Light Diode Research Articles

Merged Red and NIR Light Sources for Photobiomodulation Therapy in Diabetic Wound Healing.

Photobiomodulation (PBM) is considered an effective and safe therapeutic modality in supporting the treatment of complications from a global pandemic-diabetes. In this study, PBM therapy is investigated to accelerate wound healing in diabetic mice (DM), under the combined biological effects of red light from a red organic light-emitting diode (ROLED) and near-infrared (NIR) light from an NIR conversion film (NCF) with dispersed CuInS2/ZnS quantum dots (QDs). The QD concentration and the NCF structure were optimized to maximize the optical properties and mechanical stability. A merged red/NIR device (MRND) was produced by integrating the optimized NCF and ROLED for PBM therapy. As a result of irradiating DM with MRND at a dose of 2 J/cm2, after 10 days, the wounds recovered three times faster than DM without MRND. Additionally, MRND light not only restored the epidermal thickness to normal but also significantly reduced the levels of pro-inflammatory cytokines. The experimental results show that the proposed PBM therapy has the potential to improve the quality of life of diabetic patients by helping them with rapid wound healing.

Design and Implementation of Elevator Push-Buttons with Integrated Ultraviolet-C Light-Emitting Diode Light Sources for Disinfection

Background: More effective and automated techniques for disinfecting elevator push-buttons currently need to be developed, especially given that they are frequently touched by hundreds of individuals. Methods: An automatic elevator push-button disinfection device equipped with four 265 nm ultraviolet-C (UVC) light-emitting diode (LED) packages has been developed for disinfection after each touch to reduce the risk of infection. In this paper, the UVC leakage test, UVC LED package reliability test, and bacteria disinfection efficiency test were performed. Results: The disinfection efficiency for Staphylococcus aureus and Escherichia coli can reach over 90% in 10 s, and end users can set multiple disinfection periods in light of their circumstances. The disinfection device is safe for the human body if the distance exceeds 120 mm. The accelerated aging test result demonstrates that the disinfection device is reliable under normal operation and end-users can increase the disinfection time by compensating for the irradiance drop. Conclusions: The automatic elevator push-button disinfection device provides a safe, highly efficient, and stable disinfection solution for elevator push-buttons.

Performance Analysis of Hydrogenated Cs2AgBiBr6 Perovskite Solar Cells under White LED Illumination

The emergence of lead-free double perovskites has sparked considerable concern due to their decreased toxicity and enhanced stability. Among these, Cs2AgBiBr6 perovskite has garnered attention as promising contenders for photovoltaic (PV) applications. Herein, we introduce the design and simulation of all-inorganic lead-free Cs2AgBiBr6-based perovskite solar cells (PSCs) under the influence of white light emitting diode (WLED) lighting conditions. The preliminary calibrated cell is centered on experimental findings wherein the Cs2AgBiBr6 layer is treated with hydrogenation. Through the application of such a technique, the bandgap of Cs2AgBiBr6 films can be engineered. We investigate three different bandgap values (2.18, 1.91, and 1.64eV) and assess the performance of the constituted PSCs under the effect of WLED illumination for various color temperatures. Key parameters significantly impacting cell performance are identified and comprehensively analyzed to boost the power conversion efficiency (PCE). Key technological parameters, including conduction band offsets, thickness and defects, are adjusted in order to optimize cell performance. For Eg = 1.64eV, which shows the maximum efficiency among the other cases, the efficiency increases from 15.61% for the initial designed cell to about 41% after optimization at a color temperature of 2900K and 200lx. All simulation endeavors are performed employing the device simulator, SCAPS, ensuring accurate and reliable predictions. The present study unveils the potential of Cs2AgBiBr6 double PSCs to be used in indoor applications.

Effects of curing lights on polymerization shrinkage of composite attachments in clear aligner treatment: A microcomputed tomography study

