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Optical clearing of the lung tissue aims to make it more transparent to light by minimizing light scattering, thus allowing reconstruction of the three-dimensional structure of the tissue with a much better resolution. This is of great importance for monitoring of viral infection impact on the alveolar structure of the tissue and oxygen transport. Optical clearing agents (OCAs) can provide not only lesser light scattering of tissue components but also may influence the molecular transport function of the alveolar membrane. Air-filled lungs present significant challenges for optical imaging including optical coherence tomography (OCT), confocal and two-photon microscopy, and Raman spectroscopy, because of the large refractive-index mismatch between alveoli walls and the enclosed air-filled region. During OCT imaging, the light is strongly backscattered at each air-tissue interface, such that image reconstruction is typically limited to a single alveolus. At the same time, the filling of these cavities with an OCA, to which water (physiological solution) can also be attributed since its refractive index is much higher than that of air will lead to much better tissue optical transmittance. This review presents general principles and advances in the field of tissue optical clearing (TOC) technology, OCA delivery mechanisms in lung tissue, studies of the impact of microbial and viral infections on tissue response, and antimicrobial and antiviral photodynamic therapies using methylene blue (MB) and indocyanine green (ICG) dyes as photosensitizers.

Using fluorescence methods for visualization of human tumor cell apoptosis and necrosis in vitro, the antitumor effects of flavonoid-containing Gratiola officinalis L. and green tea extracts at ultralow concentrations on A498 human kidney carcinoma cells after 24 and 48 h were compared. Fluorescent dyes (propidium iodide and acridine orange) were used in the “living and dead” test, which made it possible to identify the total number of cells that died by necrosis and apoptosis, as well as cells in which apoptosis has started and apoptotic bodies or pycnosis of the nucleus were detected. Gratiola officinalis L. extract had the most pronounced cytostatic activity 48 h after exposure; the number of cells per field of view decreased by a factor of 1.5 compared with the control. Green tea extract at a concentration of 0.0288 mg/mL had the most pronounced cytotoxic activity; its manifestation was growing 48 h after exposure. Gratiola officinalis L. extract exhibited cytotoxic activity at lower concentrations (0.0036 mg/mL).

The purpose of this study was to investigate the prognostic factors of plasmonic photothermal therapy (PPT) efficiency in rats with transplanted liver cancer on the basis of assessment of the degree of tumor vascularization. Before any exposure, rats with transplanted liver cancer PC-1 were subjected to Doppler ultrasonography to assess the degree of vascularization of transplanted tumors. Half of the animals with the transplanted tumors were withdrawn from the experiment after Doppler ultrasonography to determine the content of vascular factors in blood serum by enzyme immunoassay and in tumor tissue by immunohistochemical method. After three intravenous injections of polyethylene glycol-coated gold nanorods (GNRs) at a dose of 0.4 mq/mL, the transplanted tumors were irradiated percutaneously with infrared laser radiation at a wavelength of 808 nm, followed by thermography of local tumor heating. The animals were withdrawn from the experiment 24 h later, and tumor tissue samples were taken for histological examination. It is found that the accumulation of gold in the tumor tissue and the PPT efficiency at repeated intravenous GNR injections are determined by the presence of formed vasculature in the tumor.

The quercetin content in aqueous EtOH extracts of covering leaves of anthocyanin Purple Saratov diploid variety of Zea mays L. grown under dry conditions reached 39.36 ± 0.41 mg/100 g of dry extract and significantly exceeded the value (26.03 ± 0.36 mg/100 g of dry extract) for maize grown under normal wetting conditions. The large amounts of polyphenolic compounds in anthocyanin Purple Saratov diploid variety showed good prospects for using it as a source of them.

