Light-emitting Diode Irradiation Research Articles

Target-Driven Z-Scheme Heterojunction Formation for ppb H2S Detection from Exhaled Breath at Room Temperature.

As a biomarker of periodontitis, sensitive and timely monitoring of hydrogen sulfide (H2S) in exhaled breath at room temperature (RT) is important for the early intervention of oral diseases. However, the required high operation temperature to achieve high sensitivity is still a technical challenge for directly monitoring exhaled breath. In this study, by integrating metal-organic frameworks (MOFs) into self-aligned TiO2 nanotube arrays (NTs), a chemiresistor gas sensor with outstanding sensitivity and selectivity was constructed for the detection of H2S at RT. The precise regulation of a Co(III)-based MOF CoBDC-NH2 (BDC-NH2 = 2-aminoterephthalic acid) not only induced more active surface for the preconcentration of the target gas but also caused a buildup of Z-scheme heterojunctions in the H2S atmosphere that induced an ultrahigh sensitivity at RT via 365 nm light-emitting diode irradiation. The response and recovery times decreased to ∼50 and ∼28%, respectively, when this system was exposed to UV light. The sensing chips based on the as-prepared TiO2/CoBDC-NH2 NTs exhibited the highest-ranking H2S sensing performance, i.e., a limit of detection of 1.3 ppb and excellent selectivity even to 100 times high concentration of interference gases, owing to the synergistic chemical environment provided by NH2-functionalized Co-MOFs and abundant photogenerated electrons provided by Z-scheme heterojunctions. This sensing chip was also used in a practical application for the timely monitoring of halitosis from direct exhaled breath. This study provides a reliable and sensitive design for clinically aiding the timely detection of H2S in a complex oral environment.

Electron and hydrogen atom donor photocatalysts in situ generated from benzimidazolium salts and hydride reagents

Photocatalytic systems consisting of 2-substituted benzimidazoliums (BI+–R, R = polycyclic aryl, triarylamine or phenyl-sulfate) and stoichiometric hydride donor reagents were developed. Light emitting diode irradiation of these photocatalysts in the presence of NaBH4 or picoline borane promotes desulfonylation reactions of an N-sulfonyl indole, N-sulfonyl amide and α-sulfonyl ketone. Absorption spectroscopic and redox potential measurements as well as density functional theory calculations were carried out to gain mechanistic information. Benzimidazolines (BIH–R), generated in situ by hydride reduction of BI+–R, serve as both an electron and hydrogen atom donor photocatalysts in these reductive desulfonylation reactions, which contrasts to ordinary reducing photocatalysts that simply donate electrons.

Effects of Red LED Irradiation in Enhancing the Mineralization of Human Dental Pulp Cells In Vitro.

Dentin regeneration is the preferred method used to preserve dental pulp vitality after pulp exposure due to caries. Red light-emitting diode irradiation (LEDI), which is based on photobiomodulation (PBM), has been used to promote hard-tissue regeneration. However, the underlying mechanism still needs elucidation. This study aimed to explore the mechanism involved in red LEDI affecting dentin regeneration. Alizarin red S (ARS) staining revealed that red LEDI induced mineralization of human dental pulp cells (HDPCs) in vitro. We further distinguished the cell proliferation (0-6 d), differentiation (6-12 d), and mineralization (12-18 d) of HDPCs in vitro and treated cells either with or without red LEDI in each stage. The results showed that red LEDI treatment in the mineralization stage, but not the proliferation or differentiation stages, increased mineralized nodule formation around HDPCs. Western blot also indicated that red LEDI treatment in the mineralization stage, but not the proliferation or differentiation stages, upregulated the expression of dentin matrix marker proteins (dentin sialophosphoprotein, DSPP; dentin matrix protein 1, DMP1; osteopontin, OPN) and an intracellular secretory vesicle marker protein (lysosomal-associated membrane protein 1, LAMP1). Therefore, the red LEDI might enhance the matrix vesicle secretion of HDPCs. On the molecular level, red LEDI enhanced mineralization by activating the mitogen-activated protein kinase (MAPK) signaling pathways (ERK and P38). ERK and P38 inhibition reduced mineralized nodule formation and the expression of relevant marker proteins. In summary, red LEDI enhanced the mineralization of HDPCs by functioning to produce a positive effect in the mineralization stage in vitro.

Suppressing cancer by damaging cancer cell DNA using LED irradiation.

