Short-wavelength Visible Light Research Articles

The effect of oxidative degradation of Dopa-melanin on its basic physicochemical properties and photoreactivity.

Melanin, particularly eumelanin, is commonly viewed as an efficient antioxidant and photoprotective pigment. Nonetheless, the ability of melanin to photogenerate reactive oxygen species and sensitize the formation of cyclobutane pyrimidine dimers may contribute to melanin-dependent phototoxicity. The phototoxic potential of melanin depends on a variety of factors, including molecular composition, redox state, and degree of aggregation. Using complementary spectroscopic and analytical methods we analyzed the physicochemical properties of Dopa-melanin, a synthetic model of eumelanin, subjected to oxidative degradation induced by aerobic photolysis or exposure to 0.1 M hydrogen peroxide. Both modes of oxidative degradation were accompanied by dose-dependent bleaching of melanin and irreversible modifications of its paramagnetic, ion- and electron-exchange and antioxidant properties. Bleached melanin exhibited enhanced efficiency to photogenerate singlet oxygen in both UVA and short-wavelength visible light. Although chemical changes of melanin subunits, including a relative increase of DHICA content and disruption of melanin polymer induced by oxidative degradation were considered, these two mechanisms may not be sufficient for a satisfactory explanation of the elevated photosensitizing ability of the bleached eumelanin. This study points out possible adverse changes in the photoprotective and antioxidant properties of eumelanin that could occur in pigmented tissues after exposure to high doses of intense solar radiation.

Evaluation of Phototoxicity of Short-Wavelength Laser Light Utilizing PCNA Accumulation.

In recent years, diseases such as age-related macular degeneration and retinal pigment degeneration caused by excessive exposure to short-wavelength visible light have become significant concerns. With the aim of quantitatively evaluating the toxicity of short-wavelength light, proliferating cell nuclear antigen (PCNA) accumulation at the irradiation site was investigated using live cell imaging techniques to irradiate individual living cells with short-wavelength laser light. By examining the dependency of PCNA accumulation on the irradiation site within the cells and their cell cycle, it was observed that PCNA accumulation occurred only when the cell nucleus of cells in the S phase of the cell cycle was irradiated. We investigated the accumulation of PCNA at the laser irradiation site using laser light at wavelengths of 405 nm and 375 nm, with intensities ranging from 0.5 μW to 9.0 μW. The results confirmed an increase in PCNA accumulation with increasing intensity, and a higher accumulation was observed with laser light irradiation at a wavelength of 375 nm compared to 405 nm. By comparing the PCNA accumulation and 24 h cell viability, we demonstrated the feasibility of quantitatively assessing laser light toxicity through the measurement of PCNA accumulation.

Photoadsorption of Cr(VI) on titanium dioxide modified by high-energy milling

Microcrystalline powders of rutile and anatase were milled in a high-energy planetary mill down to obtain nanosized TiO2 powders (the size of coherent scattering region (CSR) about 30 nm and 60 nm, respectively). The resulting powders were characterized by HRTEM, Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the ξ-potential of the aqueous suspensions was determined. High-energy milling made it possible to significantly increase the ability of TiO2 to remove chromium from aqueous solutions. The effectiveness of the powders for not only Cr(VI) removing but also total chromium adsorption under UV-irradiation and short wavelength visible light has been shown. This is important, since Cr(III) does not remain in the aqueous medium and cannot be oxidized back to Cr(VI) under the influence of some environmental factors. It is possible to remove more than 99.9% of total chromium and 100 % of chromium hexavalent from a 50 mg·L-1 solution of Cr(VI) using milled anatase. XPS showed that, upon the photoadsorption, Cr(VI) is reduced to Cr(III). The presence of an acetate buffer in the solution promotes the most efficient removal of chromium. This work shows a simple way to obtain a highly effective material with potential applications for the removal of high toxic hexavalent chromium from industrial wastewater. The milled anatase sample was successfully tested to remove Cr (VI) from a real wastewater sample.