This study aimed to investigate the polymerization shrinkage of composite attachments and changes in attachment templates during bonding in clear aligner treatments. A total of 24 extracted teeth were divided into 4 groups, and plaster models were digitized. Attachment templates were produced with beveled attachments on premolars and rectangular attachments on molars. Polymerizations used a halogen curing light (800 milliwatts per square centimeter [mW/cm2] for 20 seconds) and light-emitting diode (LED) curing light in 3 modes (1000 mW/cm2 for 20 seconds, 1000 mW/cm2 for 10 seconds, and 3200 mW/cm2 for 3 seconds). The curing distance was 5 mm, and temperature changes were recorded with a thermal camera. Microcomputed tomography scanning measured volumetric and linear attachments before and after polymerization. Statistical analyses employed a 1-way analysis of variance with Bonferroni corrected Tukey post-hoc for multiple comparisons and the Kruskal-Wallis test for temperature change. Significant differences (P<0.001) were found in temperature among curing lights. The highest temperature was in the LED unit-extra mode, and the lowest was in the halogen curing unit. The LED unit for 20 seconds caused the highest temperature change. A significant difference (P= 0.048) in occlusal attachment length was found between the LED unit for 20 seconds and the LED unit-extra mode. Polymerization resulted in increased attachment template thickness across all groups, with significant changes noted in the halogen unit, LED unit for 20 seconds, and LED unit-extra mode. Temperature generated during polymerization varied between halogen and LED curing lights. Significant differences were found in attachment length at the occlusal level and template thickness postpolymerization. Preferences in attachment bonding protocols may affect the clinical precision of clear aligner treatments.

Comparison spectral analysis and photometric parameters for different indoor and outdoor LEDs lighting

Light emitting diode (LED) lighting have gained in popularity owing to the advantages offered by them over incandescent lamps with respect to energy efficiency, strong robustness, operation life, and steadiness with time, making them suitable for a wide range of applications like residential and commercial lighting. In this work, the luminous flux and thermal stabilization time, color parameters, and spectral mismatch factors and their uncertainties have been measured and estimated for some indoor and outdoor commercial LED lamps of three different brands with nominal powers of 3, 9, and 36 watts. These lamps were classified into indoor-1, indoor-2, indoor-3, and outdoor LED lamps in order to enable the present analysis. The measurement methodology included a sophisticated luminous flux system using a 2.5-meter integrating sphere at the National Institute of Standards, NIS, equipped with the NIS photometer LMT U1000 and a series of NIS luminous flux secondary standard lamps calibrated at the National Physical Laboratory, NPL, in England. This is important for making proper, accurate measurements of the total luminous flux emitted by different LED lamps. In addition, an NIS Spectroradiometer (Ocean Optics HR 2000) and a photometric bench were used in order to measure the spectral power distribution of the lamps, by means of which we had the possibility to calculate the spectral mismatch correction factor quantify the color parameters and estimate the associated measurement uncertainties. The comprehensive approach in our study involves assessing luminous flux, thermal stabilization time, spectral mismatch correction factors, and chromaticity color coordinates, all in comparison to established standards provided by NIS Secondary Standard Lamps. This paper demonstrates that the obtained spectral mismatch correction factors and chromaticity color coordinates with their uncertainties can be used as basic corrections to luminous flux and color measurements. By doing this, the accuracy and dependability of these kinds of measurements are significantly improved, increasing the knowledge about the performance of LED lamps.

Nitrate accumulation and mineral nutrition of lettuce under varied light emitting diode lighting

This study aims to investigate strategies to minimize nitrate accumulation in lettuce to mitigate its potential harmful effects on human health. Lettuce cultivation under light-emitting diode lighting (LED) is becoming increasingly popular, and determining the effects of different LED sources on lettuce nutrition and nitrate accumulation is an important topic. The effects of different nitrate levels in the nutrient solution and different LED sources on lettuce nutrition and nitrate accumulation have been investigated under controlled conditions. Lettuce plants were grown for 48 days under White (W), Blue (B), Blue + Far Red (B + FR), Red (R), Red + Blue (R + B), Red + Far Red (R + FR), Red + Blue + Far Red (R + B + FR) LED lights using nutrient solutions containing 20, 24, and 28 mM nitrate. The highest marketable yield was obtained under B lighting, followed by R, R + B, R + FR, and R + B + FR. To reduce nitrate accumulation, lighting setups using W, R + B + FR, R + B, and R have proven to be advantageous. In these treatments, nitrate levels were determined to be 1039, 1118, 1167, and 1170 mg kg−1, which were lower compared to the other treatments. The concentrations of measured nutrients in plants were highest under B + FR, R + FR, and R + B lighting. The total chlorophyll concentration increased with the N dose, with the highest levels observed in the B, B + RF, and R + B + FR treatments. In conclusion, LED lighting influences lettuce nutrition and nitrate accumulation, with W, R + B + FR, R + B, and R treatments most effective in reducing nitrate levels. These findings should be validated in commercial greenhouse conditions to assess their practical applicability for large-scale production.

