LED Irradiation Research Articles

Efficient Tunable White Emission and Blue Light‐Excited Near‐Infrared Emission in Lead‐Free Metal Halide Crystals with Ultra‐High Luminous Efficiency for Multispectral Image Fusion and 3D Image Reconstruction

Abstract0D hybrid Sb(III) halides generally exhibit unique crystal structure and efficient emission. However, achieving efficient white light and blue light‐excited near‐infrared (NIR) emission remains an enormous challenge. Herein, a series of 0D hybrid Sb(III) halides of (18‐crown‐6@K)2SbX5 (X = Cl, Br) crystals with different Cl/Br rations are synthesized via supramolecular self‐assembly. All compounds show the broadband emission, which stems from the self‐trapped excitons in [SbX5]2− pseudo‐octahedral structure. Particularly, (18‐crown‐6@K)2SbCl5 crystal shows tunable emission under various excitation wavelengths, and the efficient white emission with an ultra‐high luminous efficiency of 92.3% is obtained under 310 nm excitation. As Br gradually replaces Cl, not only the excitation and emission bands show a red‐shift but also facilitate the intersystem crossing process from singlet to triplet excitons. Thus, an independent broadband NIR emission upon 450 nm excitation with an ultra‐high luminous efficiency of 58.2% is obtained in (18‐crown‐6@K)2SbBr5 crystals. Moreover, the high‐performance single‐component white light‐emitting diode (WLED) based on (18‐crown‐6@K)2SbCl5 and NIR LED based on (18‐crown‐6@K)2SbBr5 are fabricated, and white light and NIR image fusion is realized. Finally, combined with multiangle imaging under WLED and NIR LED irradiation, the 3D image reconstruction of a centrifuge tube wrapped in a capsule is successfully demonstrated.

Letter to the Editor: Efficacy and Safety of High Density LED Irradiation Therapy for Patients With Hand Osteoarthritis: A Single-Center Clinical Study.

Letter to the Editor: Efficacy and Safety of High Density LED Irradiation Therapy for Patients With Hand Osteoarthritis: A Single-Center Clinical Study.

Synergistic Enhancement of Ligand & Cluster Connectivity to Construct Highly Stable Fluorescein-Based MOFs with Thickened Channel Walls for Boosting Photocatalytic Activity.

Fabricating visible-light-responsive metal-organic frameworks (MOFs) with high stability and effective catalytic functionality remains a long-term pursuit yet a great challenge. Herein, a strategy of increasing ligand and cluster connectivity is developed to construct highly stable fluorescein MOFs, La-CFL, presenting a new (4,8)-connected topological structure compared to Cd-FL constructed using 6-connected dinuclear clusters and 3-connected tritopic ligands. La8(CFL)4 containers like Chinese "Ritual Wine Vessels (Jue)" resemble linear arrangements interconnected by the [La2(COO)4] clusters. This arrangement induces benzene rings and xanthene rings to locate on the inner walls of 1D channels, resulting in thicker channel walls that contribute to enhanced stability. Consequently, La-CFL demonstrates outstanding catalytic performance in thiol-ene reactions under green LED irradiation. It exhibits 2.3 times higher efficiency than Cd-FL while reducing reaction time to one-fifth at 20 min. Furthermore, La-CFL displays size-selective catalysis and retains full activity for 20 cycles without degradation, an improvement over Cd-FL's recyclability limitations.

Constructing Interfacial B-P Bonding Bridge to Promote S-Scheme Charge Migration within Heteroatom-Doped Carbon Nitride Homojunction for Efficient H2O2 Photosynthesis.

