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Advancements in optoelectronic biointerfaces have revolutionized healthcare by enabling targeted stimulation and monitoring of cells, tissues, and organs. Photostimulation, a key application, offers precise control over biological processes, surpassing traditional modulation methods with increased spatial resolution and reduced invasiveness. This perspective highlights three approaches in non-genetic optoelectronic photostimulation: nanostructured phototransducers for cellular stimulation, micropatterned photoelectrode arrays for tissue stimulation, and thin-film flexible photoelectrodes for multiscale stimulation. Nanostructured phototransducers provide localized stimulation at the cellular or subcellular level, facilitating cellular therapy and regenerative medicine. Micropatterned photoelectrode arrays offer precise tissue stimulation, critical for targeted therapeutic interventions. Thin-film flexible photoelectrodes combine flexibility and biocompatibility for scalable medical applications. Beyond neuromodulation, optoelectronic biointerfaces hold promise in cardiology, oncology, wound healing, and endocrine and respiratory therapies. Future directions include integrating these devices with advanced imaging and feedback systems, developing wireless and biocompatible devices for long-term use, and creating multifunctional devices that combine photostimulation with other therapies. The integration of light and electronics through these biointerfaces paves the way for innovative, less invasive, and more accurate medical treatments, promising a transformative impact on patient care across various medical fields. Highlights: • Non-genetic optoelectronic biointerfaces revolutionize healthcare by enabling precise biological stimulation and monitoring. • Key methods include nanostructured phototransducers, micropatterned arrays, and thin-film flexible electrodes. • Future advancements will integrate imaging, develop wireless devices, and create multifunctional therapies, transforming patient care. [ABSTRACT FROM AUTHOR]

In this paper the photobiomodulation on isolated mitochondria of bovine liver is studied as a thermodynamic process of conversion of energy. This analysis is conducted by considering a particular set-up for the photobiomodulation experiments of interest. It allows, in particular, the computation of the electromagnetic field and the related energetic quantities in the stimulated organelles. The measurements of the excess of biochemical power density produced by the illuminated mitochondria are performed at regular time intervals after the experiments. The calculations and the measurements finally allow us to obtain the first results on the efficiency of the process of conversion of electromagnetic energy into excess of biochemical energy released by the isolated organelles. [ABSTRACT FROM AUTHOR]

The two leading causes of blindness in the developed world are age-related macular degeneration and retinitis pigmentosa. The photostimulation of remaining retinal neurons using a photodiode in a proposed subretinal prosthesis is one of the solutions that hopes to restore vision. In this paper, we envision a better result through device simulation and modeling of a graphene-based photodiode that yields high-performance, wire-free, and light-induced retina implants. This study shows how the characteristics of graphene-based photodiodes have an improved result in terms of low threshold requirements for the activation of neurons. Graphene-based photodiode responsiveness is significantly improved in the visible and near-infrared ranges. Using a graphene photoconductive layer in a silicon photodiode can significantly decrease contact resistance, reduce dark current up to 20-fold, and lower the induced thermal effect and spontaneous emission by orders of magnitude of 103 and 106, respectively, compared to its Si counterparts. This advancement highlights graphene's potential for optimizing metal–semiconductor interfaces, offering improved precision and sensitivity for high-resolution retinal prosthesis applications requiring enhanced signal-to-noise ratio and finer control. We offered a range of sizes for graphene-based photodiode arrays, including [5 × 5], [6 × 6], [6 × 7], and [7 × 6], to ensure the subretinal prostheses meet thermal safety standards. Physics-based modeling and simulation of graphene-based devices help us understand charge transfer mechanisms, improve operating bias, and achieve proper band gap modulation, which ushers in the development of graphene-like 2D materials for photostimulating neurons in projected retinal prostheses. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is an age-related neurodegenerative disorder that poses a significant burden on socio-economic and healthcare systems worldwide. However, the currently available therapy of AD is limited, and new strategies are needed to enhance the clearance of β-amyloid (Aβ) protein and improve cognitive function. Photobiomodulation (PBM) is a non-invasive and effective therapeutic method that has shown promise in treating various brain diseases. Here, we demonstrate that 1267-nm PBM significantly alleviates cognitive decline in the 5xFAD mouse model of AD and is safe as it does not induce a significant increase in cortical temperature. Moreover, with the combination of 3D tissue optical clearing imaging and automatic brain region segmentation, we show that PBM-mediated reductions of Aβ plaques in different subregions of prefrontal cortex and the hippocampus are different. The PBM-induced lymphatic clearance of Aβ from the brain is associated with improvement of memory and cognitive functions in 5xFAD mice. Our results suggest that the modulation of meningeal lymphatic vessels (MLVs) should play an important role in promoting Aβ clearance. Collectively, this pilot study demonstrates that PBM can safely accelerate lymphatic clearance of Aβ from the brain of 5xFAD mice, promoting improvement of neurocognitive status of AD animals suggesting that PBM can be an effective and bedside therapy for AD. [ABSTRACT FROM AUTHOR]

