Antimicrobial action of photodynamic therapy in root canals using LED curing light, curcumin and carbopol gel.

AIM: To evaluate the capacity of carbopol gel to maintain the intensity of a LED curing light (blueLED) along the length of prepared root canals in bovine teeth, and to assess the antimicrobial capacity of curcumin photoactivated by a LED curing light in the presence of carbopol gel. METHODOLOGY: Experiment 1: Eight straight roots of bovine incisors were standardized to a length of 15 mm, and the root canals instrumented up to a size 120 K-file. The LED curing light was irradiated inside the root canals using an aluminium collimator (1.5 mm in diameter) placed at the orifice (n = 8). Initially, the irradiation was performed in empty root canals and then repeated with the root canals filled with carbopol gel. Simple standardized photographs of the roots were taken with a digital camera in the mesial perspective during the irradiation procedure and the images analysed in OriginLab software to verify the light intensity along the length of the root. Experiment 2: Twenty dentine blocks were obtained from the cervical third of bovine incisors using a trephine bur. Biofilms were induced for 21 days on the blocks using Enterococcus faecalis (ATCC 4083) at 109 cells mL-1 . The blocks were treated according to the groups (n = 5): positive control; standard PDT (methylene blue + diode Laser); curcumin; LED curing light; and curcumin + LED curing light. After the treatment, the samples were dyed with Live/Dead BacLight Bacterial Viability solution and fluorescence images were obtained by Confocal Scanning Laser Microscopy (CSLM). Experiment 3: Thirty-two roots of bovine incisors were prepared as described in experiment 1. Their dentinal tubules were contaminated and the root canals treated according to the groups (n = 8): positive control; standard PDT; curcumin + LED curing light; curcumin + carbopol gel + LED curing light. The specimens were sectioned longitudinally and the split roots were treated with the Live/Dead dye to obtain fluorescence images by CSLM. All images were processed using BioImageL software to measure the percentage of viable bacteria and the data analysed statistically using the nonparametric Kruskal-Wallis test (α < 0.05). RESULTS: In Experiment 1, carbopol gel did not improve the intensity of LED light transmission along the root canal. In Experiment 2, a significant decrease (P < 0.05) in bacterial viability occurred in the following order: positive control < only LED curing light < only curcumin < curcumin + LED curing light = standard PDT; and in Experiment 3 positive control = curcumin + LED curing light ≤ curcumin + gel + LED curing light ≤ standard PDT. CONCLUSION: Similar disinfection effectiveness was obtained using curcumin + LED curing light and methylene blue + 660 nm LASER (standard PDT). The use of carbopol gel did not favour a greater transmission of LED light along the root canal and also resulted in less bacterial killing when used in endodontic PDT.

Correction: In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans.

Correction for 'In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans' by J. C. Carmello, et al., Photochem. Photobiol. Sci., 2015, 14, 1319-1328.

The application of antimicrobial photodynamic therapy (aPDT) in dentistry: a critical review.

In recent years there have been an increasing number of in vitro and in vivo studies that show positive results regarding antimicrobial photodynamic therapy (aPDT) used in dentistry. These include applications in periodontics, endodontics, and mucosal infections caused by bacteria present as biofilms. Antimicrobial photodynamic therapy is a therapy based on the combination of a non-toxic photosensitizer (PS) and appropriate wavelength visible light, which in the presence of oxygen is activated to produce reactive oxygen species (ROS). ROS induce a series of photochemical and biological events that cause irreversible damage leading to the death of microorganisms. Many light-absorbing dyes have been mentioned as potential PS for aPDT and different wavelengths have been tested. However, there is no consensus on a standard protocol yet. Thus, the goal of this review was to summarize the results of research on aPDT in dentistry using the PubMed database focusing on recent studies of the effectiveness aPDT in decreasing microorganisms and microbial biofilms, and also to describe aPDT effects, mechanisms of action and applications.

Evaluation of Antimicrobial Photodynamic Therapy against Streptococcus mutans Biofilm in situ.

