Green Light Irradiation Research Articles

Green-light induced cycloadditions.

We introduce a red-shifted tetrazole that is able to undergo efficient nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) under blue and green light irradiation. We provide a detailed wavelength-dependent reactivity map, and employ a number of LEDs for high-conversion small molecule and polymer end-group modification.

Platinum(IV)-azido monocarboxylato complexes are photocytotoxic under irradiation with visible light.

Complexes trans,trans,trans-[Pt(N3)2(OH)(OCOR)(py)2] where py = pyridine and where OCOR = succinate (1); 4-oxo-4-propoxybutanoate (2) and N-methylisatoate (3) have been synthesized by derivation of trans,trans,trans-[Pt(OH)2(N3)2(py)2] (4) and characterised by NMR and EPR spectroscopy, ESI-MS and X-ray crystallography. Irradiation of 1–3 with green (517 nm) light initiated photoreduction to Pt(ii) and release of the axial ligands at a 3-fold faster rate than for 4. TD-DFT calculations showed dissociative transitions at longer wavelengths for 1 compared to 4. Complexes 1 and 2 showed greater photocytotoxicity than 4 when irradiated with 420 nm light (A2780 cell line IC50 values: 2.7 and 3.7 μM) and complex 2 was particularly active towards the cisplatin-resistant cell line A2780cis (IC50 3.7 μM). Unlike 4, complexes 1–3 were phototoxic under green light irradiation (517 nm), with minimal toxicity in the dark. A pKa(H2O) of 5.13 for the free carboxylate group was determined for 1, corresponding to an overall negative charge during biological experiments, which crucially, did not appear to impede cellular accumulation and photocytotoxicity.

The bright and the dark side of the sphere: light-stabilized microparticles

We introduce degradable microparticles, synthesized from prepolymers in a precipitation-like polymerization. The narrow disperse particles are stabilized with continuous irradiation of green light and can be spontaneously degraded in the dark.

Structural, dynamical, and photochemical properties of ortho-tetrafluoroazobenzene inside a flexible MOF under visible light irradiation.

Considering porous materials as host matrices is an elegant way to enable photoswitching of non-covalently attached organic dyes even in the solid state. By focusing on the resulting optical properties as a function of loading degree and synthesis procedure, the occurring host–guest and guest–guest interactions can be determined and further exploited. In the course of this study, the photochromic behavior of ortho-tetrafluoroazobenzene (tF-AZB) inside flexible DMOF-1 was investigated from these points of view. It was found that depending on the loading degree and temperature, tF-AZB shows varying E/Z ratios and switching efficiency. For systems with low loading, reversible visible light induced isomerization was observed over ten switching cycles: Upon violet light exposure, formation of 100% E isomer was generated, while green light irradiation resulted in ∼60% Z-tF-AZB. Complementary molecular dynamics simulations at DFTB (density functional tight binding)-level revealed changing binding sites for Z-tF-AZB inside DMOF-1. For the E isomer, only low oscillations have been found, which in turn display a rare T-stacking interaction. Although the interaction strengths of the E and Z isomers with DMOF-1 are in the same range, the different mobility of both isomers due to varying binding sites explains the preference of the E isomer even upon green light exposure.

Growth, cultural and morphological characteristics of strains of Laetiporus sulphureus (Polyporales, Basidiomycota) under the influence of laser irradiation

The article provides growth, cultural and morphological characteristics of the vegetative mycelium on agar nutrient medium under the influence of laser irradiation for three strains of Laetiporus sulphureus from the Collection of basidiomycete cultures of the Department of Botany and Ecology of Vasyl' Stus Donetsk National University. The study was performed on potatoglucose agar (PGA) at a temperature of 26 ± 1 °C. It has been found that cultural and morphological characteristics of the colonies and the radial rate of their growth depend on the duration of irradiation (5 and 10 s) and the wavelength of light – green (532 nm), blue (405 nm) and red light (635 nm). For all studied strains of L. sulphureus, the most effective irradiation is that with green light (irradiation energy 51.1 mJ/cm2) lasting 10 s. Under the influence of this regime, the rate of radial mycelium growth increased from 23.4% to 66.7%, respectively, and the inoculum and the central zone of the surrounding colony formed a denser and higher mycelium of a pale sandy color. In general, the cultural and morphological features of the mycelial colonies of L. sulphureus strains under different conditions were somewhat different, but they were typical for this species.

