Blue LED Light Research Articles

PENGARUH LAMA PENYINARAN LAMPU LED MERAH, BIRU, KUNING TERHADAP PERTUMBUHAN MICROGREEN KANGKUNG (Ipomoea reptant)

Microgreens are vegetables that can be harvested about 7-14 days after germinationwhich has a higher nutrient and vitamin content than commonly grown vegetables. Thisstudy aims to determine the interaction between the type of light and the duration oflighting and the effect of the types of red, blue, yellow LEDs and red, blue, yellow LEDlighting on the growth of kangkung microgreen. This research is a box experiment using aSplit Plot Experiment Design with 9 treatments and 3 replications. The results showed thatthere was an interaction between the type of lamp and the duration of lighting to thegrowth of kangkung microgreen. The combination of C3T1 treatment (Yellow LED + 6hours) produced the highest plant length, namely 6.47 cm at 7 DAS, the number of leaveswas 2.00 for all treatments. The different types of lamps in kangkung microgreen had asignificant effect on growth, where the blue LED light produced the highest number ofleaves, namely 2.00 leaves at 14 DAS. The highest fresh weight per box was 18.36 g. While the Yellow LED produced the highest plant length of 9.42 cm at 14 DAS, the highestnumber of leaves was 2.00 pieces 14 DAS, the highest root length was 7.22 cm, thehighest dry weight per box was 1.03 g. The difference in lighting time onkangkung microgreen has a significant effect on the growth, where the 6 hours lightingduration produces the highest root length, namely 7.96 cm, the highest fresh weight perbox is 23.17 g, the highest dry weight per box is 1.87 g. The length of 12 hours of lightingresulted in the highest plant length, namely 10.41 cm at 14 DAS, the highest number ofleaves was 2.00 leaf blade. Based on the results of this study it can be recommended thatthe cultivation of kangkung microgreen in the box experiment can be using lighting for 6hours and pay attention to the microelements that affect the microgreen for better growth.Keywords : Microgreen, Kangkung, Red, Blue, Yellow, LED lights

A phosphor converted RED light for automotive LED rear lamp and compliance with ECE light regulation

In conventional red color lighting LED lamp for vehicles are composed of red color lighting LED and additional transparent or red lenses. Generally red color lighting LED is based on the semiconductor materials as AlGaInP, AlGaAs or GaAsP. Such RED LEDs are mostly affected by temperature. As the temperature increases, the luminous flux droops sharply and lighting efficiency decreases accordingly. In addition, the light color changes due to the wavelength shift phenomenon. This makes the design for automotive ECE regulation for red light very demanding. In this study, it is intended to develop a high-efficiency RED LED light for automobile rear lamps with the phosphor-converted LEDs technology used the characteristics of blue light LED. The luminous flux droop affected by temperature change which is the most important parameter in vehicle lamp performance, is measured, and the compliance with the red light ECE regulation for automobiles is compared and evaluated. For measuring the optical properties, it was performed using the T3Ster TeraLED system. The PC RED LED chips for new development used blue LED based on InGaN (455 nm) and conventional RED LED chips are AllnGaP LEDs (614 nm, 620 nm). To optimize optical properties of PC RED LED, phosphor was applied in 5 grades according to concentration. The best optical properties of PC RED LED shows at the phosphor concentration of 40 %. The results have important implications for improving the performance of automotive red lamps.

A comparison of white/red and white/blue LED light fixtures on Pekin duck production, stress and behaviour

ABSTRACT 1. The objective of this study was to determine the effects of two mixed LED light spectra on duck production, stress and fear responses. Pekin ducks were reared under either white/red (WR) or white/blue (WB) LED light. 2. No differences were observed in feed conversion ratio (P = 0.690) or d 35 body weight (P = 0.919). Furthermore, no differences were observed in plasma interleukin-12 concentrations (P = 0.449), anti-keyhole limpet haemocyanin IgG titre (P = 0.503) or composite physical asymmetry score (P = 0.839). WR caused lower heterophil to lymphocyte ratios (0.40 ± 0.03, P = 0.029) and plasma corticosterone concentrations (4498 ± 534 pg/ml, P = 0.038) than WB (0.58 ± 0.08; 6518 ± 795 pg/ml, respectively). No differences were found in the number of attempts to induce tonic immobility (TI) or in inversion intensity. A shorter latency to first head movement during TI (9.44 ± 1.22 s, P = 0.06) and an overall shorter latency to right from TI (25.66 ± 2.99 s, P < 0.001) was observed for birds under WR compared to WB (20.91 ± 6.01 s; 58.76 ± 8.86 s). The duration of time spent in the second stage of TI, where birds observed their environment using head movements while still remaining immobile on their backs, was shorter in WR (16.23 ± 1.73 s, P = 0.001) compared to WB (37.85 ± 6.38 s). 3. The results indicated that rearing ducks under WR caused less stress susceptibility and fear responses compared to ducks under WB. Pekin duck welfare may be compromised by blue LED light exposure, even at supplemental levels utilised in commercial poultry lighting.