The influence of long-term peroral injection of gold nanoparticles with various sizes on the liver, spleen, and lymph nodes of adult laboratory rats and their progeny was studied. The morphometric analysis was conducted using a µVizo-103 medical digital microviser. The conglomerated gold nanoparticles were detected in tissues via the dark-field microscopy. Gold nanoparticles with sizes of 2 and 50 nm were found to cause the mostly pronounced morphological alterations in organs that testifies to their size-dependent impact. The liver in a group receiving 50-nm gold particles exhibit noticeable dystrophy of hepatocytes and activation of a monocyte macrophage system. The spleen and lymph nodes reveal the activation of proliferation and differentiation of immunocompetent cells and macrophages. Peroral injection of gold particles during gestation of females led to an increase in a number of hepatocytes with necrobiotic changes as well as to elevated amount of non-parenchymatic elements in the liver of the progeny, especially in groups containing the 2- and 50-nm gold nanoparticles.

The possibilities of using fluorescence-based analytical methods and their advantages for visualization and identification of the type of programmed cell death in human tumor cells exposed to flavonoids have been analyzed in experiments in vitro. HeLa cervical cancer cells and A498 kidney carcinoma cells were used as the objects of the study, and exposure to the flavonoid-containing extract of common hedgehyssop (Gratiola officinalis L.) was tested as the experimental treatment. The following fluorescence-based techniques were used: the “live and dead” test with double staining by propidium iodide and acridine orange and double staining with annexin and propidium iodide. Autophagy induction was confirmed by fluorescence-based tests implemented in a Muse cell analyzer with a Muse Autophagy LC3-Antibody Based Kit. The use of double staining with acridine orange and propidium iodide fluorescent dyes in the “live and dead” test and comparison with phase contrast microscopy enables the visualization of apoptotic body and autophagosome formation processes in the cells and can, therefore, be used as a method of screening assessment of the efficiency of various chemotherapy drugs.

The chemical composition of a new bioactive extract from immortelle sandy (Helichrysum arenarium (L.) Moench.) was investigated. Naringin, its soluble aggregate, prunin, quercetin, apigenin, naringenin, apigenin 5-O-glucoside, and isosalipurposide were found among the flavonoids. The tested immortelle sandy extract was shown to contain known dimers, trimers, or more complex aggregates. The compounds had similar spectral but substantially different chromatographic characteristics, which can be used for their identification based on the corresponding data on flavonoids glycosylated at different positions and/or carbohydrates of various complexities, which are also characterized by similar absorption spectra and different retention times. It was found by molecular absorption spectroscopy that the immortelle extract contained 73.48 mg of flavonoids relative to rutin or 17.94 mg relative to quercetin per 1 g of dry extract weight, which corresponded to 20.99 and 5.13%, respectively. The immortelle extract obtained by the method proposed displayed antitumor activity against the transplanted sarcoma 45 and had a beneficial effect on animals in general.

Here, we report the morphological investigation of gold nanorod (GNR)-mediated photothermal changes in transplanted liver tumors PC-1 and discuss photothermal induced therapeutic pathways of cancer cell damage. Thirty male outbred albino rats with transplanted liver cancer PC-1 are used in the experiment. The GNRs (length 41 ± 8 nm, diameter 10.2 ± 2 nm) suspended in saline with gold concentration of 400 μg/ml are injected intratumorally an hour before laser irradiation. The tumor is irradiated during 15 min with the near infrared (NIR) 808-nm laser at a power density of 2.3 W/cm2. Temperature control of the tumor heating is provided with IR imager. The withdrawal of the animal from the experiment is performed 24 h after the laser exposure. We use the standard histological and immunohistochemical staining with antibodies for Ki-67, p53, FAS receptor, FAS ligand, and EGFR for morphological study of transplanted tumors. After plasmonic photothermal therapy (PPT), the pronounced necrotic changes in the tumor tissue are revealed. The decreasing expression of the proliferation marker Ki-67 and the increasing expression of apoptosis markers (p53, FAS receptor, and FAS ligand) are observed after PPT.

