Concept Of Photodynamic Therapy Research Articles

REVISÃO DO FOTOSSENSIBILIZADOR FTALOCIANINA UTILIZADA NA TERAPIA FOTODINÂMICA E SUA APLICABILIDADE FRENTE AO TRATAMENTO DE DIVERSOS AGENTES PATOGÊNICOS

Photodynamic therapy (PDT) is a treatment modality already used in several countries to treat invasive and topical diseases. In these treatments, the combination of a photoactive drug (PS), visible light, and molecular oxygen results in the formation of singlet oxygen, a type of highly reactive/cytotoxic oxygen species. Phthalocyanines incorporated into solubilization/monomerization systems are photosensitizing substances used in PDT, even given their high hydrophobicity. Its inhibitory capacity against microorganisms and its photodynamic action against various cancer cell lines have made it the protagonist of several scientific articles. This review article provides a brief overview of the concept of PDT and its potential use in the treatment of diseases - an emerging treatment modality in Brazil.

Multiporphyrinic architectures: Advances in structural design for photodynamic therapy

AbstractRationally designed multiporphyrinic architectures for boosting photodynamic therapy (PDT) have attracted significant attentions recently years due to their great potential for light‐mediated generation of reactive oxygen species. However, there is still a gap between the structure design and their PDT performance for biomedical applications. This tutorial review provides a historical overview on (i) the basic concept of PDT for deeply understanding the porphyrin‐mediated PDT reactions, (ii) developing strategies for constructing porphyrinic architectures, like nanorings, boxes, metal‐organic frameworks (MOFs), covalent‐organic frameworks (COFs), vesicles, etc., where we classified into the following three categories: multiporphyrin arrays, porphyrinic frameworks, and others porphyrin assemblies, (iii) the various application scenarios for clinical cancer therapy and antibacterial infection. Also, the existing challenges and future perspectives on the innovation of porphyrinic architectures for clinical PDT applications are mentioned in the end section. Moreover, the porphyrinic nanomaterials with atomically precise architectures provide an ideal platform for investigating the relationship between structures and PDT outputs, design of personalized “all‐in‐one” theranostic agents, and the popularization and application in wider biomedical fields.

Active targeted photodynamic therapeutic effect of silver-based nanohybrids on melanoma cancer cells

Malignant melanoma is aggressive cancer that metastasizes along with the heterogeneity at the molecular and cellular levels, thereby reducing overall therapeutic efficacy. In the present research, the concept of photodynamic therapy (PDT) was investigated on silver-based nanohybrids for the treatment of A375 melanoma cancer cells. Hence, two different nanoparticles (NPs) namely Ag-PEG NPs and core/shell Ag@mSiO2 NPs were fabricated and conjugated to zinc phthalocyanine tetrasulfonate (ZnPcS4) photosensitizer (PS). Folic acid (FA) as a targeting moiety was also decorated onto the surface of nanohybrids to selectively target the folate receptors that are overexpressed on the A375 cells. Ultimately, the PDT efficacy of both ZnPcS4/Ag-PEG-FA and ZnPcS4/Ag@mSiO2-FA nanohybrids were compared via ATP viability, flow cytometry, and reactive oxygen species (ROS) assays. The obtained near-spherical shaped nanohybrids had zeta potential of -4.03 ± 0.3 mV for ZnPcS4/Ag-PEG-FA, and -14.4 ± 0.6 mV for the ZnPcS4/Ag@mSiO2-FA. A significant PDT effect was observed for the cells exposed to 674 nm laser irradiation after incubation with ZnPcS4/Ag@mSiO2-FA with ∼92%* ± 1.1 cell death compared to ∼70%* ± 2.9 cell death for ZnPcS4/Ag-PEG-FA nanohybrids owing to the higher generation of ROS for the former nanohybrids. The majority of the cell death was induced via apoptosis rather than necrosis as the nanohybrids successfully localized in mitochondria. The overall finding of this study concluded that an active targeting strategy significantly enhanced the cellular uptake of the nanohybrids compared to passive targeting. Moreover, strong surface plasmon-PS resonance coupling in ZnPcS4/Ag@mSiO2-FA nanohybrids enhanced singlet oxygen generation in comparison to the PS alone or ZnPcS4/Ag-PEG-FA nanohybrids.

Selective Killing of Activated T Cells by 5-Aminolevulinic Acid Mediated Photodynamic Effect: Potential Improvement of Extracorporeal Photopheresis.