Effects of growth temperature change in quantum well on luminescence performance and optical spectrum

This paper discusses the effects of extended temperature change time of InGaN well growth on the luminescent properties of blue LEDs with sapphire substrate. Extending the temperature change time will increase the area of the In composition gradient in the quantum well, thereby changing the PL luminescence peak shape, which is conducive to increasing the brightness of the LED. The change of EL-luminescent peaks under different current is further studied. In combination with PL, the source of the shoulder peak on the long-wave-side of the main luminescent peak in the blue light InGaN quantum well growing on the sapphire substrate is explored under normal temperature condition. One illumination mechanism related to a main illuminating center provides a research direction for the improvement of the photoelectric performance of the blue-light LED.

Lignin-based thermoresponsive macromolecules via vitamin-induced metal-free ATRP

An environmentally-friendly process for the modification of lignin with thermoresponsive polymers was employed, providing well-defined structures with narrow molecular weight distribution (Mw/Mn = 1.44). We report a biocompatible vitamin-inspired photoinitiation system composed of two components i.e. riboflavin (vitamin B2) as a photosensitizer and ascorbic acid (vitamin C) as a mild reducing agent. Under blue light LEDs irradiation at 460 nm (5.0 mW cm−2) the presented two-component photoinitiation setup enables grafting of poly(ethylene glycol) methyl ether methacrylate (OEGMA500) from brominated lignin via metal-free ATRP approach. A series of cyclic voltammetry (CV) measurements were conducted to electrochemically characterize ATRP initiators, both brominated lignin and lignin-based polymers, confirming preserved chain-end functionality of the prepared macromolecules. Received polymers with lignin core and POEGMA side chains exhibited thermoresponsive properties, which were investigated by determination of number average sizes of macromolecules by dynamic light scattering (DLS) and transmittance by ultraviolet/visible (UV-Vis) absorption spectroscopy of KL-g-(POEGMA-Br)10 aqueous solution. The in vitro curcumin release studies showed that the active substance is released from drug-loaded micelles in a thermo-sensitive manner. Prepared lignin-based macromolecules will show wide application as crucial components of thermoresponsive coatings, potentially creating bioactive surfaces characterized by antifouling properties, controlling cell adhesion or used as biosensors, due to PEG-containing side chains in branched polymers.

Physiological responses of sun choke’s seedlings under different wavelength LED lighting

The impacts of light sources on development, morphological characteristics, and chlorophyll fluorescence of Jerusalem artichoke (Helianthus tuberosus L; JA) seedlings were investigated under natural light (NL), fluorescence light (FL), red light LEDs (R), blue light LEDs (B) and red + blue light LEDs (R + B) (photosynthetic photon flux density 326.74, 30.61, 159.23, 445.38 and 332.56 μmol m−2·s-1, respectively). Morphological appearances of seedlings were significantly different, The R and R + B lighting significantly reduced seedling height and internode length when compare with NL. In contrast, B light could enhance JA seedling growth by increase stem dry weight and net assimilation rate (NAR). Photosynthetic efficiency in terms of photochemical quenching (qP) of seedling were higher under B light than FL light. JA response of seedlings under B light condition was much overall better yield compare to another light source condition. Taken together, R and R + B lighting facilitated plant shortening and more compact canopy, emphasizing the importance of R light spectral quality to manipulate plant growth. It therefore represents modify alternative method to obtain edible potted JA plants under control lighting.

