The history of PDT in Norway

5-Aminolevulinic Acid and Red Led in Endodontics: A Narrative Review and Case Report

The present study aims to discuss the main factors involving the use of 5-aminolevulinic acid together with red LED light and its application in endodontic treatment through a narrative review and a case report. Persistence of microorganisms remaining on chemical-mechanical preparation or intracanal dressing is reported as the leading cause of failure in endodontics. Photodynamic therapy has become a promising antimicrobial strategy as an aid to endodontic treatment. Being easy and quick to apply, it can be used both in a single session and in several sessions, as well as not allowing forms of microbial resistance. 5-aminolevulinic acid in combination with red LED light has recently been studied in many branches of medicine, with good results against numerous types of bacteria including Enterococuss faecalis. The case report showed how bacterial count of CFU decreased by half (210 CFU/mL), after 45 min of irrigation with a gel containing 5% of 5-aminolevulinic acid compared to the sample before irrigation (420 CFU/mL). The subsequent irradiation of red LED light for 7 min, the bacterial count was equal to 0. Thus, it is concluded that the use of 5-aminolevulinic acid together with red LED light is effective in endodontic treatment.

New porphyrin photosensitizers-Synthesis, singlet oxygen yield, photophysical properties and application in PDT

This research on porphyrin-based photosensitizer system has a very important theoretical and practical significance in the photodynamic therapy (PDT) treatment of cancer. Based on this, in this article, a series of porphyrin derivatives were first designed and synthesized, and a "push-pull" porphyrin photosensitizer with two symmetrical ethanethioate groups was finally constructed. Based on the characterization of their chemical structures (¹H and¹³C NMR, MS, IR, and UV-Vis spectroscopy) and the use of the density functional theory (DFT) and time-dependent DFT (TDDFT) to address the nature of the excited states as well as the dark/phototoxicity, the results have indicated the relationship between the porphyrin structure and properties. The experimental and theoretical UV-Vis absorption properties of porphyrins were discussed. The four porphyrin compounds synthesized all demonstrated a high capacity to generate singlet oxygen under long-wavelength (590 nm) light and low dark toxicity. Compared with the conventional porphyrin photosensitizers, P4 with a CT band (from 580 to 750 nm) is beneficial to the penetration of the light, presenting the potential for applications in PDT.

Evaluation of antimicrobial photodynamic activities of 5-aminolevulinic acid derivatives

BACKGROUND

Antibiotic resistance is increasing day by day, thereby increase the chances of more infections by resistant bacteria. In this situation, antimicrobial photodynamic therapy (aPDT) is gaining more attraction.

OBJECTIVE

To evaluate the antimicrobial effect of ALA derivatives using photodynamic therapy.

MATERIALS AND METHODS

In this study, we evaluated the aPDT effect of different derivatives of 5-ALA. In vivo and in vitro studies were performed to measure the antimicrobial activity. Different light doses and different concentrations of drugs were used to test anti-bacterial effect of drugs as well as to detect any physiological changes in animal model after the treatment.

RESULTS

In vivo studies revealed that ALA-methyl ester, ALA-hexyl ester, and ALA-13A are potent photosensitizers. In vitro studies involved wound healing rate, body weight, and dietary intake were evaluated, and results showed that ALA, ALA-methyl ester, ALA-hexyl ester, and ALA-13A had good anti-bacterial effects, fast healing rate, and no effect on other physical parameters.

CONCLUSION

Photodynamic therapy is increasingly used to treat different types of skin infections caused by bacterial strains. Our studies revealed that ALA-methyl ester, ALA-hexyl ester, and ALA-13A are promising photosensitizers for photodynamic therapy to inhibit the growth of resistant bacterial strains.

Evaluation of antibacterial effects of 5-aminolevulinic acid in combination with light emitting diode (LED: 635nm) with different disinfection methods