Gq-coupled receptors regulate numerous physiological processes by activating enzymes and inducing intracellular Ca2+ signals. There is a strong need for an optogenetic tool that enables powerful experimental control over Gq signaling. Here, we present chicken opsin 5 (cOpn5) as the long sought-after, single-component optogenetic tool that mediates ultra-sensitive optical control of intracellular Gq signaling with high temporal and spatial resolution. Expressing cOpn5 in HEK 293T cells and primary mouse astrocytes enables blue light-triggered, Gq-dependent Ca2+ release from intracellular stores and protein kinase C activation. Strong Ca2+ transients were evoked by brief light pulses of merely 10 ms duration and at 3 orders lower light intensity of that for common optogenetic tools. Photostimulation of cOpn5-expressing cells at the subcellular and single-cell levels generated fast intracellular Ca2+ transition, thus demonstrating the high spatial precision of cOpn5 optogenetics. The cOpn5-mediated optogenetics could also be applied to activate neurons and control animal behavior in a circuit-dependent manner. cOpn5 optogenetics may find broad applications in studying the mechanisms and functional relevance of Gq signaling in both non-excitable cells and excitable cells in all major organ systems. [ABSTRACT FROM AUTHOR]

Rhythmic light stimulation can alter the electrical activity of the human and animal brain. Moreover, the brain response to certain flicker frequencies significantly exceeds the responses to neighboring frequencies. This phenomenon is thought to be related with the effect of resonance, as evidenced by the coincidence of one of the maxima in the profile of the response to flashes with the frequency of the alpha rhythm. However, other frequencies that cause an increased response to flashes are not reflected in electroencephalogram (EEG) as dominant oscillations. The goal of this study was to reveal the relationship between local maxima in the profile of the responses to flashes of different frequencies and dominant brain oscillations recorded in electrocorticogram (ECoG) of rhesus monkeys without stimulation. The study was carried out on four male rhesus monkeys Macaca mulatta. In three animals, peak responses were elicited by flickers at 8 and 16 Hz, while one monkey showed the second peak in the 22–30 Hz range. The first maximum (8–10 Hz) in the profile of the response to rhythmic photostimulation coincided with the dominant rhythm recorded in the occipital and parietal regions at rest. The second maximum at 16 Hz coincided with the dominant ECoG rhythm in one of the primates when it was in the state of emotional arousal, which may account for the resonant origin of the increase in responses in this frequency range. The data obtained indicate that dominant brain rhythms, including latent rhythms revealed only by rhythmic photostimulation, can coincide in frequency in monkeys and humans. The mechanisms behind the selective sensitivity of neural networks to different frequencies of photostimulation are discussed. [ABSTRACT FROM AUTHOR]

The protocol of optogenetic ChR2-mediated activation of astrocytes was used in a model of artificial neurogenic niche, neurospheres implanted into ex vivo organotypic cultures of mouse hippocampus. The electrophysiological characteristics of the hippocampus and expression of molecules involved in the mechanisms of activation of astrocytes and microglia (GFAP, CD38, C3/C3b, Cx43, CD11b, and CD18) were evaluated. Photoactivation of astrocytes led to activation of neurogenesis and changes in the expression of molecules (Cx43 and CD38) that determine bioavailability of NAD+ to ensure proliferative activity of cells in the neurogenic niche. Implantation of neurospheres into organotypic slices of the hippocampus caused an increase in C3/C3b expression and suppression of the synaptic plasticity of hippocampal neurons. [ABSTRACT FROM AUTHOR]