Sustainable polylactide materials with the function of blocking a specific wavelength of light based on aloe-emodin

Polylactide, a biodegradable polymer, can alleviate white pollution, but the use of polylactide in food packaging is limited by high transmittance to light with a specific wavelength, UV (185–400 nm) and short-wavelength visible (400–500 nm) light. Herein, the polylactide end-capped with renewable light absorber aloe-emodin (PLA-En), is blended with commercial polylactide (PLA) to fabricate the polylactide film with the function of blocking light with a specific wavelength, PLA/PLA-En film. Only 40 % of light around 287 and 430 nm transmits through PLA/PLA-En film incorporating 3 mass% of PLA-En, while the film still maintains good mechanical properties and high transparency more than 90 % at 660 nm because of the good compatibility with PLA. The PLA/PLA-En film exhibits stable light-blocking properties under light irradiation and anti-solvent migration under the immersion of fat simulant. Almost no PLA-En migrated out of the film with the molecular weight of PLA-En only 2.89 × 104 g/mol. Compared with PLA film and commercial PE plastic wrap, the designed PLA/PLA-En film exhibits a better preservative effect on riboflavin and milk for inhibiting the production of 1O2. This study offers a green strategy for developing UV and short-wavelength light protective food package film based on renewable resource.

Potential Neuroprotective Role of Calretinin-N18 and Calbindin-D28k in the Retina of Adult Zebrafish Exposed to Different Wavelength Lights.

The incidence rates of light-induced retinopathies have increased significantly in the last decades because of continuous exposure to light from different electronic devices. Recent studies showed that exposure to blue light had been related to the pathogenesis of light-induced retinopathies. However, the pathophysiological mechanisms underlying changes induced by light exposure are not fully known yet. In the present study, the effects of exposure to light at different wavelengths with emission peaks in the blue light range (400-500 nm) on the localization of Calretinin-N18 (CaR-N18) and Calbindin-D28K (CaB-D28K) in adult zebrafish retina are studied using double immunofluorescence with confocal laser microscopy. CaB-D28K and CaR-N18 are two homologous cytosolic calcium-binding proteins (CaBPs) implicated in essential process regulation in central and peripheral nervous systems. CaB-D28K and CaR-N18 distributions are investigated to elucidate their potential role in maintaining retinal homeostasis under distinct light conditions and darkness. The results showed that light influences CaB-D28K and CaR-N18 distribution in the retina of adult zebrafish, suggesting that these CaBPs could be involved in the pathophysiology of retinal damage induced by the short-wavelength visible light spectrum.

The effect of a short-wave filtering contact lens on color appearance

We assessed the effect of a contact lens that filters short-wavelength (SW) visible light on color appearance. These effects were modeled and measured by direct comparison to a clear contact lens. Sixty-one subjects were enrolled, and 58 completed as cohort; 31 were 18 to 39 years old (mean ± SD, 29.6 ± 5.6), 27 were 40 to 65 years old (50.1 ± 8.1). A double-masked contralateral design was used; participants randomly wore a SW-filtering contact lens on one eye and a clear control lens on the other eye. Subjects then mixed three primaries (including a short-wave primary, strongly within the absorbance of the test lens) until a perceived perfect neutral white was achieved with each eye. Color appearance was quantified using chromaticity coordinates measured with a spectral radiometer within a custom-built tricolorimeter. Color vision in natural scenes was simulated using hyperspectral images and cone fundamentals based on a standard observer. Overall, the chromaticity coordinates of matches that were set using the SW-filtering contact lens (n = 58; x = 0.345, y = 0.325, u' = 0.222, v' = 0.470) and clear contact lens (n = 58; x = 0.344, y = 0.325, u' = 0.223, v' = 0.471) were not significantly different, regardless of age group. Simulations indicated that, for natural scenes, the SW-filtering contact lens that was evaluated changes L/(L+M) and S/(L+M) chromatic contrast by no more than -1.4% to +1.1% and -36.9% to +5.0%, respectively. Tricolorimetry was used to measure color appearance in subjects wearing a SW-filtering lens in one eye and a clear lens in the other, and the results indicate that imparting a subtle tint to a contact lens, as in the SW-filtering lens that was evaluated, does not alter color appearance for younger or older subjects. A model of color vision predicted little effect of the lens on chromatic contrast for natural scenes.

Beyond traditional light: NIR-II light-activated photosensitizers for cancer therapy.