High-energy irradiation eliminates cancer cells by destroying their genetic components. However, there are several side effects from doing this, such as fatigue, dermatitis, and hair loss, which remain obstacles to this treatment. Here, we propose a moderate method that uses low-energy white light from a light-emitting diode (LED) to selectively inhibit cancer cell proliferation without affecting normal cells. The association between LED irradiation and cancer cell growth arrest was evaluated based on cell proliferation, viability, and apoptotic activity. Immunofluorescence, polymerase chain reaction, and western blotting were performed in vitro and in vivo to identify the metabolism related to the inhibition of HeLa cell proliferation. LED irradiation aggravated the defective p53 signaling pathway and induced cell growth arrest in cancer cells. Consequently, cancer cell apoptosis was induced by the increased DNA damage. Additionally, LED irradiation inhibited the proliferation of cancer cells by suppressing the MAPK pathway. Furthermore, the suppression of cancer growth by the regulation of p53 and MAPK was observed in cancer-bearing mice irradiated with LED. Our findings suggest that LED irradiation can suppress cancer cell activity and may contribute to preventing the proliferation of cancer cells after medical surgery without causing side effects.

Photobiomodulation in human neuroblastoma under oxidative stress

AbstractBackgroundWith the increase in life expectancy, the number of people with neurodegenerative diseases such as Alzheimer’s Disease (AD) is rising rapidly. Considering the pathways of AD, one of its fundamental processes is oxidative stress, affecting the central nervous system and cell regeneration. Interestingly, in the last decades, photobiomodulation has shown positive effects on neural cells that are compromised by AD. Studies have demonstrated that LED (light emitting diode) irradiation regulates cell function, stimulating cell proliferation, promoting biomodulation in the cytoskeleton, and reducing apoptosis. To contribute with the elucidation of the importance of photobiomodulation in AD, this study aims to evaluate its neuroprotective effect, comparing different energy density of LED irradiating in SH‐SY5Y cells (human neuroblastoma) under the effect of oxidative stress induced by hydrogen peroxide (H2O2).MethodSH‐SY5Y cells (human neuroblastoma) were cultivated in DMEM/F12 medium (Dulbecco’s modified Eagles medium ‐ Gibco), supplemented with 10% fetal bovine serum and 1% antibiotic and antimycotic, at 37°C, in an atmosphere of 5% CO2. Cells were plated in 24‐well plates. After cell adhesion, cells were irradiated with LED at 660 nm (LED Biopdi/Irrad‐Led5), at energy densities of 1 J/cm2, 3 J/cm2, 5 J/cm2 and 10 J/ cm2. 24 h after irradiation, oxidative stress was induced with 200 μM H2O2 for 24h (this parameter had been previously determined by ROSSATO, R. C. et al, 2021).ResultOnce cells are irradiated and stressed, a considerable statistic difference is observed for all energy densities evaluated, compared to the stressed‐only group (H2O2). Importantly, the energy density of 3 J/cm2 was the lowest one that obtained better statistical increase in mithocondrial activity (p < 0.0001).ConclusionIt was possible to determine and compare the energy densities of LED irradiation to promote cellular photobiomodulation, inducing mithocondrial activity on neubroblastoma. Importantly, this study demonstrated the neuroprotective effect of LED in an in vitro model of AD oxidative stress, approaching novel concepts and a preventive tool.ROSSATO, R. C. et al. Neuroprotective effects of taurine on SH‐SY5Y cells under hydrocortisone induced stress. Research, Society and Development, v. 10, n. 9, p. e55510918426‐e55510918426, 2021

625 nm Light Irradiation Prevented MC3T3-E1 Cells from Accumulation of Misfolded Proteins via ROS and ATP Production.

Osteoblasts must acquire a considerable capacity for folding unfolded and misfolded proteins (MPs) to produce large amounts of extracellular matrix proteins and maintain bone homeostasis. MP accumulation contributes to cellular apoptosis and bone disorders. Photobiomodulation therapy has been used to treat bone diseases, but the effects of decreasing MPs with photobiomodulation remain unclear. In this study, we explored the efficacy of 625 nm light-emitting diode irradiation (LEDI) to reduce MPs in tunicamycin (TM) induced-MC3T3-E1 cells. Binding immunoglobulin protein (BiP), an adenosine triphosphate (ATP)-dependent chaperone, is used to evaluate the capacity of folding MPs. The results revealed that pretreatment with 625 nm LEDI (Pre-IR) induced reactive oxygen species (ROS) production, leading to the increased chaperone BiP through the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1s (XBP-1s) pathway, and then restoration of collagen type I (COL-I) and osteopontin (OPN) expression relieving cell apoptosis. Furthermore, the translocation of BiP into the endoplasmic reticulum (ER) lumen might be followed by a high level of ATP production. Taken together, these results suggest that Pre-IR could be beneficial to prevent MP accumulation through ROS and ATP in TM-induced MC3T3-E1cells.