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This paper examines the effect of electromagnetic waves, with maxima in the green or red regions of the spectrum, on the morphofunctional state of multipotent mesenchymal stromal cells. The illumination regimes used in our experiments did not lead to any substantial heating of the samples; the physical parameters of the lighting were carefully monitored. When the samples were illuminated with a green light, no significant photostimulatory effect was observed. Red light, on the other hand, had an evident photostimulatory effect. It is shown that photostimulation with a red light decreases the enzymatic activities of mitochondrial dehydrogenases and enhances the viability of cells, their proliferative activity, and their ability to form bone tissue. It is also established that red light stimulates cell proliferation, while not activating the genes that increase the risk of the subsequent malignant transformation of cells or their death. This paper discusses the possible role of hydrogen peroxide in the processes examined. [ABSTRACT FROM AUTHOR]

Low-level laser therapy (LLLT) has been used for more than 30 years to heal wounds. In recent years, LLLT or photostimulation has been indicated as an effective tool for regenerative and dental medicine by using monochromatic light. The aim of this study is to indicate the usability of plasma arc light source for bone regeneration. This is why we used polychromatic light source providing effective wavelengths in the range of 590-1500 nm for cellular response and investigated photostimulation effects on osteogenic differentiation of human mesenchymal stem cells (hMSCs) seeded on 3D silk scaffolds. Cellular responses were examined by using cell culture methods in terms of proliferation, differentiation, and morphological analyses. The results showed that photostimulation with a polychromatic light source (applied for 5 min from the 3rd day after seeding up to the 28th day in 2-day intervals with 92-mW/cm2 power from 10-cm distance to the cells) enhanced osteogenic differentiation of hMSCs according to higher alkaline phosphatase (ALP) activity, collagen and calcium content, osteogenic gene expressions, and matrix mineralization. In conclusion, we suggest that the plasma arc light source that was used here has a great potential for bone regeneration. [ABSTRACT FROM AUTHOR]

One of the central problems in the study of brain-computer interface and the processes of operant conditioning is the optimal organization of feedback signals. In this paper we have analyzed the question about comparative efficiency of immediate or 2.56-s delayed presentation of feedback signals as photic stimulation automatically controlled by subject's electroencephalogram (EEG). Strictly controlled experiments showed a significant increase in EEG power and positive shifts in subjective characteristics only under the minimum feedback delay, i.e., in cases where photic stimuli are controlled directly by the current EEG characteristics of the subjects. [ABSTRACT FROM AUTHOR]

Copyright of HNO is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ascending sensory information is conveyed from the thalamus to layers 4 and 6 of the sensory cortical areas. Interestingly, receptive field properties of cortical layer-6 neurons differ from those in layer 4. Do such differences reflect distinct inheritance patterns from the thalamus, or are they derived instead from local cortical circuits? To distinguish between these possibilities, we utilized in vitro slice preparations containing the thalamo-cortical pathways of the auditory and somatosensory systems. Responses from neurons in layers 4 and 6 that resided in the same column were recorded using whole-cell patch clamp. Laser-scanning photostimulation via uncaging of glutamate in the thalamus and cortex was used to map the functional topography of thalamo-cortical and intracortical inputs to each layer. In addition, we assessed the functional divergence of thalamo-cortical inputs by optical imaging of flavoprotein autofluorescence. We found that the thalamo-cortical inputs to layers 4 and 6 originated from the same thalamic domain, but the intracortical projections to the same neurons differed dramatically. Our results suggest that the intracortical projections, rather than the thalamic inputs, to each layer contribute more to the differences in their receptive field properties. [ABSTRACT FROM AUTHOR]

There are many methods of healing wounds. Among these, light therapy is reported to be beneficial, as beams assist the human body in treating, sterilizing, and regenerating cells. Both Laser and LED irradiation with specific wavelengths induce proliferation of fibroblasts depending on the wound area or wavelength and are effective in wound healing. This study used 8-week-old 250-300 g Male Sprague-Dawley Rats (ILAR Code: NTacSam:SD). The experiment was carried out for the non-irradiation group and the Red-Green-Blue LEDs irradiation groups ( n of each group = 5). The experiment animals were relieved for 24 h after wounds had been excised and then the Red-Green-Blue LEDs irradiation groups were given irradiation therapy over 9 days 1 h per day. Immunohistochemical staining was conducted for cytokeratin in order to precisely measure the defect size. Also, Masson's trichrome staining was conducted for comparison of collagen between the Red-Green-Blue LEDs irradiation groups and the non-irradiation group. Animals treated with Blue LEDs irradiation ( p < 0.05), Green LEDs irradiation ( p < 0.05), and Red LEDs irradiation (N.S.) healed at a faster rate than non-irradiated group. The LEDs irradiated groups also had more collagen, according to Masson's trichrome staining for collagen analysis. The Red-Green-Blue LEDs irradiation had a beneficial effect on wound healing and could probably replace low power laser treatment. [ABSTRACT FROM AUTHOR]

