Penetration Depth Of Light Research Articles

Whole Tissue Imaging of Cellular Boundaries at Sub-Micron Resolutions for Automatic Cell Segmentation: Applications in Epithelial Bending of Ectodermal Appendages.

For decades, biologists have relied on confocal microscopy to understand cellular morphology and the fine details of tissue structure. However, traditional confocal microscopy of tissues have limited penetration depths of light ∼ 100 µm due to tissue opaqueness. Researchers have, thus, developed tissue clearing protocols to be used with confocal microscopy, however, current clearing protocols are not compatible with labels of cell boundaries, especially at high enough resolution to precisely segment individual cells. In this work, we devise a method to retain markers of cell boundaries, and refractive index-match the tissues with water to enable tissue imaging at high magnification using long working distance water dipping objectives. The sub-micron resolution of these images allows us to automatically segment each individual cell using a trained neural network segmentation model. These segmented images can then be utilized to quantify cell properties and morphology of the entire three-dimensional tissue. As an example application, we first test our methodology on mandibles of mutant mice that express fluorescent proteins in their membranes. We then examine a non-model animal, the catshark, and explore the cellular properties of their dental lamina and dermal denticles, which are invaginating and evaginating ectodermal structures, respectively. We, thus, demonstrate that the technique presented here provides a powerful tool to quantify, in high-throughput, the 3D structures of cells and tissues during organ morphogenesis.

Conjugate of Natural Bacteriochlorin with Doxorubicin for Combined Photodynamic and Chemotherapy.

Chemotherapy is among the main classical approaches to the treatment of oncologic diseases. Its efficiency has been comprehensively proven by clinical examinations; however, the low selectivity of chemotherapeutic agents limits the possibilities of this method, making it necessary to search for new approaches to the therapy of oncologic diseases. Photodynamic therapy is the least invasive method and a very efficient alternative for the treatment of malignant tumors; however, its efficiency depends on the depth of light penetration into the tissue and on the degree of oxygenation of the treatment zone. In this work, a hitherto unknown conjugate of a natural bacteriochlorin derivative and doxorubicin was obtained. In vitro and in vivo studies showed a more pronounced activity of the conjugate against MCF-7 and 4T1 cells and its higher tumorotropicity in animal tumor-bearing animals compared to free anthracycline antibiotic. The suggested conjugate implements the advantages of photodynamic therapy and chemotherapy and has great potential in cancer treatment.

Research on the design and application of efficient catalysts based on interfacial chemistry: Molecular catalysts in gas-liquid mixed systems

Major challenges existing in the photocatalytic gas-liquid mixing system model include the mass transfer limit at the gas-liquid interface and the depth of light penetration. For this purpose, amphiphilic molecular catalysts were prepared by monovacancy phosphomolybdate modified by propyltrimethoxysilane. It is also used as a photocatalyst in the model reaction (molecular oxygen oxidation of aromatic alcohol). The amphiphilic molecular catalyst in the reaction is similar to surfactant behavior, not only can adsorb in the gas-liquid interface, ensure the direct contact between oxygen, catalyst and reactants, improve the efficiency of mass transfer, and also reduce the surface tension of aromatic alcohol, gas-liquid-solid three-phase system into foam system. The formed foam system amplifies the interface area of the reaction, enhances the light penetration depth and significantly promotes the reaction rate. The insights gained from our study provide a new perspective on the design of photocatalysis in a gas-liquid hybrid system.

Re-evaluation of Padre Secchi’s visual method for modern oceanography

Secchi-disk is an instrument that enables investigating water transparency, being reflective of sunlight to be used to measure the depth of light penetration in the water column. In biological marine research, the device is used to determine the intensity of primary production of planktonic algae. In the present study, we re-evaluated the practicality of Secchi’s method, developed some 160 years ago, for modern oceanography by using the same locations, methods, objectives, and comparable Secchi disk that were used in his survey in 1865. We show that the Secchi-disk is still a valid scientific method in environmental marine research and therefore defends its place reliably among modern electronical research infrastructure. Observer’s subjectivity didn’t have a significant effect on measuring but environmental conditions can influence ZSD determination in general. It is therefore justified to follow, for example, the general recommendations for the use of the Secchi net issued by HELCOM. Our results also revealed that ZSD was located about twofold deeper in 1865 than presently which cannot be explained only by annual variation. We show that green(ish) sea areas have today extended to larger sea areas than they were 160 years ago, due to an increase in the turbidity of the water resulting from, e.g., general eutrophication.