Unraveling the effects of blue light in an artificial solar background light on growth of tomato plants

While the use of narrowband irradiance regimes containing different blue light fractions has proven useful to unravel blue light effects on plants at a fundamental level, it does not quantify the responses to blue light under natural daylight conditions. The objective of this study is to understand the blue light growth responses by combining photosynthetic measurements with measurements of whole plant light absorption in a simulated daylight spectrum enriched with different levels of blue light. To achieve this, tomato plants were grown under six different combinations of artificial solar light and blue LED light. Light treatments were defined by the blue light (400–500 nm) fraction of total photosynthetic photon flux density (400–700 nm) and included 27 % (no additional blue LED), 28 %, 31 %, 38 %, 43 % and 61 % blue light with a total photosynthetic photon flux density of 100 μmol m−2 s-1 in all treatments. Whole plant light absorption was estimated by using ray tracing simulation combined with measured 3-dimensional structure of the plant and optical properties of the leaves. The total dry weight of the plants decreased linearly with the increase of blue light fraction; the dry weight of the plants grown under 27 % blue being 1.6 times greater than that of the plants grown under 61 % blue. This large difference was related to lower light absorption by the plants when fraction blue light increased, due to more compact morphology, i.e. lower leaf area, leaf length/width ratio and shorter stem. Light-limited quantum yield and maximum photosynthetic capacity were not affected by blue light fraction. In the case of the latter, which in other studies has often been found to be positively related to blue light fraction, it may be that the blue light fraction already present in the daylight source had saturated this response. Overall, increasing the blue light fraction in a solar light background decreases growth mainly through its effect on plant morphology and light interception. It remains to be elucidated whether the responses observed using the low growth light intensity in the present study are maintained in high light growth environments more characteristic for tomato growth and production.

Efficacy of light-emitting diodes emitting 395, 405, 415, and 425 nm blue light for bacterial inactivation and the microbicidal mechanism

We investigated the bactericidal effects against Escherichia coli O157:H7 of light-emitting diodes (LEDs) emitting blue light of four different peak wavelengths ranging from 395 to 425 nm in water. Furthermore, we investigated inactivation in the presence of reactive oxygen species (ROS) scavengers to elucidate the contribution of bacterial inactivation. An aluminum chamber was constructed and coated in carbon to block exterior light, and a single blue light LED with a rear heat sink was attached to the chamber lid. Effective inactivation of the pathogen was observed for all blue light LED irradiation at 305, 405, 415, and 425 nm. The log-linear with shoulder and tail model and log-linear model described the survival of the bacteria after blue light LED treatments. Not just the effects of ROS but also photophysical effects were shown with the addition of mannitol, a ROS scavenger. The integrity of the cell membrane was damaged regardless of the presence of ROS, which indicates that photophysical effects were sufficient to induce damage to the cell membrane. In addition, activity of succinate-coenzyme Q reductase, which participates in respiratory metabolism to generate energy, decreased in the absence of ROS and decreased further in the presence of ROS.

Near-Infrared-Light emitting diode driven white light Emission: Upconversion nanoparticles decorated Metal-Organic Frame-works thin film

The existing white light-emitting diodes (WLEDs) are mostly fabricated with downshifting phosphors and ultraviolet (UV) or blue light LED chips. To achieve unconventional upconversion white-light-emitting phosphors, a novel strategy by encapsulating upconversion nanoparticles and organic dyes into metal–organic frameworks (MOFs) at room temperature is put forward. Herein, lanthanide-doped upconversion nanoparticles (NaYF4:Yb,Tm@NaYF4 core–shell UCNPs), dye 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) and dye Coumarin 6 (C6) with blue, red and green light emission, respectively, are encapsulated together into ZIF-8 through a facile one-pot solid-confinement conversion process. Owing to their appropriate spectral overlaps and efficient energy transfer processes between two pairs of UCNPs/DCM and UCNPs/C6 within ZIF-8, the optimized UCNP/DCM/C6@ZIF-8 thin film exhibits high-quality white-light emission upon a commercial 980 nm LED chip with ideal CIE coordinates of (0.33, 0.33), high color rendering index (CRI) value of 93 and moderate correlated color temperature (CCT) value of 5567 K. This strategy paves the way for other upconversion phosphorous nanoparticles and fluorescent molecules for WLEDs applications excited by near infrared light.