Extracorporeal photopheresis (ECP), a modality that exposes isolated leukocytes to the photosensitizer 8-methoxypsoralen (8-MOP) and ultraviolet-A (UV-A) light, is used to treat conditions such as cutaneous T-cell lymphoma and graft-versus-host disease. However, the current procedure of ECP has limited selectivity and efficiency; and produces only partial response in the majority of treated patients. Additionally, the treatment is expensive and time-consuming, so the improvement for this modality is needed. In this study, we used the concept of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA), a precursor of an endogenously synthesized photosensitizer protoporphyrin IX (PpIX) in combination with blue light to explore the possibility of targeting activated human blood T cells ex vivo. With various T-cell activation protocols, a high ALA-induced PpIX production took place in activated CD3+, CD4+CD25+, and CD8+ T cell populations with their subsequent killing after blue light exposure. By contrast, resting T cells were much less damaged by the treatment. The selective and effective killing effect on the activated cells was also seen after co-cultivating activated and resting T cells. Under our clinically relevant experimental conditions, ALA-PDT killed activated T cells more selectively and efficiently than 8-MOP/UV-A. Monocyte-derived dendritic cells (DCs) were not affected by the treatment. Incubation of ALA-PDT damaged T cells with autologous DCs induced a downregulation of the co-stimulatory molecules CD80/CD86 and also upregulation of interleukin 10 (IL-10) and indoleamine 2,3-dioxygenase expression, two immunosuppressive factors that may account for the generation of tolerogenic DCs. Overall, the data support the potential use of ALA-PDT strategy for improving ECP by selective and effective killing of activated T cells and induction of immune tolerance.

Photodynamic therapy: An adjunct to conventional root canal disinfection strategies.

Although chemical-based root canal disinfectants are important to reduce microbial loads and remove infected smear layer from root dentin, they have only a limited ability to eliminate biofilm bacteria, especially from root complexities. This paper explores the novel photodynamic therapy (PDT) for antimicrobial disinfection of root canals. The combination of an effective photosensitizer, the appropriate wavelength of light and ambient oxygen is the key factor in PDT. PDT uses a specific wavelength of light to activate a non-toxic dye (photosensitizer), leading to the formation of reactive oxygen species. These reactive oxygen molecules can damage bacterial proteins, membrane lipids and nucleic acids, which promote bacterial cell death. In, addition PDT may enhance cross-linking of collagen fibrils in the dentin matrix and thereby improving dentin stability. The concept of PDT is plausible and could foster new therapy concepts for endodontics. The available knowledge should enable and encourage steps forward into more clinical-oriented research and development. This article discusses PDT as related to root canal disinfection, including its components, mechanism of action, reviews the current endodontic literature and also highlights the shortcomings and advancements in PDT techniques.

ChemInform Abstract: The Role of Porphyrin Chemistry in Tumor Imaging and Photodynamic Therapy

AbstractReview: 205 refs.

The role of porphyrin chemistry in tumor imaging and photodynamic therapy

In recent years several review articles and books have been published on the use of porphyrin-based compounds in photodynamic therapy (PDT). This critical review is focused on (i) the basic concept of PDT, (ii) advantages of long-wavelength absorbing photosensitizers (PS), (iii) a brief discussion on recent advances in developing PDT agents, and (iv) the various synthetic strategies designed at the Roswell Park Cancer Institute, Buffalo, for developing highly effective long-wavelength PDT agents and their utility in constructing the conjugates with tumor-imaging and therapeutic potential (Theranostics). The clinical status of certain selected PDT agents is also summarized (205 references).

97 FROM LASER AND LED THERAPY TO NOVEL “USEFUL SUN” STRATEGY

The combination of light and chemicals to treat skin diseases is widely practiced in dermatology. Within this broad use of light and drugs, in recent years the concept of photodynamic therapy (PDT) has emerged. PDT is a promising modality for the management of various tumors and nonmalignant diseases, based on the combination of a photosensitizer that is selectively localized in the target tissue and illumination of the lesion with visible light, resulting in photodamage and subsequent cell death. Moreover, the fluorescence of photosensitizing compounds is also utilized as a helpful diagnostic tool for the detection of neoplastic tissue. Intensive basic and clinical research culminated in the worldwide approval of PDT for bladder, esophageal, and lung cancer. The expanding use of this relatively new therapeutic modality in dermatology at many centers around the world has revealed its efficacy for the treatment of cutaneous precancer and cancer, as well as selected benign skin disorders. The following article summarizes the main principles of PDT considering the most recent developments and provides a comprehensive synopsis of the present status of the use of PDT in dermatology. (J Am Acad Dermatol 2000;42:389-413.) Learning Objective: At the conclusion of this learning activity, participants should be able to describe the basic concepts of PDT, including fundamental knowledge of the most relevant photosensitizers, the light sources, the mechanisms involved in PDT-mediated cell destruction, as well as the indications and limitations of photodynamic treatment of skin diseases.

Photophysics and photochemistry of photodynamic therapy: fundamental aspects

Photodynamic therapy (PDT) is a treatment modality for cancer and various other diseases. The clinical protocol covers the illumination of target cells (or tissue), which have been loaded with a photoactive drug (photosensitizer). In this review we describe the photophysical and primary photochemical processes that occur during PDT. Interaction of light with tissue results in attenuation of the incident light energy due to reflectance, absorption, scattering, and refraction. Refraction and reflection are reduced by perpendicular light application, whereas absorption can be minimized by the choice of a photosensitizer that absorbs in the far red region of the electromagnetic spectrum. Interaction of light and the photosensitizer can result in degradation, modification or relocalization of the drug, which differently affect the effectiveness of PDT. Photodynamic therapy itself, however, employs the light-induced chemical reactions of the activated photosensitizer (triplet state), resulting in the production of various reactive oxygen species, amongst them singlet oxygen as the primary photochemical product. Based on these considerations, the properties of an ideal photosensitizer for PDT are discussed. According to the clinical experience with PDT, it is proposed that the innovative concept of PDT is most successfully implemented into the mainstream of anticancer therapies by following an application-, i.e. tumor-centered approach with a focus on the actual clinical requirements of the respective tumor type.