A Review of Factors Affecting the Lighting Performance of Light Shelves and Controlling Solar Heat Gain

In areas with a deep floor plan, the distribution of natural light is not uniform. Consequently, relying solely on daylight may not suffice to meet the space’s lighting requirements, necessitating the use of artificial lighting in darker areas. Therefore, a lighting system is needed that not only controls the glare near the windows but also increases the light at the end of the room and provides uniform daylight. One of the widely used systems is the “light shelf”, which has three main functions: shading, increasing the depth of light penetration, and reducing glare. Review articles about light shelves were published in 2015 and 2017, while more than 80% of the studies have been carried out since 2016, and light shelves with more diverse forms and dynamic elements and many consolidations have been proposed. Therefore, there is a need for a more comprehensive review. The main question of this research is how different parameters (including climate, material, ceiling, and integrated systems) can help to increase the efficiency of light shelves. By using a systematic review, studies in the past three decades were classified in order to determine the effect of these parameters on improving lighting performance and controlling solar heat gain.

Sonosynthetic Cyanobacteria Oxygenation for Self-Enhanced Tumor-Specific Treatment.

Photosynthesis, essential for life on earth, sustains diverse processes by providing nutrition in plants and microorganisms. Especially, photosynthesis is increasingly applied in disease treatments, but its efficacy is substantially limited by the well-known low penetration depth of external light. Here, ultrasound-mediated photosynthesis is reported for enhanced sonodynamic tumor therapy using organic sonoafterglow (ultrasound-induced afterglow) nanoparticles combined with cyanobacteria, demonstrating the proof-of-concept sonosynthesis (sonoafterglow-induced photosynthesis) in cancer therapy. Chlorin e6, a typical small-molecule chlorine, is formulated into nanoparticles to stimulate cyanobacteria for sonosynthesis, which serves three roles, i.e., overcoming the tissue-penetration limitations of external light sources, reducing hypoxia, and acting as a sonosensitizer for in vivo tumor suppression. Furthermore, sonosynthetic oxygenation suppresses the expression of hypoxia-inducible factor 1α, leading to reduced stability of downstream SLC7A11 mRNA, which results in glutathione depletion and inactivation of glutathione peroxidase 4, thereby inducing ferroptosis of cancer cells. This study not only broadens the scope of microbial nanomedicine but also offers a distinct direction for sonosynthesis.

Quantitative Evaluation of Color Enhancement Methods for Underwater Photogrammetry in Very Shallow Water: a Case Study

Abstract. Underwater photogrammetry is often hampered by chromatic aberration, leading to degraded 2D and 3D products. This study investigates the effectiveness of various color enhancement methods in addressing these challenges.Theoretical considerations indicate that light penetration depth varies inversely with wavelength, causing underwater images to exhibit a blue or green cast with increasing depth. Color enhancement techniques can restore natural colors by compensating for this spectral attenuation. Additionally, scattering, caused by light reflected by particles in the water, can introduce haze into underwater images. Color enhancement can mitigate scatter and improve image clarity. In this contribution, to quantitatively evaluate color enhancement methods, we compare original images with images processed using gray-world assumption methods and physical methods that account for the physical properties of light underwater. Using artificial intelligence (AI) for underwater image color enhancement, a data-driven approach was also employed. These methods were applied to a case study concerning a Roman Navis Lapidaria shipwreck carrying five monumental cipollino marble columns at a depth of 4.5 meters in the Porto Cesareo Marine Protected Area (Italy). These methods were compared quantitatively and qualitatively, and the results are presented and discussed.