Linked Color Imaging with Light-Emitting Diode Light Enhances the Visibility of Gastric Neoplasm: A Prospective, Multicenter, Comparative Trial.

Early detection of gastric cancer can play a key role in improving prognosis. Recently, light-emitting diodes (LED) have been developed as novel endoscopic systems. However, the differences in the visibility of gastric neoplastic lesions between LED and laser endoscopy remains unclear. We conducted a prospective multicenter trial to evaluate the non-inferiority of LED endoscopy in the visibility of gastric neoplastic lesions undergoing endoscopic submucosal dissection (ESD) in comparison to laser endoscopy. A multicenter, prospective, cross-sectional study was conducted in patients undergoing ESD for gastric neoplastic lesions at five hospitals throughout Japan. Seventy patients with 74 lesions were included in this study. The primary endpoint was the non-inferiority of the difference in the individual scores of linked color imaging (LCI) and white-light imaging (WLI) for LED and laser endoscopy for gastric neoplastic lesions. The mean individual score was 2.66 ± 1.02, 3.17 ± 0.83, 2.75 ± 1.05, and 3.21 ± 0.84 in LED-WLI, LED-LCI, laser-WLI, and laser-LCI, respectively. The difference in individual scores of LCI and WLI was 0.51 ± 0.77 and 0.46 ± 0.80 in LED and laser endoscopy, respectively. The mean difference between LED and laser endoscopy was 0.04 (95% confidence interval [CI]: - 0.05 to 0.13, P < 0.001). This study revealed the non-inferiority of the differences in individual scores between LCI and WLI in the comparison of LED and laser endoscopy for gastric neoplastic lesions.

Impact of Light-Emitting Diode (LED) Lighting and Microbial Inoculum on Rice Seedling Phenotype, Physiology, and Microbial Communities

Raising rice (Oryza sativa L.) seedlings under LED lighting reduces nursing space and labor while ensuring health and quality. This study compared rice seedlings grown under natural light (NL) and LED lighting (AL), with and without inoculation of the beneficial fungus Falciphora oryzae. The results showed that NL-grown seedlings had greater stem diameters and shoot and root weights. The AL treatment induced higher plant height in some cultivars and longer root lengths in others. Microbial inoculation minimally affected phenotypes but increased root length in one cultivar. Chlorophyll content was unchanged across the treatments, while malondialdehyde (MDA) levels rose under AL in one cultivar, and catalase (CAT) levels were elevated in two cultivars under AL. Microbial inoculation reduced CAT levels under AL. The AL + M treatment increased rhizosphere prokaryotic community evenness and altered prokaryotic compositions in the rhizosphere and root endosphere, with Burkholderia and Paraburkholderia taxa showing differential responses to the treatments. These findings underscore the role of microbial inoculation in enhancing rice seedling health and resilience under artificial lighting, contributing to sustainable agriculture and food security.

Compression‐Assisted Improvement of Electrochemical Performances of Carbon Nanotube in Symmetric Supercapacitors

The unique geometry of carbon nanotubes (CNTs) contributes to their excellent rate capability when used as electrode materials for supercapacitors (SCs). However, the practical application of low‐cost commercial CNTs is limited by their moderate specific capacitance due to the relatively low surface area which is around 220 m2 g−1. This limitation can be addressed by applying proper compressive stress to the CNTs, resulting in improved capacitance. The effects of compression on capacitance vary depending on the length and inner diameter of the CNTs, which have been systematically investigated. It has been found that longer and narrower CNTs exhibit more significant improvements in capacitance due to compression. Specifically, under 12 MPa, there is an ≈135% increase in specific capacitance compared to that under 1 MPa, with the optimum value of 68.2 F g−1 at 1 A g−1. An excellent rate capability of 93.5% at 40 A g−1 is also obtained by compression. Furthermore, when an light emitting diode light is powered by a compressed CNT‐based SC, both brightness and lasting time are dramatically enhanced compared to the case without compression. This cost‐efficient strategy for improving the energy storage performance of CNTs may facilitate their practical application as electrode materials for ultrafast supercapacitors.

