Effects of Photodynamic Therapy on Rapidly Growing Nontuberculous Mycobacteria Keratitis

Photodynamic Therapy for Early Stage Central Type of Lung Cancer

Chicken chorioallantoic membrane (CAM) assays have been proven to be very effective models to study the impact of chemical and biological agents on its vascular network. The study of pharmaceutical drugs, xenografts and photosensitizers on these assays are current areas of research. In particular, the use of photodynamic therapy (PDT) has been shown to induce a significant decrease in both the diameter and number of blood vessel ramifications of the CAM. Given that molecular oxygen is so important for the effectiveness of this therapy, it opens the possibility of testing bio-compatible photosynthetic microalgae capable of locally producing oxygen. Even though there is ample evidence of the use of bio-compatible microalgae in scaffolds for wound recovery, there is little to no research done on the combination of microalgae and PDT in CAM essays. In this thesis work, we present a study that explores how microalgae, PDT and the combination of these two change the vascularization of the CAM. Throughout this experiment, the photosensitizer that was used was methylene blue whilst the microalgae that was used was Chlamydomonas reinhardtii. In order to perform the quantitative measurements, an image analysis software allowed us to count the number of bifurcation points. Firstly, four groups were defined to study how the PDT at different days of embryonic development (EDD) might change blood vessel ramifications. These groups were defined as control, only light, only methylene blue and the PDT groups. It was found that after 24 hours, for EDD8, the ramifications for the PDT case dropped by 40% whilst for EDD10 they dropped by 60% with light at 630 nm with 30 mW/cm2 for 5 minutes. Second, it was explored how illuminated microalgae might possibly increase the vascular networks with the same light parameters. It was found that after 24 hours for EDD8 the network grew by 30% and for EDD10 it grew by 20%. Moreover, the combination of a photosensitizer and microalgae was studied to analyze if it might change the effectiveness of the PDT. It was found after 24 hours that for all the explored permutations for both EDD8 and EDD10 all the eggs were dead, showcasing the effect of an oxygen-enriched PDT. Given that the effect was way to strong, the methylene blue solution was diluted by a factor of x10 (0.03 mg of MB/mL) to see if this resulted in a measurable effect on the eggs for the combination case. Indeed, it was found that the decrease from the baseline ramification levels was 30% for the PDT and 60% for the oxygen enhanced PDT. The novel element of this work was that it was one of the first to explore the possibility of creating an oxygen-rich PDT in a CAM assay. This showed that it is possible to combine microalgae and a photosensitizer in a way that enhances the effectiveness of the PDT. This might translate into the possibility of employing this technique in an in-vivo trail with mice or other mammals to guarantee its safety. In conclusion, we found that illuminated photosynthetic microalgae raises the effectiveness of PDT in the vascular network of CAM assays.

Chicken chorioallantoic membrane (CAM) assays have been proven to be very effective models to study the impact of chemical and biological agents on its vascular network. The study of pharmaceutical drugs, xenografts and photosensitizers on these assays are current areas of research. In particular, the use of photodynamic therapy (PDT) has been shown to induce a significant decrease in both the diameter and number of blood vessel ramifications of the CAM. Given that molecular oxygen is so important for the effectiveness of this therapy, it opens the possibility of testing bio-compatible photosynthetic microalgae capable of locally producing oxygen. Even though there is ample evidence of the use of bio-compatible microalgae in scaffolds for wound recovery, there is little to no research done on the combination of microalgae and PDT in CAM essays. In this thesis work, we present a study that explores how microalgae, PDT and the combination of these two change the vascularization of the CAM. Throughout this experiment, the photosensitizer that was used was methylene blue whilst the microalgae that was used was Chlamydomonas reinhardtii. In order to perform the quantitative measurements, an image analysis software allowed us to count the number of bifurcation points. Firstly, four groups were defined to study how the PDT at different days of embryonic development (EDD) might change blood vessel ramifications. These groups were defined as control, only light, only methylene blue and the PDT groups. It was found that after 24 hours, for EDD8, the ramifications for the PDT case dropped by 40% whilst for EDD10 they dropped by 60% with light at 630 nm with 30 mW/cm2 for 5 minutes. Second, it was explored how illuminated microalgae might possibly increase the vascular networks with the same light parameters. It was found that after 24 hours for EDD8 the network grew by 30% and for EDD10 it grew by 20%. Moreover, the combination of a photosensitizer and microalgae was studied to analyze if it might change the effectiveness of the PDT. It was found after 24 hours that for all the explored permutations for both EDD8 and EDD10 all the eggs were dead, showcasing the effect of an oxygen-enriched PDT. Given that the effect was way to strong, the methylene blue solution was diluted by a factor of x10 (0.03 mg of MB/mL) to see if this resulted in a measurable effect on the eggs for the combination case. Indeed, it was found that the decrease from the baseline ramification levels was 30% for the PDT and 60% for the oxygen enhanced PDT. The novel element of this work was that it was one of the first to explore the possibility of creating an oxygen-rich PDT in a CAM assay. This showed that it is possible to combine microalgae and a photosensitizer in a way that enhances the effectiveness of the PDT. This might translate into the possibility of employing this technique in an in-vivo trail with mice or other mammals to guarantee its safety. In conclusion, we found that illuminated photosynthetic microalgae raises the effectiveness of PDT in the vascular network of CAM assays.