Enhancing photon recycling of perovskite nanosheet by two-photon excitation

Nanometer scale light penetration depths of halide perovskite (HP) set an intrinsic limit on the performance improvement of optoelectronic devices. Here, we show that two-photon excitation can overcome this limit by markedly increasing the light penetration depth and significantly enhance photon recycling. Through a comparison study between one-photon and two-photon excitations by femtosecond laser pulses in a CsPbBr3 nanosheet, our results demonstrate that two-photon excitation can increase photocarrier transport distance by about 900 nm, which is even comparable to the photocarrier diffusion length. Our work provides substantial insights into the photon recycling of HP induced by nonlinear optical excitations, which can benefit the performance optimization of advanced optoelectronic devices.

Biocompatible and Implantable Hydrogel Optical Waveguide with Lens‐Microneedles for Enhancing Light Delivery in Photodynamic Therapy

The finite penetration depth of light in biological tissues is a practical constraint in light‐induced therapies, such as antimicrobial light therapy, photothermal therapy, and photodynamic cancer therapy. Herein, a biocompatible and implantable device, termed hydrogel planar waveguide with lens‐microneedles, for light delivery in deep tissue is demonstrated. The prototype device, integrated planar waveguide and lens‐microneedles, is fabricated by press‐molding polyethylene glycol diacrylate polymers. The optical beams through the lens‐microneedles are focused at a specific point to realize the optimal intensity profile in the tissue. The adequate treatment depth and region for the hydrogel planar waveguide with five lens‐microneedles are extended to 24 mm and 3.1 cm2. The photoswitchable chemotherapeutic against colorectal cancer cells is switched by using different hydrogel waveguides. The performances of hydrogel‐waveguide‐enabled photoswitching are characterized by the dose responses from the optical microscope, crystal violet staining, and MTT assays. The anticancer drug activated by the hydrogel planar waveguide with five lens‐microneedles is shown to be twice as effective as the other fibers and waveguides in causing cancer cell death. The proposed biodegradable waveguide can be utilized for long‐term light delivery and does not require to be removed as it is gradually resorbed by the tissue. The results point to a new paradigm for widespread use in photomedicine.

Photodynamic therapy in the treatment of HPV-associated cervical cancer: mechanisms, challenges and future prospects

Photodynamic therapy (PDT) has shown promise as a modality for the treatment of cervical cancer caused by the human papillomavirus (HPV). This review provides a comprehensive examination of the role of PDT in overcoming the challenges presented by conventional treatments for cervical cancer. Beginning with an overview of the relationship between cervical cancer and HPV infection, the review introduces the principles of PDT, its mechanism of action, and its potential as an innovative treatment strategy. The review highlights preclinical studies in animal models that demonstrate the efficacy of PDT in targeting HPV-infected cervical cells and provide mechanistic insights into its cytotoxic effects. We reviewed clinical studies and case reports highlighting the potential of PDT as an alternative or adjunctive treatment option. Challenges and limitations, including depth of light penetration, photosensitizer specificity, and standardization of protocols, will be discussed in the context of potential side effects and comparison with conventional treatments. Future directions include ongoing research, combination therapies with immunotherapy or targeted agents, advances in photosensitizer development, and personalized approaches. The advancement of PDT promises to change the landscape of HPV-associated cervical cancer treatment by providing a targeted, personalized, and minimally invasive approach.

Programmable Singlet Oxygen Battery for Automated Photodynamic Therapy Enabled by Pyridone-Pyridine Tautomer Engineering.