Photodegradation of Dacarbazine Catalyzed by Vitamin B2 and Flavin Adenine Dinucleotide Under Visible-Light Irradiation

PurposeDrug photodegradation is a matter of great concern because it can result in potency loss and adverse side effects. This study examines the light-induced degradation of dacarbazine catalyzed by vitamin B2 and flavin adenine dinucleotide (FAD) under light-emitting diode (LED) or fluorescent light irradiation.MethodsDacarbazine was irradiated with LED (405 nm) or fluorescent light in the presence of various equivalents of vitamin B2 or FAD. The photodegradation of the drug in D2O was monitored by 1H nuclear magnetic resonance spectroscopy.ResultsDacarbazine dissolved in D2O decomposed in the presence of vitamin B2 or FAD under irradiation with LED or fluorescent light. The decomposition products were 2-azahypoxanthine 2, which has previously been observed after light irradiation in the absence of vitamin B2, and 1H-imidazole-5-carboxamide 6, a new product formed in the presence of vitamin B2. Irradiation with LED light was more effective than irradiation with fluorescent light in degrading dacarbazine.ConclusionVitamin B2 and FAD induced dacarbazine photodegradation. Thus, the interfusion of vitamin B2 or FAD under excessive light exposure should be avoided during the intravenous administration of dacarbazine.Graphical

Reducing Total Plate Count of Bacteria through Dark Sealed Storage for Plant Factory Nutrient Solution Sterilization

Plant factories are efficient systems for vegetable production under a clean and controlled environment. To improve the sterilization efficiency of nutrient solutions (NS) in plant factories, this study examined the changes in the number and composition of colonies from in-use and post-use stored NS. The sterilization effect under ultraviolet (UV) light-emitting diode light was also investigated. The results indicated that the total plate count of bacteria (TPC) of newly prepared NS was 3.99 lg CFU/mL (9870 CFU/mL); within 7 days of cultivation, this number sharply increased ∼7.8 times to 4.88 lg CFU/mL (76,000 CFU/mL), then remained stable. After dark sealed storage (DSS) of post-use NS, TPC dramatically decreased by 82.8% and reached its lowest point at 4.29 lg CFU/mL (19,566 CFU/mL) on day 3, equivalent to a log survival ratio of −0.76, then rapidly rebounded by 235.6% to 4.82 lg CFU/mL (65,666 CFU/mL) on day 4. During storage, bacterial community composition was also remarkably changed, and the relative abundance of heterotrophic bacteria such as Variovorax paradoxus and Pararhizobium giardinii and photosynthetic bacteria such as Pseudo-Nitzschia multiseries were greatly decreased. The log survival ratio for in-use and post-use stored NS under UV sterilization were −1.29 and −1.30, respectively, and was not significantly different. Coupled with the dramatic decrease in TPC during DSS, the overall log survival ratio of post-use NS UV sterilization was −2.06 and was the most effectively form of sterilization in our study. In short, TPC of in-use NS remained high for a long period, and DSS may serve as a low-cost NS sterilization method in plant factories.

Development of an Integrating Sphere-Based Wide-Range Light Source System for the Linearity Evaluation of a Photodetector Used in Radiation Detection and Bioanalysis Instruments.

We developed a compact wide-range light source system for evaluating the linearity of photomultiplier tube (PMT) output. This system utilizes two integrating spheres equipped with a continuously variable slit and output aperture to modulate a stabilized light-emitting diode light source, producing an output light range as wide as seven orders of magnitude. To verify the wide linearity range of the integrating sphere system, three silicon photodiodes coupled with electric current readers monitored the light intensity and simultaneously confirmed each other's linearity. Using this system, we evaluated the linearity of the PMT used in a neutron detector we are currently developing and found it to have a linear range of more than four orders of magnitude. Non-linearity characteristics were also successfully measured in detail at a higher output range. Neutron detector operation requires both calibration of the detection efficiency and evaluation of the linearity between the neutron dose and its output. These results indicate that this system is a simple and useful method to evaluate the linearity of photodetectors used in radiation detectors and other applications.

Optimizing Red Light-Based Photodynamic Therapy for Effective Bactericidal Action Against Fusobacterium nucleatum Subspecies.

Fusobacterium nucleatum (F. nucleatum), a key pathogen implicated in periodontal disease, contributes to oral biofilm maturation and is linked to development of systemic diseases like colorectal cancer and liver cirrhosis. Photodynamic therapy (PDT) combined with 5-aminolevulinic acid (5-ALA) treatment (ALA-PDT) selectively targets F. nucleatum by inducing porphyrin accumulation. The bactericidal effect of red light-based PDT on F. nucleatum has not been evaluated previously. This study investigates the effect of ALA-PDT using red light-emitting diode (LED) light on F. nucleatum subspecies and their porphyrin accumulation. F. nucleatum subspecies were cultured with varying concentrations of 5-ALA under anaerobic conditions. Porphyrin accumulation was measured via fluorescence spectroscopy, and colony-forming units were measured to determine bacterial viability post-treatment. Additionally, other subspecies responded well to 0.01% 5-ALA, and uroporphyrin I accumulation correlated with bacterial death, revealing optimal bactericidal conditions. These results suggest that optimizing light intensity and 5-ALA concentration can significantly enhance the therapeutic potential of ALA-PDT in oral healthcare.