The emerging step (S)-scheme heterojunction systems became a powerful strategy in promoting photogenerated charge separation while maintaining their high redox potentials. However, the weak interfacial interaction limits the charge migration rate in S-scheme heterojunctions. Herein, we construct a unique S-scheme carbon nitride (CN) homojunction with boron (B)-doped CN and phosphorus (P)-doped CN (B-CN/P-CN) for hydrogen peroxide (H2O2) photosynthesis. The B-CN/P-CN nanosheet composites revealed extensively tight interfacial contact, improved visible-light harvesting, and reduced carrier lifetime. The structural investigation results also indicate that the interfacial chemical B-P bonding is formed between B-CN and P-CN nanosheets, inducing an accelerated interfacial S-scheme charge migration. Density functional theory calculations further clarify the S-scheme charge transfer mechanism. Consequently, the 2e- oxygen reduction reaction was the predominant pathway of H2O2 production, facilitated by the B-CN/P-CN homojunction. The optimal H2O2 yield rate reached 2199.5 μmol L-1 h-1 over the B-CN/P-CN homojunction (S3) photocatalyst under monochromatic LED irradiation, increasing 2-8 times as against most of the C3N4 photocatalysts. This study highlights the crucial role of interfacial charge transfer between heterojunction/homojunction materials, accompanied by an unveiling reaction mechanism for solar-energy conversions.

Furan-Indole-Chromenone-Based Organic Photocatalyst for α-Arylation of Enol Acetate and Free Radical Polymerization Under LED Irradiation.

In this study we report on the efficiency of a furane-indole-chromenone-based organic derivative (FIC) as a photocatalyst in the α-arylation of enol acetate upon LED irradiation at 405 nm, and as a photoinitiator/photocatalyst in the free radical polymerization of an acrylate group in the presence of bis-(4-tert-butylphenyl)iodonium hexafluorophosphate (Iod) as an additive, or in the presence of both Iod and ethyl-4-(dimethyl amino) benzoate (EDB) under LED irradiation at 365 nm. The photochemical properties of this new light-sensitive compound are described, and the wide redox window (3.27 eV) and the high excited-state potentials FIC*/FIC●- (+2.64 V vs. SCE) and FIC●+/FIC* (-2.41 V vs. SCE) offered by this photocatalyst are revealed. The chemical mechanisms that govern the radical chemistry are discussed by means of different techniques, including fluorescence-quenching experiments, UV-visible absorption and fluorescence spectroscopy, and cyclic voltammetry analysis.

Performance of Ti/TiO2-ZIF-67 photoanode under LED irradiation applied to the photoelectrodegradation of the antidepressant venlafaxine (VEN) in municipal wastewater effluent

This work describes the direct deposition of ZIF-67 metal-organic framework (MOF) onto Ti/TiO2 nanotubes forming a photoanode for the degradation of the antidepressant Venlafaxine (VEN). This material combines the excellent characteristics of ZIF-67 MOF in enhancing photocatalytic reduction and oxidation reactions induced by UV LED irradiation, as well as the storage of VEN molecules in its pores. Ti/TiO2-ZIF-67 features an eco-friendly technology for degradation of pharmaceutical micropollutants such as antidepressants. The photoanode was prepared, characterized and applied in the degradation of VEN by photocatalysis (PC), electrocatalysis (EC), photolysis (PL) and PEC processes. PEC process presented the best performance when compared to the others processes in both simulated solutions and real wastewater, achieving 100% and 89% degradation of VEN after 60 and 90 min, with TOC removal rates of 50% and 4%, respectively. The lower mineralization rate suggests that the degradation of VEN in complex matrices such as that of real wastewater produced recalcitrant by-products that are difficult to convert into CO2 and H2O. Zeta potential measurement showed that at pH 6 and 8 there is an effect of attraction of opposite electrostatic charges between the surface of ZIF-67 (positive) and VEN (negative), favoring the degradation of VEN in this pH range. The good performance of the Ti/TiO2-ZIF-67 can be attributed to the formation of the Z-scheme heterojunction between the TiO2 nanotubes and the ZIF-67 MOF which contributed to a lower rate of electron-hole (e-/h+) pairs recombination, favoring VEN degradation mainly to higher generation of •OH radical and less contribution of O2•- superoxide produced by UV irradiation forming some degradation by-products through demethylation and oxidation reactions.