This study evaluates the in vitro antibacterial effects of 5-ALA (photoactive dye) in regard to different disinfection methods (2% Chlorhexidine gluconate, 1% Sodium Hypochlorite) on cariogenic bacteria (Streptococcus mutans and Streptococcus sobrinus). After inoculation of dentin specimens with S. mutans and S. sobrinus separately, the reduction in bacterial count was evaluated by the colony counting method. A total of sixty specimens were assigned to six groups (Ten per each group, with five in each group inoculated with S. mutans and the other five inoculated with S.sobrinus); group one: positive control where no treatment was performed, group two: 1% NaOCl was applied, group three: 2% CHX was used, group four: 5-ALA with LED light (635 nm) was applied, group five: 5-ALA was used without LED light activation, group six: LED light was used without dye application. There was a significant reduction in the number of S. mutans in the group treated with 5-ALA with LED light, followed by CHX and then NaOCl, whilst minimum bacterial reduction was detected in the groups that were treated with LED light alone and 5-ALA without LED. However, NaOCl exhibited a better effect regarding reduction of S. sobrinus, followed by 5-ALA and LED light and then CHX. All the disinfected groups showed a significant relation with the positive control non-treated group(p < 0.05).

Photodynamic therapy in endodontics

Photodynamic therapy (PDT) is a treatment modality that was initiated in 1900; however, it was not until the last decade that PDT regained attention for its several favourable features during the treatment of microbial infections in endodontics. Recently, several papers advocated its use for root canal treatment. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near-infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components and consequently produce cell inactivation and death. Recently, PDT has been suggested as a promising effective adjunct to standard antimicrobial intracanal cleaning and shaping for the treatment of periapical lesions. Current publications tested PDT in terms of bacterial load reduction in vivo, in vitro and ex vivo, showing promising results. The purpose of this article was to review the existing literature on PDT in the endodontic field regarding its mechanism of action, photosensitizers and light sources, limitations and clinical procedures. Although positive results have been demonstrated in vitro, there are considerably fewer in vivo investigations. In conclusion, more in vivo studies are needed on the use of antimicrobial PDT in root canal treatment.

The effect of aloe-emodin-induced photodynamic activity on the apoptosis of human gastric cancer cells: A pilot study

The aim of the present study was to explore the effect of aloe-emodin (AE)-induced photodynamic activity in human gastric cancer cells. AE was used as a photosensitizer to explore the effect of photodynamic therapy (PDT) in human gastric cancer cells (SGC-7901). An MTT assay was used to detect the effect of AE-induced PDT in optimal concentrations and illumination energy densities in human gastric cancer cells. Following AE-induced PDT, morphological changes of the cells and the rate of cell death were evaluated by TUNEL assay and flow cytometry, respectively. The expression levels of caspase-9 and caspase-3 were determined by western blot analysis. The AE and AE-induced PDT demonstrated a significant inhibitive effect on the proliferation of human gastric cancer cells in dose-dependent and energy-dependent manners. For subsequent experiments, 10 µM AE and 12.8 J/cm² illumination energy density were used. Typical morphological changes of apoptosis were observed in the cells using a TUNEL assay 12 h subsequent to AE-induced PDT. The percentage of apoptotic cells treated with AE-induced PDT significantly increased when compared with the control group, the 10 µM AE group and the illumination group (P<0.05). Upregulation of caspase-9 and caspase-3 protein levels was also observed following AE-induced PDT. The present study revealed that 10 µM AE-induced PDT had an inhibitory effect on human gastric cancer cells, and it may induce cell apoptosis by upregulating caspase-9 and caspase-3, which indicated that the mitochondrial pathway may be involved. AE-induced PDT has the potential to be a novel therapy for the treatment of human gastric cancer. However, further investigations are required.

Time course of apoptosis induced by photodynamic therapy with PsD007 in LT12 acute myeloid leukemia cells

Apoptosis is one of the major mechanisms of photodynamic therapy (PDT) that leads to tumor degradation. Apoptosis-related genes and proteins function in a certain order and timing in the complex network of apoptosis. To further understanding of the apoptotic mechanism of PDT, this research examined the time course of apoptosis from PsD007 (a second-generation photosensitizer developed in China) induced PDT on the rat acute myeloid leukemia cell line LT12. MTT was used to detect the temporal dynamic of PDT killing effects and identified the "apoptotic window" of 2-24 h. Apoptosis showed a basal peak at 2 h, and the duration of apoptosis depended on PDT dose, which disappeared quickly at low concentrations but lasted to higher levels to 6 or 12 h at high concentrations as detected by flow cytometry. High-content imaging confirmed these results. An 84-gene apoptosis PCR array identified 15 genes with an expression level change of over twofold at 6 h post-PDT. Nine apoptosis-related genes showed changes in expression at 2-12 h after PDT. TNF family genes TNF and FASLG showed a maximal change of 3.47- and 4.42-fold from baseline. Key apoptosis proteins such as activated caspases showed strong up-regulation after PDT, with the expression peaks of cleaved caspase-7, caspase-9 and PARP at 4-6 h, and cleaved caspase-3 delayed to 6-12 h. Our findings help clarify the time course of apoptosis events in response to PDT treatment in a leukemia cell line and may help contribute to the clinical application of PDT in leukemia treatment.