Light Intensity Effects on Productivity and Post-Harvest Quality in Perilla frutescens Cultivated in CEA

Leafy vegetables, mainly lettuces, are currently the main crop cultivated in controlled environment agriculture (CEA), including vertical farming and plant factories. There is a rising demand to expand this portfolio with a wider variety of underutilized edible plants containing various bioactive compounds and sensory properties seeking to enrich human diets. However, the optimal cultivation conditions for these underutilized plants significantly differ from those optimized for lettuce, basil, and other popular CEA crops. Therefore, this study aims to explore the impacts of light-emitting diode (LED) lighting intensity (photosynthetic photon flux density, PPFD) on green leaf Perilla frutescens cultivated in CEA. Plants were grown under four levels of LED lighting PPFDs from 150 to 300 µmol m−2s−1 for 4 weeks. Plant biomass productivity, soluble sugar contents, antioxidant properties (DPPH, ABTS free radical scavenging activities, FRAP antioxidant power), and total contents of phenolic compounds in leaves were evaluated at harvesting time. Further, harvested plant material was stored in the dark, at +6 °C, and the water content, water loss and transpiration rate, leaf sugar contents, and antioxidant properties were monitored 1, 3, and 5 days after harvesting. The summarized data suggest that higher cultivation lighting PPFD results in better harvest quality preservation during post-harvest storage.

Enhancing energy efficiency in Bangladesh’s readymade garment sector: the untapped potential of LED lighting retrofits

Purpose Previous studies emphasized the substantial energy-saving potential of light emitting diode (LED) lighting systems, especially in the clothing industry. However, the specific quantification of energy conservation potential in industrial factories, particularly in Bangladesh’s readymade garment (RMG) sector, remains unexplored. The purpose of this study is to investigate the potential energy savings and efficiency improvements of lighting systems in Bangladesh’s RMG sector using LED technology. Design/methodology/approach Understanding and optimizing energy consumption is crucial in the RMG sector because this sector contributes significantly to the country’s export earnings. For this, an RMG factory was surveyed and possible lighting system retrofitting was estimated and compared. Findings The adoption of energy-efficient lighting options, particularly LED, could decrease the current lighting energy usage from 15% to 7.5% in Bangladesh. First, this study reveals, that the reduction of annual energy consumption was determined to be 18,220 kWh due to the retrofitting of the lighting system with LED tube. Second, it conducts real-time measurements to assess the suitability of in-building lighting systems, providing insights into the current scenario. Lastly, it evaluates the economic and environmental benefits of the proposed lighting system in the RMG industries. Due to the retrofitting of the lighting system, the reduction of equivalent CO2 gas emissions was found to be 119.896 tCO2. Originality/value For the first time, this study explored the potential for enhancing energy-efficient lighting system design through retrofitting in the RMG industry, with a focus on Bangladesh. By addressing these aspects, this study aims to contribute to the advancement of energy efficiency and conservation efforts in the RMG sector, ultimately fostering sustainable industrial development in Bangladesh and beyond.

Performance of Triple-Cation Perovskite Solar Cells under Different Indoor Operating Conditions.

We systematically analyze triple-cation perovskite solar cells for indoor applications. A large number of devices with different bandgaps from 1.6 to 1.77 eV were fabricated, and their performance under 1-sun AM1.5 and indoor white light emitting diode (LED) light was compared. We find that the trends agree well with the detailed balance limit; however, the devices near the optimal bandgap (1.77 eV) perform worse due to the lower perovskite quality. Instead, we achieve the highest power conversion efficiency (PCE) of 34.0% under 870 lx with 1.67 eV and Al2O3 passivation. The perovskite with a bandgap of 1.71 eV is not far behind, with a high VOC of 1.02 V. Measurements under different white LED color temperatures confirm that the highest PCE is achieved under the warmest colors. All measurements were carried out in a dedicated indoor setup that ensures the diffuse light typical of indoor environments and allows both short- and long-term measurements. In the best case, we observe no degradation during the 33-day test under simulated office conditions with regular switching on and off of the light and a T80 of 30 days under continuous illumination. The results were obtained from multiple batches, which corroborates our findings and gives them statistical relevance.