Fabrication and synergistic effect of nitrogen defective crystalline carbon nitride for enhanced photocatalytic selective oxidation of benzyl alcohol under blue LED irradiation

Exploring efficient visible-light-catalytic system for benzyl alcohol selective oxidation is highly desirable in sustainable and green chemistry. Herein, nitrogen-defective crystalline polymeric carbon nitride (g-C3N4) was successfully synthesized by a molten...

Preliminary insights into Red LED Irradiation for thawing cryopreserved boar semen

Preliminary insights into Red LED Irradiation for thawing cryopreserved boar semen

Monitoring Radical Intermediates in Photoactivated Palladium-Catalyzed Coupling of Aryl Halides to Arenes by an Aryl Radical Assay.

An aryl radical assay is used to provide information about the formation of aryl radicals from aryl halides in coupling reactions to arenes in the presence of palladium sources and under LED irradiation (λ = 456 nm). The assay uses 2-halo-m-xylenes as substrates. Aryl radical formation is indicated both by a defined product composition and by signature deuterium isotope effects. Comparison with our recently published results for corresponding ground-state palladium-catalyzed reactions shows three principal differences: (i) in the photoactivated reactions, evidence supports the formation of aryl radical intermediates with all the phosphine ligands tested, in contrast to thermal ground-state chemistry where only specific ligands had encouraged this pathway, while others had promoted a nonradical coupling mechanism; (ii) oxidative addition complexes that are formed from the reaction of Pd(0) sources with aryl halides react under photoactivation to form biaryl coupled products through radical intermediates, in contrast to their behavior under thermal activation - so Ar-Pd bonds are homolyzed under LED irradiation; (iii) the photoreactions work well with mild bases like Cs2CO3, while the thermal reactions required KOtBu as the base due to the different roles for base under the thermal versus photochemical mechanisms.

Kinetics of multifunctional (meth)acrylates photopolymerization in the presence of aromatic imidazole

The photolysis of phenanthroline-containing imidazole in DMSO solution and the initiating ability of the compound in photopolymerization of multifunctional (meth)acrylates under LED irradiation (λ = 395 nm) under aerobic conditions were investigated for the first time. The relationship of kinetic parameters of photopolymerization with light intensity, chemical structure, and viscosity of multifunctional monomers was established.

Effect of 850nm LED irradiation on the alignment of crowded mandibular anterior teeth: a randomized controlled clinical trial.

This study aims to determine if intraoral 850nm LED irradiation could reduce the duration of lower anterior crowding alignment. In a parallel-designed, randomized controlled clinical trial 60 patients with 2 to 6mm of lower incisor crowding who need non-extraction treatment, were randomly assigned to the intervention and control groups by block randomization (36 females, 24 males, mean age: 19.93 ± 3.05). MBT brackets (0.022 × 0.28-inch) were bonded for both groups and the NiTi wires in sequences were put in place until correction of crowding. The intra-oral LED device with a wavelength of 850nm and power density of 70 mW/cm2 was used for 5min per day in the intervention group. The control group did not receive any light. The primary outcome was the duration of crowding correction. The patient's pain according the modified McGill pain questionnaire was the secondary outcome. The Cox regression model was used to compare groups. Mann-Whitney test was used for pain analysis. The crowding at baseline was the same between the two groups (P > 0.05). Duration of treatment in the intervention group was 104.7days (95% CI: 95.6 -113.8) and significantly shorter than 161.9days (95% CI: 151.5 -171.2) in the control group. The control group experienced a significantly higher pain score of 6.8 (95% CI: 6.1-7.5) immediately after archwire placement than the intervention group 5.4 (95% CI: 4.6-6.3). Intra-oral LED 850nm significantly decreased the relieving time of lower incisor crowding by up to 36% and reduced pain experience.

