Intense Red Light Research Articles

Red Light Responsive Cre Recombinase for Bacterial Optogenetics.

Optogenetic tools have been used in a wide range of microbial engineering applications that benefit from the tunable, spatiotemporal control that light affords. However, the majority of current optogenetic constructs for bacteria respond to blue light, limiting the potential for multichromatic control. In addition, other wavelengths offer potential benefits over blue light, including improved penetration of dense cultures and reduced potential for toxicity. In this study, we introduce OptoCre-REDMAP, a red light inducible Cre recombinase system in Escherichia coli. This system harnesses the plant photoreceptors PhyA and FHY1 and a split version of Cre recombinase to achieve precise control over gene expression and DNA excision. We optimized the design by modifying the start codon of Cre and characterized the impact of different levels of induction to find conditions that produced minimal basal expression in the dark and induced full activation within 4 h of red light exposure. We characterized the system's sensitivity to ambient light, red light intensity, and exposure time, finding OptoCre-REDMAP to be reliable and flexible across a range of conditions. In coculture experiments with OptoCre-REDMAP and the blue light responsive OptoCre-VVD, we found that the systems responded orthogonally to red and blue light inputs. Direct comparisons between red and blue light induction with OptoCre-REDMAP and OptoCre-VVD demonstrated the superior penetration properties of red light. OptoCre-REDMAP's robust and selective response to red light makes it suitable for advanced synthetic biology applications, particularly those requiring precise multichromatic control.

Plant Phytochrome Interactions Decode Light and Temperature Signals.

Plant phytochromes perceive red and far-red light to elicit adaptations to the changing environment. Downstream physiological responses revolve around red-light-induced interactions with phytochrome-interacting factors (PIF). Phytochromes double as thermoreceptors, owing to the pronounced temperature dependence of thermal reversion from the light-adapted Pfr to the dark-adapted Pr state. Here, we assess whether thermoreception may extend to the phytochrome:PIF interactions. While the association between Arabidopsis (Arabidopsis thaliana) PHYTOCHROME B (PhyB) and several PHYTOCHROME-INTERACTING FACTOR (PIF) variants moderately accelerates with temperature, the dissociation does more so, thus causing net destabilization of the phytochrome:PIF complex. Markedly different temperature profiles of PIF3 and PIF6 might underlie stratified temperature responses in plants. Accidentally, we identify a photoreception mechanism under strong continuous light, where the extent of phytochrome:PIF complexation decreases with red-light intensity rather than increases. Mathematical modeling rationalizes this attenuation mechanism and ties it to rapid red-light-driven Pr⇄Pfr interconversion and complex dissociation out of Pr. Varying phytochrome abundance, e.g., during diurnal and developmental cycles, and interaction dynamics, e.g., across different PIFs, modify the nature and extent of attenuation, thus permitting light-response profiles more malleable than possible for the phytochrome Pr⇄Pfr interconversion alone. Our data and analyses reveal a photoreception mechanism with implications for plant physiology, optogenetics, and biotechnological applications.

Boosting the in-vitro effectiveness of photodynamic therapy on MCF-7 breast cancer cells with encapsulated malachite green by silica nanoparticles

Photodynamic therapy (PDT) is a promising cancer treatment strategy utilizing photosensitizers (PS) and light to generate singlet oxygen, with Malachite Green (MG) showing high singlet oxygen quantum yield. Effective delivery of MG to the target tissue remains a key challenge. Encapsulation techniques have been investigated to improve PS delivery, minimize PS leakage, inhibit diaphorase-induced reduction, and mitigate PS-related toxicity. Silica nanoparticles (SiNPs) offer favorable characteristics for drug delivery in PDT and serve as promising delivery carriers. In this study, SiNPs were synthesized and employed as carriers for MG. The size and shape of nanoparticles were determined using Transmission Electron Microscopy (TEM). A range of concentrations of MG were applied to MCF-7 breast cancer cells in order to evaluate the cytotoxicity of both naked and encapsulated MG. This helped identify the most effective concentrations and exposure durations required to induce damage under red laser light (Intensity ∼110 mW/cm2). The results indicated that SiNPs-encapsulated MG exhibited superior efficacy compared to naked MG, with a concentration efficacy increase of +50 % and an exposure time efficacy increase of +45 %. This underlines the enhanced capability of encapsulated MG to eliminate MCF-7 cells when compared to naked MG. The application of synthesized SiNPs for MG delivery improved the effectiveness of photodynamic therapy by augmenting MG bioavailability in target cells.