We examined 12- to 13-year-old children, inhabitants of industrial regions of Ukraine with high levels of environmental contamination; these children suffered from autonomic disorders. Conventional norms for the contents of lead and calcium were exceeded in samples of biologically stable tissues (hairs) of these children; strontium concentrations corresponded to reference values. The analysis of correlations of the absolute and relative spectral powers of EEG frequency components under conditions of rhythmic photoand phonostimulation with the contents of the above elements showed that there were both similarities and specificities of neurotropic effects of these elements at the systemic level. With higher lead concentrations, we observed lower, in general, values of the integral power of EEG activity, while the balance of excitatory and inhibitory neural processes was preserved. The patterns of effects of calcium and strontium were more similar to each other but were dissimilar in the levels of expression. The described effects were, to a great extent, found in EEG samples recorded under conditions of rhythmic photostimulation. We conclude that lead and calcium demonstrated relatively higher neurotropic activities within the examined group. [ABSTRACT FROM AUTHOR]

Experimental studies of photostimulation of the visual analyzer by combinations of red, green, blue, and yellow colors in a pulsed mode were carried out. Significant improvement of a visual acuity is shown after photostimulation course in patients with macular degeneration and degenerative changes of the optic nerve. [ABSTRACT FROM AUTHOR]

High yields of free radicals (10-10 spin g) were found upon the low-temperature (77 K) chlorination of solid synthetic polymers on irradiation with light with λ ≥ 360 nm. The stage of radical formation was considered in the framework of the mechanism of concerted reactions in the polymolecular complex [polymer-Cl]. [ABSTRACT FROM AUTHOR]

A large body of evidence indicates that astrocytes play an important role in a range of brain functions through calcium (Ca2+) signaling. Experimentally evoking Ca2+ signaling is a useful technique for investigating the functions of astrocytes. However, conventional stimulation methods typically have poor spatio-temporal precision, and some are invasive. Our group has developed a technique to overcome these problems, in which astrocytes are photostimulated with a femtosecond laser. In the current study, we applied this method to a hippocampal neural network to explore astrocytic functions in detail. The results revealed that applying photostimulation to astrocytes in a cultured hippocampal astrocyte-neuron network caused the following changes: (i) Synchronous Ca2+ oscillations in neurons were induced; (ii) spontaneous Ca2+ synchrony instantaneously emerged; and (iii) high-frequency spontaneous Ca2+ synchrony was regulated. Thus, astrocytic Ca signaling evoked by photostimulation was found to modulate synchronous Ca2+ oscillations in hippocampal neurons. We propose that photostimulation with a femtosecond laser will serve as a powerful tool in investigating astrocytic functions at the network level. [ABSTRACT FROM AUTHOR]

The effects of photostimulation with different colors on α-rhythm amplitude and parameters of variation pulsometry were studied. Green color stimulation modulates human functions: α-rhythm amplitude increases by 1.06 μV/√Hz ( p<0.05) and the index of regulatory systems strain decreases significantly ( p<0.05). [ABSTRACT FROM AUTHOR]