Photocatalytic Degradation of PCB 153 Using Fe3O4@SiO2@TiO2‐Co Core‐Shell Nanocomposite

AbstractThis study investigates the photocatalytic degradation of PCB 153 using Fe3O4@SiO2@TiO2‐Co core‐shell nanocomposites under LED irradiation. The unique core‐shell structure, incorporating a magnetic Fe3O4 core, a protective SiO2 layer, and a photoactive TiO2 shell doped with Co, enhances light absorption, charge separation, and stability. The effects of various parameters, including catalyst dosage, initial pollutant concentration, solution pH, H2O2 concentration, reaction time, and cosolvent type, were investigated to optimize the degradation process. The results demonstrated the high efficiency of the Fe3O4@SiO2@TiO2‐Co nanocomposite in degrading PCB 153, with a maximum degradation efficiency of 95.2% under optimal conditions. The magnetic properties of the Fe3O4 core enable easy separation and recovery of the catalyst, making it a sustainable and cost‐effective solution. This study provides valuable insights into the design and application of advanced photocatalysts for environmental remediation.

Fabrication of a novel Z-scheme 2D/1D g-C3N4/polyaniline decorated on activated carbon with effective visible-light photocatalytic activity.

In recent years, visible-light driven photocatalysts present a significant role in different photocatalytic performances. Herein, a novel Z-scheme graphitic carbon nitride nanosheet/polyaniline nanowire (2D/1D CN/PAni) nanocomposite decorated on activated carbon (AC) support was synthesized by solution mixing combined with a calcination process for removal of CR dye under LED irradiation. The chemical, nanostructure, surface and optical properties of as-prepared nanocomposites were analyzed by different spectroscopic and microscopic techniques. The AC support had a fundamental role in modification of the surface area, preventing the CN/PAni accumulation and improving the separation of CN/PAni from the solution. The results of DRS and PL analyses displayed that the combining of CN nanosheet with PAni nanowire has an efficient role in the optical properties compared to pure CN. The effect of photo-reaction parameters such as CN/PAni loading on AC and CN/PAni/AC dosage on CR removal was examined. The CN/PAni/AC/light system presented effective degradation ability on CR, and the removal efficiency reached 91% after 100min. The modified photocatalytic activity could be described by transferring photo-generated charges between 2D CN and 1D PAni via the Z-scheme mechanism. Furthermore, the CN/PAni decorated on AC support illustrated good recycling ability.

Novel p-ZnCo2O4/n-Bi2WO6 heterojunctions for efficient rhodamine B and tetracycline photodegradation, and Cr(VI) photoreduction under visible LED and sunlight irradiation

Novel p-ZnCo2O4/n-Bi2WO6 heterojunctions for efficient rhodamine B and tetracycline photodegradation, and Cr(VI) photoreduction under visible LED and sunlight irradiation

Blue-LED assisted Photodegradation kinetics of rhodamine-6G dye, enhanced anticancer activity and cleavage of plasmids using Au-ZnO nanocomposite.

The plasmonic metal doping on the UV-active metal oxide nanoparticle turns the resultant plasmonic metal-metal oxide (PMMO) into visible light active and upon exogenous illumination the photogenerated energetic charge carriers and the in situ generated reactive oxygen species (ROS, e.g. ·OH and O2 -·) authoritatively enhances its biological and catalytic activity. Herein, a hexagonal rod-shaped ZnO nanoparticles (NP) precursor was prepared using the sol-gel method, which in the presence of varying concentrations of gold (0.005M, 0.01M, and 0.015M) via a greener citrate reduction method afforded a nanocrystalline Au-ZnO nanocomposite. Using which, the visible-light driven photo-degradation kinetics investigation of rhodamine-6G (R6G) dye under blue LED irradiation were carried out. The use of 20mg 0.015-Au-ZnO completes the degradation of R6G (97.0%, k=6.5 X 10-3s-1at pH 7) within 55min while 50mg of 0.015-Au-ZnO catalyst improves the rate of R6G degradation (15min 97.8%, k=14.8×10-3 s-1) and it is reusable up to three cycles. The LC-MS spectra of the remains of R6G (after 15min) identified various low molecular ions (up m/z=65). Further, the blue-LED assisted anti-cancer studies (MTT assay) using 0.015-Au-ZnO towards human lung cancer cells (A549), breast cancer cells (SKBr3) show high anti-proliferation rate and low cytotoxicity against healthy human embryonic kidney cells (HEK-293) with an IC50 value of 65, 53 and 124μg/mL respectively. Also, the AO-EB dual staining and DCFH-DA analysis of SKBr3 and A549cells revealed ROS-mediated cell death via apoptosis. Moreover, plasmid cleavage studies against supercoiled pBR322 DNA result in single-stranded linear DNA without traversing the nicked circular form, suggesting the possible DNA targeting activity of Au-ZnO nanozyme. Thus, the synthesized Au-ZnO nanocomposite shows excellent photocatalytic and biological activity.