The efficacy of photodynamic therapy is hindered by the hypoxic environment in tumors and limited light penetration depth. The singlet oxygen battery (SOB) has emerged as a promising solution, enabling oxygen- and light-independent 1O2 release. However, conventional SOB systems typically exhibit an "always-ON" 1O2 release, leading to potential 1O2 leakage before and after treatment. This not only compromises therapeutic outcomes but also raises substantial biosafety concerns. In this work, we introduce a programmable singlet oxygen battery, engineered to address all the issues discussed above. The concept is illustrated through the development of a tumor-microenvironment-responsive pyridone-pyridine switch, PyAce, which exists in two tautomeric forms: PyAce-0 (pyridine) and PyAce (pyridone) with different 1O2 storage half-lives. In its native state, PyAce remains in the pyridone form, capable of storing 1O2 (t1/2 = 18.5 h). Upon reaching the tumor microenvironment, PyAce is switched to the pyridine form, facilitating rapid and thorough 1O2 release (t1/2 = 16 min), followed by quenched 1O2 release post-therapy. This mechanism ensures suppressed 1O2 production pre- and post-therapy with selective and rapid 1O2 release at the tumor site, maximizing therapeutic efficacy while minimizing side effects. The achieved "OFF-ON-OFF" 1O2 therapy showed high spatiotemporal selectivity and was independent of the oxygen supply and light illumination.

Precision Phenotyping of Wild Rocket (Diplotaxis tenuifolia) to Determine Morpho-Physiological Responses under Increasing Drought Stress Levels Using the PlantEye Multispectral 3D System

The PlantEye multispectral scanner is an optoelectrical sensor automatically applied to a mechatronic platform that allows the non-destructive, accurate, and high-throughput detection of morphological and physiological plant parameters. In this study, we describe how the advanced phenotyping platform precisely assesses changes in plant architecture and growth parameters of wild rocket salad (Diplotaxis tenuifolia L. [DC.]) under drought stress conditions. Four different irrigation supply levels from moderate to severe, required to keep 100, 70, 50, and 30% of the water-holding capacity, were adopted. Growth rate and plant architecture were recorded through the digital measure of biomass, leaf area, Canopy Light Penetration Depth, five convex hull traits, plant height, Surface Angle Average, and Voxel Volume Total. Vegetation color assessments included hue, lightness, and saturation. Vegetation and senescence indices were calculated from canopy reflectance in the red (620–645 nm), green (530–540 nm), blue (peak wavelength 460–485 nm), near-infrared (820–850 nm), and 3D laser (940 nm) ranges. The temperature, relative humidity, and solar radiation of the environment were also recorded. Overall, morphological parameters, color, multispectral data, and vegetation indices provided over 7200 data points through daily scans over three weeks of cultivation. Although a general decrease in growth parameters with increasing stress severity was observed, plants were able to maintain the same morpho-physiological performances as the control during the early growth stages, keeping both 70% and 50% of the total water-holding capacity. Among indices, the Normalized Differential Vegetation Index (NDVI) contributed the most to the differentiation between different stress levels during the cultivation cycle. Across the 3 weeks of growth, statistically significant differences were observed for all traits except for the Saturation Average. Comparisons with respect to the control highlighted the strong impact of drought stress on morphological plant traits. This study provided meaningful insights into the health status of wild rocket salad under increasing drought stress.

Enhancing purity and crystallinity of carbon nanotubes by magnetically assisted arc discharge and thermal purification and their field emission characteristics

This study used a magnetically assisted arc discharge (AD) method and thermal purification to enhance the purity and crystallinity of multi-walled carbon nanotubes (MWCNTs). CNT synthesis in the presence of a magnetic field increased the densities of ionic carbon species and the arc plasma temperature, thereby improving CNT production. AD-MWCNTs produced at an optimal magnetic strength exhibited enhanced purity, crystallinity, and thermal stability. Thermal purification was also conducted to increase the purity of the AD-MWCNTs further. Purity was evaluated using Raman spectroscopy. AD-MWCNTs were homogenized to overcome limitations in light-penetration depths to ensure accurate evaluation. The calculated purities were consistent with the analytical results, confirming the reliability of Raman spectroscopy for purity assessment. The number of working CNT emitters on the film surface was directly related to the purity. Highly pure crystalline AD-MWCNTs exhibited high-performance field-emission properties, namely a high current density of 2.7 A/cm2 and long-term emission stability (12 h at a current density of 500 mA/cm2), with no performance reduction.