Deep Drug Penetration of Nanodrug Aggregates at Tumor Tissues by Fast Extracellular Drug Release.

Herein, a new nanodrug of azobenzene-functionalized interfacial cross-linked reverse micelles (AICRM) with 5-fluorouracil loading (5-FU@AICRM) is reported. Upon irradiation with 530nm light in water, the surface azobenzenes of the nanoparticles change from polar cis-conformation to nonpolar trans-conformation, resulting in the aggregation of 5-FU@AICRM within minutes. Simultaneously, the conformation change unlocks hydrophilic 5-FU with a strong water immigration propensity, allowing them to spray out from the AICRM quickly. This fast release ensures a thorough release of the drug, before the aggregates are internalized by adjacent cells, making it possible to achieve deep tissue penetration. A study of in vivo anticancer activity in A549 tumor-bearing nude mice shows that the tumor inhibition rate (TIR) of 5-FU@AICRM is up to ≈86.2%, 31.6% higher than that of group without green light irradiation and 20.7% higher than that of carmofur (CF, a hydrophobic analog of 5-FU)-loaded AICRM (CF@AICRM), in which CF is released slowly under light irradiation because of its hydrophobicity. Fast drug release upon nanodrug aggregation provides a good solution for balancing the contradiction of "aggregation and penetration" in tumor treatment with nanodrugs.

Photo-induced sp3 C-H bond arylation, cyanation and nitroalkylation of tetrahydroisoquinolines (THIQs) under visible light irradiation using a combination of NHPI and Rose Bengal.

This work reports a sustainable protocol for α-arylation of tetrahydroisoquinolines (THIQs) with aryl diazonium salts using a combination of a cheap and stable oxidant, N-hydroxyphthalimide (NHPI), and an inexpensive dye photosensitizer, Rose Bengal (RB), for the first time. The reaction was performed at ambient temperature using green LED light irradiation under an oxygen atmosphere. The developed α-arylation protocol shows a diverse substrate scope for various THIQs and aryl diazonium salts. The work also explores nitroalkylation and cyanation under the developed reaction conditions. A possible SET mechanism is involved which was confirmed by ESI-MS analysis of the reaction mixture.

Optical Trapping of Photosoftened Solid Polymers

We present evidence of optical trapping of solid polymer films by a tightly focused near-infrared (NIR) laser beam (785 nm) when the polymer is softened by green laser (532 nm) irradiation, which is uniformly distributed over the film surface. While the whole film is softened by the green laser, only the part which is subjected to the NIR laser is trapped. The film, which is transparent in the NIR range and strongly absorbs the visible light, is deposited on a glass substrate. The NIR laser is focused at the sample plane and attracts the polymer to the laser focus, by the optical gradient force, during the green light irradiation, indicating that molecular mobility is strongly reduced and the optical gradient force of the NIR laser is inefficient in moving the polymer below the glass-transition temperature of the polymer without photosoftening. The observations are consistent with the theory of photochemical tweezing, which rests on the assumption that photosensitive polymers, containing azo dyes, are softened, i.e., molecular mobility is enhanced, by photoisomerization of the azo dyes during green light irradiation, and are moved in gradients of light fields. We also found that this two-color laser tweezing scheme is sensitive to light polarization, owing to the polarization sensitivity of the azo dye chromophores.

