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We examined hematological changes influenced by the experimental hypervitaminosis A. The 3D confocal optical profilometer was applied for assessment of the erythrocytes’ membrane structural changes influenced by an overdose of vitamin A. The blood smears were evaluated in terms of alterations of geometrical and optical parameters of erythrocytes for two groups of animals: oil base and retinol palmitate (n = 9 animals for each group). The results demonstrate that an overdose of retinol palmitate causes changes in the torus curvature and pallor of discocytes, their surface area and volume. The observed structural malformations of the shape of red blood cells become visible at the earlier preclinical stage of changes in animal state and behavior. With this in mind, the results of the study open a new area of research in the certain dysfunction diagnosis of red blood cells and have a great potential in the further development of new curative protocols.

Significance: Mueller-matrix polarimetry is a powerful method allowing for the visualization of malformations in biological tissues and quantitative evaluation of alterations associated with the progression of various diseases. This approach, in fact, is limited in observation of spatial localization and scale-selective changes in the poly-crystalline compound of tissue samples. Aim: We aimed to improve the Mueller-matrix polarimetry approach by implementing the wavelet decomposition accompanied with the polarization-singular processing for express differential diagnosis of local changes in the poly-crystalline structure of tissue samples with various pathology. Approach: Mueller-matrix maps obtained experimentally in transmitted mode are processed utilizing a combination of a topological singular polarization approach and scale-selective wavelet analysis for quantitative assessment of the adenoma and carcinoma histological sections of the prostate tissues. Results: A relationship between the characteristic values of the Mueller-matrix elements and singular states of linear and circular polarization is established within the framework of the phase anisotropy phenomenological model in terms of linear birefringence. A robust method for expedited (up to ∼15 min) polarimetric-based differential diagnosis of local variations in the poly-crystalline structure of tissue samples containing various pathology abnormalities is introduced. Conclusions: The benign and malignant states of the prostate tissue are identified and assessed quantitatively with a superior accuracy provided by the developed Mueller-matrix polarimetry approach.

Background: Our study has immunohistochemically examined T cells localization and number as well as proliferative activity level for the bulbourethral gland epithelium in men of different ages, using monoclonal antibodies against CD45RO and proliferating cell nuclear antigen (PCNA). Results: We have found that the T cells have been localized mainly in excretory ducts epithelium of the glands in any age group, meanwhile their relative number varies with age. The excretory ducts epithelium has shown a high proliferative activity when in acini the PCNA index has been low. Postnatal dynamics of the epithelium proliferative activity positively correlates with age-related density fluctuations in lymphocytic infiltration of the glands. Conclusions: We consider that intraepithelial T cells may contribute to the regulation of epithelial cells proliferation in the bulbourethral glands.

A multimode optical fiber supports excitation and propagation of a pure single optical mode, i.e., the field pattern that satisfies the boundary conditions and does not change along the fiber. When two counterpropagating pure optical modes are excited, they could interact through the stimulated Brillouin scattering (SBS) process. Here, we present a simple theoretical formalism describing SBS interaction between two individual optical modes selectively excited in an acoustically isotropic multimode optical fiber. Employing a weakly guiding step-index fiber approach, we have built an analytical expression for the spatial distribution of the sound field amplitude in the fiber core and explored the features of SBS gain spectra, describing the interaction between modes of different orders. In this way, we give a clear insight into the sound propagation effects accompanying SBS in multimode optical fibers, and demonstrate their specific contributions to the SBS gain spectrum.

We consider the origin of unpolarized light resulting from the backscattering of circularly polarized light by a random turbid tissuelike disperse medium. We reveal the dynamics of the backscattered fraction of unpolarized light, disclosing its meticulous decomposition into two rigorously polarized components characterized by opposing helicities, with fully defined polarization states. Concurrently, their superposition, driven by multiple scattering within the medium, leads to the appearance of a fraction of linear polarization. We emphasize that the in-depth binding of circular polarization memory of light when the helicity flips occurs within the scattering medium, meaning the conservation of spin angular momentum. We anticipate that the results obtained hold significant implications for future studies, particularly in the field of tissue polarimetry and light vortices.