Background and Objective: Colorectal adenocarcinoma is considered one of the major causes of cancer-related lethality among other type of malignancies. Given the several limitations and adverse outcomes of conventional therapeutic regimens against colorectal cancer, the focus of many investigations has been attributed to the introduction of a novel combined regimen with harmless agents. The purpose of the present study was to investigate the effect of combined doxorubicin (DOX) treatment and photodynamic therapy (PDT) on colorectal adenocarcinoma cells. Material and Methods: HT-29 cells were exposed to different concentrations of DOX, low-level (630 nm) diode laser, and methylene blue (MB) as a photosensitizer substrate separately and a combination of them. The cytotoxic effect of the DOX, laser, MB, and their combination and the IC50 value for each treatment group were calculated by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT). The malondialdehyde (MDA) content as a biomarker of the lipid peroxidation process and liberated lactate dehydrogenase (LDH) enzyme into supernatant was determined. Results: The results of our study evidenced that a combination of photodynamic light (laser plus MB) and DOX caused a significant reduction in the percentage of HT-29 viable cells compared with control and other treatment groups. In addition, this mentioned combination led to a considerable decrease in IC50 of DOX. Increased cell membrane lipid peroxidation and cell destruction processes in the combination therapy group were proven through significant elevation of MDA content and LDH activity in the medium, respectively. Conclusion: The findings of the present study suggested that DOX combined with PDT had a better therapeutic impact on HT-29 colorectal adenocarcinoma cells. Hence, the simultaneous application of PDT along with antineoplastic drugs improves the chemosensitivity of cancerous cells via the disruption of their membrane and triggering death processes that lead to the decrease of chemotherapeutic agents required doses and undesirable effects.

Effect of photodynamic therapy and endostatin on human glioma xenografts in nude mice

Objective To study the application of photodynamic therapy (PDT) for dental caries prevention using whole body luminescence fiber, and to investigate the effects of PDT on the content of Ca and P in rat molar enamel. Method The rat dental caries model was established by inoculating with S.mutans. Eighty male rats were randomly divided into five groups, including three experimental groups: 17 mW (8 mW/cm2) PDT (group A), 34 mW (15 mW/cm2) PDT (group B), 68 mW (30 mW/cm2) PDT (group C), a positive control group: 20 g/L NaF solution (group D), and a negative control group: 0.9% physiological saline (group E). The experimental groups were treated by 40 μg/mL hematoporphyrin monomethyl ether (HMME) and 650 nm diode laser irradiation. The experiments were conducted for 4 weeks. The contents of Ca and P in the molars of each group were measured by inductively coupled plasma emission spectrometry. Results The contents of Ca and P in group B, C and D after PDT were significantly higher than those in group A and E (all P<0.05). The contents of Ca and P in group A showed no significant difference before and after PDT, while those in groups B and C showed significant increase after PDT (all P<0.05). The increment of Ca in group A after PDT was lower than that in group D (P<0.05), while those in group B and C were significantly higher than those in group D (all P<0.05). There was no significant difference in the increment of Ca and P between group B and C after PDT. Conclusions In the range of the experimental parameters, the PDT promoted effect of tooth remineralization is better than 20 g/L NaF. The levels of Ca and P in the tooth enamel can be promoted by PDT treatment, and the contents of Ca and P are related to the pewer of PDT. The effect of low power PDT on the remineralization of enamel is not obvious. The contents of Ca and P in the tooth enamel are increased with laser power of PDT. When the laser power increased to a certain value, the change in contents of the two elements is not obvious. PDT can maintain the tooth remineralization microenvironment. Key words: Photodynamic therapy; Trace elements; Inductively coupled plasma optical emission spectrometer; Remineralization