A novel bright and thermally stable red phosphor Mg2YVO6:Eu3+

Utilizing the standard high-temperature solid-phase reaction, a novel red phosphor Mg2YVO6:xEu3+ (0.05 ≤ x ≤ 0.35) was synthesized, and its preparation parameters and luminescence characteristics were examined. The phosphor emits an intense red light, in which the strong energy transfer between Eu3+ and VO43− leads to intense light, while the local symmetry of the lattice around Eu3+ determines the color of the emitted light. With an intensity ratio of 3.89 between the electric dipole and magnetic dipole transitions, it's evident that Eu3+ is located at the non-inversion symmetry site in Mg2YVO6. Additionally, there was a mere 23 % reduction in brightness at 423 K, sufficient to demonstrate the phosphor's robust thermal stability. The fluorescence lifetime for the Mg2YVO6:0.2Eu3+ phosphor was ascertained by analyzing its decay curve at 618 nm following stimulation at 395 nm, and the recorded fluorescence lifetime stood at 423.87 μs. When kept at room temperature, the CIE coordinates for Mg2YVO6:0.1Eu3+ phosphor when excited at 328 nm stand at (0.6564, 0.3527), with its color purity at 99.82 %, and the CIE coordinates for Mg2YVO6:0.2Eu3+ when excited at 395 nm are (0.6616, 0.3378), and its color purity at 99.9 %. The creation of a white light-emitting diode involved blending Mg2YVO6:0.2Eu3+ phosphor with BaMgAl10O17:Eu2+ blue phosphor and green phosphor (Ba, Sr)2SiO4:Eu2+ in a ratio of 40:2:1, applied to the n-UV chip at 395 nm, acquiring a CIE coordinate (0.3687, 0.4074), a color temperature of 4495 K, Ra = 89, R9 = 87.5. Observations reveal that Mg2YVO6:Eu3+, a phosphor characterized by its high color purity and good thermal stability, holds significant promise for white light-emitting diodes.

Light quality-dependent roles of REVEILLE proteins in the circadian system.

Several closely related Myb-like activator proteins are known to have partially redundant functions within the plant circadian clock, but their specific roles are not well understood. To clarify the function of the REVEILLE 4, REVEILLE 6, and REVEILLE 8 transcriptional activators, we characterized the growth and clock phenotypes of CRISPR-Cas9-generated single, double, and triple rve mutants. We found that these genes act synergistically to regulate flowering time, redundantly to regulate leaf growth, and antagonistically to regulate hypocotyl elongation. We previously reported that increasing intensities of monochromatic blue and red light have opposite effects on the period of triple rve468 mutants. Here, we further examined light quality-specific phenotypes of rve mutants and report that rve468 mutants lack the blue light-specific increase in expression of some circadian clock genes observed in wild type. To investigate the basis of these blue light-specific circadian phenotypes, we examined RVE protein abundances and degradation rates in blue and red light and found no significant differences between these conditions. We next examined genetic interactions between RVE genes and ZEITLUPE and ELONGATED HYPOCOTYL5, two factors with blue light-specific functions in the clock. We found that the RVEs interact additively with both ZEITLUPE and ELONGATED HYPOCOTYL5 to regulate circadian period, which suggests that neither of these factors are required for the blue light-specific differences that we observed. Overall, our results suggest that the RVEs have separable functions in plant growth and circadian regulation and that they are involved in blue light-specific circadian signaling via a novel mechanism.