In optogenetics, as in nature, sensory photoreceptors serve to control cellular processes by light. Bacteriophytochrome (BphP) photoreceptors sense red and far-red light via a biliverdin chromophore and, in response, cycle between the spectroscopically, structurally, and functionally distinct Pr and Pfr states. BphPs commonly belong to two-component systems that control the phosphorylation of cognate response regulators and downstream gene expression through histidine kinase modules. We recently demonstrated that the paradigm BphP from Deinococcus radiodurans exclusively acts as a phosphatase but that its photosensory module can control the histidine kinase activity of homologous receptors. Here, we apply this insight to reprogram two widely used setups for bacterial gene expression from blue-light to red-light control. The resultant pREDusk and pREDawn systems allow gene expression to be regulated down and up, respectively, uniformly under red light by 100-fold or more. Both setups are realized as portable, single plasmids that encode all necessary components including the biliverdin-producing machinery. The triggering by red light affords high spatial resolution down to the single-cell level. As pREDusk and pREDawn respond sensitively to red light, they support multiplexing with optogenetic systems sensitive to other light colors. Owing to the superior tissue penetration of red light, the pREDawn system can be triggered at therapeutically safe light intensities through material layers, replicating the optical properties of the skin and skull. Given these advantages, pREDusk and pREDawn enable red-light-regulated expression for diverse use cases in bacteria.

Despite a rapid growth in the application of modern techniques for visualization studies in life sciences, the classical methods of histological examination are yet to be outdated. Herein, we introduce a new approach that involves combining silver nitrate pretreatment and impregnation with consequent Nissl (cresyl violet) staining for cortex and striatum architectonics study on the same microscopy slide. The developed approach of hybrid staining provides a high-quality visualization of cellular and subcellular structures, including impregnated neurons (about 10%), Nissl-stained neurons (all the remaining ones), and astrocytes, as well as chromatophilic substances, nucleoli, and neuropil in paraffin sections. We provide a comparative study of the neuronal architectonics in both the motor cortex and striatum based on the differences in their tinctorial properties. In addition to a comparative study of the neuronal architectonics in both the motor cortex and striatum, the traditional methods to stain the cortex (motor and piriform) and the striatum are considered. The proposed staining approach compiles the routine conventional methods for thin sections, expanding avenues for more advanced examination of neurons, blood–brain barrier components, and fibers both under normal and pathological conditions. One of the main hallmarks of our method is the ability to detect changes in the number of glial cells. The results of astrocyte visualization in the motor cortex obtained by the developed technique agree well with the alternative studies by glial fibrillary acidic protein (GFAP) immunohistochemical reaction. The presented approach of combined staining has great potential in current histological practice, in particular for the evaluation of several neurological disorders in clinical, pre-clinical, or neurobiological animal studies.

Nowadays, photonics-based techniques are used extensively in various applications, including functional clinical diagnosis, progress monitoring in treatment, and provision of metrological control. In fact, in the frame of practical implementation of optical methods, such as laser Doppler flowmetry (LDF), the qualitative interpretation and quantitative assessment of the detected signal remains vital and urgently required. In the conventional LDF approach, the key measured parameters, index of microcirculation and perfusion rate, are proportional to an averaged concentration of red blood cells (RBC) and their average velocity within a diagnostic volume. These quantities compose mixed signals from different vascular beds with a range of blood flow velocities and are typically expressed in relative units. In the current paper we introduce a new signal processing approach for the decomposition of LDF power spectra in terms of ranging blood flow distribution by frequency series. The developed approach was validated in standard occlusion tests conducted on healthy volunteers, and applied to investigate the influence of local pressure rendered by a probe on the surface of the skin. Finally, in limited clinical trials, we demonstrate that the approach can significantly improve the diagnostic accuracy of detection of microvascular changes in the skin of the feet in patients with Diabetes Mellitus type 2, as well as age-specific changes. The results obtained show that the developed approach of LDF signal decomposition provides essential new information about blood flow and blood microcirculation and has great potential in the diagnosis of vascular complications associated with various diseases.