With increasing demand for the accurate and safe treatment of cancer, non-invasive photodynamic therapy (PDT) has received widespread attention. However, most conventional photosensitizers are typically excited by short-wavelength visible light (400-700 nm), thus substantially hindering the penetration of light and the therapeutic effectiveness of the PDT procedure. Fortunately, near-infrared (NIR) light (>700 nm), in particular, light in the second near-infrared region (NIR-II, 1000-1700 nm) has a higher upper radiation limit, greater tissue tolerance, and deeper tissue penetration compared with traditional short-wavelength light excitation, and shows considerable potential in the clinical treatment of cancer. Therefore, it is of paramount importance and clinical value to develop photosensitizers that are excited by NIR-II light. In this review, for the first time we focus completely on recent progress made with various NIR-II photosensitizers for cancer treatment via PDT, and we briefly present the ongoing challenges and prospects of currently developed NIR-II photosensitizers for clinical practice in the near future. We believe that the above topics will inspire broad interest in researchers from interdisciplinary fields that include chemistry, materials science, pharmaceuticals, and clinical medicine, and provide insightful perspectives for exploiting new NIR-II photosensitizers for biomedical applications.

Are Blue-Cut Lenses Safe for Children? Potential Effects on Eye Length and Refractive Disorders

Blue-blocking lenses, including both spectacles and intraocular lenses, are designed to selectively reduce the intensity of short-wavelength visible light and UV radiation using a chromophore. Unlike standard spectacle lenses, which only offer varying degrees of UV protection, blue-blocking lenses provide additional benefits such as enhancing visual performance, reducing eye fatigue from digital screens, protecting the retina from phototoxicity, and minimizing disruption of the circadian rhythm caused by blue light-emitting devices used in the evening. Research has shown that the length of the eye tends to increase over time, especially during the first 10 months of life, indicating the importance of this period in eye development. The Purkinje shift is a phenomenon where the eye becomes more sensitive to blue light in the dark, and it is a normal physiological process. However, there is concern that prolonged use of blue-cut lenses in children may affect the development of eye length and contribute to an increase in refractive eye disorders.

Detection of luminescence from Vitamin B2 plate during alpha particle irradiation

Vitamin B2 (V-B2) is a material that converts shorter-wavelength light such as ultraviolet (UV) light to longer-wavelength light. However, it is not clear whether longer-wavelength light is produced by the irradiation of alpha particles. Because UV light such as Cherenkov light is required to produce longer-wavelength light for V-B2 and alpha particles do not produce Cherenkov light in a material, no light is expected to be emitted in V-B2 by the irradiation of alpha particles. However, we irradiated alpha particles to a V-B2 plate and measured the produced light in the plate. During irradiation of alpha particles, a significant amount of longer-wavelength light was observed from the V-B2 plate. The luminescence intensity of the V-B2 plate during irradiation of alpha particles was ∼1/6 of that of the plastic scintillator. The spectrum of luminescence from the V-B2 plate during this irradiation was the same as that emitted by the irradiation of ultraviolet (UV) light, which possibly indicates UV or shorter-wavelength light production in the V-B2 plate by the irradiation of alpha particles. This longer-wavelength light is not attributed to the UV light from the air scintillation by the alpha particles but to the direct irradiation of alpha particles to the V-B2 plate. From these results, we conclude that the luminescence of the V-B2 plate was the scintillation by the irradiation of alpha particles, or other phenomenon that was; UV as well as shorter-wavelength visible light was produced in the V-B2 plate by the irradiation of alpha particles and that the longer-wavelength light was produced from this light. The UV light was produced from the light generated by the dipole interaction of moving secondary electrons with V-B2 or binder molecules and then converted to the longer-wavelength light with a slower decay of the V-B2 in the plate that had high intensity due to the decreased simultaneity of the light emission.

Machine Learning Models for Predicting Breast Cancer Risk in Women Exposed to Blue Light from Digital Screens.