BackgroundDentists now have access to a wide range of unique treatment methods as a result of substantial scientific and technological breakthroughs in the field of dentistry. Photodynamic therapy (PDT) is a non-invasive treatment procedure that use photosensitizers, a specific wavelength of light, and the production of singlet oxygen and reactive oxygen species (ROS) to kill undesired eukaryotic cells (such as oral tumors) and harmful microbes. In several disciplines of dentistry, it is seen as a valid therapeutic option. The purpose of this study was to examine the effectiveness and side effects of PDT in the treatment of oral premalignant lesions. Material and MethodsThree search engines (PubMed, ISI Web of Science, and the Cochrane Library) were used to conduct a systematic review using the phrases photodynamic therapy and PDT in combination with other terms. To define our study eligibility criteria, we used the Population, Intervention and Comparison, Outcomes, and Study design technique. ResultsInitial results were 33. Definitely, 18 studies met our selection criteria. ConclusionsOur analysis suggests ALA- PDT as a promising therapeutic modality for OEL lesions which should be treated first with the topical ALA-PDT using either the LED or laser light for successful clinical outcome for OEL lesions. Key words:Photodynamic Therapy, Photosensitizer, Aminolevulinic Acid (ALA), Methylene Blue (MB), Toludine Blue, Oral Leukoplakia, Oral Erythroplakia, Oral Verrucous hyperplasia, Oral Lichen Planus.

Background: Methylene blue has a long history of clinical application. Thanks to phenothiazine chromophore, it has potential in photodynamic anticancer therapy. In spite of the growing body of literature that has evaluated the action of this dye on different types of cancer, the systematic understanding of this problem is still lacking. Therefore, this systematic review was performed to study the efficacy of methylene blue in photodynamic anticancer therapy.Methods: This systematic review was carried out in accordance with the PRISMA guidelines, and the study protocol was registered in PROSPERO (CRD42022368738). Articles for the systematic review were identified through the PubMed database. SYRCLE’s risk of bias tool was used to assess the studies. The results of systematic analysis are presented as narrative synthesis.Results: Ten studies met the inclusion criteria and these full texts were reviewed. In the selected articles, the dosage of dye infusion ranged from 0.04 to 24.12 mg/kg. The effectiveness of photodynamic therapy with methylene blue against different types of cancer was confirmed by a decrease in tumor sizes in seven articles.Conclusion: The results of the systematic review support the suggestions that photodynamic therapy with methylene blue helps against different types of cancer, including colorectal tumor, carcinoma, and melanoma. In cases of nanopharmaceutics use, a considerable increase of anticancer therapy effectiveness was observed. The further research into methylene blue in photodynamic anticancer therapy is needed.Systematic Review Registration: (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=368738), identifier (CRD42022368738).

Breast cancer is a major cause of morbidity and mortality in women worldwide.Conventional therapies have undesirable side effects and in some cases are ineffective; therefore, the search for alternative therapies, such as photodynamic therapy (PDT), is essential.In this work, the effect of PDT on two breast cancer cell lines and one non-cancerous breast cell line was investigated using non-porphyrin photosensitizers (PS), such as methylene blue (MB) and rose bengal (RB).The efficacy of each treatment was evaluated by measuring cell viability with the MTT assay and by morphological observations.Before evaluating the effects of PDT, the intracellular uptake of each PS was measured in the cell lines studied.The results showed that the MDA-MB-231 cell line exhibited the highest sensitivity to PDT for both PS.The T47D cell line showed almost 50% inhibition in both cases.Surprisingly, the non-cancerous cell line MCF10A showed a selective response to PDT.In particular, no significant inhibition was observed with MB-PDT treatment.However, inhibition was observed with RB-PDT treatment.The morphological changes supported the cytopathic effect induced by PDT, it was found that non-cancerous MCF10A cells showed remarkable changes only with the highest dose of RB-PDT.In conclusion, this study presents, to the best of our knowledge, for the first time the effect of PDT using RB as a PS for the inhibition of MDA-MB-231, T47D and MCF10A breast cells, and using MB for PDT inhibition onT47D cells.Furthermore, no direct relationship was observed between the effect of PDT and the intracellular concentration of PS.Finally, these findings highlight the potential of MB and RB as effective PS in PDT and suggest the importance of considering cell line-specific responses and characteristics in optimizing PDT efficacy and selectivity.