Sustained graphene oxide coated superhydrophilicity and superwetting using humidity control

The use of superhydrophilic surfaces for superwetting applications can be hampered by their wetting degradation over time. In this work, superhydrophilic surfaces were fabricated by graphene oxide (GO) deposition on roughened polyvinyl chloride (PVC) substrates. These surfaces were found to exhibit zero contact angle when enhanced green fluorescent protein (EGFP) was deposited on the surface immediately after GO was applied. However, when the GO-coated substrate was stored for 3 h, the surface displayed a contact angle of 54°. The main contact line spreading of the EGFP drop was more easily discernible using normal (500 lx, low glare and shadow free) lighting than with blue LED lighting in the dark. The average radius of the spreading main contact line was found to follow a power-law relationship that increased at a faster rate with higher relative humidity. Confocal imaging revealed rings of EGFP deposition following superwetting that is attributable to pinning around the islands of GO accumulation. Substrate superhydrophilic and superwetting properties can be preserved by adequate control of relative humidity. Relative humidity of 80 % was easily maintained for 150 min by incorporating a 20 μL water drop in a sealed 240-mL container.

Efficacy of antimicrobial photodynamic therapy with Rose Bengal and blue light against cariogenic bacteria

ObjectiveWe evaluated the effect of antimicrobial photodynamic therapy (a-PDT) with Rose Bengal and blue light LED on bacteria that initiate and promote dental caries. DesignColony forming units of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, and Lactobacillus salivarius under planktonic and biofilm conditions were counted after a-PDT treatment using Rose Bengal and blue light LED. In addition, cariogenic bacteria from saliva and dental plaques from ten volunteers were used for evaluation of a-PDT treatment. ResultsWe found that a-PDT using Rose Bengal at > 10 μg/mL had antimicrobial effects on oral Gram-positive S. mutans, S. sobrinus, S. sanguinis, and L. salivarius under both planktonic and biofilm conditions. The effect was also observed for cariogenic bacteria that formed biofilms containing water-insoluble glucans, through which the bacteria are firmly attached to the tooth surface. Moreover, a-PDT led to a marked reduction in cariogenic bacteria in saliva and dental plaques. Conclusiona-PDT could be a useful approach for controlling dental caries in dental surgery.

Vertical Production of ‘Konstancin’ Rose Cuttings in the Growth Chamber Under Led Light

Abstract The impact of light quality generated by light-emitting diodes (LEDs) on the adventitious root formation and cuttings’ quality of rose hip ‘Konstancin’ under controlled conditions in multilevel growth chamber without access to natural light and in the greenhouse was evaluated. In the growth chamber, the lighting was provided by a combination of red and blue LED arrays and white LED tubes, while in the greenhouse, red and blue LED lights were used as a supplement to natural light. The number of rooted cuttings under both growth conditions was not affected by the light conditions generated by LEDs. However, light quality showed significant effects on the biomass production and development of adventitious roots, with the most stimulating red light generated by LEDs. In the growth chamber, the root biomass of the cuttings illuminated with white LEDs supplemented with red LEDs was on average 2.2 times higher than of the cuttings illuminated with white LEDs only. A similar reaction was noted under greenhouse conditions. Supplementation of natural light with red LEDs resulted in 1.7 times increase of the fresh biomass of roots. Both in the growth chamber and in the greenhouse, illumination with red LEDs promoted axillary bud outgrowth. LED lamps can be used in the production of high-quality rose cuttings, both in greenhouses as a complement to natural light and in multilevel rooms as a sole-source lighting for plants.

Post-harvest alterations in quality and health-related parameters of cherry tomatoes at different maturity stages following irradiation with red and blue LED lights