Enhancing photodynamic therapy efficacy through silica nanoparticle-mediated delivery of temoporfin for targeted in vitro breast cancer treatment

Photodynamic therapy (PDT), an approach to cancer treatment, relies fundamentally on two key elements: a light source and a photosensitizing agent. A primary challenge in PDT is the efficient delivery of photosensitizers to the target tissue, hindered by the bodyʼs reticuloendothelial system (RES). Silica nanoparticles (SiNPs), known for their unique properties, emerge as ideal carriers in this context. In this study, SiNPs are utilized to encapsulate Temoporfin, a photosensitizer, aiming to enhance its delivery and reduce toxicity, particularly for treating MCF-7 cancer cells in vitro. The synthesized SiNPs were meticulously characterized by their size and shape using Transmission Electron Microscopy (TEM). The study also involved evaluating the cytotoxicity of both encapsulated and naked Temoporfin across various concentrations. The objective was to determine the ideal concentration and exposure duration using red laser light (intensity approximately 110 mW/cm2) to effectively eradicate MCF-7 cells. The findings revealed that Temoporfin, when encapsulated in SiNPs, demonstrated significantly greater effectiveness compared to its naked form, with notable improvements in concentration efficiency (50 %) and exposure time efficiency (76.6 %). This research not only confirms the superior effectiveness of encapsulated Temoporfin in eliminating cancer cells but also highlights the potential of SiNPs as an efficient drug delivery system in photodynamic therapy. This sets the groundwork for more advanced strategies in cancer treatment.

Preparation and photoluminescence study of rare-earth-free red emitting La3Ga5SiO14:Mn4+ phosphors

Given the growing interest in eco-friendly lighting solutions, the use of high-quality phosphors has become integral to the advancement of all-solid white light-emitting diodes (WLEDs). One novel phosphor, La3Ga5SiO[Formula: see text]:Mn[Formula: see text] (LGS), has been successfully synthesized via a high-temperature solid-state reaction. The crystal structure of LGS is classified as belonging to the trigonal phase, with a space group P321. The excitation spectrum exhibits a wide peak within the wavelength range of 280–440 nm. It emits a highly intense red light, with a peak emission occurring at 715 nm within the spectral range of 670–740 nm is attributed to the transition of Mn[Formula: see text] from 4A2g to 4T2g. LGS:Mn[Formula: see text] demonstrates a favorable quantum efficiency of 16% when doped with a concentration of 0.25 mol% Mn. The decay curve of LGS:Mn[Formula: see text] exhibits a pattern of decreasing lifetime as the dopant concentration increases. Additionally, the LGS:Mn[Formula: see text] products demonstrate a CIE chromaticity of (0.688, 0.2644), which is located within the deep red light region. All the aforementioned findings support the potential application of LGS:Mn[Formula: see text] specimens in WLEDs, thereby contributing to the progress of environmentally friendly and energy-efficient lighting.

Reddening of the Unicellular Green Alga Euglena gracilis by Dried Bonito Stock and Intense Red Light Irradiation.

This study confirms for the first time that the significant red coloration of Euglena gracilis is induced by bonito stock (BS), a traditional Japanese food, and intense red light exposure (605~660 nm, 1000~1300 µmol photons/m2/s). Under the condition, excessive photosynthetic activity destroyed many chloroplasts, while carotenoids were maintained, resulting in the formation of reddened cells. The HPLC analysis revealed that diadinoxanthin was the primary carotenoid present in reddened cells. Additionally, an undefined xanthophyll, not produced under normal culture conditions, was synthesized and suggested to contain a C=O bond. While it has been reported that strong light stress can increase the total carotenoid content of cells, this study did not verify this claim, and it should be investigated further in future research. Under white light irradiation conditions (90 μmol photons/m2/s) in BS medium, no reddening of cells was observed, and good growth was achieved (over four times the cell density in CM medium on the seventh day). This cell suspension is considered to have a high nutritional value because it is composed of functional food, BS and E. gracilis. The fact that this method does not involve genetic modification suggests the possibility of industrial applications, including food use, even in reddened cells.