Biocompatibility and performance of new generation dental composites

Dental composites have undergone significant advancements in recent years, with new-generation materials being developed to improve both biocompatibility and mechanical performance. These innovations have led to the increased use of dental composites in restorative dentistry, particularly in both anterior and posterior restorations. Biocompatibility remains a key concern, as the release of unreacted monomers, such as bisphenol A glycidyl methacrylate (Bis-GMA), can cause local tissue irritation or systemic effects. Modern composites aim to reduce these risks by incorporating alternative resin systems and advanced photo initiators. Nanotechnology has further enhanced the performance of these materials by improving mechanical strength and wear resistance, but questions about the safety of nanoparticles and their long-term biological effects continue to be explored. In addition to biocompatibility, the mechanical properties of new-generation composites have been significantly optimized. The introduction of bulk-fill composites allows for deeper polymerization and faster placement, reducing clinical procedure times while maintaining high mechanical integrity. Polymerization shrinkage, a common issue in traditional composites, has been minimized in newer formulations, reducing the risk of marginal gaps and microleakage. The effectiveness of different light-curing units, such as light-emitting diode (LED) versus halogen lights, plays a crucial role in achieving optimal polymerization depth, especially in posterior restorations where light penetration can be limited. Long-term clinical outcomes depend on several factors, including material choice, placement technique, and patient adherence to oral hygiene. Despite the improvements in composite materials, the longevity of restorations still faces challenges such as wear, fracture, and degradation over time. Continued research into the safety, effectiveness, and clinical performance of new-generation composites is essential to ensuring patient safety and enhancing the durability of restorations in the future. These advancements promise to address many of the limitations seen in earlier dental materials while offering superior performance and patient satisfaction.

Bacterial volatile organic compounds supplemented with light‐emitting diode lighting enhance antioxidant capacity and delay senescence in broccoli

Bacterial volatile organic compounds supplemented with light‐emitting diode lighting enhance antioxidant capacity and delay senescence in broccoli

Effects of different LED light spectra and nutrient solution strength on the growth, photosynthetic parameters, and nutrients uptake in tomato seedlings

Light-emitting diode (LED) lighting is currently the most energy-efficient lighting technology, and its use in agriculture is rapidly increasing. This research aimed to investigate the interaction effect of nutrient solution concentration and light quality on tomato seedlings growth. The tested factors included two nutrient solution concentrations (50% and 33% Hoagland solution) and four ratios of blue (440 nm) to red (660 nm) light in LED lighting at a constant light intensity (B2R1, B1R1, B1R2, and B1R3). Height growth was greatest in the 33% nutrient solution × B1R2 light treatment and smallest in the 33% nutrient solution × B2R1 light treatment. Regardless of the nutrient solution concentration, total chlorophyll and carotenoid concentrations decreased with an increase in the proportion of blue light. Plant absorption of sulfur was highest in the 50% nutrient solution × B1R2 light treatment, significantly higher than all other treatments. Although the 50% nutrient solution × B1R2 light treatment also showed the greatest magnesium absorption, it did not differ significantly from most of the other treatments. In general, for growing tomato seedlings, a high ratio of blue light regime (B2R1) with a dilute nutrient solution, enriched with magnesium and sulfur, can be recommended to prevent elongation disorder and have no negative impact on various growth and physiological indicators.

Protein and lysine improvement harnessed by a signal chain of red light-emitting diode light in Chlorella pyrenoidosa

Microalgae are emerging as a novel single-cell protein source that can substitute traditional plant protein feeds. In this investigation, lysine and protein accumulation in Chlorella pyrenoidosa were significantly enhanced under red light-emitting diode light, addressing challenge of limiting amino acid in plant proteins. The study employed targeted metabolomics, HPLC, and qRT-PCR to validate the light-induced pathway triggering lysine biosynthesis. Specifically, the pathway involves Ca2+-CaM as an intermediary in signal transduction, which directly inhibits PEPC activity. This inhibition directs a significant carbon flux towards central carbon metabolism, resulting in increased pyruvate levels—a critical precursor for lysine biosynthesis via the diaminopimelate pathway. Ultimately, the content of protein and lysine under red light increased by 36.02 % and 99.56 %, respectively, compared to those under white light. These findings provide a novel orientation for the precise regulation of lysine accumulation in microalgae, and moreover lay a solid theoretical foundation for producing microalgal proteins.