ABSTRACT Green-mature and turning cherry tomatoes (Solanum lycopersicum L.) of a red (‘Cherry Little Wonder’) and a yellow (‘Goldilocks’) cultivar (cv) were illuminated, post-harvest, with either red (118 µmol m–2 s – 1 at 638 nm) or blue LED light (118 µmol m–2 s – 1 at 454 nm) for 48 h and subsequently stored for up to 21 days at room temperature. The effects of the treatments on colour, firmness, sugars and carotenoids were evaluated throughout storage. The light treatments did not have any effect on firmness and mass; however, light exposure, particularly red light, enhanced the a* colour component of the red cv significantly; similarly, colour coordinate b* of the yellow cv, treated at both stages of development, was significantly enhanced by both light treatments, resulting in visually redder and yellower tomatoes, respectively. These effects were more so observed on green-mature than on turning fruit. In addition, the treatments significantly increased lycopene concentrations in the red cv at both ripening stages, and β-carotene concentrations in both, the yellow and red cv treated at the green-mature stage. Total soluble solids (%TSS) also increased significantly following treatment. Findings reported suggest that illuminating tomato fruit with LED lights at the green-mature stage enhances colour development and the concentration of sugars, pigments and other health-related compounds without significantly affecting fruit mass and firmness.

Efek Penggunaan Beberapa Sinar LED pada Tanaman Buah Naga Merah (Hylocereus polyrhizus)

Effects of Using Multiple LED Beams on Red Dragon Fruit (Hylocereus polyrhizus). Red dragon fruit plant (H. polyrhizus) is a tropical plant and is very adaptable to growing environments and weather changes such as sunlight, wind, and rainfall. Dragon fruit plants is a long day plants (plants that require long enough sun exposure), which means that to produce this plant requires at least 12 hours of radiation. Knowing this, there needs to be a solution so that production stability can be controlled, one of which is by modifying the environment. The purpose of this study was to determine the effect of several colors of LED light (Light Emitting Diode) at the initiation stage of dragon fruit flowers in an effort to increase production. This study used a randomized block design with four treatments and nine replications, while the treatment consisted of control plants, the administration of white LED lights, yellow LED lights and blue LED lights. Three variables were observed, namely the number of flower buds, the number of blooming flowers and the number of young fruits. The results showed that the use of yellow LED lights give the best light intensity when compared to other treatments so that the yellow LED light treatment gave the best results on each variable including 6.44 pieces for flower buds, 7.56 pieces for flowers blooms and 7.56 pieces for young fruit.

Titania Inverse-Opal Photonic Crystals Incorporating Gold Nanoparticles in Void Spaces for Photoabsorption Enhancement

Designing of three-dimensional (3D) materials such as inverse-opal (IO) photonic crystals (PCs) has been identified as an effective pathway to enhance light harvesting to longer electromagnetic absorption regions such as visible and infrared [1]. IO PCs exhibit photonic band gap (PBG) and this band structure predicts the translation of photons with reduced velocity, namely as slow photons at certain crystallographic directions. The photonic effect from titania (TiO2)-IO structure was reported to enhance light-material interactions thus allowing better absorption of light at the wavelength at which the materials absorb poorly [2]. On the other hand, utilization of gold-nanoparticles (Au-NPs) on TiO2 could aid in charge separation and play its role as an amplifier for visible-light absorption due to its effects originating from localized surface plasmon resonance (LSPR) [3]. In this study, TiO2-IO PC with incorporated gold nanoparticles (Au-NPs) per void space was developed by implementing five important steps to achieve a good quality of TiO2-IO structure. Both photonic effects due to the slow photons in TiO2-IO structure and LSPR effects contributed by Au-NPs were expected to give visible-light absorption by the photocatalyst material.The experimental procedure consists of five steps as shown in Scheme 1 starting from (i) synthesis of Au-NPs, (ii) silica (SiO2) coating on Au-NP to form Au/SiO2 core-shells, (iii) self-assembly of Au/SiO2 to form high-quality opal structure, (iv) infiltration of TiO2 precursor via forced impregnation method and (v) selective etching of SiO2 to obtain the final TiO2-IO structure. Photodegradation of acetic acid was carried out in the presence of the photocatalyst material by using blue LED light (450 nm) with optical power of 0.3 W. SiO2 containing Au-NP (Au/SiO2) was used as the opal template for the 3D macroporous TiO2-IO containing Au-NP per void space (TiO2(Au)-IO). Figures 1a and 1b are images observed for Au/SiO2 opal structure exhibiting face-centered cubic (FCC) arrangement. As is observed, the closely packed opal structure could be obtained as the minimum variation among each particle was less than 5 %. However, extra precautions should be taken to avoid cracking on the opal structure to sustain the quality of the final desired material. Figures 1c and 1d are images of TiO2(Au)-IO which was successfully obtained after TiO2 infiltration via forced impregnation method followed by the removal of SiO2 to form the nanovoids. The strategy that has been implemented to enhance the light harvesting process was by designing the TiO2-IO structure with different diameter of nanovoids, which can be controlled by altering the SiO2 shell thickness in the second step of the synthesis process.Photocatalytic activities of those samples were evaluated by measuring the amount of carbon-dioxide (CO2) generated from acetic acid by TiO2(Au)-IO with different diameter of nanovoid diameters (Au-NP size: 44 nm) under LED light irradiation (4 h). Enhanced CO2 evolution was detected with TiO2(Au)-IO with nanovoid diameter of 215 nm suggesting the successful matching of photonic and LSPR effects in TiO2(Au)-IO.[1] X. Zheng, D. Li, X. Li, L. Yu, P. Wang, X. Zhang, J. Fang, Yu. Shao and Y. Zheng. Phys. Chem. Chem. Phys. 16 (2014) 15299–15306.[2] V. Jovic, H. Idriss and G.I.N. Waterhouse. Chem. Phys. 479 (2016) 109–121.[3] S.M. Yoo, S.B. Rawal, J.E. Lee, J. Kim, H. Ryu, D. Park and W.E. Lee. Appl. Catal. A Gen. 499 (2015) 47–54. Figure 1