Upturn Strategies for Arachidonic Acid-Induced MC3T3-E1—625 nm Irradiation in Combination with NSAIDs: Dissipating Inflammation and Promoting Healing

Oral surgery, such as tooth extractions and dental implantations, can cause inflammation in the surrounding tissue, especially in bones. Anti-inflammatory drugs are crucial for pain relief and wound healing. Nonsteroidal anti-inflammatory drugs (NSAIDs) and light-emitting diode irradiation (LEDI) at 625 nm have been used as therapies to reduce inflammation, which ultimately promotes wound healing. The mechanism of these two methods, however, is different, which possibly makes the combined use of the two approaches effective. Therefore, the efficacy of 625 nm LEDI, NSAIDs, or a combination of both on anti-inflammatory and wound healing effects were analyzed in MC3T3-E1. In this study, piroxicam, ibuprofen, indomethacin, and celecoxib were selected as the NSAIDs. The effect of LEDI at 625 nm was investigated by cell viability, prostaglandin E2 (PGE2) release, and the expression of inflammation-related proteins and cell migration-related proteins were evaluated. Additionally, alkaline phosphatase staining with activity, cell migration assay and BrdU cell proliferation assays were performed. Both LEDI and NSAIDs reduced cyclooxygenase-2 (COX-2) and PGE2. Additionally, LEDI promoted cell migration, proliferation, and bone formation as well, but not by NSAIDs. Thus, a combination of LEDI and NSAIDs can benefits the cells in inflammation, which provides upturn strategies for bone healing after tooth extraction.

Effect of copper oxide nanoparticles and light-emitting diode irradiation on the cell viability and osteogenic/odontogenic differentiation of human stem cells from the apical papilla

ObjectivesThis experimental study aimed to assess the effect of copper oxide nanoparticles (CuONPs) and light-emitting diode (LED) irradiation on the cell viability and osteogenic/odontogenic differentiation of human SCAPs.MethodsAfter the culture of SCAPs, the effects of different concentrations of CuONPs on cell viability were evaluated by the methyl thiazolyl tetrazolium (MTT) assay after 24 and 48 h, and the optimal concentration was determined (n = 12). SCAPs were then divided into four groups based on the type of treatment: (I) no-treatment control group, (II) exposure to CuONPs, (III) LED irradiation (635 nm, 200 mW/cm2) for 30 s, and (IV) exposure to CuONPs combined with LED irradiation. CuONPs were synthesized by a green technique, which was based on reduction and simultaneous stability of copper ions by using the pomegranate peel extract. After treatments, the expression of osteogenic/odontogenic markers including dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), alkaline phosphatase (ALP), and dentin matrix acidic phosphoprotein 1 (DMP1) was evaluated in all four groups using quantitative real-time polymerase chain reaction (PCR) (n = 16). Also, osteogenic differentiation of SCAPs was evaluated qualitatively by alizarin red staining (ARS) to assess the matrix mineralization (n = 4). SPSS version 18 was used for data evaluation. The Kruskal–Wallis and Mann–Whitney tests were used to compare the groups.ResultsExposure to 1 µg/mL CuONPs resulted in maximum viability of SCAPs. Concentrations of CuONPs over 10 µg/mL significantly decreased the viability of SCAPs. Real-time PCR showed that the expression of DMP1, BSP, ALP, and DSPP in CuONPs + LED and LED groups was significantly higher than that in CuONPs and control groups at both 24 and 48 h (P < 0.05). The density of ARS increased in all experimental groups after 24 h, and in CuONPs + LED and CuONPs groups after 48 h, compared to the control group.ConclusionAddition of CuONPs and LED irradiation of SCAPs in the culture medium significantly enhanced their osteogenic/odontogenic differentiation.