A Mueller matrix imaging approach is employed to disclose the three-dimensional composition framework of optical anisotropy within cancerous biotissues. Visualized by the Mueller matrix technique spatial architecture of optical anisotropy of tissues is characterised by high-order statistical moments. Thus, quantitative analysis of the spatial distribution of optical anisotropy, such as linear and circular birefringence and dichroism, is revealed by using high-order statistical moments, enabling definitively discriminate prostate adenoma and carcinoma. The developed approach provides greater (>90%) accuracy of diagnostic achieved by using either the 3-rd or 4-th order statistical moments of the linear anisotropy parameters. Noticeable difference is observed between prostate adenoma and carcinoma tissue samples in terms of the extinction coefficient and the degree of depolarisation. Juxtaposition to other optical diagnostic modalities demonstrates the greater accuracy of the approach described herein, paving the way for its wider application in cancer diagnosis and tissue characterization.

Laser speckle contrast imaging is a modern technique uniquely suited for the full-field, non-invasive measurement of the motion of particles within randomly inhomogeneous highly scattering and absorbing media, including biological tissues. This technique is based on illuminating the medium with a coherent laser light, detecting the arising speckle pattern and further statistical analysis of the speckle pattern fluctuations caused by the motion of the scattering particles in the observed medium. Despite the active use of laser speckle contrast imaging for biomedical applications, this technique suffers from several issues complicating the understanding of obtained speckle contrast data. The present work is aimed at the investigation of limitations, improving, and discovering new potentials of currently existing methods of laser speckle contrast imaging. In particular, the influence of effects of non-ergodicity on the results of speckle contrast analysis was investigated using the phantom and animal models. It was shown that the presence of a thin static layer above the dynamic layer does not introduce significant errors in speckle contrast calculation. The simple approach for the adjustment of speckle contrast values in different types of brain vasculature during transcranial visualisation was introduced. For the first time, the protocol for the monitoring of skin acute vascular permeability reaction in response to simultaneous application of tree different chemical substances has been described. Moreover, in a new approach, the optical setup combining a hyperspectral camera and multi-wavelength light source was implemented for the depth-resolved blood flow and perfusion assessment. The proposed technique was applied for skin perfusion monitoring. Finally, the unprecedented use of laser speckle contrast imaging was introduced for handwriting pressure and kinematics evaluation., Tiivistelmä Lasertäpläkontrastikuvantaminen on nykyaikainen tekniikka, joka soveltuu ainutlaatuisesti koko havainnointikentän alueella tunkeutumattomasti tapahtuville liikkuvien hiukkasten mittauksille satunnaisesti epähomogeenisten, suuresti sirottavien ja absorboivien väliaineiden kuten biologisten kudosten tapauksessa. Kyseinen tekniikka perustuu väliaineen valaisemiseen koherentilla laservalolla, ilmaantuvan täpläkuvion havainnointiin ja sirottavien hiukkasten tutkittavassa väliaineessa tapahtuvan liikkeen aiheuttamien täpläkuvion vaihteluiden tilastolliseen analyysiin. Huolimatta lasertäpläkuvantamisen aktiivisesti käytöstä biolääketieteellisissä sovelluksissa kyseinen tekniikka kärsii useista ongelmista, jotka hankaloittavat saadun täpläkontrastitiedon ymmärtämistä. Esiteltävä työ tähtää olemassa olevien lasertäpläkontrastikuvantamisen menetelmien rajoitteiden tutkimiseen, menetelmien parantamiseen ja uusien sovellusmahdollisuuksien löytämiseen. Työssä tutkittiin erityisesti epäergodisuuden vaikutusta täpläkontrastianalyysin tuloksiin fantomien ja eläinmallien avulla. Tutkimus osoitti, että dynaamisen kerroksen yläpuolella oleva ohut staattinen kerros ei aiheuta täpläkontrastilaskelmiin merkittäviä virheitä. Työn tuloksena kehitettiin yksinkertainen lähestymistapa täpläkontrastiarvojen säätämiseen erityyppisissä aivojen verisuonistoissa transkraniaalisen visualisoinnin aikana. Työssä on ensimmäistä kertaa a) kuvattu menettely ihon äkillisen suonensisäisen läpäisevyysreaktion vasteen tarkkailuun kolmen eri kemikaalin samanaikaisen käytön tapauksessa, b) käytetty hyperspetrikameran ja moniaallonpituuksisen valonlähteen muodostamaa optista kokoonpanoa syvyyserotteiseen veren virtauksen arviointiin sovellettaessa ehdotettua menetelmää ihon perfuusion tarkkailuun sekä c) käytetty lasertäpläkuvantamista käsialan paineen ja kinematiikan arvioinnissa.