Transcriptional analysis reveals new insights into the different light intensities of red and blue light on the growth and synthesis of medicinal ingredients in Dendrobium denneanum

The intensity of red-blue light has important impacts on plant growth and medicinal ingredients. To identify the key genes of Dendrobium denneanum responsive to red-blue light intensity, and to reveal the regulatory mechanism of red-blue light intensity on the growth, development and medicinal quality in D. denneanum. In this experiment, D. denneanum was treated with red-blue light (2R/3B) under various light intensity (50, 100, 200, 400, 800 μmol•m−2•s−1), while the control group was white light, the photoperiod was 8/16 h (day/night). And the changes of plant growth, development, and medicinal components were studied by physiological, biochemical and transcriptome analysis. The results demonstrated that the light intensity of 400 μmol•m−2•s−1 was most conducive to the growth, development, and accumulation of the medicinal ingredients in D. denneanum. Transcriptome analysis revealed that the difference genes between the 400 μmol•m−2•s−1 treatment and CK (white light) were mostly enriched in the metabolic pathways of MAPK signaling, phenylpropanoid biosynthesis and flavonoid biosynthesis. Among them, CAM, PP2C, PYR1 may be the critical genes regulating the growth and development of D. denneanum. The combination of CAM and Ca2+ activates MPKs to maintain ROS homeostasis in D. denneanum. PP2C and PYR1 induced ABA synthesis to control the growth, development, and resistance of D. denneanum. Moreover, 4CL, CAD, BGLU, CCoAOMT and CHI may be the hub genes involved in regulating the synthesis of its key medicinal ingredients. This experiment provides scientific evidence for the application of red-blue light in the artificial cultivation in D. denneanum, and offers the mechanism of in-depth research foundation.

Red light intensity modulation, temperature sensing and bioimaging of NaLuF4:Er3+/Tm3+/Yb3+ microcrystals under 1532 nm laser excitation

This paper reports on microcrystals with deep tissue penetration depth, strong red light emission, and thermometric function. The red light emission of NaLuF4:20 % Er3+/1 % Tm3+/10 % Yb3+ microcrystals is exceptionally strong, thanks to the introduction of Tm3+ and Yb3+ ions energy capture centers. In bioimaging, the 1532 nm laser exhibits deeper imaging depth due to weak photon scattering and autofluorescence. Furthermore, red light emission has the greatest tissue penetration depth in the visible region. The luminescence intensity and tissue penetration depth of both the excitation and emission light make them suitable for deep tissue imaging. We investigated temperature sensing performance of NaLuF4:20 % Er3+/1 % Tm3+/10 % Yb3+ microcrystals, and found that the maximum relative sensitivity of LIR (I521/I540) reaches 0.92 %K−1. The microcrystals NaLuF4:20 % Er3+/1 % Tm3+/10 % Yb3+ are anticipated to have application in deep tissue imaging and temperature sensing.

Strawberry (Fragaria ananassa) seedlings formation under different intensities of violet, blue and red LED light