Activation of persulfate by TiO2 -Fe3 O4 nanocomposite for reactive red 198 degradation along with modeling and optimization approach

Background: Recently, sulfate radical-based photocatalytic processes have attracted significant interests because of unique advantages in pollutants purification. In this study, TiO2 -Fe3 O4 nanocomposites in the presence of persulfate and under ultraviolet light-emitting diode (UV-LED) irradiation were applied for reactive red 198 removal with a focus on the main operating parameters such as pH, persulfate molar concentration, irradiation time, and catalyst dosages in different initial concentrations. Methods: The nanoparticles were synthesized by co-precipitation technique. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR) analysis were used to evaluate TiO2 - Fe3 O4 nanocomposites. The response surface methodology (RSM) was employed for modeling and optimization. The kinetics and mechanisms of decolorization by sulfate and hydroxyl radicals were investigated. The mineralization of dye was evaluated using total organic carbon (TOC) analysis. Results: Modeling and optimization through RSM showed that the maximum decolorization of reactive red 198 is accursed an initial concentration of 10-50 mg/L was reached under UV-LED irradiation of 62- 85 min, persulfate concentration=0.8-1 mM, 0.19-0.3 g/L TiO2 -Fe3 O4 nanocomposites concentration, and pH=3. The kinetics of process was in agreement with pseudo-first order. The mineralization of reactive red 198 during the optimum conditions was determined at about 61.1% and 49.6%, meanwhile, the decolorization efficiency in the same conditions was approximately 98.1% and 87.6%, respectively. Conclusion: The use of TiO2 -Fe3 O4 nanocomposites under UV-LED irradiation in the presence of persulfate can be used as an efficient and promising method for dye removal from textile wastewater.

S modified manganese oxide for high efficiency of peroxydisulfate activation: Critical role of S and mechanism

Mn2O3 as a typical Mn based semiconductor has attracted growing attention due to its peculiar 3d electron structure and stability, and the multi-valence Mn on the surface is the key to peroxydisulfate activation. Herein, an octahedral structure of Mn2O3 with (111) exposed facet was synthesized by a hydrothermal method, which was further sulfureted to obtained a variable-valent Mn oxide for the high activation efficiency of peroxydisulfate under the light emitting diode irradiation. The degradation experiments showed that under the irradiation of 420 nm light, S modified manganese oxide showed an excellent removal for tetracycline within 90 min, which is about 40.4% higher than that of pure Mn2O3. In addition, the degradation rate constant k of S modified sample increased 2.17 times. Surface sulfidation not only increased the active sites and oxygen vacancies on the pristine Mn2O3 surface, but also changed the electronic structure of Mn due to the introduce of surface S2−. This modification accelerated the electronic transmission during the degradation process. Meanwhile, the utilization efficiency of photogenerated electrons was greatly improved under light. Besides, the S modified manganese oxide had an excellent reuse performance after four cycles. The scavenging experiments and EPR analyses showed that •OH and 1O2 were the main reactive oxygen species. This study therefore provides a new avenue for further developing manganese-based catalysts towards high activation efficiency for peroxydisulfate.

The effect of BVOCs produced by Lysinibacillus fusiformis and LED irradiation on pigment metabolism in stored broccoli

Volatile organic compounds produced by bacteria (BVOCs) have been proven to effect the postharvest metabolism of fruits and vegetables. The quality, color and antioxidant capacity of membrane lipids of broccoli in storage were effectively maintained by fumigation with BVOCs produced by Lysinibacillus fusiformis combined with white light emitting diode (LED) technology. An analysis of the transcriptome and metabolome of broccoli treated with the combined LED-BVOCs technology resulted in the identification of 49 differentially expressed genes (DEGs) and 13 differentially abundant metabolites (DAMs) involved in photosynthesis (32/0 DEGs upregulated/downregulated; 0/0 DAMs with increased/decreased abundance), chlorophyll (7/0; 1/2), carotenoid (5/0; 1/4) and flavonoid (3/3; 3/2) metabolism. The maintenance of green color in harvested broccoli treated by LED-BVOCs was associated with DEGs and DAMs that inhibited chlorophyll degradation and carotenoid accumulation. Our study provides a theoretical basis for understanding the delayed senescence of broccoli during storage using BVOCs-LED technology.

Light-emitting diode irradiation and glycine differentially affect photosynthetic performance of black henbane (Hyoscyamus niger L.)

Light-emitting diode irradiation and glycine differentially affect photosynthetic performance of black henbane (Hyoscyamus niger L.)

