Light Of Specific Wavelength Research Articles

Vertebrate Bistable Pigment Parapinopsin: Implications for Emergence of Visual Signaling and Neofunctionalization of Non-visual Pigment

Opsins are light-sensor proteins, each absorbing a specific wavelength of light. This, in turn, drives a specific G protein-mediated phototransduction cascade, leading to a photoreceptor cell response. Recent genome projects have revealed an unexpectedly large number of opsin genes for vision and non-visual photoreception in various animals. However, the significance of this multiplicity of opsins remains largely unknown, except for that of cone visual opsins, which are diversified with respect to spectral sensitivity to achieve vertebrate color vision. Here, an implication of multiplicity is discussed, with focus on an ultraviolet-sensitive non-visual opsin—parapinopsin—that underlies pineal wavelength discrimination in lower vertebrates. Parapinopsins are phylogenetically close to vertebrate visual opsins, which have bleaching properties, but interestingly, parapinopsins are bleach-resistant bistable pigments, which photo-convert to stable photoproducts that revert to their original dark state by subsequent light absorption, similar to invertebrate rhodopsins. The unique characteristics of parapinopsin as an evolutionary intermediate between bistable and bleaching pigments provide insight into the evolutionary transition between signaling molecules that interact with two types of opsin-based pigments. Furthermore, the parapinopsin gene was duplicated in the teleost lineage and the spectral sensitivities of the duplicated parapinopsins were different from each other. On the basis of these results, together with the histochemical findings of parapinopsin, a plausible link between the diversification of a non-visual opsin parapinopsin and diverse pineal functions, wavelength discrimination, and melatonin secretion, implying why multiple opsins exist in animals, is proposed.

Tarantula tint inspires new ways of making colors

Creatures of the night that stalk their prey underground are rarely clad in bright colors. But a surprising number of tarantulas—ground-dwelling, nocturnal predators—carry hairs that are a vivid shade of blue. Last year, researchers found that this hue was surprisingly common; it actually had evolved multiple times in different lineages and converged on remarkably similar shades of blue across 40 of 53 tarantula groups (1). Several types of tarantulas, including this green bottle blue tarantula, have evolved to display a vivid shade of blue that results not from pigments, but from a phenomenon known as structural color. Image courtesy of Shutterstock/Cathy Keifer. Like many shades of blues in the natural world, tarantulas’ tints are not formed by colored pigments. Instead, they’re a result of nanostructure patterns that interfere with specific wavelengths of light, a phenomenon known as structural color. Unlike pigments, which are colored because excited electrons absorb certain wavelengths of light and emit others, structural colors are purely physical arrangements, often created by colorless materials. Figuring out the precise patterns that create tarantulas’ brilliant hues may not only offer up insights into animal adaptations, but could point to means for creating colors from new, less toxic materials: for example, longer lasting, brighter paints. One of the keys to such advances could be a tool most wouldn’t consider for the study of animal hair: 3D printing. The nanostructures in tarantulas take myriad shapes: some are smooth cylinders, …

Seasonal affective disorder (SAD) and light therapy: State of the science

Major depression with a fall/winter seasonal pattern, also known as seasonal affective disorder (SAD), is a recurrent and prevalent disorder. Treatment may include either pharmacological (antidepressant) or non-pharmacological options, most commonly light therapy. Over the years, light therapy has been explored using various delivery methods including light-emitting diode (LED) devices. For over 20 years, cool-white fluorescent sources that yield 10,000 lux of polychromatic white light have been the standard treatment for SAD. Many investigations have confirmed the clinical effectiveness of white light, its overall tolerability, and adverse reactions, such as agitation, insomnia, and headache. Building upon this, more recent studies have compared alternative light sources and different wavelengths of light, such as white, red, green, and blue. If certain wavelengths are more potent and effective, lower intensities of light could reduce side effects and increase tolerability and adherence. Furthermore, studies of the ocular system particularly, intrinsically photosensitive retinal ganglion cells, discovered differences among specific wavelengths of light. While some reports have suggested that 446–477 nm wavelengths of blue light may be the most potent, published clinical trials have revealed mixed results. The purpose of this session is to review the state of the science on light therapy in the treatment of SAD, and suggest recommendations for clinical practice and implications for patients.Disclosure of interestThe author has not supplied his/her declaration of competing interest.