Introduction. Seedlings formation under controlled conditions is essential for growing species of importance as strawberry. Since the artificial LED lighting technologic has allowed greater control of light, the variation of components such as the wavelength and intensity can be manipulated to form seedlings with different characteristics. However, it is necessary to generate original scientific information for the development of precise and efficient practices on light control. Objective. The aim of the present study was to evaluate the strawberry seedlings formation under different intensities of violet, blue and red LED light. Material and methods. The study was performed in 2020 at the Plant Genetics Laboratory of the Agronomy Department of the Universidad de Guanajuato, in the municipality of Irapuato, in the state of Guanajuato, Mexico. Seeds were recovered from San Andreas cultivar fruits and seedlings were formed under violet, blue and red LED light at high, medium, and low intensities. Color determination of cotiledon area, chroma saturation index and Hue angle were performed. Physiotechnical variables, chemical and antioxidant activity were measured. Results. The most suitable treatments were violet light of high and medium intensities; as well as blue light of high intensity, due to the germination percentage exceeded at least 60 %. Seedlings did not lengthen or thin, presented the largest cotyledons areas and the highest chlorophyll concentrations. In addition, these light treatments consumed 31.2 % less electrical energy on average. Conclusions. Besides the white light, the most suitable treatments for strawberry seedlings formation were violet light at high and medium intensities, as well as blue light at high intensity. It is suggested that the violet and blue light treatments be evaluated in other cultivars to confirm the beneficial effect on the strawberry seedlings. Red light limited germination and the highest antioxidant activity was observed in this treatment.

Co-doped NaYF4:Yb/Er/Tm upconversion luminescent coating to enhance the efficiency of photovoltaic cells.

The use of upconversion luminescent materials to broaden the utilization range of the solar spectrum to enhance the efficiency of photovoltaic cells offers a promising and sustainable approach. However, the low luminescence intensity and easy quenching of upconversion luminescent materials bring serious challenges to the practical application. Herein, a novel method using Co2+ ion doping to regulate the luminescence properties of NaYF4:Yb/Er/Tm is proposed. NaYF4:Yb/Er/Tm microcrystals doped with different proportions of Co2+ ions are prepared and used as coatings on the surface of photovoltaic cells. Co2+ ions regulate the crystallinity and size of the NaYF4:Yb/Er/Tm microcrystals and reduce the crystal field symmetry of the activator (Er3+ and Tm3+) ions. The results show that the emission intensity of green and red light is 18.19% and 83.24% times higher than that of undoped Co2+ ion materials, respectively. Besides, the efficiency of photovoltaic cells after coating Co2+ ion doped NaYF4:Yb/Er/Tm is 2.08% higher than that of the uncoated one. This work underscores the importance of Co2+ ion doping to improve and enhance the luminescence properties of NaYF4:Yb/Er/Tm, to further enhance the efficiency of photovoltaic cells.

LED red and blue light intensity affected productivity and nitrogen metabolisms of ryegrass

Light intensity plays a critical regulatory role in determining plant yield and quality, and energy consumption in plant factory with artificial light (PFAL). The effects of different light intensities (200, 300, 400, 500, and 600 µmol·m−2·s−1) of light-emitting diodes (LED) red and blue light with ratio 4:1 on growth, quality, nitrogen and amino acid metabolisms of ryegrass were investigated. The results showed the tiller number and shoot fresh weight in ryegrass were increased, while plant height and stem diameter remained stable with the improvement of light intensity. The highest levels of soluble protein, free amino acid, and DPPH free radical clearance rate in photon flux density (PPFD) at 500 µmol·m−2·s−1, and then significantly decreased with light intensity increased. The highest soluble sugar content was found at PPFD of 600 µmol·m−2·s−1, while malondialdehyde (MDA) content remained stable in all treatments. As the light intensity increased, nitrate content decreased, while nitrate reductase (NR) activity and the ammonium content increased. As light intensity was increased from 200 to 600 µmol·m−2·s−1, nitrite reductase (NiR) activity first decreased and then increased. Moreover, glutamate and cysteine contents increased first and then decreased, while glutamate synthase (GOGAT), glutamine synthase (GS), glutamate dehydrogenase (GDH), and cysteine synthases (CS) activities increased continuously with light intensity. Light intensity was significantly correlated with the parameters of growth, quality, nitrogen and amino acid metabolisms in ryegrass. It was recommended that PPFD at 400–500 µmol·m−2·s−1, photoperiod of 16 h/d was suitable for ryegrass high-efficient production in PFAL with relatively low energy cost.