AIM: This study investigated the effect of antimicrobial photo-dynamic therapy (aPDT) over Streptococcus mutans biofilm. MATERIALS AND METHODS: Eighteen (n = 18) patients were selected and one palatine device with dental blocks was used. The biofilm was treated by curcumin and Photogem® with a LED and the effect was analyzed by CFU/ml. RESULTS: Although, statistical analysis showed significant reductions for aPDT mainly with Photogem® (p = 0.02), these were low. CONCLUSION: The results suggest a low antimicrobial effect of aPDT over S. mutans biofilm. Some parameters used need to be improved. CLINICAL SIGNIFICANCE: This technique can be a promising in Dentistry.

In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans.

This study describes the photoinactivation of Candida albicans in a murine model of oral candidosis, mediated by Photodithazine® (PDZ). Six-week-old female Swiss mice were immunosuppressed, and inoculated with C. albicans to induce oral candidosis. After five days, photodynamic inactivation (PDI) mediated by PDZ at concentrations of 75, 100, 125 and 150 mg L(-1) was applied on the tongue of mice. Next, microbiological evaluation was performed by recovering C. albicans from the tongue via colony forming units (CFU mL(-1)). After 24 h of treatment, the animals were killed and the tongues were surgically removed for histological analysis. PDI was effective in reducing C. albicans on the tongue of mice using 100 mg L(-1) of PDZ, when compared to the positive control group (without treatment). No adverse effect on the tongue tissue was verified after PDI. Therefore, PDI was effective for inactivation of C. albicans without causing any harmful effects on host tissues, which is promising for future clinical trials.

Phototherapy during treadmill training improves quadriceps performance in postmenopausal women.

OBJECTIVE: To evaluate the effects of infrared-light-emitting diode (LED) during treadmill training on functional performance. METHODS: Thirty postmenopausal women aged 50-60 years were randomly assigned to one of three groups and successfully completed the full study. The three groups were: (1) the LED group, which performed treadmill training associated with phototherapy (n = 10); (2) the exercise group, which carried out treadmill training only (n = 10); and (3) the sedentary group, which neither performed physical training nor underwent phototherapy (n = 10). Training was performed over a period of 6 months, twice a week for 45 min per session at 85-90% of maximal heart rate, which was obtained during progressive exercise testing. The irradiation parameters were 100 mW, 39 mW/cm(2) and 108 J/cm(2) for 45 min. Quadriceps performance was measured during isokinetic exercise testing at 60°/s and 300°/s. RESULTS: Peak torque did not differ amongst the groups. However, the results showed significantly higher values of power and total work for the LED group (∆ = 21 ± 6 W and ∆ = 634 ± 156 J, p < 0.05) when compared to both the exercise group (∆ = 13 ± 10 W and = 410 ± 270 J) and the sedentary group (∆ = 10 ± 9 W and ∆ = 357 ± 327 J). Fatigue was also significantly lower in the LED group (∆ = -7 ± 4%, p < 0.05) compared to both the exercise group (∆ = 3 ± 8%) and the sedentary group (∆ = -2 ± 6%). CONCLUSIONS: Infrared-LED during treadmill training may improve quadriceps power and reduce peripheral fatigue in postmenopausal women.

Photodynamic antimicrobial therapy of curcumin in biofilms and carious dentine.

Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizers by light in the presence of oxygen, resulting in the production of reactive radicals that are capable of inducing cell death. The present study evaluated the susceptibility of Streptococcus mutans and Lactobacillus acidophilus to PDT grown as multi-species in the biofilm phase versus in dentine carious lesions. A brain-heart infusion culture medium supplemented with 1% glucose, 2% sucrose, and 1% young primary culture of L. acidophilus 10(8) CFU/mL and S. mutans 10(8) CFU/mL was used to develop multi-species biofilms and to induce caries on human dentine slabs. Five different concentrations of curcumin (0.75, 1.5, 3.0, 4.0, and 5.0 g/L) were used associated with 5.7 J/cm(2) light emission diode. Four different groups were analyzed L-D- (control group), L-D+ (drug group), L+D- (light group), and L+D+ (PDT group). ANOVA/Tukey's tests were conducted to compare groups. A significant reduction (p <0.05) in cell viability was observed in the biofilm phase following photosensitization with all curcumin concentrations tested. To achieve significant bacterial reduction (p <0.05) in carious dentine, it was necessary to utilize 5.0 g/L of curcumin in association with blue light. No significant reduction was found for L-D+, supporting the absence of the drug's dark toxicity. S. mutans and L. acidophilus were susceptible to curcumin in the presence of blue light. However, due to light penetration and drug diffusion difficulties, these microorganisms within dentine carious lesions were less affected than they were in the biofilm phase.

A proof-of-principle for decontamination of transplantation kidney through UV-C exposition of the perfusate solution.

Kidney transplantation is a common yet highly demanding medical procedure worldwide, enhancing the quality of life for patients with chronic kidney disease. Despite its prevalence, the procedure faces a shortage of available organs, partly due to contamination by microorganisms, leading to significant organ disposal. This study proposes utilizing photonic techniques associated with organ support machines to prevent patient contamination during kidney transplantation. We implemented a decontamination system using ultraviolet-C (UV-C) irradiation on the preservation solution circulating through pigs' kidneys between harvest and implant. UV-C irradiation, alone or combined with ultrasound (US) and Ps80 detergent during ex-vivo swine organ perfusion in a Lifeport® Kidney Transporter machine, aimed to reduce microbiological load in both fluid and organ. Results show rapid fluid decontamination compared to microorganism release from the organ, with notable retention. By including Ps80 detergent at 0.5% during UV-C irradiation 3 log10 (CFU mL-1) of Staphylococcus aureus bacteria previously retained in the organ were successfully removed, indicating the technique's feasibility and effectiveness.

Tkachenko polarons in vortex lattices.

We analyze the properties of impurities immersed in a vortex lattice formed by ultracold bosons in the mean field quantum Hall regime. In addition to the effects of a periodic lattice potential, the impurity is dressed by collective modes with parabolic dispersion (Tkachenko modes). We derive the effective polaron model, which contains a marginal impurity-phonon interaction. The polaron spectral function exhibits a Lorentzian broadening for arbitrarily small wave vectors even at zero temperature, in contrast with the result for optical or acoustic phonons. The anomalous damping of Tkachenko polarons could be detected experimentally using momentum-resolved spectroscopy.

Photodynamic inactivation of clinical isolates of Candida using Photodithazine®.

This study evaluated the photodynamic inactivation (PDI) mediated by Photodithazine(®) (PDZ) against 15 clinical isolates of Candida albicans, Candida glabrata and Candida tropicalis. Each isolate, in planktonic and biofilm form, was exposed to PDI by assessing a range of PDZ concentrations and light emitting diode fluences. Cell survival of the planktonic suspensions was determined by colony forming units (CFU ml(-1)). The antifungal effects of PDI against biofilms were evaluated by CFU ml(-1) and metabolic assay. Data were analyzed by non-parametric tests (α = 0.05). Regardless of the species, PDI promoted a significant viability reduction of planktonic yeasts. The highest reduction in cell viability of the biofilms was equivalent to 0.9 log10 (CFU ml(-1)) for C. albicans, while 1.4 and 1.5 log10 reductions were obtained for C. tropicalis and C. glabrata, respectively. PDI reduced the metabolic activity of biofilms by 62.1, 76.0, and 76.9% for C. albicans, C. tropicalis, and C. glabrata, respectively. PDZ-mediated PDI promoted significant reduction in the viability of Candida isolates.

Two-photon cooperative absorption in colliding cold Na atoms.