The Effect of Fine Bubbles Application and LED Irradiation on Damage and Chlorophyll Content of Cut Romaine Lettuce

The current change in society’s lifestyle reflects a tendency towards a more practical life, including food consumption. Romaine lettuce is one of the minimally processed vegetables sold in ready-to-eat packaging and is a common component in salads. However, minimal processing makes romaine lettuce more susceptible to deterioration and a decrease in chlorophyll content. Efforts was made to reduce damage and decrease chlorophyll content in romaine lettuce through fine bubbles application and blue and white LED irradiation. In this study, cut romaine lettuce was washed using fine bubbles and irradiated with blue and white LEDs with various exposure times. The results showed that fine bubbles increased dissolved oxygen and their application in washing cut romaine lettuce reduced surface damage by 20.55%. Chlorophyll content was tested by extracting the lettuce in ethanol solvent and measuring its absorbance using a UV-Vis spectrophotometer. The chlorophyll content test results showed that, after irradiation and six days of storage, the romaine lettuce did not show an increase in chlorophyll content. This indicates that while fine bubble washing can reduce surface damage, blue and white LED irradiation has not been able to maintain or increase chlorophyll content, as the chlorophyll degraded during the storage period.

In situ growth of bismuth oxybromide/bismuth molybdate 2D/2D Z-scheme heterojunctions with rich interfacial oxygen vacancies for photocatalytic benzylic C(sp3)-H bond activation

The selective oxidation of toluene into valuable chemicals via photocatalytic C(sp3)-H bond activation represents a significant, yet challenging process. Here, the in situ construction of bismuth oxybromide/bismuth molybdate (BiOBr/Bi2MoO6) 2D/2D Z-scheme heterojunctions featuring interface-induced oxygen vacancies (OVs) is introduced. The optimized BiOBr/Bi2MoO6 sample has a remarkable yield rate of benzaldehyde at 2134.28 μmol g−1 h−1 under blue LED irradiation, surpassing the performance of BiOBr and Bi2MoO6 by 8.1 and 2.9 times, respectively. Insights from density functional theory (DFT) calculations, electron paramagnetic resonance (EPR), and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies highlight the critical role of the Z-scheme electronic configuration and OVs in attaining the superior photocatalytic toluene conversion efficiency. This study advances the photocatalytic conversion of benzaldehyde within an OV-enhanced direct Z-scheme system, facilitating the activation of inert C(sp3)-H bonds, and contributes to the development of high-performance catalysts for sustainable chemical processes.

Combined catalytic strategies applied to in-office tooth bleaching: whitening efficacy, cytotoxicity, and gene expression of human dental pulp cells in a 3D culture model.