Comparative Study of Impact of Gamma and MeV Ion Irradiations on Electrical and Optical Properties Polystyrene/Eu2O3 Nanocomposites.

In the present study, the effect of gamma irradiation and 90 MeV carbon ion beam irradiation on electrical properties and optical of Polystyrene/Eu2O3 nanocomposites at different fluences were examined. Modified electrical and optical responses of polymer nanocomposites were investigated using Impedance, Photoluminescence and UV-VIS spectroscopies. FTIR analysis shows a reduction of various modes of molecular vibrations caused by 90 MeV carbon ion beam irradiation. The polymer nanocomposites change into a graphite-like structure upon both kinds of irradiations as evidenced by the decrease in the optical band gap. The photoluminescence emission spectra show three characteristic peaks of Eu3+ ions, when excited at 247 nm wavelength. It emits intense red light suggesting its potential for usage in LED technology. The peak intensity of PL emission spectra is enhanced after ion beam irradiation and is because of the formation new radiative combination; however, it decreases upon gamma irradiation. Dielectric responses of pristine and irradiated polymer nanocomposites were studied over the frequency range of 100 Hz to 100 kHz using LCR meter. There appears a significant improvement in the dielectric response as a result of structural changes in both types of irradiations. AFM images show that the film becomes smoother upon both types of irradiations.

All‐Optically Controlled Retinomorphic Memristor for Image Processing and Stabilization

AbstractImage stabilization is a crucial field in machine vision, aiming to eliminate image blurring or distortion caused by the camera or object jitter. However, traditional image stabilization techniques often suffer from the drawbacks of requiring complex equipment or extensive computing resources, resulting in inefficiencies. In contrast, the human retina performs a highly efficient all‐in‐one system, encompassing the detection and processing of light stimuli. In this study, an all‐optically controlled retinomorphic memristor based on the CsxFAyMA1‐x‐yPb(IzBr1‐z)3 is proposed, which integrates perception, storage, and processing functions. This memristor exhibits significant advantages in image stabilization. It is capable of positively and negatively modulating its conductance using specific intensities (11.8 and 0.9 mW cm−2, respectively) of red light (630 nm). To demonstrate the effectiveness of the proposed approach, handwritten digit recognition simulations are conducted. The application of specific light stimuli effectively highlights the characteristics of blurred images. The processed images are then fed into a conductance‐mapped neural network for rapid recognition. Remarkably, the recognition rates of the processed images reach 83.5% after 19 000 iterations, surpassing the performance of blurred images (only 56.2% after 19 000 iterations). These results highlight the immense potential of retinomorphic memristors as the hardware foundation for next‐generation image stabilization systems.

The effects of intensity, spectral purity and duty cycle on red light-induced hyperopia in tree shrews.

There have recently been several clinical studies suggesting that brief periods of exposure to red light (repeated low-level red light, 'RLRL') may produce a dramatic anti-myopia effect, calling for further investigations into its therapeutic parameters. Unfortunately, many experimental species used in refractive studies develop myopia in response to this wavelength. Tree shrews are the only animal model other than rhesus monkeys that consistently exhibit hyperopic responses to ambient red light. Here, tree shrews were used to study the influence of the spectral purity, duty cycle and intensity of red light on its anti-myopic effect. Juvenile tree shrews (Tupaia belangeri) were raised from 24 to 35 days after eye opening under ambient lighting that was: standard white colony fluorescent light; pure narrow band red light of either 600, 50-100 or 5 lux; red light that was diluted with 10% white light (by lux) or 50% white and 2 s of pure red light that alternated with 2 s of pure white light (50% duty cycle). Refractive measures were taken with a NIDEK ARK-700 autorefractor and axial dimensions with a LenStar LS-900 Axial Biometer. The pro-hyperopia effect of ambient red light was greatly reduced by even small amounts of concurrent white light 'contamination', but remained robust if 2-s periods of pure white light alternated with 2 s of red. Finally, the hyperopic effect of red light was maintained at reduced luminance levels in the 50-100 lux range and only failed at 5 lux. These results have implications for understanding the mechanisms by which ambient red light affects refractive development, and possibly also for clinical therapies using RLRL. Nevertheless, it remains to be determined if the mechanism of the current clinical RLRL therapy is the same as that operating on tree shrews in ambient red light.