Two-photon cooperative absorption is common in solid-state physics. In a sample of trapped cold atoms, this effect may open up new possibilities for the study of nonlinear effects. The experiment described herein starts with two colliding Na atoms in the S hyperfine ground state. The pair absorb two photons, resulting in both a P(1/2) and a P(3/2) atom. This excitation is observed by ionization using an external light source. A simple model that considers only dipole-dipole interactions between the atoms allows us to understand the basic features observed in the experimental results. Both the pair of generated atoms and the photons originating from their decay are correlated and may have interesting applications that remain to be explored.

In vitro evaluation of the cis-[Ru(phen)2(pPDIp)]2+⁎⁎ complex for antimicrobial photodynamic therapy against Sporothrix brasiliensis and Candida albicans.

BACKGROUND: Photodynamic therapy (PDT) activates a photosensitizer by visible light to generate cytotoxic oxygen species that lead to cell death. With proper illumination, PDT is often used in applications on superficial and sub-surface lesions. Sporotrichosis infection occurs by Sporothrix fungi which causes a skin wound, worsened by Candida albicans infections. This study investigated the photosensitizing efficiency of the Ru(phen)2(pPDIp)(PF6)2 complex, RupPDIp, against S. brasiliensis and C. albicans. MATERIAL AND METHODS: RupPDIp efficiency against these fungi was tested using 450 nm (blue light and 36 J/cm2) and 525 nm (green light, 25.2 J/cm2) at 0.05-20 µM concentrations. To ensure PDT effectiveness, control groups were tested in the absence and in the presence of RupPDIp under light irradiation and in the dark. RESULTS: RupPDIp eliminated both fungi at ≤5.0 µM. Green light showed the best results, eliminating S. brasiliensis and C. albicans colonies at RupPDIp 0.5 µM and 0.05 µM, respectively. CONCLUSION: RupPDIp is a promising photosensitizer in aPDT, eliminating 106 CFU/mL of both fungi at 450 nm and 525 nm, with lower light doses and concentrations when treated with the green light compared to the blue light.

Efficiency of an air circulation decontamination device for micro-organisms using ultraviolet radiation.

BACKGROUND: The concern with environmental security to avoid contamination of individuals was intensified with the crisis established by SARS-CoV-2. The COVID-19 pandemic has shown the necessity to create systems and devices capable of clearing the air in an environment of micro-organisms more efficiently. The development of systems that allow the removal of micro-droplets mainly originating from breathing or talking from the air was the motivation of this study. AIM: This article describes a portable and easy-to-operate system that helps to eliminate the droplets or aerosols present in the environment by circulating air through an ultraviolet-C (UV-C) reactor. METHODS: An air circulation device was developed, and a proof-of-principle study was performed using the device against bacteria in simulated and natural environments. The microbiological analysis was carried out by the simple sedimentation technique. In order to compare the experimental results and the expected results for other micro-organisms, the reduction rate values for bacteria and viruses were calculated and compared with the experimental results based on technical parameters (clean air delivery rate (CADR) and air changes per hour (ACH)). FINDINGS: Results showed that the micro-organisms were eliminated with high efficiency by the air circulation decontamination device, with reductions of 99.9% in the proof-of-principle study, and 84-97% in the hospital environments study, contributing to reducing contamination of individuals in environments considered to present risk. CONCLUSION: This study resulted in a low-cost and relatively simple device, which was shown to be effective and safe, and could be replicated, especially in low-income countries, respecting the standards for air disinfection using UV-C technologies.

Photonic effects in natural nanostructures on Morpho cypris and Greta oto butterfly wings.

Photonic crystals are some of the more spectacular realizations that periodic arrays can change the behavior of electromagnetic waves. In nature, so-called structural colors appear in insects and even plants. Some species create beautiful color patterns as part of biological behavior such as reproduction or defense mechanisms as a form of biomimetics. The interaction between light and matter occurs at the surface, producing diffraction, interference and reflectance, and light transmission is possible under suitable conditions. In particular, there are two Colombian butterflies, Morpho cypris and Greta oto, that exhibit iridescence phenomena on their wings, and in this work, we relate these phenomena to the photonic effect. The experimental and theoretical approaches of the optical response visible region were studied to understand the underlying mechanism behind the light-matter interaction on the wings of these Colombian butterflies. Our results can guide the design of novel devices that use iridescence as angular filters or even for cosmetic purposes.