Selective oxidation of toluene to benzaldehyde over Pd/BiVO4 particles under blue to green light irradiation

Selective synthesis of organic chemicals such as oxidation of toluene to benzaldehyde using sunlight is necessary for its sustainable and environment-friendly applications. The photocatalytic reaction using semiconductor photocatalysts is a promising approach for sunlight-induced organic synthesis due to its significant advantages of operation under mild conditions, stability, and recyclicity. TiO2 is one of the most widely studied photocatalysts; however, the low selectivity for partial oxidation due to the complete decomposition to CO2 and lack of utilization of visible-light hampers its practical application. Here, we successfully demonstrated selective oxidation of toluene to benzaldehyde using a Pd-loaded BiVO4 photocatalyst under visible light irradiation. Furthermore, we confirmed that the reaction proceeds even under light irradiation up to 520 nm; this is the first report using blue-to-green light-responsive semiconductor photocatalyst for converting toluene to benzaldehyde. Achieving efficient organic synthesis under visible light using semiconductor photocatalyst is an important step toward solar-to-chemical conversion.

Intrinsically Visible Light-Responsive Liquid Crystalline Physical Gels Driven by a Halogen Bond.

Photoresponsive physical gels using liquid crystals (LCs) as solvents have attracted great interest owing to their potential applications. But, current investigations mainly focus on UV light, which is not environment-friendly enough. On the other hand, the halogen bond is a novel tool for constructing supramolecular gels because of good hydrophobicity, high directionality, tunable strength, and large size of halogen atoms. Herein, to construct an LC physical gel with both the advantages of a halogen bond and visible light response, azopyridine-containing Azopy-C10 is chosen as a halogen bond acceptor, while 1,2-bis(2,3,5,6-tetrafluoro-4-iodophenyl)diazene is selected both as the halogen bond donor and for the intrinsically visible light response. Such a binary gelator can self-assemble in the anisotropic solvent of nematic LC 5CB to form an LC physical gel. It experiences the gel-to-sol transition by green light irradiation. As the gelator concentration increases, the saturation voltage increases, but the switch-off time decreases. The combination of the halogen bond and controllable visible light-responsive LC physical gel provides the feasibilities of manipulating these smart soft materials.

From UV to NIR: A Full-Spectrum Metal-Free Photocatalyst for Efficient Polymer Synthesis in Aqueous Conditions.

Photo-mediation offers unparalleled spatiotemporal control over controlled radical polymerizations (CRP). Photo-induced electron/energy transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization is particularly versatile owing to its oxygen tolerance and wide range of compatible photocatalysts. In recent years, broadband- and near-infrared (NIR)-mediated polymerizations have been of particular interest owing to their potential for solar-driven chemistry and biomedical applications. In this work, we present the first example of a novel photocatalyst for both full broadband- and NIR-mediated CRP in aqueous conditions. Well-defined polymers were synthesized in water under blue, green, red, and NIR light irradiation. Exploiting the oxygen tolerant and aqueous nature of our system, we also report PET-RAFT polymerization at the microliter scale in a mammalian cell culture medium.

From UV to NIR: A Full‐Spectrum Metal‐Free Photocatalyst for Efficient Polymer Synthesis in Aqueous Conditions

AbstractPhoto‐mediation offers unparalleled spatiotemporal control over controlled radical polymerizations (CRP). Photo‐induced electron/energy transfer reversible addition–fragmentation chain transfer (PET‐RAFT) polymerization is particularly versatile owing to its oxygen tolerance and wide range of compatible photocatalysts. In recent years, broadband‐ and near‐infrared (NIR)‐mediated polymerizations have been of particular interest owing to their potential for solar‐driven chemistry and biomedical applications. In this work, we present the first example of a novel photocatalyst for both full broadband‐ and NIR‐mediated CRP in aqueous conditions. Well‐defined polymers were synthesized in water under blue, green, red, and NIR light irradiation. Exploiting the oxygen tolerant and aqueous nature of our system, we also report PET‐RAFT polymerization at the microliter scale in a mammalian cell culture medium.

Photodynamic Therapy for Infectious Keratitis.