Flowering and fruit-set in cassava under extended red-light photoperiod supplemented with plant-growth regulators and pruning

BackgroundCassava (Manihot esculenta Crantz) is staple food and major source of calories for over 500 million people in sub-Saharan Africa. The crop is also a source of income for smallholder farmers, and has increasing potential for industrial utilization. However, breeding efforts to match the increasing demand of cassava are impeded by its inability to flower, delayed or unsynchronized flowering, low proportion of female flowers and high fruit abortions. To overcome these sexual reproductive bottlenecks, this study investigated the effectiveness of using red lights to extend the photoperiod (RLE), as a gateway to enhancing flowering and fruit set under field conditions.Materials and methodsPanels of cassava genotypes, with non- or late and early flowering response, 10 in each case, were subjected to RLE from dusk to dawn. RLE was further evaluated at low (LL), medium (ML) and high (HL) red light intensities, at ~ ≤ 0.5; 1.0 and 1.5PFD (Photon Flux Density) in µmol m−2 s−1 respectively. Additionally, the effect of a cytokinin and anti-ethylene as plant growth regulators (PGR) and pruning under RLE treatment were examined.ResultsRLE stimulated earlier flower initiation in all genotypes, by up to 2 months in the late-flowering genotypes. Height and number of nodes at first branching, particularly in the late-flowering genotypes were also reduced, by over 50%. Number and proportion of pistillate flowers more than doubled, while number of fruits and seeds also increased. Number of branching levels during the crop season also increased by about three. Earlier flowering in many genotypes was most elicited at LL to ML intensities. Additive effects on flower numbers were detected between RLE, PGR and pruning applications. PGR and pruning treatments further increased number and proportion of pistillate flowers and fruits. Plants subjected to PGR and pruning, developed bisexual flowers and exhibited feminization of staminate flowers. Pruning at first branching resulted in higher pistillate flower induction than at second branching.ConclusionsThese results indicate that RLE improves flowering in cassava, and its effectiveness is enhanced when PGR and pruning are applied. Thus, deployment of these technologies in breeding programs could significantly enhance cassava hybridizations and thus cassava breeding efficiency and impact.

Light in the box—photobiological examination chamber with light trap ventilation system for studying fungal surface cultures illustrated with Metarhizium brunneum and Beauveria brongniartii

Due to their versatile way of life as saprophytes, endophytes, and entomopathogens, fungi of the genera Metarhizium and Beauveria are exposed to varying illumination conditions in their natural habitats, which makes a thorough adaptation to light very likely. While the few available studies for these genera support this assumption, research in this field is still in its infancy and the data material restricted to only a few fungal species. Thus, the aim of this work was to explore how light influences growth, conidial production and secondary metabolite formation of two industrial relevant strains of M. brunneum (MA 43, formerly M. anisopliae var. anisopliae BIPESCO 5/F52) and B. brongniartii (BIPESCO 2). To achieve this, we constructed an easily adjustable illumination device for highly standardized photophysiological studies of fungi on Petri dishes, the so-called LIGHT BOX. With the aid of this device, M. brunneum and B. brongniartii were grown on S4G or S2G agar at 25 °C for 14 days either in complete darkness or under constant illumination with red light (λpeak = 635 nm), green light (λpeak = 519 nm) or blue light (λpeak = 452 nm). In addition, for each wavelength the effect of different illumination intensities was tested, i.e., intensities of red light ranging from 22.1 ± 0.1 to 136.5 ± 0.3 µW cm-2, green light from 16.5 ± 0.1 to 96.2 ± 0.1 µW cm-2, and blue light from 56.1 ± 0.2 to 188.9 ± 0.6 µW cm-2. Both fungi strongly responded in terms of growth, conidial production, pigmentation and morphology to changes in the wavelength and irradiation intensity. The wavelength-dependent production of the well-known secondary metabolite oosporein which is secreted by the genus Beauveria in particular, was also increased under green and blue light exposure. The established LIGHT BOX system allows not only to optimize conidial production yields with these biotechnologically relevant fungi, but also allows the photobiological exploration of other fungi.