Norovirus recovery from floors and air after various decontamination protocols.

BACKGROUND: The dispersal of airborne norovirus (NoV) particles from the floor after contamination with faeces or vomit is a challenge for infection control, as this pathogen is infectious at low doses. Therefore, it is imperative to establish a safe protocol for floor decontamination. AIM: To assess the presence of residual NoV-GII particles on floors and airborne particles following various floor decontamination procedures. METHODS: Two types of floor (vinyl and granite) were contaminated intentionally with 10% human faeces, positive for NoV-GII. Two decontamination protocols were implemented: cleaning followed by disinfection using 1% sodium hypochlorite, and cleaning followed by disinfection using a manual ultraviolet C (UV-C) light device. Swab samples were taken from the floors, and air samples were obtained using an air sampler. The TaqMan method for real-time reverse transcription-quantitative polymerase chain reaction was employed for analysis. FINDINGS: The disinfection protocol using 1% sodium hypochlorite after cleaning proved to be more effective than cleaning followed by UV-C light exposure (P<0.001). Viral particles were detected in 27 of 36 air samples after cleaning, with no significant difference between the two floor types. On average, 617 genome copies/sample were identified in air samples after cleaning, but the number decreased gradually after disinfection. CONCLUSION: NoV-GII can be aerosolized during floor cleaning, and its particles may be inhaled and then swallowed or can settle on surfaces. Therefore, residual viral particles on floors must be fully eliminated. Cleaning followed by 10 min of 1% sodium hypochlorite disinfection proved to be the superior decontamination protocol.

Prophylactic Use of Laser Light and Methylene Blue on Ischemia and Liver Reperfusion Injury.

OBJECTIVE: This study aimed to evaluate the effect of hepatic preconditioning with laser light in the presence of methylene blue (MB) in the liver ischemia-reperfusion injury process. METHOD: Forty male Wistar rats were divided into 8 experimental groups (n = 5). Saline (.5 mL) or MB (15 mg/kg) was injected intravenously (inferior vena cava). After 2 minutes, 660 nm laser light was applied at a dose of 112.5 DE. Fifteen minutes after the application of saline or MB, 1 hour partial ischemia followed by 15 minutes of reperfusion was applied when the rats were sacrificed. The mitochondrial function parameters (O2 consumption rates in states 3 and 4 and the respiratory control ratio), osmotic swelling, and determination of malondialdehyde were evaluated. Hepatic function was studied using the serum determination of the alanine aminotransferase and aspartate aminotransferase enzymes. RESULTS AND CONCLUSIONS: MB therapy alone showed the capacity of preserving the rate of oxygen consumption in the mitochondrial respiratory state of the group submitted to ischemia compared to the sham group. However, when combined with low-intensity laser therapy, it failed to replicate the relevant protective effects in relation to oxidative phosphorylation or the mitochondrial membrane ischemia/reperfusion injury. Whether or not MB was combined with laser treatment, it was shown to be efficient in reducing oxidative stress. In relation to alanine aminotransferase enzymes, whether or not laser treatment was combined with MB had a protective effect on the hepatic lesion, whereas in relation to aspartate aminotransferase enzymes only laser treatment was able to provide this protection.

Autofluorescence spectroscopy in liver transplantation: preliminary results from a pilot clinical study.

The evaluation of graft function at various stages after transplantation is relevant, particularly at the moment of organ harvest, when a decision must be made whether to use the organ. Autofluorescence spectroscopy is noninvasive technique to monitor the metabolic condition of a liver graft throughout its course, from an initial evaluation in the donor, through cold ischemia transportation, to reperfusion and reoxygenation in the recipient. Preliminary results are presented in six liver transplantations spanning the periods from liver harvest to implant. The laser-induced fluorescence spectrum at 532-nm excitation was investigated before cold perfusion (autofluorescence), during cold ischemia, at the back table procedure, as well as 5 and 60 minutes after reperfusion. The results showed that the fluorescence analysis was sensitive to changes during the transplantation procedure. Fluorescence spectroscopy potentially provides a real-time, noninvasive technique to monitor liver graft function. The information could potentially be valuable for surgical decisions and transplant success.