Infectious keratitis is a sight-threatening microbial infection. The prevalence of antimicrobial resistance in cases of infectious keratitis has increased the demand for fortified compounded antimicrobial drops. Even with proper medical management, severe cases of infectious keratitis can further evolve into corneal perforation, requiring surgical intervention in the form of keratoplasty to control the infectious process. Due to the invasive nature of the procedure and the shortage of available donor tissue around the world, alternative treatments are needed for the management of progressive infectious keratitis. In ophthalmology, photodynamic therapy (PDT) has been used for numerous applications. PDT with Rose Bengal as a photosensitizer combined with green light optical irradiation (RB-PDAT) is a novel treatment with dual purpose: to arrest the infection from progressing and strengthen the collagen of the cornea. RB-PDAT may be considered as an adjunct therapy in severe cases of infectious keratitis to minimize the need for a therapeutic keratoplasty.

Green light–triggered antimicrobial cotton fabric for wastewater disinfection

Water pollution by pathogenic bacteria is a major threat to human health, and less-than-ideal disinfection and antimicrobial strategies have been developed to address waterborne pathogens. A green light–triggered photocatalytic antimicrobial rose bengal (RB)–modified cotton fabric (CF) (RB-CF) was prepared for wastewater disinfection by covalently binding RB to a CF surface. The antimicrobial rates of RB-CF against gram-positive Staphylococcus aureus and gram-negative Escherichia coli were both greater than 99.99% due to the generation of singlet oxygen that inactivates microbes under green light irradiation. Most importantly, RB-CF exhibited high stability, negligible cytotoxicity, and no release of free RB during the photocatalytic process, which was the key to its long-term antimicrobial activity and use security. Its long-term antimicrobial activity was further verified by the repeated photocatalytic disinfection; more than 99.99% of bacteria were inactivated even after five cycles. Therefore, this work may offer a potential avenue to develop low-cost, non-toxic, and durable antimicrobial fabrics with great potential for industrial and health-care applications, including but not limited to water purification, wastewater disinfection, masks, and protective clothing.

Acryloylnitrenes: Spectroscopic Characterization, Spin Multiplicities, and Rearrangement to Vinyl Isocyanates.

The simplest acryloylnitrene, CH2═CHC(O)N (1b), and two halogenated derivatives, CH2═CFC(O)N (2b) and CH2═CBrC(O)N (3b), were generated through the 266 nm laser photolysis of the corresponding azide precursors in solid N2-matrices at 15 K. The IR spectroscopic characterization of these new acylnitrenes is supported by 15N-labeling and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level of theory. For the three nitrenes 1b, 2b, and 3b, two conformers exhibiting syn and anti configurations between the C═C and C═O bonds with respect to the C-C bonds have been identified. Consistent with the CBS-QB3 calculated singlet-triplet energy gaps (ΔEST < 0 kcal mol-1), the IR spectral analysis suggests that all these acryloylnitrenes adopt oxazirine-like structures with closed-shell singlet spin multiplicity. Upon subsequent green light (532 nm) irradiation, these acryloylnitrenes rearrange to form vinyl isocyanates CH2═CXNCO (X = H, F, Br), for which the IR spectra have also been obtained. According to the calculations on the α,β-fluorinated acryloylnitrenes at the CBS-QB3 level, their spin multiplicities can be switched from singlet CH2═CFC(O)N (ΔEST = -0.86 kcal mol-1) to triplet CF2═CFC(O)N (ΔEST = +0.61 kcal mol-1), whereas CFH═CFC(O)N is magnetically bistable due to a rather small ΔEST (+0.09 kcal mol-1).

Effects of green light photobiomodulation on Dental Pulp Stem Cells: enhanced proliferation and improved wound healing by cytoskeleton reorganization and cell softening.