Analysis of Fiber Bragg Gratings for the Elimination of Realignment During the Life of the System While FBG Is Spliced Directly to the Doped Fiber

Fiber Bragg Grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. A fiber Bragg grating can therefore be used as an inline optical filter to block certain wavelengths, or as a wavelength-specific reflector.

Sequential self-folding of polymer sheets.

Shape plays an important role in defining the function of materials, particularly those found in nature. Several strategies exist to program materials to change from one shape to another; however, few can temporally and spatially control the shape. Programming the sequence of shape transformation with temporal control has been driven by the desire to generate complex shapes with high yield and to create multiple shapes from the same starting material. This paper demonstrates a markedly simple strategy for programmed self-folding of two-dimensional (2D) polymer sheets into 3D objects in a sequential manner using external light. Printed ink on the surface of the polymer sheets discriminately absorbs light on the basis of the wavelength of the light and the color of the ink that defines the hinge about which the sheet folds. The absorbed light gradually heats the underlying polymer across the thickness of the sheet, which causes relief of strain to induce folding. These color patterns can be designed to absorb only specific wavelengths of light (or to absorb differently at the same wavelength using color hues), thereby providing control of sheet folding with respect to time and space. This type of shape programming may have numerous applications, including reconfigurable electronics, actuators, sensors, implantable devices, smart packaging, and deployable structures.

Highly Narrowband Photomultiplication Type Organic Photodetectors.

Filterless narrowband response organic photodetectors (OPDs) present a great challenge due to the broad absorption range of organic semiconducting materials. The reported narrowband response OPDs also suffer from low external quantum efficiency (EQE) in the desired response window and low rejection ratio. Here, we report highly narrowband photomultiplication (PM) type OPDs based on P3HT:PC71BM (100:1, wt/wt) as active layer without an optical filter. The full width at half-maximum (fwhm) of the PM-type OPDs can be well retained less than 30 nm under different biases. Meanwhile, the champion EQE and rejection ratio approach 53 500% and 2020 at -60 V bias, respectively. The small fwhm should be attributed to the sharp absorption edge of active layer with small amount of PC71BM. The PM phenomenon is attributed to hole tunneling injection from the external circuit assisted by trapped electron in PC71BM near the Al electrode under light illumination. These highly narrowband PM-type OPDs should have great potential applications in sensitively detecting specific wavelength light and be blind to light outside of the desired response window.

Application of photodynamic therapy in gastrointestinal disorders: an outdated or re-emerging technique?

Photodynamic therapy (PDT) is a promising therapeutic modality that involves the administration of a photosensitizer followed by local illumination with a specific wavelength of light in the presence of oxygen. PDT is minimally invasive, has high selectivity for cancer, and has good patient compliance due to the simplicity of the procedure; therefore, PDT is widely used as a palliative and salvage treatment in patients with various gastrointestinal malignancies. When used as a salvage treatment for locoregional failures after definitive chemoradiotherapy for esophageal cancer, favorable results have been reported. PDT in conjunction with biliary stenting is a promising palliative treatment for unresectable cholangiocarcinoma, and can be used as an advanced diagnostic and therapeutic strategy in peritoneal dissemination of gastric cancer. Recent clinical reports of PDT for treating non-resectable pancreatic cancer also show promising results. To widen the application of PDT, the integration of PDT with molecular imaging and nanotechnology is being extensively studied. Based on these new developments, PDT is likely to re-emerge as a valuable technique in the treatment of diverse gastrointestinal diseases.

Nanostructures for NIR light-controlled therapies.

In general, effective clinical treatment demands precision medicine, which requires specific perturbation to disease cells with no damage to normal tissue. Thus far, guaranteeing that selective therapeutic effects occur only at targeted disease areas remains a technical challenge. Among the various endeavors to achieve such an outcome, strategies based on light-controlled therapies have received special attention, mostly due to their unique advantages, including the low-invasive property and the capability to obtain spatial and temporal precision at the targeted sites via specific wavelength light irradiation. However, most conventional light-mediated therapies, especially those based on short-wavelength UV or visible light irradiation, have potential issues including limited penetration depth and harmful photo damage to healthy tissue. Therefore, the implemention of near-infrared (NIR) light illumination, which can travel into deeper tissues without causing obvious photo-induced cytotoxcity, has been suggested as a preferable option for precise phototherapeutic applications in vitro and in vivo. In this article, an overview is presented of existing therapeutic applications through NIR light-absorbed nanostructures, such as NIR light-controlled drug delivery, NIR light-mediated photothermal and photodynamic therapies. Potential challenges and relevant future prospects are also discussed.