Photobiomodulation ameliorates inflammatory parameters in fibroblast-like synoviocytes and experimental animal models of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic destructive inflammatory disease that afflicts over one percent of the world's population. Current pharmacological treatments remain relatively ineffective. In this context, photobiomodulation (PBM) is a potential resource for the treatment of RA. This study investigates investigate the anti-arthritic effects and related mechanisms of PBM on fibroblast-like synoviocytes (FLSs) from RA patients and a mouse model of collagen-induced arthritis (CIA). The RA-FLSs were irradiated with a light emitting diode (LED) at a wavelength of 610 nm for 20min, and the corresponding power intensities were 5 and 10 mW/cm2. After the LED irradiation, cell viability, proliferation, migration, and invasion assays were performed. Male DBA/1J mice were used to establish an animal model of CIA. Light stimulation with 10 mW/cm2 was applied to the ankle joints via direct contact with the skin for 40min, daily for 2 weeks. PBM significantly reduced tumor necrosis factor (TNF)-α-induced increase in proliferation, migration, and invasion in RA-FLSs, and downregulated the activation of nuclear factor-κappa B (NF-κB) and NLRP3 inflammasome by TNF-α. Moreover, PBM greatly inhibited the induction and development of CIA, resulting in the inhibition of synovial inflammation and cartilage degradation. PBM therapy decreased the serum levels of pro-inflammatory cytokines, while increasing the anti-inflammatory cytokines. PBM suppressed the translocation of NF-κB and activation of NLRP3 inflammasome in the ankle joint. Furthermore, PBM showed a more pronounced anti-arthritic effect when combined with methotrexate (MTX), a disease-modifying anti-rheumatic drug (DMARD). The results showed that the effectiveness of MTX + PBM in CIA is superior to that of either MTX or PBM and that both work synergistically. Therefore, PBM with LED may be a potential therapeutic intervention for against RA.

Light-emitting diode (LED) photobiomodulation regulates thermogenesis and lipogenesis markers in adipose tissue and improves anthropometric and metabolic parameters in obese mice

To evaluate the effects of Light-Emitting Diode (LED) irradiation on the expression of thermogenesis and lipogenesis-associated markers in adipose tissue and metabolic parameters of obese mice. Twenty-four male mice were divided into four groups:i) ST fed standard diet;ii) HCD fed hyperglycemic diet;iii) LED + I fed hyperglycemic diet and irradiated with LED in the interscapular region;iv) LED + A fed hyperglycemic diet and irradiated with LED in the abdominal region. The first phase of the study comprehended the induction of obesity for 12weeks. Next, the animals were submitted to six irradiation sessions (days 1, 3, 7, 10, 14, and 21) using a 660-nm LED (5.77J/cm2at 48,1mW/cm2). Anthropometric, biochemical, and histological parameters and the expression of thermogenesis and lipogenesis-associated markers were assessed in adipose tissue. There was diminished weight gain between the HCD and LED + A groups (ST: 0.37 ± 0.65; HCD: 3.10 ± 0.89; LED + I: -1.26 ± 0.83; LED + A: -2.07 ± 1.27g; p < 0.018). There was a 33.3% and 23.8% reduction in epidydimal adipose tissue weight and a 25% and 10.7% in the visceral adiposity for the LED + I and LED + A groups, respectively, when compared with HCD. There was adecreased accumulation of fat droplets in adipose tissue in LED + A and LED + I groups. Additionally, LED irradiation was associated with increased mRNA expression of uncoupling protein 1 (UCP1) in the brown adipose tissue (ST: 2.27 ± 0.19; HCD: 1.54 ± 0.12; LED + I: 2.44 ± 0.22; p = 0.014) and decreased fatty acid synthetase (FAS) expression in epidydimal adipose tissue (ST: 0.79 ± 0.13; HCD: 1.59 ± 0.13; LED + A: 0.85 ± 0.04; p = 0.0008). LED treatment improved anthropometric parameters, possibly associated with the histological alterations, thermogenesis and lipogenesis markers in white adipose tissue, and expression modulation in brown adipose tissue.