Photobiomodulation (PBM) has been shown to improve cell proliferation and cell migration. Many cell types have been investigated, with most studies using deep penetrating red light irradiation. Considering the interest of surface biostimulation of oral mesenchymal cells after surgical wound, the present study aimed to assess green light irradiation effects on Dental Pulp Stem Cells' (DPSC) proliferation and migration. To understand the mechanisms underlying these effects, we investigated cytoskeleton organization and subsequent cell shape and stiffness. A 532-nm wavelength Nd:YAG laser (30mW) was applied between 30 and 600s on DPSC in vitro. Cell proliferation was analyzed at 24, 48, and 72h after irradiation, by cell counting and enzymatic activity quantification (paranitrophenylphosphate phosphatase (pNPP) test). A wound healing assay was used to study cell migration after irradiation. Effects of PBM on cytoskeleton organization and cell shape were assessed by actin filaments staining. Elasticity changes after irradiation were quantified in terms of Young's modulus measured using Atomic Force Microscopy (AFM) force spectroscopy. Green light significantly improved DPSC proliferation with a maximal effect obtained after 300-s irradiation (energy fluence 5J/cm2). This irradiation had a significant impact on cell migration, improving wound healing after 24h. These results were concomitant with a decrease of cells' Young's modulus after irradiation. This cell softening was explained by actin cytoskeleton reorganization, with diminution of cell circularity and more abundant pseudopodia. This study highlights the interest of green laser PMB for the proliferation and migration of mesenchymal stem cells, with encouraging results for clinical application, especially for surgical wound healing procedures.

Analysis of the influence of laser irradiation on the accumulation of biomass and polysaccharides pleurotus ostreatus (JACQ.) Р. Kumm

The aim of the study was to investigate the effect of laser irradiation of mycelium on the amount of biomass and synthesis of P. ostreatus polysaccharides.Materials and methods. For the study, 6 strains of P. ostreatus from the Collection of cultures of basidiomycetes of the Department of Botany and Ecology of Vasyl Stus DonNU were used. A device consisting of LED lasers was used for laser irradiation of vegetative mycelium: BRP – 3010–5, with red spectrum radiation with a wavelength of 635 nm; BBP – 3010–5 with blue spectrum radiation with a wavelength of 405 nm and BGP – 3010–5 with green spectrum radiation with a wavelength of 532 nm. The level of biomass accumulation was determined by weight. The polysaccharide content was determined by the phenol-sulfur method.Results. The most effective was green light irradiation with a wavelength of 532 nm. For strain P-192 – the amount of biomass increased by 71.4 %. For strains P-191 and P-155 biomass increased by 60 % and 53.5 %. For strains P-108, P-154 and P-6v, the amount of biomass increased from 33.3 to 50 %. For strain P-192, the amount of mycelial endopolysaccharides increased by 42.0 %. For strains P-191 and P-6v, the amount of endopolysaccharides increased by 39.3 % and 38.7 %. For strains P-108, P-155 and P-154 the amount of mycelium endopolysaccharides increased from 30.7 % to 35.8. For strain P-192 the content of exopolysaccharides increased by 30.5 %. For strains P-154 and P-191, the amount of exopolysaccharides increased by 28.1 % and 27.8 %. For strains P-108, P-155 and P-6v the content of exopolysaccharides increased from 24.6 % to 25.8 %.Conclusions. The most effective mode of photoactivation of P. ostreatus mycelium for obtaining target products was determined. In particular, the best response was observed in response to green light with a wavelength of 532 nm for strain P-192 – the amount of biomass increased by 71.4 %, the amount of mycelium endopolysaccharides increased by 42.0 %, and the content of exopolysaccharides increased by 30.5 %

Alternative Route Triggering Multistep Spin Crossover with Hysteresis in an Iron(II) Family Mediated by Flexible Anion Ordering.