Renal ischemia in rats: mitochondria function and laser autofluorescence.

Ischemia-reperfusion injury is the major cause of organ dysfunction or even nonfunction following transplantation. It can attenuate the long-term survival of transplanted organs. To evaluate the severity of renal ischemia injury determined by histology, we applied laser- (442 nm and 532 nm) induced fluorescence (LIF), mitochondria respiration, and membrane swelling to evaluate 28 Wistar rats that underwent left kidney warm ischemia for 20, 40, 60, or 80 minutes. LIF performed before ischemia (control) was repeated at 20, 40, 60, and 80 minutes thereafter. We harvested left kidney tissue samples immediately after LIF determination for histology and mitochondrial analyses: state 3 and 4 respiration, respiration control rate (RCR), and membrane swelling. The association of optic spectroscopy with histological damage showed: LIF, 442 nm (r2 = 0.39, P < .001) and 532 nm, (r2 = 0.18, P = .003); reflecting laser/fluorescence-induced, 442 nm (r2 = 0.20, P = .002) and 532 nm (r2 = 0.004, P = .67). The associations between mitochondria function and tissue damage were: state 3 respiration (r2 = 0.43, P = .0004), state 4 respiration (r2 = 0.03, P = 0.38), RCR (r2 = 0.28, P = .007), and membrane swelling (r2 = 0.02, P = .43). The intensity of fluorescence emitted by tissue excited by laser, especially at a wave length of 442 nm, was determined in real time. Mitochondrial state 3 respiration and respiratory control ratio also exhibited good correlations with the grade of ischemic tissue damage.

The use of light-emitting diodes to stimulate mitochondrial function and liver regeneration of partially hepatectomized rats.

The biostimulating effect of laser radiation has been observed in many areas of Medicine. However, there are still several questions to be answered, among them the importance of light coherence in the stimulatory process. In the present study, we used light-emitting diodes (LED) to promote the stimulation of liver regeneration after partial hepatectomy in rats. Fourteen male Wistar rats weighing 200-250 g were submitted to partial hepatectomy (70%) followed by LED light irradiation (630 nm) of the remaining part of the liver at two doses, i.e., 10 (N = 7) and 140 (N = 7) J/cm(2). A group irradiated with laser, 590 nm (N = 7, 15 J/cm(2)) was performed for the study of proliferating cell nuclear antigen-labeling index. Data are reported as mean +/- SEM. Statistical comparisons of the groups were performed by analysis of variance for parametric measurements followed by the Bonferroni post-test, with the level of significance set at P < 0.05. Respiratory mitochondrial activity was increased in the irradiated groups (states 3 and 4; P < 0.05), with better results for the group exposed to the lower LED dose (10 J/cm(2)). The proliferating cell nuclear antigen-labeling index, by immunohistochemical staining, was similar for both LED-exposed groups (P > 0.05) and higher than for the control group (P < 0.05). The cell proliferation index obtained with LED and laser were similar (P > 0.05). In conclusion, the present results suggest that LED irradiation promotes biological stimulatory effects during the early stage of liver regeneration and that LED is as effective as laser light, independent of the coherence, divergence and cromaticity.

Tunable eletro-optical modulators based on a split-ring resonator.

We present a novel design of an electro-optical modulator setup, consisting of a mechanically tunable cavity which allows the modulation frequency to be varied over a broad range. The design is based on the frequently used geometry of a split-ring resonator which allows for high-efficiency sideband generation. Normally such a configuration has the limitation of a narrow excitation band width ( approximately 20 MHz). Our adjustable setup offers broad-range tunability over several hundred megahertz while still keeping the modulation efficiency. Such a widely tunable modulator may find applications in a variety of experiments in atomic physics.