

Prostate cancer is an extremely common cancer among older men. Conventional chemotherapy has proven to be not effective enough in battling it due to its high systemic toxicity and low selectivity. An alternative method of cancer treatment known as photodynamic therapy (PDT) has been shown to be effective. It is not without its faults either: one of the issues it’s been known to have is the insufficient selectivity of photosensitizer accumulation in tumor tissues. Recent studies, however, seem to indicate that introducing a PSMA-targeted moiety into photosensitizer might prove to be a solution to this problem. The present paper is concerned with synthesis of PSMA-targeted 131- and 152-substituted chlorin e6 conjugates and their biological characteristics. Our data suggests that the developed conjugates show potential as targeted agents for photodynamic therapy.

Photodynamic therapy activity of zinc phthalocyanine linked to folic acid and magnetic nanoparticles

In this work, the photodynamic therapy (PDT) activities (using human carcinoma adherent MCF-7 cells) of zinc phthalocyanine derivatives: complexes 1 (Zn mono cinnamic acid phthalocyanine) and 2 (zinc mono carboxyphenoxy phthalocyanine) when covalently linked to folic acid (FA) and amine functionalized magnetic nanoparticles (AMNPs) are reported. The covalent linkage of asymmetric zinc cinnamic acid Pc (1) to FA (1-FA) through an amide bond is reported for the first time. Complex 1 is insoluble in water, but upon linkage to FA, (to form 1-FA) the molecule become water soluble, hence the UV-Vis spectrum and singlet oxygen quantum yield for 1-FA were also done in water since water solubility is essential for biological applications. The reported 2-FA is also water soluble. Linking complexes 1 and 2 to FA and AMNPs decreased the dark toxicity of 1 and 2 on MCF-7 cells. Pc-FA (1-FA and 2-FA) conjugates had better singlet oxygen quantum yields (Φ_∆) in DMSO as compared to Pc-AMNPs (1-AMNPs and 2-AMNPs). The water- soluble 1-FA and 2-FA also achieved a better photodynamic therapy (PDT) activity as compared to 1-AMNPs and 2-AMNPs. Folic acid targeting on the tumor cells may have also facilitated better bioavailability of 1-FA and 2-FA and improved PDT activity on MCF-7 cells over AMNPs carriers.

Titania and silica nanoparticles coupled to Chlorin e6 for anti-cancer photodynamic therapy

In this study, light-sensitive photosensitizers (Chlorin e6, Ce6) were linked to TiO₂ and SiO₂ nanoparticles (NPs) in order to develop new kinds of NP-based drug delivery systems for cancer treatment by PDT. TiO₂ or SiO₂ NPs were modified either by the growth of a polysiloxane layer constituted of two silane reagents ((3-aminopropyl)triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS)) around the core (PEGylated NPs: TiO₂@4Si-Ce6-PEG, SiO₂@4Si-Ce6-PEG) or simply modified by APTES alone (APTES-modified NPs: TiO₂-APTES-Ce6, SiO₂-APTES-Ce6). Ce6 was covalently attached onto the modified TiO₂ and SiO₂ NPs via an amide bond. The absorption profile of the hybridized NPs was extended to the visible region of the light. The physicochemical properties of these NPs were explored by TEM, HR-TEM, XRD, FTIR and zeta potential. The photophysical characteristics including the light absorption, the fluorescence properties and the production reactive oxygen species (¹O₂ and HO) were also addressed. In vitro experiments on glioblastoma U87 cells were performed to evaluate the photodynamic efficiency of the new hybridized NPs. The cells were exposed to different concentrations of NPs and illuminated (λ_exc = 652 nm, fluence rate 10 J/cm²). In contrast to the PEGylated NPs, the APTES-modified nanosystems were found to be more efficient for PDT. An interesting photodynamic effect was observed in the case of TiO₂-APTES-Ce6 NPs. After illumination, the viability of U87 was decreased by 89% when they were exposed to 200 μg/mL of TiO₂-APTES-Ce6 NPs, which corresponds to 0.22 μM of Ce6. The same effect can be obtained with free photosensitizer but using a higher concentration of 10 μM of Ce6.

Synthesis and characterization of a new meso-tetra-dihydro benzocyclobutacenaphthylene free-base porphyrin

A meso-tetra-6b,10b-dihydrobenzo[j]cyclobut[a]acenaphthylene free-base porphyrin was synthesised and its photophysical, photochemical and electrochemical properties were compared with those of free-base meso-tetraphenylporphyrin. The frontier orbitals and the HOMO–LUMO energy gaps of both compounds were also determined. It was demonstrated that the meso6b,10b-Dihydrobenzo[j]cyclobut[a]acenaphthylene porphyrin retained the same properties as the tetraphenylporphyrin.