An optically-gated AuNP-DNA protonic transistor.

Bio-interface transistors, which manipulate the transportation of ions (i.e. protons), play an important role in bridging physical devices with biological functionalities, because electrical signals are carried by ions/protons in biological systems. All available ionic transistors use electrostatic gates to tune the ionic carrier density, which requires complicated interconnect wires. In contrast, an optical gate, which offers the advantages of remote control as well as multiple light wavelength selections, has never been explored for ionic devices. Here, we demonstrate a light-gated protonic transistor fabricated from an Au nanoparticle and DNA (AuNP-DNA) hybrid membrane. The device can be turned on and off completely by using light, with a high on/off current ratio of up to 2 orders of magnitude. Moreover, the device only responds to specific light wavelengths due to the plasmonic effect from the AuNPs, which enables the capability of wavelength selectivity. Our results open up new avenues for exploring remotely controlled ionic circuits, in vivo protonic switches, and other biomedical applications.

Verteporfin based silica nanoparticle for in vitro selective inhibition of human highly invasive melanoma cell proliferation

Photodinamic therapy (PDT) has gained an increasing interest as a new tool to treat skin cancers such as melanoma. This clinical approach take advantage from the combination of a photosensitizer and a specific light wavelength able to induce singlet oxygen production. Mesoporous silica nanoparticles (MSNs) have been widely investigated as drug nanocarriers as their structure and morphology could be customized to produce suitable nanoplatforms enabling high cargo capacity.In the present study MSNs were successfully conjugated with the second generation photosensitizer verteporfin and the resulting nanoplatform (Ver-MSNs) was tested in an in vitro PDT model as a potential tool for melanoma treatment. Ver-MSNs based PDT did not affect cell proliferation of neither a normal human keratinocyte cell line (HaCaT) or a low mestastatic melanoma cell line (A375P). On the other hand Ver-MSNs based PDT deeply affect the highly invasive SK-MEL-28 melanoma cell line behavior, as testified by the strong reduction in cell proliferation along with the dramatic change in cellular morphology, through a nanoparticle internalization dependent mechanism. In fact, experiments performed in the presence of endocytosis inhibitors (chlorpromazine and amiloride) resulted in an attenuation of Ver-MSNs based PDT induced cell death, along with a recover in cellular morphology. MSN doped with verteporfin could thus represent a promising and useful tool for PDT treatment of highly invasive melanoma.

Multiwavelength micromirrors in the cuticle of scarab beetle Chrysina gloriosa.

Many insects own a tessellated carapace with bumps, pits or indentations. Little is known on the physical properties of these geometric variations and biological functions are unknown or still debated. We show that the polygonal cells in scarab beetle Chrysina gloriosa behave as multiwavelength selective micromirrors over the visible and infrared spectra, with a variety of spatial patterns. In the context of biomimetic materials, we demonstrate that the carapace has concave cells whereas the artificial films have convex cells, contrary to expectation in the literature. Thermoregulation, communication or camouflage are discussed as advanced functions. Results may provide inspiration for fabricating spatial wavelength-specific light modulators and optical packet switching in routing technologies.

Simultaneous determination of ordinary and extraordinary refractive index dispersions of nematic liquid crystals in the visible and near-infrared regions from an interference spectrum

An improved interference method is proposed to determine ordinary and extraordinary refractive index dispersions of nematic liquid crystals (LCs). In this method, an LC cell coated with a thin metal layer is used as a Fabry-Perot interferometer, which shows us a sharp transmission fringe. To ensure high reliability, the wavelength dispersion of the refractive index of the metal is taken into account in fitting calculation. In spite of measuring ordinary and extraordinary components, the LC cell, polarizers, and other equipment are not rotated during the experiment. The index evaluation from a single spectrum avoids errors depending on the measurement position owing to non-uniformities of molecular orientation and cell thickness because we can obtain the two indices at exactly the same position. This system can adapt to a wide frequency range and does not require any specific wavelength light source or laser. We demonstrate the determination of ordinary and extraordinary refractive index dispersions of a nematic liquid crystal in the visible and near-infrared regions. Furthermore, we quantitatively reproduce the measured spectrum by calculation using the measured refractive indices.