Cholangiocarcinoma is a relatively rare neoplasm with increasing incidence. Although chemotherapeutic agent such as gemcitabine has long been used as standard treatment for cholangiocarcinoma, the interindividual variability in target and drug sensitivity and specificity may lead to therapeutic resistance. In the present study, we found that photodynamic therapy (PDT) treatment inhibited gemcitabine-resistant cholangiocarcinoma cells via repressing cell viability, enhancing cell apoptosis, and eliciting G1 cell cycle arrest through modulating Cyclin D1 and caspase 3 cleavage. In vivo, PDT treatment significantly inhibited the growth of gemcitabine-resistant cholangiocarcinoma cell-derived tumors. Online data mining and experimental analyses indicate that KLF10 expression was induced, whereas EGFR expression was downregulated by PDT treatment; KLF10 targeted the EGFR promoter region to inhibit EGFR transcription. Under PDT treatment, EGFR overexpression and KLF10 silencing attenuated the anti-cancer effects of PDT on gemcitabine-resistant cholangiocarcinoma cells by promoting cell viability, inhibiting apoptosis, and increasing S phase cell proportion. Importantly, under PDT treatment, the effects of KLF10 silencing were significantly reversed by EGFR silencing. In conclusion, PDT treatment induces KLF10 expression and downregulates EGFR expression. KLF10 binds to EGFR promoter region to inhibit EGFR transcription. The KLF10/EGFR axis participates in the process of the inhibition of PDT on gemcitabine-resistant cholangiocarcinoma cells.

Photodynamic therapy (PDT) is a promising therapeutic modality using a tumor localizing photosensitizer and light to destroy tumor cells. A major limitation of PDT is tumor recurrence, which is partly due to neovascularization. The objective of the present study was to determine whether combination therapy with PDT and antiangiogenic agents (i.e. SU5416 and SU6668) would be more effective in controlling tumor recurrence in a mouse model of human CNE2 poorly differentiated nasopharyngeal carcinoma compared with PDT or antiangiogenic agents administered alone. Athymic mice bearing CNE2 tumor xenografts received daily i.p. injections of 20 mg/kg SU5416 or 100 mg/kg SU6668 for 28 consecutive days either alone or following a single hypericin-PDT treatment. Significant inhibition of CNE2 tumor growth was observed in all treatment groups. Differences in 4x tumor growth time, the number of mice with 4x tumor growth, tumor growth inhibition as well as the percent of mice surviving were not statistically significant among individual treatment groups. However, the number of mice with 4x tumor growth observed in SU6668 monotherapy and combined PDT and SU6668 treatment groups was significantly less than that in the control group (P<0.05 and 0.01, respectively). Moreover, compared with the control group, only the combined PDT and SU6668 treatment significantly extended survival of tumor-bearing host mice (P<0.05). The semiquantitative RT-PCR results showed that the expression of HIF-1alpha, VEGF, COX-2 and bFGF were increased in PDT-treated tumor samples collected 24 h post-PDT, suggesting that PDT-induced damage to tumor microvasculature and the resultant hypoxia upregulate the expression of certain proangiogenic factors. The effectiveness of PDT can be enhanced by antiangiogenic treatment with the synthetic RTK inhibitors. Of the two synthetic RTK inhibitors tested, SU6668 was more effective than SU5416 in enhancing tumor responsiveness to PDT.