Nowadays, there is a growing global concern over rapidly increasing screen time (smartphones, tablets, and computers). An accumulating body of evidence indicates that prolonged exposure to short-wavelength visible light (blue component) emitted from digital screens may cause cancer. The application of machine learning (ML) methods has significantly improved the accuracy of predictions in fields such as cancer susceptibility, recurrence, and survival. To develop an ML model for predicting the risk of breast cancer in women via several parameters related to exposure to ionizing and non-ionizing radiation. In this analytical study, three ML models Random Forest (RF), Support Vector Machine (SVM), and Multi-Layer Perceptron Neural Network (MLPNN) were used to analyze data collected from 603 cases, including 309 breast cancer cases and 294 gender and age-matched controls. Standard face-to-face interviews were performed using a standard questionnaire for data collection. The examined models RF, SVM, and MLPNN performed well for correctly classifying cases with breast cancer and the healthy ones (mean sensitivity> 97.2%, mean specificity >96.4%, and average accuracy >97.1%). Machine learning models can be used to effectively predict the risk of breast cancer via the history of exposure to ionizing and non-ionizing radiation (including blue light and screen time issues) parameters. The performance of the developed methods is encouraging; nevertheless, further investigation is required to confirm that machine learning techniques can diagnose breast cancer with relatively high accuracies automatically.

The Inhibitory Effect of Blue Light on Phagocytic Activity by ARPE-19 Cells.

Chronic exposure of the retina to short wavelength visible light is a risk factor in pathogenesis of age-related macular degeneration. The proper functioning and survival of photoreceptors depends on efficient phagocytosis of photoreceptor outer segments (POS) by retinal pigment epithelium. The purpose of this study was to analyze the phagocytic activity of blue light-treated ARPE-19 cells, and to examine whether the observed effects could be related to altered levels of POS phagocytosis receptor proteins and/or to oxidation of cellular proteins and lipids. POS phagocytosis was measured by flow cytometry. Phagocytosis receptor proteins αv and β5 integrin subunits and Mer tyrosine kinase (MerTK) were quantified by western blotting. The intact functional heterodimer αvβ5 was quantified by immunoprecipitation followed by immunoblotting. Cellular protein and lipid hydroperoxides were analyzed by coumarin boronic acid probe and iodometric assay, respectively. Cell irradiation induced reversible inhibition of specific phagocytosis and transient reductions in phagocytosis receptor proteins. Full recovery of functional heterodimer was apparent. Significant photooxidation of cellular proteins and lipids was observed. The results indicate that transient inhibition of specific phagocytosis by blue light could be related to the reduction in phagocytosis receptor proteins. Such changes may arise from oxidative modifications of cell phagocytic machinery components.

Theoretical exploration of mechanical, electronic structure and optical properties of aluminium based double halide perovskite.

The mechanical, electronic structure and optical properties of aluminium based double halide perovskite were calculated by density functional theory. The formation energy and elastic constant confirm the stability of the cubic perovskite materials. The materials are all ductile and suitable for flexible photovoltaic and optoelectronic devices. The band gap values vary from 0.773 eV to 3.430 eV, exactly corresponding to the range of ideal band gap values for good photoresponse. The band structure analysis shows that all the materials possess small effective mass, which indicates a good transport of carriers. And these materials have a broad energy range of optical absorption for utilization and a detector of photons. Moreover, less expensive K2AgAlBr6 were investigated for comparison with materials containing a cesium element, and according to the results, is also a candidate for photoelectronic devices due to the similar properties.

Cell Phone Acne: New Acne Clinical Features in the Coronavirus Disease-19 Era

Technological developments in telecommunications, especially cell phone, enable us to keep communicate without meeting each other. Especially during the latest coronavirus outbreak, when people need to keep up social distance. Meanwhile, electronic devices such as smartphone, tablets, laptops, and light-emitting diode screens are the sources of visible lights that can emit high levels of short-wavelength visible light (blue region in the light spectrum). Prolonged exposure to high-energy blue light, heat dissipation from cell phone, friction, trapped sweat and oil, accumulation of dust, and increased bacterial growth can cause cell phone acne. Management of cell phone acne from prevention to combination therapy based on the results of the evaluation of the severity of acne is needed.