Exemplary Advancement of EPON Communication by FBG based Splitters

Objectives: In the last few years, researchers in the field of optical fibre communication have focused on designing optical filter for blocking certain wavelength using Fiber Bragg Grating (FBG). In this paper inculcates the study and research on FBG base splitters with alteration of grating length for Ethernet Passive Optical Network (EPON) is carried out. Methods/Analysis: The simulation is incorporated on simulation Software MATLAB 7.2 of Mathworks. The simulation model is constructed by varying design parameters such as grating length, which in turn attains the maximum reflectivity for the wavelengths required for EPON. We fix the values of the effective refractive index of grating and radius of the core. Here the grating length and centre wavelengths are fixed 35 mm and 1550 nm respectively and findings obtained. Findings: FBG is one of the renowned distributed Bragg reflector manoeuvred in an optical fiber of small segment and it possesses the stupendous attribute of reflecting particular wavelengths of light whilst traversing all other wavelengths. As per observations the reflectivity of the grating or the effectiveness of the grating in extracting the wavelength has a tremendous value of 100%. This filter has various applications which improve the quality and reduce the cost of an optical network.

Photodetection and Photoswitch Based On Polarized Optical Response of Macroscopically Aligned Carbon Nanotubes

Light polarization is extensively applied in optical detection, industry processing and telecommunication. Although aligned carbon nanotube naturally suppresses the transmittance of light polarized parallel to its axial direction, there is little application regarding the photodetection of carbon nanotube based on this anisotropic interaction with linearly polarized light. Here, we report a photodetection device realized by aligned carbon nanotube. Because of the different absorption behavior of polarized light with respect to polarization angles, such device delivers an explicit response to specific light wavelength regardless of its intensity. Furthermore, combining both experimental and mathematical analysis, we found that the light absorption of different wavelength causes characteristic thermoelectric voltage generation, which makes aligned carbon nanotube promising in optical detection. This work can also be utilized directly in developing new types of photoswitch that features a broad spectrum application from near-ultraviolet to intermediate infrared with easy integration into practical electric devices, for instance, a "wavelength lock".

Different Narrow-Band Light Ranges Alter Plant Secondary Metabolism and Plant Defense Response to Aphids.

Light of different wavelengths affects various physiological processes in plants. Short-wavelength radiation (like UV) can activate defense pathways in plants and enhance the biosynthesis of secondary metabolites (such as flavonoids and glucosinolates) responsible for resistance against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. In this study, broccoli (Brassica oleracea var. italica) plants were grown for 4weeks in a climate chamber under conventional fluorescent tubes and were additionally treated with UV-B (310nm), UV-A (365 or 385nm), or violet (420nm) lightgenerated with UV-B tubes or light-emitting diodes (LEDs). The objective was to determine the influence of narrow bandwidths of light (from UV-B to violet) on plant secondary metabolism and on the performance of the cabbage aphid Brevicoryne brassicae (a specialist) and the green peach aphid Myzus persicae (a generalist). Among flavonol glycosides, specific quercetin and kaempferol glycosides increased markedly under UV-B, while among glucosinolates only 4-methoxy-3-indolylmethyl showed a 2-fold increase in plants exposed to UV-B and UV-A. The concentration of 3-indolylmethyl glucosinolate in broccoli plants increased with UV-B treatment. Brevicoryne brassicae adult weights and fecundity were lower on UV-B treated plants compared to UV-A or violet light-treated plants. Adult weights and fecundity of M. persicae were increased under UV-B and UV-A treatments. When specific light wavelengths are used to induce metabolic changes in plants, the specificity of the induced effects on herbivores should be considered.

Advances in Optogenetic-based Auditory Implants

Advances in Optogenetic-based Auditory Implants

Broadband Photoreceptors Are Involved in Violet Light Preference in the Parasitoid Fly Exorista Japonica.