Rational Design of High-Performance Hemithioindigo-Based Photoswitchable AIE Photosensitizer and Enabling Reversible Control Singlet Oxygen Generation

A photosensitizer furnishing with reversible control singlet oxygen generation (1O2) is highly desirable for precise photodynamic therapy (PDT), lessening non-specific harm to healthy tissues. Here, a novel photoswitchable aggregation-induced emission (AIE) photosensitizer based on a triarylamine (TPA)-modified hemithioindigo (HTI), 6Br-HTI-TPA-OMe, was rationally designed. The triarylamine AIE photosensitizing moiety and HTI switch unit were covalently linked in one molecule, permitting reversible regulation of 1O2 production. The photophysical evaluations revealed that 6Br-HTI-TPA-OMe possessed excellent AIE properties and Z/E photoswitch performance in different solvents. Additionally, the amphiphilic phospholipid-fabricated nanoparticles (NPs) also exhibited photochromic behavior in water. The Z-NPs initiated the generation of 1O2 upon 520 nm light-emitting diode (LED) irradiation, but after switching to E-NPs, the generation of 1O2 was inhibited by the competitive energy transfer, suggesting that reversible Z/E isomerization could photocontrol 1O2 generation. The in vitro anti-tumor experiment verified that the 6Br-HTI-TPA-OMe can act as a photoswitchable AIE photosensitizer. This is the first report on the photoswitchable AIE photosensitizer of HTI-based molecules, to the best of our knowledge.

Physiological, biochemical, and postharvest characteristics of two cut rose cultivars are regulated by various supplemental light sources

Light is not only a photosynthetic energy source for biochemically plant cellular accumulation but also the most important signaling messenger for plant growth, development, and environmental adaptations, influencing the postharvest quality and longevity. In this study, to optimize the biochemical and physiological responses of cut rose flowers cv. ‘Jumilia’ and ‘Samurai’ to the different light quality provided by metal halide (MH), high pressure sodium (HPS), and light-emitting diode (LED) lamps and two light intensities of LED (75 and 150 μmol m−2 s−1 PPFD) on the postharvest life. The results showed that flower water content, as well as total carbohydrate, anthocyanin, and carotenoid content, were significantly induced by LED irradiation, but didn't influence the starch content of cut roses. Furthermore, MH and HPS lighting changed the osmotic potential, decreased the membrane stability index, and consequently increased the color change after harvest, resulting in shorter postharvest life of cut roses comparing to the LED environment. More specifically, plants produced by LED lighting reached higher activity of phenylalanine ammonia-lyase (PAL) enzymes and the following higher lignin concentration. LED-exposed rose flowers showed an increase in antioxidant activity and limitation of lipid peroxidation and hydrogen peroxide but were not effective in ascorbate peroxidases (APX) enzyme activity of cut rose flowers. Overall, LED irradiation delayed the senescence of postharvest cut roses mainly by inducting protein biosynthesis, activating the enzymatic system, and inhibiting microbial proliferation. These results suggest that the spectral quality of lighting altered biochemical function, cell wall lignification, and antioxidative defense mechanisms that affect postharvest attributes in roses.

Dual red and near-infrared light-emitting diode irradiation ameliorates LPS-induced otitis media in a rat model.

Objective: Otitis media (OM) is an infectious and inflammatory disease of the middle ear (ME) that often recurs and requires long-term antibiotic treatment. Light emitting diode (LED)-based devices have shown therapeutic efficacy in reducing inflammation. This study aimed to investigate the anti-inflammatory effects of red and near-infrared (NIR) LED irradiation on lipopolysaccharide (LPS)-induced OM in rats, human middle ear epithelial cells (HMEECs), and murine macrophage cells (RAW 264.7). Methods: An animal model was established by LPS injection (2.0mg/mL) into the ME of rats via the tympanic membrane. A red/NIR LED system was used to irradiate the rats (655/842nm, intensity: 102mW/m2, time: 30min/day for 3 days and cells (653/842nm, intensity: 49.4mW/m2, time: 3h) after LPS exposure. Hematoxylin and eosin staining was performed to examine pathomorphological changes in the tympanic cavity of the ME of the rats. Enzyme-linked immunosorbent assay, immunoblotting, and RT-qPCR analyses were used to determine the mRNA and protein expression levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). Mitogen-activated protein kinases (MAPKs) signaling was examined to elucidate the molecular mechanism underlying the reduction of LPS-induced pro-inflammatory cytokines following LED irradiation. Results: The ME mucosal thickness and inflammatory cell deposits were increased by LPS injection, which were reduced by LED irradiation. The protein expression levels of IL-1β, IL-6, and TNF-α were significantly reduced in the LED-irradiated OM group. LED irradiation strongly inhibited the production of LPS-stimulated IL-1β, IL-6, and TNF-α in HMEECs and RAW 264.7 cells without cytotoxicity in vitro. Furthermore, the phosphorylation of ERK, p38, and JNK was inhibited by LED irradiation. Conclusion: This study demonstrated that red/NIR LED irradiation effectively suppressed inflammation caused by OM. Moreover, red/NIR LED irradiation reduced pro-inflammatory cytokine production in HMEECs and RAW 264.7 cells through the blockade of MAPK signaling.