The first report of covalently grafted semiconductors; n‐TiO2‐P25@ECH@WO3 as a new, efficient, robust and visible‐light‐responsive photocatalyst

AbstractBACKGROUNDSemiconductor nanomaterials have gained great attention as potential photocatalysts to promote environmentally benign organic reactions. Degussa P25, known as commercial TiO2, is the most applicable semiconductor photocatalyst. However, the wide band‐gap of TiO2 limits its application. A simple way to address this issue is to form heterojunction structures.RESULTSIn the present work, n‐TiO2‐P25@ECH@WO3 heterostructure photocatalyst was synthesized for the first time by a two‐step covalent grafting strategy. In this photocatalyst, two nano‐semiconductors, TiO2‐P25 and WO3 were anchored with epichlorohydrin (ECH) as the covalent linker. The properties of n‐TiO2‐P25@ECH@WO3 were investigated through Fourier‐transform infrared spectroscopy (FTIR), X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X‐Ray (EDX) and UV‐visible/DRS techniques. Under blue LED light, n‐TiO2‐P25@ECH@WO3 oxidized benzyl alcohol to benzaldehyde with excellent selectivity and high yield.CONCLUSIONIn this study, n‐TiO2‐P25@ECH@WO3 heterostructure photocatalyst was successfully synthesized and evaluated. ECH as the organic linker stably grafted two nano‐semiconductors, n‐TiO2‐P25 and n‐WO3. The heterojunction that formed between n‐TiO2 and n‐WO3 significantly improved the light absorption performance with a considerable redshift to the visible region. Also, the photocatalyst showed an increased activity compared to individual semiconductors. © 2020 Society of Chemical Industry (SCI)

Construction and investigation of photo-switch property of azobenzene-bridged pillar[5]arene-based [3]rotaxanes

Series of azobenzene-bridged pillar[5]arene-based [3]rotaxanes with different alkyl chain length of guest molecules were constructed by threading-endcapping method with alkylenetriazole as axile and tetrahydrochromene as endcapping group. The encapsulation of pillar[5]arenes were proved by high-resolution mass, 1H NMR and NOESY spectra. The photo-responsive property were examined by irradiation of the synthesized [3]rotaxanes with 365 nm and blue light LED, which caused trans to cis and cis to trans isomerization, respectively. Irradiation of corresponding model guest compounds without pillar[5]arene encapsulation resulted in near completely trans to cis and cis to trans isomerization, indicating the existence of pillar[5]arenes is the determining factor for the comprised photo isomerization efficiency.