Lethal effect of blue light on the developmental stages of the urban mosquito, Culex pipiens form molestus (Diptera: Culicidae)

We previously reported that short-wavelength visible light (blue light: 400–500 nm) has a lethal effect on various insect species and that the most toxic wavelength to the pupae of the hygiene pest, the mosquito, Culex pipiens form molestus Forskal (Diptera: Culicidae), is 417 nm. However, previous reports on Drosophila melanogaster Meigen (Diptera: Drosophilidae), and Galerucella grisescens (Joannis) (Coleoptera: Chrysomelidae) demonstrated that the most harmful wavelengths of blue light differed among different developmental stages. The most toxic wavelengths to the developmental stages of C. pipiens f. molestus, besides the pupal stage, remain unclear. We investigated the lethal effect of various wavelengths of the blue-light spectrum on the eggs, larvae, and adults of C. pipiens f. molestus using light-emitting diodes (LEDs). Blue light irradiation had a lethal effect on all life stages tested. Furthermore, our results reaffirmed the results of previous studies, where 417 nm light had a strong effect on all life stages. To our knowledge, this is the first report of an insect species where the most effective wavelength does not vary among developmental stages. In addition, our findings indicate that ~ 420 nm is the most promising wavelength to control C. pipiens f. molestus populations using blue-light irradiation.

Red-Light Driven Photocatalytic Oxime Ligation for Bioorthogonal Hydrogel Design.

Light-mediated polymer cross-linking is frequently employed for the preparation of hydrogels for biomedical applications. However, most photopolymerization processes require activation by UV light or short wavelength visible light, which are highly absorbed by skin and tissue, limiting their uses in transdermal initiation. Herein, we introduce red light-enabled oxime ligation by the in situ photogeneration of aldehydes, which rapidly react with hydroxylamines. We demonstrate efficient polymer cross-linking behind a dermal tissue model by red light initiation. Optimization of the photopolymerization conditions allows for 3D encapsulation of human foreskin fibroblasts with good cell viability postencapsulation.

Application of transparent a-ITZO/Al2O3 coupled an MSIM diode into a photo-sensing switch

We introduce a transparent diode that consists of a coupled junction of amorphous indium tin zinc oxide and Al2O3. In addition, the photo-sensing behavior under visible light was investigated. In the initial dark state, the diode exhibited maximum on current density of 10 A/cm2 and off current density of 10−9 A/cm2–10−10 A/cm2. Because of the extremely low off current level, it exhibited an excellent on/off ratio of 1010–1011. The light sensibility of the diode started from as low as 250 lux, and the off current density increased about three orders of magnitude under the exposure of 3000 lux. Such an off current density increase turned out to be mainly due to the short wavelength (400 nm) visible light, which has enough energy to generate photo-electrons from the valence band or deep level trap site to the conduction band. Meanwhile, a square pulse type dynamic light sensing test resulted in residual current at the dark state. The residual current was electrically removed by applying a forward bias, and the identical light sensing reproducibility was confirmed by repetitive trials.

On-demand and tunable dual wavelength release of antibody using light-responsive hydrogels.

There has been an increased interest in the use of protein therapeutics, especially antibodies, for the treatment of a variety of diseases due to their high specificity to tissues and biological pathways of interest. However, the use of antibodies can be hindered by physical aggregation, degradation, and diffusion when injected in vivo leading to the need for antibody-releasing depots for the controlled and localized delivery within tissues of interest. Here, we investigated photolabile hydrogel chemistries for creating on-demand and tunable antibody release profiles. Innovative, scalable synthetic procedures were established and applied for fabricating hydrogels with nitrobenzyl (NB) and coumarin (CMR) photolabile crosslinks that responded to clinically relevant doses of long-wavelength UV and short-wavelength visible light. This synthetic procedure includes a route to make a CMR linker possessing two functional handles at the same ring position with water-stable bonds. The photocleavage properties of NB and CMR crosslinked hydrogels were characterized, as well as their potential for translational studies by degradation through pig skin, a good human skin mimic. The mechanism of hydrogel degradation, bulk versus surface eroding, was determined to be dependent on the wavelength of light utilized and the molar absorptivity of the different photolabile linkers, providing a facile means for altering protein release upon hydrogel degradation. Further, the encapsulation and on-demand release of a model monoclonal antibody was demonstrated, highlighting the ability to control antibody release from these hydrogels through the application of light while retaining its bioactivity. In particular, the newly designed CMR hydrogels undergo surface erosion-based protein release using visible light, which is more commonly used clinically. Overall, this work establishes scalable syntheses and relevant pairings of formulation-irradiation conditions for designing on-demand and light-responsive material systems that provide controlled, tunable release of bioactive proteins toward addressing barriers to preclinical translation of light-based materials and ultimately improving therapeutic regimens.