Multistep spin crossover (SCO) compounds have attracted much attention, since they can be great candidates for high-density multinary memory devices. The introduction of substituents, such as methyl (Me), chloro (Cl), bromo (Br), and methoxy (MeO) groups, at para positions to the phenyl-substituted tripodal N6 ligand-coordinated SCO FeII material, [FeLPh](NTf2)2 [where LPh = tris(2-{[(1-phenyl-1H-1,2,3-triazol-4-yl)methylidene]amino}ethyl)amine and NTf2 = bis(trifluoromethanesulfonyl)imide], affords a new family of solvent-free FeII complexes: [FeL4-R-Ph](NTf2)2 {where L4-R-Ph = tris[2-({[1-(4-R-phenyl)-1H-1,2,3-triazol-4-yl]methylidene}amino)ethyl]amine, where R = Me (1), Cl (2), Br (3), and MeO (4)}. 1 shows temperature invariant high-spin (HS) state, whereas the others show spin transitions with different characteristics, such as half-SCO (4), two-step SCO (3), and unusual three-step SCO with hysteresis (2). Mössbauer and X-ray absorption fine structure (XAFS) spectroscopic studies of them support the magnetic susceptibilities results. Density functional theory calculations indicate that the electronic effect of different substituents on magnetic properties is negligible in this FeII family. Single-crystal X-ray diffraction studies reveal that 1-4 has a similar packing arrangement with three-dimensional supramolecular network via intermolecular π-π and CH···π interactions between complex cations, and CH···X (X = O, N, and F) hydrogen bonding interactions between cations and inherently frustrated NTf2 anions. Variable-temperature structural studies unveil a variety of stepped SCO behaviors of 2-4 and deactivation of SCO in 1 are governed by the regulation of ordering of NTf2 counteranions through the subtle modification of terminal substituents of complex cations. Quantitative light-induced excited spin-state trapping (LIESST) effect was observed for 2-4 via green light irradiation (532 nm) at 10 K. This study opens up a new way for systematic control of magnetic response from no SCO to half-, two-step, and finally three-step SCO with hysteresis by precise tuning of the ordering of flexible NTf2 anions included in the supramolecular network with potentially SCO-active complex cations.

Wholly Visible-Light-Responsive Host-Guest Supramolecular Gels Based on Methoxy Azobenzene and β-Cyclodextrin Dimers.

Much attention has been paid to construct photoresponsive host-guest supramolecular gels; however, red-shifting the responsive wavelength remains a formidable challenge. Here, a wholly visible-light-responsive supramolecular gel was fabricated through the host-guest interaction between a β-cyclodextrin (β-CD) dimer and a tetra-ortho-methoxy-substituted azobenzene (mAzo) dimer (binary gelator) in DMSO/H2O (V/V = 8/2). The minimum gelation concentration of the low-molecular-weight binary gelator was 6 wt % measured via the tube inversion method. The substituted methoxy groups shifted the responsive wavelengths of trans-mAzo and cis-mAzo to the green and blue light regions, respectively. The host-guest interaction between mAzo and β-CD as the driving force for gelation was confirmed using the 1H-NMR and 2D 1H NOESY spectra. The supramolecular gel showed good self-supporting ability with a storage modulus higher than 104 Pa. The release of Rhodamine B loaded in the gel as a model drug could be controlled by green light irradiation. We envisioned the potential applications of the wholly visible-light-responsive supramolecular compounds ranging from biomedical materials to smart materials.

Synergistic photocatalytic effect between green LED light and Fe3O4/ZnO-modified natural pumice: A novel cleaner product for degradation of methylene blue

Herein, an efficient photocatalytic system is prepared and applied for photocatalytic degradation of methylene blue (MB), under green light irradiation. This catalytic system is made of the nanosized ingredients including iron oxide nanoparticles (Fe3O4 NPs) and zinc oxide nano-rods (ZnO NRs), to provide a wide surface active area. The first and foremost point from the structural aspect is the magnetic property enhancement through well composition of the natural pumice micro-plates with Fe3O4 NPs, as two magnetic ingredients. Through this property, the catalyst’s particles are conveniently collected and reused for additional eight times. Concisely, the highest photocatalytic efficiency (85.5%) has been obtained through using 50?mg of ZnO/Fe3O4@pumice photocatalyst under green LED light (7?W, 526?nm) irradiation, for 60?min. In this study, a plausible photocatalytic mechanism for degradation of the MB by the produced photocatalytic system is suggested as well.