Effects of Light-Emitting Diodes on the Accumulation of Phenolic Compounds and Glucosinolates in Brassica juncea Sprouts

Recent improvements in light-emitting diode (LED) technology afford an excellent opportunity to investigate the relationship between different light sources and plant metabolites. Accordingly, the goal of the present study was to determine the effect of different LED (white, blue, and red) treatments on the contents of glucosinolates (glucoiberin, gluconapin, sinigrin, gluconasturtiin, 4-methoxyglucobrassicin, 4-hydroxyglucobrassicin, glucobrassicin, and neoglucobrassicin) and phenolic compounds (4-hydroxybenzonate, catechin, chlorogenic acid, caffeate, gallate, sinapate, and quercetin) in Brassica juncea sprouts. The sprouts were grown in a growth chamber at 25 °C under irradiation with white, blue, or red LED with a flux rate of 90 μmol·m−2·s−1 and a long-day photoperiod (16 h light/8 h dark cycle). Marked differences in desulfoglucosinolate contents were observed in response to treatment with different LEDs and different treatment durations. In addition, the highest total desulfoglucosinolate content was observed in response to white LED light treatment, followed by treatment with red LED light, and then blue LED light. Among the individual desulfoglucosinolates identified in the sprouts, sinigrin exhibited the highest content, which was observed after three weeks of white LED light treatment. The highest total phenolic contents were recorded after one week of white and blue LED light treatment, whereas blue LED irradiation increased the production of most of the phenolic compounds identified, including 4-hydroxybenzonate, gallate, sinapate, caffeate, quercetin, and chlorogenic acid. The production of phenolics decreased gradually with increasing duration of LED light treatment, whereas anthocyanin accumulation showed a progressive increase during the treatment. These findings indicate that white LED light is appropriate for glucosinolate accumulation, whereas blue LED light is effective in increasing the production of phenolic compounds in B. juncea sprouts.

PH interferes in photoinhibitory activity of curcumin nanoencapsulated with pluronic® P123 against Staphylococcus aureus.

Microbial contamination control is a public health concern and challenge for the food industry. Antimicrobial technologies employing natural agents may be useful in the food industry for these purposes. This work aimed to investigate the effect of photodynamic inactivation using curcumin in Pluronic® P123 nanoparticles (Cur/P123) at different pH and blue LED light against Staphylococcus aureus. Bacterial photoinactivation was conducted using different photosensitizer concentrations and exposure times at pH 5.0, 7.2 and 9.0. A mixture design was applied to evaluate the effects of exposure time (dark and light incubation) on the photoinhibitory effect. S. aureus was completely inactivated at pH 5.0 by combining low concentrations of Cur/P123 (7.80-30.25 μmol/L) and light doses (6.50-37.74 J/cm2). According to the mathematical model, dark incubation had low significance in bacterial inactivation at pH 5.0 and 9.0. No effect in bacterial inactivation was observed at pH 7.2. Cur/P123 with blue LED was effective in inactivating S. aureus. The antimicrobial effect of photodynamic inactivation was also pH-dependent.

The effect of combined curcumin-mediated photodynamic therapy and artificial skin on Staphylococcus aureus-infected wounds in rats.

Healing wounds represent a major public health problem, mainly when it is infected. Besides that, the antibiotics misuse and overuse favor the development of bacterial resistance. This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) combined with artificial skin on disinfection of infected skin wound in rats. Twenty-four Wistar rats were randomly distributed into 4 groups (n = 6): (i) control-untreated; (ii) aPDT-treated with curcumin-mediated aPDT (blue light); (iii) artificial skin-treated with artificial skin alcohol-based; and (iv) aPDT plus artificial skin-treated with aPDT associated with artificial skin alcohol-based. For the in vivo model, a full-thickness biopsy with 0.80 cm was performed in order to inoculate the microorganism Staphylococcus aureus (ATCC 25923). The aPDT was performed with a curcumin gel and a blue LED light (450 nm, 80 mW/cm2) at the dose of 60 J/cm2 and the treatment with alcohol-based artificial skin was done with the topical application of 250 μL. Additional animals were submitted to aPDT combined with the artificial skin. After treatments, the number of colony-forming units (CFU) and the damage area were determined. Data were analyzed by two-way repeated measures ANOVA and Tukey tests. The highest reduction of the bacterial viability was observed in the PDT plus artificial skin group (4.14 log10), followed by artificial skin (2.38 log10) and PDT (2.22 log10) groups. In addition, all treated groups showed higher relative area of wound contraction (36.21% for the PDT, 38.41% for artificial skin, and 35.02% for PDT plus artificial) in comparison with the control group. These findings provide evidence for the positive benefits of aPDT with blue light and curcumin associated with artificial skin to decontaminate and accelerate the wound contraction.