Nanomaterials are an essential part of modern life due to their extensive use in industrial and commercial products and future personalized medicine. In recent years, new nanoparticles (NPs) have been introduced in bioimaging, diagnostics, drug delivery, and therapy. Along with the production growth of NPs, concerns about NPs safety for human health have been raised. As blood is an inevitable target for NP-based pharmaceutics at systemic NP-based drug administration, the investigation of the poorly understood effects of NPs on blood properties is of high demand. The present thesis focuses on the assessment of commercial and novel synthesized NPs towards the haemorheologica l properties of the main blood cellular component — red blood cells (RBCs). In the research for this thesis, RBC morphology, deformability and mutual interactions were examined at non-haemolytic concentrations of NPs. A revolutionary optical tweezers technique revealed subtle effects of indirect toxicity towards mutual RBCs interactions and deformability. Further, additional conventional optical microscopy analysis revealed the influence of NPs on RBC interactions on a multicellular level, while scanning electron microscopy (SEM) enabled high-resolution monitoring of RBCs surfaces and morphological alterations triggered by NPs. Another aim of the study addressed the unclear mechanism behind RBC interactions. Experimental evidence of the definitive role of the size and proportion of macromolecules in RBC interactions was provided. The mixture of natural polymer dextran mimicking plasma protein composition induced an RBC interaction mode similar to one observed in blood plasma. Thus, the new hybrid model combining “cross-bridges” and “depletion” effects was proposed. The reported findings contribute to the fundamental understanding of RBC interactions and can help to facilitate the design and clinical validation of polymer-based plasma expanders and novel NPs for safe and beneficial use., Tiivistelmä Nanomateriaalit ovat olennainen osa nykyaikaista elämäntapaa, sillä niitä käytetään laajasti teollisissa ja kaupallisissa tuotteissa sekä tulevaisuuden yksilöllisessä lääketieteessä. Viime vuosina uusia nanopartikkeleita (NP) on otettu käyttöön biolääketieteellisessä kuvantamisessa ja diagnostiikassa sekä lääkkeiden antamisessa ja terapiassa. NP:iden tuotannon kasvun myötä on noussut esiin huoli niiden turvallisuudesta ihmisten terveydelle. Koska veri on väistämätön kohde NP-pohjaisille lääkkeille systeemisessä NP-pohjaisessa lääkkeen annossa, on nanopartikkelien vähän tutkittujen, veren ominaisuuksiin kohdistuvien vaikutusten selvittämiselle suuri tarve. Kyseinen opinnäytetyö keskittyy kaupallisten ja uusien syntetisoitujen nanaopartikkelien arviointiin verisolujen pääkomponentin eli punasolujen (RBC) hemorheologisten ominaisuuksien osalta. Tämän työn tutkimuksessa tarkasteltiin punasolujen morfologiaa, muodonmuutoksia ja keskinäisiä vuorovaikutuksia ei-hemolyyttisissä NP-pitoisuuksissa. Vallankumouksellinen optinen pinsettitekniikka paljasti epäsuoran myrkyllisyyden hienovaraiset vaikutukset punasolujen keskinäiseen vuorovaikutukseen ja muodonmuutokseen. Lisäksi tavanomainen optinen mikroskopia-analyysi paljasti NP:iden ja RBC:n vuorovaikutukset monisoluisella tasolla, kun taas pyyhkäisyelektronimikroskopia (SEM) mahdollisti punasolujen pintojen ja NP:iden laukaisemien morfologisten muutosten korkearesoluutioisen seurannan. Tutkimuksen toisena tavoitteena oli selvittää punasolujen vuorovaikutuksen taustalla olevaa epäselvää mekanismia. Työssä esitettiin kokeellisia todisteita makromolekyylien koon ja osuuden lopullisesta roolista punasolujen vuorovaikutuksessa. Plasmaproteiinikoostumusta jäljittelevän luonnollisen polymeerin dekstraanin seos indusoi punasolujen vuorovaikutusmuodon, joka on samanlainen kuin veriplasmassa havaittu. Siten työssä ehdotettiin uutta "ristisiltoja" ja "tyhjennystä” yhdistävää hybridimallia. Raportoidut löydökset auttavat ymmä