Effect of light on the calretinin and calbindin expression in skin club cells of adult zebrafish

In the last decade, zebrafish has been used as a model for the study of several human skin diseases. The epidermis of Danio rerio is composed of keratinocytes and two types of secretory cells: mucous cells and club cells. Club cells have multiple biological functions and among them may be important in the protection against ultraviolet damage through the proliferative response or through the increased production of protective substances. Calcium-binding proteins such as calbindin D28K and calretinin are used as markers of nervous and enteric nervous systems, but they are present in numerous other cells. These proteins are involved in a wide variety of cell activities, such as cytoskeletal organization, cell motility and differentiation, cell cycle regulation and neuroprotective function. In this study we demonstrated, for the first time, the presence of calretinin and calbindin D28K in skin club cells of Danio rerio exposed to different wavelengths by immunohistochemistry analysis. Exposure to white-blue light and blue light causes the expression and colocalization of calbindin-D28K and calretinin. These proteins were moderately expressed and no colocalization was observed in the club cells of the control fish. In zebrafish exposed to continuous darkness for 10days, in the club cells the two antibodies did not detect any proteins specifically. These results demonstrate that calbindin and calretinin could be involved in the pathophysiology of skin injury due to exposure to short-wavelength visible light spectrums.

Visible-Light-Driven Photoswitching of Aggregated-Induced Emission-Active Diarylethenes for Super-Resolution Imaging.

Photoswitchable fluorescent diarylethenes are promisingly widely applied in the fields of optical memory, all-optical transistors, bioimaging, and super-resolution imaging, and so on. However, they face the problems of fluorescence quenching in an aggregated/solid state, the inadequate fluorescence ON/OFF switching ratio, and the necessity of UV-light irradiation. Herein, we report a novel kind of high-performance diarylethenes with aggregated-induced emission (AIE) by conjugating two diarylethene groups on one AIE-gen (i.e., TPE-2DTE (blue-green fluorescent) and OTPE-2DTE (orange fluorescence)). Their open forms show enhanced fluorescence in the aggregated and solid states. The closed form of TPE-2DTE/OTPE-2DTE was effectively generated upon short-wavelength visible-light (400 nm-450 nm) irradiation, whose fluorescence was dramatically quenched by intra- and inter-molecular energy transfer. Remarkably, 405 nm purple irradiation gives fluorescence ON/OFF ratios of 1196:1 and 1983:1 for TPE-2DTE and OTPE-2DTE, respectively. The reverse process can be accomplished after another longer wavelength irradiation such as 621 nm and shows considerable fatigue resistance. Taking advantage of superior photoswitching properties under visible-light irradiation, TPE-2DTE and OTPE-2DTE were used for super-resolution imaging with a high resolution of sub 50 nm. This work offers guidance to design bright-emitting and high-performance visible-light-controlled diarylethene photoswitches for practical applications.

Removing Short Wavelengths From Polychromatic White Light Attenuates Circadian Phase Resetting in Rats.

Visible light is the principal stimulus for resetting the mammalian central circadian pacemaker. Circadian phase resetting is most sensitive to short-wavelength (blue) visible light. We examined the effects of removing short-wavelengths < 500 nm from polychromatic white light using optical filters on circadian phase resetting in rats. Under high irradiance conditions, both long- (7 h) and short- (1 h) duration short-wavelength filtered (< 500 nm) light exposure attenuated phase-delay shifts in locomotor activity rhythms by (∼40–50%) as compared to unfiltered light exposure. However, there was no attenuation in phase resetting under low irradiance conditions. Additionally, the reduction in phase-delay shifts corresponded to regionally specific attenuation in molecular markers of pacemaker activation in response to light exposure, including c-FOS, Per1 and Per2. These results demonstrate that removing short-wavelengths from polychromatic white light can attenuate circadian phase resetting in an irradiance dependent manner. These results have important implications for designing and optimizing lighting interventions to enhance circadian adaptation.