Phototherapy stimulates metabolic processes in healing wounds. Despite worldwide interest, phototherapy is not firmly established or practiced in South Africa. This study aimed to determine which dose and wavelength would better induce healing in vitro. Diabetic-induced wounded fibroblasts were irradiated with 5 or 16 J/cm2 at 632.8, 830, or 1,064 nm. Cellular morphology, viability (Trypan blue and apoptosis), and proliferation (basic fibroblast growth factor) were then determined. Cells irradiated with 5 J/cm2 at 632.8 nm showed complete wound closure and an increase in viability and basic fibroblast growth factor (bFGF) expression. Cells irradiated at 830 nm showed incomplete wound closure and an increase in bFGF expression. Cells irradiated at 1,064 nm showed incomplete closure and increased apoptosis. All cells irradiated with 16 J/cm2 at all three wavelengths showed incomplete wound closure, increased apoptosis, and decreased bFGF expression. This study showed that diabetic-wounded cells respond in a dose- and a wavelength-dependent manner to laser light. Cells responded the best when irradiated with a fluence of 5 J/cm2 at a wavelength of 632.8 nm. [ABSTRACT FROM AUTHOR]

Copyright of HNO is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

New hypotheses are advanced relating to the functional role and mechanisms of interaction of afferentation from the two eyes in the visual cortex of animals with poorly developed binocular vision. The proposed approach sheds light on a number of questions, particularly those concerning the relatively large level of disparity of the receptor fields in cortical neurons, the role of non-overlapping fibers in the visual tract, and others. Hypothesis relating to the evolutionary relationships between these mechanisms and the mechanisms of stereopsis are discussed. [ABSTRACT FROM AUTHOR]

We investigated the electrical activity of the occipital, sensorimotor, and frontal zones in the right and left hemispheres of the cerebral cortex and times for bimanual motor response in healthy adult experimental subjects between the ages of 15 and 25 receiving photostimulation by means of pulse trains with frequencies increasing from 15 to 25 Hz and pulse trains with frequencies decreasing from 15 to 5 Hz. We observed nonspecific physiological reactions in the organism regardless of the type of photostimulation presented and also observed specific reactions dictated by the parameters of the light stimulus acting upon the brain. It was demonstrated that the action of the light was most effective when the frequency of the stimuli was gradually increased. The expressiveness of the α-band of oscillations in the electrical brain activity increased in this case, and the asymmetry of the bimanual motor responses changed significantly. A definite connection was noted between the physiological reactions of the experimental subjects and their subjective states. [ABSTRACT FROM AUTHOR]

Background: Photostimulation using low-power laser had been used for nervous repair with interesting results. This study aimed to evaluate the influence of 20 mW low-power He-Ne laser on the regeneration of a peripheral sciatic nerve after trauma using the Albino rabbit as an animal model for experimental treatment.Methods: Six adult male rabbits were randomly assigned into two equal groups (control- and laser-treated). General anesthesia was administered intramuscularly, and exploration of the sciatic nerve was done in the lateral aspect of the legs. Complete longitudinal and reverse sections of the nerve were performed, which was followed by crushing of the neural sheath. Treatment was carried out directly after the trauma. Irradiation doses of low-level laser therapy (LLLT-31.5 J/cm2) with once a day application for 10 consecutive days and observed for 30 days. The animals were followed up for an extra 2 weeks. Two important factors were examined histopathology and functionality of the nerve.Results: Compared to the control group, significant variations in regeneration were observed, including thicker nerve fibers, and more regular myelin layers in the treated group.Conclusions: The results of the present study suggest that laser therapy may be a viable approach for nerve regeneration and repair. [ABSTRACT FROM AUTHOR]

The trivalent ytterbium (Yb 3+ ) ion has been extensively used as an emitter in short-wave infrared (SWIR) lasers, a sensitizer to activate other lanthanide ions for up-conversion luminescence, and a spectral converter in Ln 3+ -Yb 3+ doubly doped quantum cutting phosphors. Here we report a new function of the Yb 3+ ion-as an efficient emitting center for SWIR persistent luminescence. We have developed the first real SWIR persistent phosphor, MgGeO 3 :Yb 3+ , which exhibits very-long persistent luminescence at around 1000 nm for longer than 100 h. The MgGeO 3 :Yb 3+ phosphor is spectrally transparent to visible/near-infrared light (~400-900 nm) and is a promising ultraviolet-to-SWIR spectral convertor. The MgGeO 3 :Yb 3+ phosphor also exhibits a photostimulated persistent luminescence capability, where the SWIR persistent emission in an ultraviolet-light pre-irradiated sample can be rejuvenated by low-energy light (white or red light) stimulation. The MgGeO 3 :Yb 3+ phosphor is expected to have promising applications in biomedical imaging, night-vision surveillance and photovoltaics., Competing Interests: The authors declare no conflict of interest.