Terapia fotodinâmica: princípios, potencial de aplicação e perspectivas

Photodynamic Therapy (PDT) has been designated as a promising new modality in the treatment of cancer and other diseases since the early 1980s. It has been used with success for the treatment of a variety of tumours, and attempts are being made to extend this treatment modality to other clinical conditions (as example, the inactivation of viruses in blood and blood components). This can be partly attributed to the very attractive basic concept of PDT: the combination of a photosensitizing drug and light, which are relatively harmless by themselves but combined (in the presence of oxygen) ultimately cause more or less selective tumour destruction.

Photodynamic therapy in dermatology

The combination of light and chemicals to treat skin diseases is widely practiced in dermatology. Within this broad use of light and drugs, in recent years the concept of photodynamic therapy (PDT) has emerged. PDT is a promising modality for the management of various tumors and nonmalignant diseases, based on the combination of a photosensitizer that is selectively localized in the target tissue and illumination of the lesion with visible light, resulting in photodamage and subsequent cell death. Moreover, the fluorescence of photosensitizing compounds is also utilized as a helpful diagnostic tool for the detection of neoplastic tissue. Intensive basic and clinical research culminated in the worldwide approval of PDT for bladder, esophageal, and lung cancer. The expanding use of this relatively new therapeutic modality in dermatology at many centers around the world has revealed its efficacy for the treatment of cutaneous precancer and cancer, as well as selected benign skin disorders. The following article summarizes the main principles of PDT considering the most recent developments and provides a comprehensive synopsis of the present status of the use of PDT in dermatology. (J Am Acad Dermatol 2000;42:389-413.) Learning Objective: At the conclusion of this learning activity, participants should be able to describe the basic concepts of PDT, including fundamental knowledge of the most relevant photosensitizers, the light sources, the mechanisms involved in PDT-mediated cell destruction, as well as the indications and limitations of photodynamic treatment of skin diseases.

A vehicle for photodynamic therapy of skin cancer: influence of dimethylsulphoxide on 5-aminolevulinic acid in vitro cutaneous permeation and in vivo protoporphyrin IX accumulation determined by confocal microscopy

Topical application of 5-aminolevulinic acid (5-ALA) followed by light irradiation is a new concept of photodynamic therapy (PDT) of skin cancers. 5-ALA is a prodrug that can be converted by the heme biosynthetic pathway into protoporphyrin IX, an effective photosensitizer. In the present work we propose the enhancement of 5-ALA-induced protoporphyrin IX accumulation by dimethylsulphoxide (DMSO) and ethylenediamine–tetraacetic acid disodium salt (EDTA). The presence of 20% DMSO (w/w) in oil-in-water emulsions increased the in vitro permeation of 5-ALA through hairless mouse skin. In vivo studies demonstrated a significant increase in the amount of protoporphyrin IX extracted from healthy hairless mouse skin after 3 h treatment with an oil-in-water emulsion containing 10% 5-ALA (w/w), 3% EDTA (w/w) and 20% DMSO (w/w). By confocal scanning laser microscopy imaging, an observed increase in red fluorescence, at 476 nm excitation and emission detected longer than 590 nm, in skin that had received this treatment, was attributed to protoporphyrin IX accumulation. Although no effect of EDTA on short-term protoporphyrin IX accumulation in skin was detected, this chelator could protect 5-ALA from decomposition during prolonged topical administration. The results obtained indicate that association of 5-ALA, EDTA and 20% DMSO may enhance the delivery of 5-ALA to the skin in the topical PDT.

Photodynamic Therapy in Dermatology

To most dermatologists, the concept of photodynamic therapy (PDT) is synonymous with the use of porphyrins such as Photofrin (Quadra Logic Technologies Inc, Vancouver, British Columbia) in combination with laser light for treating cutaneous malignancies. In broader terms, PDT encompasses the therapeutic use of photochemical reactions mediated through the interaction of light, photosensitizing drugs, and oxygen. Thus, psoralen-ultraviolet A light treatment may represent a form of PDT in the sense that oxygen-consuming photoreactions may be involved in this form of phototherapy. 1 As psoralen-ultraviolet A light treatment is already a familiar and wellestablished form of phototherapy, it will not be discussed further here. With the recent introduction of second generation PDT photosensitizing drugs into clinical trials and the application of PDT for nononcologic indications, it now seems appropriate to review the current and potential roles of PDT in dermatologic practice. See also p 1597. Most patients undergoing PDT have been