Rare earth ions doped Bi2MoO6 luminescent materials: Pechini sol-gel synthesis, down-conversion and up-conversion multicolor emissions, and potential applications

A series of rare earth ions (Eu3+, Sm3+, Yb3+/Er3+, Yb3+/Ho3+, Yb3+/Tm3+) doped bismuth molybdate (Bi2MoO6) phosphors with excellent multicolor luminescence have been synthesized by a facile Pechini sol-gel method. XRD, EDX, and XPS results confirm the highly crystalline orthorhombic phase of Bi2MoO6 and verify that the rare earth ions (RE3+) are effectively integrated into the Bi2MoO6 matrix. During the synthesis process, the calcination conditions play an important role in obtaining the luminescent host matrix, and the optimal calcination condition for the Bi2MoO6 products is determined of 800 °C for 2 h. The Eu3+ and Sm3+ doped Bi2MoO6 samples display intense red and orange-red light under UV/visible excitation whereas the Yb3+/Ln3+ (Ln = Er, Ho, and Tm) doped Bi2MoO6 materials emit green, green, and blue colors when excited by NIR light. Both down-conversion (DC) and up-conversion (UC) multicolor luminescence are obtained by doping the proper Ln3+ activators into the Bi2MoO6 host. The doping concentrations of various RE3+ ions are optimized to generate advantageous phosphors and the luminescence mechanisms of RE3+ ions are systematically studied. The LED devices fabricated by Bi2MoO6:Yb3+/Ln3+ UC phosphors exhibit dazzling multicolor emissions under an injection current, which directly discloses that the as-prepared materials may be of great potential in LEDs and optoelectronic devices. Interestingly, the Bi2MoO6:Yb3+/Er3+/Eu3+ phosphors can simultaneously exhibit red and yellow-green DC emissions and green UC light under excitation of 464, 488, and 980 nm. The multi-mode emission features illustrate that the as-synthesized phosphors may have application prospects in anti-counterfeiting applications.

Photosensitiser-incorporated microparticles for photodynamic inactivation of bacteria.

Antimicrobial resistance is an ever-growing global concern, making the development of alternative antimicrobial agents and techniques an urgent priority to protect public health. Antimicrobial photodynamic therapy (aPDT) is one such promising alternative, which harnesses the cytotoxic action of reactive oxygen species (ROS) generated upon irradiation of photosensitisers (PSs) with visible light to destroy microorganisms. In this study we report a convenient and facile method to produce highly photoactive antimicrobial microparticles, exhibiting minimal PS leaching, and examine the effect of particle size on antimicrobial activity. A ball milling technique produced a range of sizes of anionic p(HEMA-co-MAA) microparticles, providing large surface areas available for electrostatic attachment of the cationic PS, Toluidine Blue O (TBO). The TBO-incorporated microparticles showed a size-dependent effect on antimicrobial activity, with a decrease in microparticle size resulting in an increase in the bacterial reductions achieved when irradiated with red light. The >6 log10Pseudomonas aeruginosa and Staphylococcus aureus reductions (>99.9999%) achieved within 30 and 60min, respectively, by TBO-incorporated >90μm microparticles were attributed to the cytotoxic action of the ROS generated by TBO molecules bound to the microparticles, with no PS leaching from these particles detected over this timeframe. TBO-incorporated microparticles capable of significantly reducing the bioburden of solutions with short durations of low intensity red light irradiation and minimal leaching present an attractive platform for various antimicrobial applications.