Alzheimer&rsquo, s disease (AD) is an incurable pathology associated with progressive decline in memory and cognition. Phototherapy might be a new promising and alternative strategy for the effective treatment of AD, and has been actively discussed over two decades. However, the mechanisms of therapeutic photostimulation (PS) effects on subjects with AD remain poorly understood. The goal of this study was to determine the mechanisms of therapeutic PS effects in beta-amyloid (A&beta, )-injected mice. The neurological severity score and the new object recognition tests demonstrate that PS 9 J/cm2 attenuates the memory and neurological deficit in mice with AD. The immunohistochemical assay revealed a decrease in the level of A&beta, in the brain and an increase of A&beta, in the deep cervical lymph nodes obtained from mice with AD after PS. Using the in vitro model of the blood-brain barrier (BBB), we show a PS-mediated decrease in transendothelial resistance and in the expression of tight junction proteins as well an increase in the BBB permeability to A&beta, These findings suggest that a PS-mediated BBB opening and the activation of the lymphatic clearance of A&beta, from the brain might be a crucial mechanism underlying therapeutic effects of PS in mice with AD. These pioneering data open new strategies in the development of non-pharmacological methods for therapy of AD and contribute to a better understanding of the PS effects on the central nervous system.

A new application of the photodynamic treatment (PDT) is presented for the opening of blood-brain barrier (BBB) and the brain clearing activation that is associated with it, including the use of gold nanoparticles as emerging photosensitizer carriers in PDT. The obtained results clearly demonstrate 2 pathways for the brain clearing: (1) using PDT-opening of BBB and intravenous injection of FITC-dextran we showed a clearance of this tracer via the meningeal lymphatic system in the subdural space; (2) using optical coherence tomography and intraparenchymal injection of gold nanorods, we observed their clearance through the exit gate of cerebral spinal fluid from the brain into the deep cervical lymph node, where the gold nanorods were accumulated. These data contribute to a better understanding of the cerebrovascular effects of PDT and shed light on mechanisms, underlying brain clearing after PDT-related opening of BBB, including clearance from nanoparticles as drug carriers.

Microcapsules, made of biodegradable polymers, containing magnetite nanoparticles with tunable contrast in both the T1 and T2 MRI modes, were successfully prepared using a layer-by-layer approach. The MRI contrast of the microcapsules was shown to depend on the distance between magnetite nanoparticles in the polymeric layers, which is controlled by their concentration in the microcapsule shell. A fivefold increase in the average distance between the nanoparticles in the microcapsule shell led to a change in the intensity of the MR signal of 100% for both the T1 and T2 modes. Enzyme treatment of biodegradable shells resulted in a change of the microcapsules' MRI contrast. In vivo degradation of nanocomposite microcapsules concentrated in the liver after intravenous injection was demonstrated by MRI. This method can be used for the creation of a new generation of drug delivery systems, including drug depot, with combined navigation, visualization and remote activated release of bioactive substances in vivo.

Magnetic fluid-loaded liposomes (MFLs) were fabricated using magnetite nanoparticles (MNPs) and natural phospholipids via the thin film hydration method followed by extrusion. The size distribution and composition of MFLs were studied using dynamic light scattering and spectrophotometry. The effective ranges of magnetite concentration in MNPs hydrosol and MFLs for contrasting at both T2 and T1 relaxation were determined. On T2 weighted images, the MFLs effectively increased the contrast if compared with MNPs hydrosol, while on T1 weighted images, MNPs hydrosol contrasting was more efficient than that of MFLs. In vivo magnetic resonance imaging (MRI) contrasting properties of MFLs and their effects on tumor and normal tissues morphology, were investigated in rats with transplanted renal cell carcinoma upon intratumoral administration of MFLs. No significant morphological changes in rat internal organs upon intratumoral injection of MFLs were detected, suggesting that the liposomes are relatively safe and can be used as the potential contrasting agents for MRI.