Photo-acoustic imaging, also known as opto-acoustic imaging, has become a widely popular modality for biomedical applications. This hybrid technique possesses the advantages of high optical contrast and high ultrasonic resolution. Due to the distinct optical absorption properties of tissue compartments and main chromophores, photo-acoustics is able to non-invasively observe structural and functional variations within biological tissues including oxygenation and deoxygenation, blood vessels and spatial melanin distribution. The detection of acoustic waves produced by a pulsed laser source yields a high scaling range, from organ level photo-acoustic tomography to sub-cellular or even molecular imaging. This review discusses significant novel technical solutions utilising photo-acoustics and their applications in the fields of biomedicine and life sciences.

In biophotonics, novel techniques and approaches are being constantly sought to assist medical doctors and to increase both sensitivity and specificity of the existing diagnostic methods. In such context, tissue polarimetry holds promise to become a valuable optical diagnostic technique as it is sensitive to tissue alterations caused by different benign and malignant formations. In our studies, multiple Mueller matrices were recorded for formalin-fixed, human, ex vivo colon specimens containing healthy and tumor zones. The available data were pre-processed to filter noise and experimental errors, and then all Mueller matrices were decomposed to derive polarimetric quantities sensitive to malignant formations in tissues. In addition, the Poincaré sphere representation of the experimental results was implemented. We also used the canonical and natural indices of polarimetric purity depolarization spaces for plotting our experimental data. A feature selection was used to perform a statistical analysis and normalization procedure on the available data, in order to create a polarimetric model for colon cancer assessment with strong predictors. Both unsupervised (principal component analysis) and supervised (logistic regression, random forest, and support vector machines) machine learning algorithms were used to extract particular features from the model and for classification purposes. The results from logistic regression allowed to evaluate the best polarimetric quantities for tumor detection, while the use of random forest yielded the highest accuracy values. Attention was paid to the correlation between the predictors in the model as well as both losses and relative risk of misclassification. Apart from the mathematical interpretation of the polarimetric quantities, the presented polarimetric model was able to support the physical interpretation of the results from previous studies and relate the latter to the samples’ health condition, respectively.

Proper rheological properties of red blood cells (RBC) including flexibility and aggregability are essential for healthy blood microcirculation. Excessive RBC aggregation has been observed to be associated with many pathological conditions and is crucial in acute circulatory problems. Low-level laser radiation (LLLR) has been found to have positive effects on the rheology of human blood, however, the detailed mechanisms of blood photobiomodulation remains unclear. In this study, utilizing the single-cell technique optical tweezers (OT) and traditional light microscopy, the influence of photobiomodulation of human RBC was examined under different conditions of laser irradiation. The results revealed that high radiant exposure (over 170.5 J/cm² radiant fluence) caused enhanced RBC aggregation and cell shape transformation while the aggregation force between single RBC remained unchanged. LLLR with radiant fluence below 9.5 J/cm² by 450 nm wavelength improved the RBC deformability, weakened the strength of cell-cell interaction in the RBC disaggregation process, and showed rejuvenating effects on RBC suspended in a harsh cell environment.