Polymer Membrane Modified with Photocatalytic and Plasmonic Nanoparticles for Self-Cleaning Filters.

In this study, we developed a filtering material for facial masks, which is capable of trapping and subsequent inactivation of bacteria under white light emitting diodes (LED) or sunlight irradiation. Such a functionality is achieved via the modification of the composite membrane based on porous polymer with photocatalytic (TiO2) and plasmonic (Ag) nanoparticles. The porous polymer is produced by means of a computer numerical control machine, which rolls a photoresist/thermoplastic mixture into a ~20-µm-thick membrane followed by its thermal/ultraviolet (UV) hardening and porosification. TiO2 nanoparticles are prepared by hydrothermal and sol-gel techniques. Colloidal synthesis is utilized to fabricate Ag nanoparticles. The TiO2 photocatalytic activity under UV excitation as well as a photothermal effect generated by plasmonic Ag nanoparticles subjected to LED irradiation are studied by the assessment of methylene blue (MB) decomposition. We demonstrate that, in contrast to the filter of the standard facial medical mask, the polymer membrane modified with spray-coated TiO2 and Ag nanoparticles prevents the penetration of bacillus subtilis from its top to bottom side and significantly inhibits bacterial growth when exposed to LED or sunlight.

High-Performance Photoinitiating Systems for LED-Induced Photopolymerization

Currently, increasing attention has been focused on light-emitting diodes (LEDs)-induced photopolymerization. The common LEDs (e.g., LED at 365 nm and LED at 405 nm) possess narrow emission bands. Due to their light absorption properties, most commercial photoinitiators are sensitive to UV light and cannot be optimally activated under visible LED irradiation. Although many photoinitiators have been designed for LED-induced free radical polymerization and cationic polymerization, there is still the issue of the mating between photoinitiators and LEDs. Therefore, the development of novel photoinitiators, which could be applied under LED irradiation, is significant. Many photoinitiating systems have been reported in the past decade. In this review, some recently developed photoinitiators used in LED-induced photopolymerization, mainly in the past 5 years, are summarized and categorized as Type Ⅰ photoinitiators, Type Ⅱ photoinitiators, and dye-based photoinitiating systems. In addition, their light absorption properties and photoinitiation efficiencies are discussed.

In vitro investigation of the antibacterial and anti-inflammatory effects of LED irradiation.

This study aimed to investigate the proper wavelengths for safe levels of light-emitting diode (LED) irradiation with bactericidal and photobiomodulation effects in vitro. Cell viability tests of fibroblasts and osteoblasts after LED irradiation at 470, 525, 590, 630, and 850 nm were performed using the thiazolyl blue tetrazolium bromide assay. The bactericidal effect of 470-nm LED irradiation was analyzed with Streptococcus gordonii, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannerella forsythia. Levels of nitric oxide, a proinflammatory mediator, were measured to identify the anti-inflammatory effect of LED irradiation on lipopolysaccharide-stimulated inflammation in RAW 264.7 macrophages. LED irradiation at wavelengths of 470, 525, 590, 630, and 850 nm showed no cytotoxic effect on fibroblasts and osteoblasts. LED irradiation at 630 and 850 nm led to fibroblast proliferation compared to no LED irradiation. LED irradiation at 470 nm resulted in bactericidal effects on S. gordonii, A. actinomycetemcomitans, F. nucleatum, P. gingivalis, and T. forsythia. Lipopolysaccharide (LPS)-induced RAW 264.7 inflammation was reduced by irradiation with 525-nm LED before LPS treatment and irradiation with 630-nm LED after LPS treatment; however, the effects were limited. LED irradiation at 470 nm showed bactericidal effects, while LED irradiation at 525 and 630 nm showed preventive and treatment effects on LPS-induced RAW 264.7 inflammation. The application of LED irradiation has potential as an adjuvant in periodontal therapy, although further investigations should be performed in vivo.