Objective: Identify yeast species isolated from unexposed, exposed and HIV-carrier children, and verify the effectiveness of low power laser photodynamic therapy (PDT) on the yeasts species belonging to the Candida genus. Methods: Fifty children assisted by the Public Health Program of the city of Vitória da Conquista, Bahia, were selected and divided into three groups: unexposed to HIV, exposed to HIV during pregnancy, and HIV-carrier. Saliva samples were collected in a disposable sterile universal container and were plated to Sabouraud dextrose agar supplemented with 0.1 mg/mL chloramphenicol. The plates were incubated at 37°C for 48 h. Three strains of each patient were identified by using an API 20 C AUX system. The strains were submitted to photodynamic therapy (PDT) with a 660 nm low power laser and methylene blue dye at different times of irradiation (90, 180 and 282 sec.). Results: The results showed that the most prevalent species was Candida albicans followed by Candida famata (second most prevalent in unexposed to HIV and HIV carriers)) and Candida parapsilosis (second most prevalent in exposed to HIV group). The CFU/mL of Candida spp. decreased significantly (p&lt;0,05) in all groups treated with PDT compared to the controls. Photodynamic therapy treatments at different exposure times (e.g., PS+L90+, PS+L180+, PS+L282+) revealed that the exposure time of 282 sec. gave the highest reduction of the mean logarithmic CFU/mL. Conclusion: Candida albicans was the most prevalent Candida species in these three groups and Candida non-albicans species, when combined, amounted to a significant percentage of Candida isolates. Photodynamic therapy was effective in inactivating the Candida spp. isolated from the oral cavity of children not exposed to HIV, exposed to HIV and HIV-carriers, with the best photodynamic therapy irradiation time being 282 sec.

Event Abstract Back to Event Using photodynamic therapy to combat bacterial biofilms and reduce infection on orthopaedic implants. Melanie Coathup1, David Mckenna1, Simon Hislop1, Briggs Timothy1, 2, Rita Cardoso Ramalhete1, Caroline Bagley1 and Gordon Blunn1 1 UCL, Institute of Orthopaedics, United Kingdom 2 Royal National Orthopaedic Hospital, United Kingdom Introduction: Periprosthetic Joint Infection (PJI) is one of the greatest challenges to orthopaedics. The quoted rate for deep infection varies from 0.28% to 4% for a primary hip replacement, 0.39% to 3.9% for primary total knee replacement, and a higher incidence of infection in spinal implants [1]. It is associated with high patient morbidity and has huge financial cost. Current treatments are long, invasive, and often ineffective. Increasing antibiotic resistance of microorganisms and the inefficacy of antibiotic treatment against biofilms on prosthetic implants means alternative treatments are needed. Photodynamic Therapy (PDT) is a known broad-spectrum antimicrobial treatment providing rapid results with few systemic side effects and no bacterial resistance. It uses a photosensitiser that targets and kills bacterial cells following activation by an appropriate light source [2]. This study investigates the use of PDT as a means of eradicating strains of bacteria that commonly cause prosthetic joint infections (methicillin sensitive staphylococcus aureus (MSSA), methicillin resistant staphylococcus aureus (MRSA), staphylococcus epidermidis, and pseudomonas aeruginosa both as planktonic culture and in a biofilm on titanium alloy and hydroxyapatite (HA)-coated titanium. Hypothesis: Photodynamic therapy is an effective means of eradicating common strains of bacteria that cause biofilms on orthopaedic implants. Methods: The concentration of the photosensitizer Methylene Blue (MB), and the laser power that was the most effective was determined using lawns of all bacteria in plate culture. Planktonic cultures of 4 bacteria grown in well-plates with4 treatment regimes - PDT (MB+L+), photo sensitizer alone (MB+L-), laser alone (MB-L+), and control (MB-L) using 0.3mM MB and 35jcm-2 laser. Following treatment the wells were analysed for the number of bacteria present using a standard serial dilution. Biofilms were formed for each of the 4 bacteria by placing titanium discs in bacterial suspension, which were oscillated and incubated for 3 days. The attached biofilms were treated (as per planktonic culture). Following treatment the discs were washed and sonicated to displace biofilm bacteria and standard serial dilution was performed to quantify remaining bacteria. This experiment was then repeated for P. aeruginosa biofilms on HA-coated discs Results: Staphylococci colony forming units were eradicated at the lowest strength of MB. With P. aeruginosa and A. baumannii, increasing the MB concentration had an improved bactericidal effect (Figure 1). The higher the power of the laser used in PDT the more bacteria were eradicated. Laser power ≥35 jcm-2 eradicated all bacterial colonies (figure2) but below this level there were slight differences in the susceptibility of different species. PDT had a significant bactericidal effect against planktonic MRSA and S. epidermidis compared to MB alone, laser alone, or the control. PDT was shown to have significantly higher bactericidal effects than MB alone or laser alone for all four strains of bacterial biofilms. For P. aeruginosa on HA-coated titanium discs, PDT was shown to have significantly higher bactericidal effects than photosensitiser alone, laser alone and the control however the effects of PDT were not as large as those seen with a titanium alloy surface (Figure 3). Discussion: This study demonstrates that PDT is an effective treatment for killing common gram-positive and gram-negative bacteria that cause PJI. It is effective not just for planktonic bacteria but bacteria within a biofilm on a prosthetic surface. Its speed of action and lack of bacterial resistance makes it an attractive therapy. The future challenge will be to find the optimal way of delivering this treatment.