Phototaxis has been described in many insects, which are often attracted to specific wavelengths of light. However, little is known about phototaxis in parasitoid insect species that are potentially useful for integrated pest management. In this study, we investigated the wavelength dependency of the phototactic behavior of the parasitoid fly Exorista japonica and its possible mechanism. Multiple-choice tests with six monochromatic stimuli revealed that the flies were specifically attracted to violet light peaking at 405 nm, which was unexpected because insects are generally attracted to ultraviolet or green light. We measured the spectral sensitivity of the compound eye, and found that the sensitivity peaked at 340 nm, as in other brachyceran flies. We used statistical modeling and optimization of the process parameters to predict the type of photoreceptor contributing to the violet preference. The analysis revealed that the wavelength preference could be explained by linear models of the quanta received by photoreceptors, including the R1-6 broadband receptors. The broadband receptors appear to contribute positively, whereas the R7-8 narrowband receptors contribute negatively to achieve the violet preference; i.e., spectral opponency might be involved.

Growth of monolithic full-color GaN-based LED with intermediate carrier blocking layers

Specially designed intermediate carrier blocking layers (ICBLs) in multi-active regions of III-nitride LEDs were shown to be effective in controlling the carrier injection distribution across the active regions. In principle, the majority of carriers, both holes and electrons, can be guided into targeted quantum wells and recombine to generate light of specific wavelengths at controlled current-densities. Accordingly we proposed and demonstrated a novel monolithic InGaN-based LED to achieve three primary colors of light from one device at selected current densities. This LED structure, which has three different sets of quantum wells separated with ICBLs for three primary red-green-blue (RGB) colors, was grown by metal-organic chemical vapor deposition (MOCVD). Results show that this LED can emit light ranging from 460 to 650 nm to cover the entire visible spectrum. The emission wavelength starts at 650 nm and then decreases to 460 nm or lower as the injection current increases. In addition to three primary colors, many other colors can be obtained by color mixing techniques. To the best of our knowledge, this is the first demonstration of monolithic full-color LED grown by a simple growth technique without using re-growth process.

발광다이오드를 이용한 광파장에 따른 Chlorella vulgaris의 생장과 지방산 생산에 미치는 효과

Microalgae are considered as superior biodiesel producers, because they could effectively produce high amount of lipid with fast growth rate. In this study, Chlorella vulgaris was exposed to various light wavelengths (<TEX>${\lambda}_{max}$</TEX> 470 nm, <TEX>${\lambda}_{max}$</TEX> 525 nm, and <TEX>${\lambda}_{max}$</TEX> 660 nm) using light emitting diodes (LEDs) to examine effect of light quality on their growth and fatty acid production in 0.4-L bubble column photobioreactors. Fluorescent lamps were also used as polychromatic light sources (control). From the results, biomass productivity was varied by light wavelength from 0.05 g/L/day to 0.30 g/L/day. Maximum biomass productivity was obtained from red LED among tested ones. We also observed that contents of oleic acid and linolenic acid, which affect biodiesel properties, were significantly changed depending on supplied wavelength. These results indicated that production of algal biomass, and fatty acid content and productivity could be improved or controlled by supplying specific light wavelength.

Protein Microspheres with Unique Green and Red Autofluorescence for Noninvasively Tracking and Modeling Their in Vivo Biodegradation.

Bovine serum albumin (BSA) microspheres were prepared through a facile and low-cost route including a high-speed dispersion of BSA in cross-linking solution followed by spray drying. Interestingly the as-prepared BSA microspheres possess unique blue-green, green, green-yellow, and red fluorescence when excited by specific wavelengths of laser or LED light. The studies of UV-visible reflectance spectra and fluorescence emission spectra indicated that four classes of fluorescent compounds are presumably formed during the fabrication processes. The formation and the potential contributors for the unique green and red autofluorescence were also discussed and proposed though the exact structures of the fluorophores formed remain elusive due to the complexity of the protein system. The effect of spray-drying conditions on the morphology of spray-dried samples was investigated and optimized. FTIR was further employed to characterize the formation of the functional groups in the as-prepared autofluorescent microspheres. Good in vitro and in vivo biocompatibility was demonstrated by the cytotoxicity test on the A549 cancer cells and tissue histological analysis, respectively. The autofluorescent BSA microspheres themselves were then applied as a novel tracer for convenient tracking/modeling of the biodegradation of autofluorescent BSA microspheres injected into mouse model based on noninvasive, time-dependent fluorescence images of the mice, in which experimental data are in good agreement with the proposed mathematical model. All these studies indicate that the as-developed protein microspheres exhibiting good biocompatibility, biodegradability, and unique autofluorescence, can significantly broaden biomedical applications of fluorescent protein particles.