The in vitro PDT efficacy of a novel metallophthalocyanine (MPc) derivative and established 5-ALA photosensitizing dyes against human metastatic melanoma cells

BACKGROUND AND OBJECTIVE

Numerous worldwide clinical trials have shown that photodynamic therapy (PDT) represents an effective and safe modality for various skin disorders, but little research has been done in terms of its effect on malignant melanomas (MM). Thus, the aim of this study was to compare the effect of both established porphyrin photosensitizer 5-aminolevulinic acid (5-ALA) and novel metallophthalocyanine (MPc) photosensitizer on human metastatic skin cells which produce a MM.

MATERIALS AND METHODS

The cellular responses following PDT were assessed using changes in cell morphology, cell viability, cytotoxicity, apoptosis, and proliferation.

RESULTS

Findings reported that in vitro human MM cell line A375 (EACC no: 88113005) are highly sensitive to growth inhibition and apoptosis induction by the cytotoxic side-effects induced by MPc and 5-ALA photosensitizing treatments post-laser irradiation at 680 and 636 nm, respectively. The decrease of cell viability accompanied by an increased cytotoxicity and apoptotic and necrotic levels, with a time-dependant decrease in cellular proliferation was found to be far more significant for MPc-treated cells than 5-ALA-treated cells, since MPc was applied in far lower concentrations and exhibited far less photoxicity to control cells.

CONCLUSION

Hence, novel MPc proved to be the better photosensitizing dye for metastatic melanoma tumor destruction in combination with laser irradiation and is a particularly attractive photosensitizer since it exhibits so many ideal properties of a photosensitizing agent, thus further research of this possible anticancer agent could contribute to its potential application in PDT cancer treatment of MMs.

Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO(2)-NH(2)-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO(2)-NH(2)-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

Photodynamic therapy (PDT): a short review on cellular mechanisms and cancer research applications for PDT

Photodynamic therapy (PDT) has been used for many years, but it is only now becoming widely accepted and utilized. Originally it was developed as a tumor therapy and some of its most successful applications are for non-malignant diseases. This article provides a broad review of different parameters used and mechanisms instituted in PDT such as photosensitizers (PS), photochemistry and photophysics, cellular localization, cellular signaling, cell metabolism and modes of cell death that operate on a cellular level, as well as photosensitizer pharmacokinetics, biodistribution, tumor localization and modes of tumor destruction. These specific cellular mechanisms are most commonly applied in PDT and for the most part are often researched and exploited. If the combination of these specific parameters and mechanisms can be optimized within PDT it could possibly be used as a suitable alternative for the treatment and management of specific cancers.

Photodynamic Therapy: Porphyrins and Phthalocyanines as Photosensitizers

The present work is focussed on the principles of photodynamic therapy (PDT), emphasizing the photochemical mechanisms of reactive oxygen species formation and the consequent biochemical processes generated by the action of reactive oxygen species on various biological macromolecules and organelles. This paper also presents some of the most used photosensitizers, including Photofrin, and the new prototypes of photosensitizers, analysing their physicochemical and spectroscopic properties. At this point, the review discusses the therapeutic window of absorption of specific wavelengths involving first- and second-generation photosensitizers, as well as the principal light sources used in PDT. Additionally, the aggregation process, which consists in a phenomenon common to several photosensitizers, is studied. J-aggregates and H-aggregates are discussed, along with their spectroscopic effects. Most photosensitizers have a significant hydrophobic character; thus, the study of the types of aggregation in aqueous solvent is very relevant. Important aspects of the coordination chemistry of metalloporphyrins and metallophthalocyanines used as photosensitizers are also discussed. The state-of-the-art in PDT is evaluated, discussing recent articles in this area. Furthermore, macrocyclic photosensitizers, such as porphyrins and phthalocyanines, are specifically described. The present review is an important contribution, because PDT is one of the most auspicious advances in the therapy against cancer and other non-malignant diseases.