Calcium carbonate microparticles with a size of 0.9 ± 0.2 μm containing a photosensitizer Photosens in a concentration of 2.0 ± 0.2 wt % were prepared by ultrasound-stimulated coprecipitation (20 kHz, 1W/cm2). It is shown that the encapsulated photosensitizer can be released by ultrasonic irradiation (0.89MHz, 1 W/cm2, 5 min) as a result of the destruction and recrystallization of calcium carbonate micro-particles. It is established that the combined ultrasonic (0.89 MHz, 1 W/cm2) and light (670 nm, 10 mW/cm2) in vivo influence on the transferred PC-1 strain tumors of rat liver containing intratumorally injected micro-containers with a photosensitizer gives rise to dystrophic changes in tumor cells and to the appearance of extensive necrotic centers, pointing to the presence of the evident destructive effect. Such microcontainers are proposed for use in treating external tumors or tumors accessible for ultrasonic and optical irradiation.

MRI and morphological investigations into internal organ tissues and tumors in rats with liver cancer PC-1 under the intraperitoneal administration of magnetite hydrosols have been performed. The absence of any toxic effect of magnetite nanoparticles at low concentrations (0.325 mg/mL) has been determined using neutrophil granulocytes. A technique for the synthesis of citrate-stabilized magnetite hydrosols by the coprecipitation of Fe2+ and Fe3+ salts is described. Their electrokinetic potential is −32 ± 2 mV at pH 6.5 ± 0.1. The size distribution of magnetite nanoparticles is obtained by dynamic light scattering. The average size of magnetite nanoparticles is 23 ± 6 nm. The absorption spectra of magnetite hydrosols have been measured. The dependence of the optical density on the concentration has also been obtained. Molar absorption coefficients of magnetite nanoparticles have been calculated at the following wavelengths: 532, 633, 660, and 785 nm.

In this study, we analyzed the time-depended scenario of stress response cascade preceding and accompanying brain hemorrhages in newborn rats using an interdisciplinary approach based on: a morphological analysis of brain tissues, coherent-domain optical technologies for visualization of the cerebral blood flow, monitoring of the cerebral oxygenation and the deformability of red blood cells (RBCs). Using a model of stress-induced brain hemorrhages (sound stress, 120 dB, 370 Hz), we studied changes in neonatal brain 2, 4, 6, 8 h after stress (the pre-hemorrhage, latent period) and 24 h after stress (the post-hemorrhage period). We found that latent period of brain hemorrhages is accompanied by gradual pathological changes in systemic, metabolic, and cellular levels of stress. The incidence of brain hemorrhages is characterized by a progression of these changes and the irreversible cell death in the brain areas involved in higher mental functions. These processes are realized via a time-depended reduction of cerebral venous blood flow and oxygenation that was accompanied by an increase in RBCs deformability. The significant depletion of the molecular layer of the prefrontal cortex and the pyramidal neurons, which are crucial for associative learning and attention, is developed as a consequence of homeostasis imbalance. Thus, stress-induced processes preceding and accompanying brain hemorrhages in neonatal period contribute to serious injuries of the brain blood circulation, cerebral metabolic activity and structural elements of cognitive function. These results are an informative platform for further studies of mechanisms underlying stress-induced brain hemorrhages during the first days of life that will improve the future generation's health.

Delivery and spatial localization of upconversion luminescent microparticles [Y2O3;Yb, Er] (mean size ~1.6 μm) and quantum dots (QDs) (CuInS2ZnS nanoparticles coated with polyethylene glycol-based amphiphilic polymer, mean size ~20 nm) inside rat skin was studied in vivo using a multimodal optical imaging approach. The particles were embedded into the skin dermis to the depth from 300 to 500 μm through microchannels performed by fractional laser microablation. Low-frequency ultrasound was applied to enhance penetration of the particles into the skin. Visualization of the particles was revealed using a combination of luminescent spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis. Optical clearing was used to enhance the image contrast of the luminescent signal from the particles. It was demonstrated that the penetration depth of particles depends on their size, resulting in a different detection time interval (days) of the luminescent signal from microparticles and QDs inside the rat skin in vivo. We show that luminescent signal from the upconversion microparticles and QDs was detected after the particle delivery into the rat skin in vivo during eighth and fourth days, respectively. We hypothesize that the upconversion microparticles have created a long-time depot localized in the laser-created channels, as the QDs spread over the surrounding tissues.