Enriched photosensitizer for deep-seated-tumor photodynamic therapy

Photodynamic therapy (PDT) is an innovative approach that utilizes photochemical reactions for non-invasive disease treatment. Conventional PDT is limited by the low penetration depth of visible light required for activation. Herein, we employed upconversion nanoparticles (UCNPs) to extend the activation wavelength of photosensitizers into the infrared range, enabling a treatment depth of over 10 mm. Furthermore, we also used the abundant amino groups of branched polyethyleneimine (PEI) with spatial structure to enhance the loading capacity of protoporphyrin (PPIX), and we ultimately improved skin tumor clearance rates. Moreover, we achieved tumor-specific treatment by utilizing folic acid (FA) targeting and active enrichment of PPIX. According to cellular experimental results, we demonstrated the remarkable reactive oxygen species generation capability of the material and ultra-low dark toxicity. Additionally, we investigated the apoptosis mechanism and demonstrated that the synthesized nanoparticle stimulates the up-regulation of apoptosis-associated proteins Bax/Bcl-2 and Cyto c. During in vivo experiments involving intravenous injection in mouse tails, we investigated the anticancer efficacy of the nanoparticle, confirming its excellent PDT effects. This research provides a promising avenue for future non-invasive treatment of deep-seated tumors, offering a method for the treatment and management of specific cancers.

Floquet engineering of axion and high-Chern number phases in a topological insulator under illumination

Quantum anomalous Hall, high-Chern number, and axion phases in topological insulators are characterized by its Chern invariant C (respectively, C=1, integer C>1, and C=0 with half-quantized Hall conductance of opposite signs on top and bottom surfaces). They are of recent interest because of novel fundamental physics and prospective applications, but identifying and controlling these phases has been challenging in practice. Here we show that these states can be created and switched between in thin films of Bi_22Se_33 by Floquet engineering, using irradiation by circularly polarized light. We present the calculated phase diagrams of encountered topological phases in Bi_22Se_33, as a function of wavelength and amplitude of light, as well as sample thickness, after properly taking into account the penetration depth of light and the variation of the gap in the surface states. These findings open pathways towards energy-efficient optoelectronics, advanced sensing, quantum information processing and metrology.

Ultrasmall copper-based nanoplatforms for NIR-II light-triggered photothermal/ photodynamic and amplified nanozyme catalytic therapy of hypoxic tumor

The clinical applications of the photothermal therapy (PTT) and photodynamic therapy (PDT) are restricted by the limited tissue penetration depth of excitation light, while the enzyme catalysis therapy is hindered on account of the low treatment efficiency. Herein, we modify artificial nanozyme Pt nanoparticles on the surface of CuCo2S4 nanoparticles to prepare ultrasmall copper-based ternary bimetallic chalcogenides CuCo2S4-Pt-PEG nanocomposites for PTT/PDT/enzyme catalysis synergistic therapy. The as-fabricated CuCo2S4-Pt-PEG nanocomposites display peroxidase (POD)-like and catalase (CAT)-like activities, which can catalyze hydrogen peroxide to emerge highly toxic hydroxyl radicals and oxygen, respectively. The integration of Pt nanozyme significantly improves the POD-like and CAT-like activity of CuCo2S4 −PEG that can produce more hydroxyl radicals and oxygen to improve the effects of PDT. Furthermore, the nanocomposites exhibit outstanding photothermal properties derived from the enhanced photothermal conversion efficiency (η = 78.46 %) exposed to 1064 nm NIR-II light irradiation with a low power density (0.8 W cm−2). In particular, the photothermal performance of CuCo2S4-Pt-PEG significantly enhances the enzyme-like activity. Additionally, the T1-weighted magnetic resonance and photoacoustic imaging endow CuCo2S4-Pt-PEG with the advantages of guiding the treatment process. The synergistic treatment demonstrates significant anticancer treatment efficiency while also elicits immune response that suppressed metastasis. This study could further promote the application of ternary bimetallic chalcogenides in cancer diagnosis and treatment.