Photodynamic therapy (PDT) is the use of a light-sensitive drug, in combination with light of a visible wavelength, to destroy target cells. PDT is used either as a primary treatment or as an adjunctive treatment. It is fairly well accepted in clinical practice for some types of skin cancer but has yet to be fully explored as a treatment for other forms of cancer. To systematically review the clinical effectiveness and safety of PDT in the treatment of Barrett's oesophagus, pre-cancerous skin conditions and the following cancers: biliary tract, brain, head and neck, lung, oesophageal and skin. The search strategy included searching electronic databases (between August and October 2008), followed by update searches in May 2009, along with relevant bibliographies, existing reviews, conference abstracts and contact with experts in the field. Randomised controlled trials (RCTs) in skin conditions and Barrett's oesophagus, non-randomised trials for all other sites. People with Barrett's oesophagus, pre-cancerous skin conditions or primary cancer in the following sites: biliary tract, brain, head and neck, lung, oesophageal and skin. Any type of PDT for either curative or palliative treatment. Any comparator including differing applications of PDT treatments (relevant comparators varied according to the condition). The outcomes measured were mortality, morbidity, quality of life, adverse events and resource use. A standardised data extraction form was used. The quality of RCTs and non-randomised controlled studies was assessed using standard checklists. Data extracted from the studies were tabulated and discussed in a narrative synthesis, and the influence of study quality on results was discussed. Meta-analysis was used to estimate a summary measure of effect on relevant outcomes, with assessment of both clinical and statistical heterogeneity. Two reviewers independently screened all titles and abstracts, and data extracted and quality assessed the trials, with discrepancies resolved by discussion or referral to a third reviewer. A scoping review was also undertaken. Overall, 88 trials reported in 141 publications were included, with some trials covering more than one condition. For actinic keratosis (AK), the only clear evidence of effectiveness was that PDT appeared to be superior to placebo. For Bowen's disease, better outcomes with PDT were suggested when compared with cryotherapy or fluorouracil. For basal cell carcinoma (BCC), PDT may result in similar lesion response rates to surgery or cryotherapy but with better cosmetic outcomes. For nodular lesions, PDT appeared to be superior to placebo and less effective than surgery but suggestive of better cosmetic outcome. For Barrett's oesophagus, PDT in addition to omeprazole appeared to be more effective than omeprazole alone at long-term ablation of high-grade dysplasia and slowing/preventing progression to cancer. No firm conclusions could be drawn for PDT in oesophageal cancer. Further research into the role of PDT in lung cancer is needed. For cholangiocarcinoma, PDT may improve survival when compared with stenting alone. There was limited evidence on PDT for brain cancer and cancers of the head and neck. A wide variety of photosensitisers were used and, overall, no serious adverse effects were linked to PDT. There were few well-conducted, adequately powered RCTs, and quality of life (QoL) and resource outcomes were under-reported. Problems were identified with reporting of key study features and quality parameters, making the reliability of some studies uncertain. Methodological limitations and gaps in the evidence base made it difficult to draw firm conclusions. Evidence of effectiveness was found for PDT in the treatment of AK and nodular BCC in relation to placebo, and possibly for treating Barrett's oesophagus. However, the effectiveness of PDT in relation to other treatments is not yet apparent. High-quality trials are needed to compare PDT with relevant comparators for all meaningful outcomes, including QoL and adverse effects. Further research is also needed on patient experience of PDT, as well as on the cost-effectiveness of PDT.

Switchable PDT for reducing skin photosensitization by a NIR dye inducing self-assembled and photo-disassembled nanoparticles.