To evaluate the feasibility of using a 3D model with human dental pulp cells (HDPCs) to compare bleaching therapies and assess whether coating enamel with a nanofiber scaffold (NS) and polymeric catalyst primer (PCP), combined with violet LED (LEDv) irradiation, enhances bleaching efficacy (BE) and reduces cytotoxicity (CT). After using NS + PCP to cover enamel of enamel/dentin discs adapted to artificial pulp chambers containing 3D culture with HDPCs, a bleaching gel with 35%H2O2 was applied and then irradiated with LEDv. The following groups were established (n = 8): NC - no treatment; PC- 35%H2O2 for 45min, and EXP: NS + PCP + 35%H2O2 + LEDv for 15min. The study evaluated BE (ΔE00 and ΔWID), CT (alamarBlue), and HDPCs gene modulation (TNF, IL1B, PTGS2, IL8, IL6, PPRAG, HMOX1, DSPP, DMP1, SPP1, BGLAP, and ALPL; RTqPCR). BE showed no significant difference between PC and EXP (p > 0.05). EXP had lower oxidative stress, higher cell viability, reduced inflammatory marker expression, and increased mineralization marker expression compared to PC (p < 0.05). The 3D model using HDPCs effectively compared bleaching protocols. Coating enamel with NS + PCP and applying violet LED (LEDv) reduced bleaching time from 45 to 15min while lowering cytotoxicity compared to conventional in-office treatments. This study shows that a 3D model with human dental pulp cells (HDPCs) effectively compares tooth bleaching protocols. The combination of a nanofiber scaffold with violet LED (LEDv) reduces bleaching time, as well as minimizes cytotoxicity and inflammation, offering a safer alternative to conventional treatments.

Synergic effect of Fe-Sn-Ag tri-metallic nanoparticles synthesized by a green chemistry method on their photocatalytic activity

This research work reports a novel co-precipitation methodology for the green synthesis of tri-metallic nanoparticles (TMNPs) of type: magnetite (Fe3O4NPs), tin (Sn), and silver (Ag), using an aqueous extract of Crocus sativus (ExCs) as a stabilizing agent (TMNPs Fe3O4NPs@Sn-Ag/ExCs), for the first time. The resulting TMNPs Fe3O4NPs@Sn-Ag/ExCs were characterized by Fourier-transform Infrared Spectroscopy (FT-IR), physical adsorption of nitrogen gas at low temperature by Brunauer–Emmett–Teller (BET) analysis, X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field-Emission Scanning Microscopy-Energy Dispersive Spectroscopy (FE-SEM-EDS) and Transmission Electron Microscopy-Energy Dispersive Spectroscopy (TEM-EDS). The TEM-EDS analysis presented TMNPs Fe3O4NPs@Sn-Ag/ExCs with a spherical morphology and a mode size of 13 nm. The crystallographic study of the TMNPs Fe3O4NPs@Sn-Ag/ExCs showed a proportionality between the full width at half maximum (FWHM) XRD peaks and the crystallite size, as well as the dhkl spacing (111) associated with the Ag in the TMNPs structure. The TMNPs Fe3O4NPs@Sn-Ag/ExCs were successfully used in the photodegradation of two over the counter commercial dyes, sky blue No. 39 and emerald green No. 27, resulting in a 100% efficiency for both dyes (90 min of reaction), using sunlight or LED radiation, and a high mineralization rate (>99% TOC removal).

Inactivation of deposited bioaerosols on food contact surfaces with UV-C light emitting diode devices.

The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms such as Escherichia coli (C3040- Kanamycin resistant), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their usage in the food industry. A 50 µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto the surface of the coupons. The serial dilution approach was used for the microbial enumeration, followed by duplicate plating. With a low Root Mean Square Error (RMSE) and high R2 values, the biphasic kinetic model for UV-C inactivation curves of all three pathogens demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ cm-2, glass surfaces showed the maximum microbial inactivation (i.e., 2.80, 3.81, and 3.56 log CFU/mL for E. coli, Salmonella, and P. fragi, respectively). Stainless steel and silicon rubber surfaces showed significant microbial inactivation, but log10 reductions observed were consistently lower than glass surface. Our research indicates that UV-C LEDs (279 nm) can effectively disinfect bioaerosols on food contact surfaces.IMPORTANCEFood safety is a major public health concern, with contaminated food causing serious illnesses. UV-C light, used for germicidal action, is effective in disinfecting surfaces and is not subject to the same strict legal restrictions as chemical disinfectants, simplifying compliance with food safety regulations. In this study, we evaluated the efficacy of UV-C (279 nm) LED systems for inactivation of surface-deposited bioaerosols of kanamycin-resistant Escherichia coli (C3040), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973). The research outcomes can be used to develop UV-based surface disinfection systems to minimize the risk of foodborne illnesses and enhance safety in high-traffic food preparation areas.