Laser-induced transverse voltage effect in c-axis inclined La x Sr1−x TiO3 thin films prepared by MOCVD

Light and thermal detectors based on the laser-induced transverse voltage (LITV) effect have garnered significant interest for their rapid and broad spectral response. In this study, we prepared the La-doped SrTiO3 (STO) epitaxial thin films on the 12° inclined single crystal LaAlO3 (LAO) (100) substrates using our home-designed metal–organic chemical vapor deposition system. Under the illumination of a 248 nm laser, the LITV signals of La x Sr1−x TiO3 films were observed and showed dependence on the La doping level, which can be explained by the changes in the light absorption coefficient, thermal conductivity, and optical penetration depth. The optimized LITV signal was observed with a peak voltage of 23.25 V and a decay time of 106 ns under the laser power density of 1.0 mJ mm−2. The high peak voltage and fast response time of La x Sr1−x TiO3 show great potential in the field of light and thermal detection.

Generalized channel separation algorithms for accurate camera-based multi-wavelength PTT and BP estimation

Single-site multi-wavelength (MW) pulse transit time (PTT) measurement was recently proposed using contact sensors with sequential illumination. It leverages different penetration depths of light to measure the traversal of a cardiac pulse between skin layers. This enabled continuous single-site MW blood pressure (BP) monitoring, but faces challenges like subtle skin compression, which importantly influences the PPG morphology and subsequent PTT. We extended this idea to contact-free camera-based sensing and identified the major challenge of color channel overlap, which causes the signals obtained from a consumer RGB camera to be a mixture of responses in different wavelengths, thus not allowing for meaningful PTT measurement. To address this, we propose novel camera-independent data-driven channel separation algorithms based on constrained genetic algorithms. We systematically validated the algorithms on camera recordings of palms and corresponding ground-truth BP measurements of 13 subjects in two different scenarios, rest and activity. We compared the proposed algorithms against established blind source separation methods and against previous camera-specific physics-based method, showing good performance in both PTT reconstruction and BP estimation using a Random Forest regressor. The best-performing algorithm achieved mean absolute errors (MAEs) of 3.48 and 2.61 mmHg for systolic and diastolic BP in a leave-one-subject-out experiment with personalization, solidifying the proposed algorithms as enablers of novel contact-free MW PTT and BP estimation.

Optical design of a tunable microneedle array for photodynamic therapy of metastatic melanomas

The need for photodynamic therapy is increasing with the rise of skin cancer melanoma detection. However, low penetration depth of light in the UV range and higher scattering of skin tissues cause harsh clinical practices and reduced irradiance for the activation of chemicals such as photosensitizers to facilitate cell necrosis of malignant tumors. In this paper, a tunable microlens integrated on a microneedle array is designed for variable focusing to reduce melanomas at multiple sites with an improved intensity for reactive oxygen species production. A light distribution of 36% percent of the input intensity is achieved at the targeted distance of 4.35 mm for blue light. Red light attained a light distribution of 13% of the input intensity at a targeted distance of 6.5 mm. Designing such a light, delivery-based in-vivo biomedical device is of extreme importance for photodynamic therapy of skin cancer on and beyond the epidermal tissue layer.

Ultrasound mediated sonochemical internalization (SCI): overcoming the depth limitations of light-based therapies

SignificanceFocused ultrasound activation of sonosensitizers i.e. sonodynamic therapy (SDT) is an alternative to light-activated photodynamic therapy (PDT). Sonochemical internalization (SCI), is comparable to light based photochemical internalization (PCI) but without the intrinsic drawback of limited penetration depth of light in biological tissues including the skull. ApproachSCI experiments were performed both in vitro on monolayers and in vivo, in a rat breast tumor model, using the sononsensitizer AlPcS2a and the drug bleomycin (BLM). Resultsin vitro; Growth inhibition of tumor cells in monolayer was significantly greater than that seen with either BLM or SDT acting alone. Similar results were also seen in vivo, with significant reduction in breast tumor development following BLM-SCI ConclusionThe synergist effect of SCI, employing relatively low drug concentrations and focused ultrasound power levels, would reduce the problems of nonspecific tissue damage caused by thermal effects at high power and unwanted systemic drug side effects.