This thesis reports on studies of the fundamental interaction dynamics of human red blood cells (RBC) by optical tweezers (OT) and the application of the OT-based RBC-investigation protocol in facilitating blood photobiomodulation research at a single-cell level. The motivation for the present study arises from the scientific and clinical significance of examining RBC interaction mechanisms as a model for studying general cell interaction in cytological science. Exploring the phenomenon and mechanism of the photobiomodulation of laser radiation on the rheological properties of RBC has a great potential in the field of laser blood therapy. Interaction dynamics and the role of intercellular interaction time and mutual contact in RBC aggregation and OT-induced disaggregation in autologous plasma are presented as new evidence, clarifying the RBC interaction mechanism. The rheological alterations of RBC induced by laser radiation with various irradiation conditions were thoroughly explored at a single-cell level for the first time to provide a better understanding of the underlying mechanism of photobiomodulation on blood. This study demonstrated the beneficial effects of low-level laser irradiation by a 450-nm wavelength with a radiant exposure below 9.5 J/cm2 of improving RBC deformability and preserving cell shape in a harsh environment. Additionally, irradiated RBC aggregates were easily destroyed by the external influence (i.e., optical force), which could be the flow shearing force in a blood vessel and geometrical resistance by vasculature for in vivo conditions. The current work is important for optimizing the technique of the OT-based RBC evaluation system. It will contribute to the development of effective approaches for improving blood cell viability and blood microcirculation based on the reported photobiomodulation effects., Tiivistelmä Tässä opinnäytetyössä raportoidaan ihmisen punasolujen (RBC) perustavanlaatuisen vuorovaikutusdynamiikan tutkimuksista optisilla pinseteillä (OT) ja OT-pohjaisen RBC-tutkimusprotokollan soveltamisesta veren fotobiomodulaatiotutkimuksen helpottamiseksi yksisolutasolla. Motivaatio nykyiselle tutkimukselle syntyy punasolujen vuorovaikutusmekanismien tutkimisen tieteellisestä ja kliinisestä merkityksestä mallina yleisen soluvuorovaikutuksen tutkimiseen sytologiassa. Kun lasersäteilyn fotobiomodulaation ilmiötä ja mekanismia tutkitaan punasolujen reologisissa ominaisuuksissa, siinä on paljon potentiaalia laserveriterapian alalla. Interaktiodynamiikka ja solunvälisen interaktioajan ja keskinäisen kontaktin rooli punasolujen aggregaatiossa ja OT:n aiheuttamassa hajoamisessa autologisessa plasmassa esitetään uutena todisteena punasolujen yhteisvaikutusmekanismia selventävänä näyttönä. Punasoluissa tapahtuneita, lasersäteilyn erilaisissa valaistusolosuhteissa aiheuttamia reologisia muutoksia tarkasteltiin nyt ensimmäistä kertaa perusteellisesti yksittäisten solujen tasolla, minkä seurauksena saatiin aiempaa parempi ymmärrys veren fotobiomodulaation taustalla olevasta mekanismista. Tutkimus havainnollisti matalaenergisen, teholtaan alle 9,5 J/cm2:n säteilyaltistuksen ja aallonpituudeltaan 450 nm:n lasersäteilyn hyödylliset vaikutukset punasolujen muodonmuutoksen parantamisessa ja solujen kyvyssä säilyttää muotonsa ankarissakin olosuhteissa. Lisäksi säteilytetyt RBC-aggregaatit tuhoutuivat helposti ulkoisen vaikutuksen vaikutuksesta (optinen voima), joka voi olla virtauksen leikkausvoima verisuonessa ja geometrinen vastus verisuonissa in vivo -olosuhteissa. Tutkimuksen saavutukset ovat merkittäviä optimoitaessa optiseen pinsettiin perustuvan punasolujen arviointijärjestelmän tekniikoita. Raportoitujen fotobiomodulaatio vaikutusten kautta työ edistää verisolujen elinkelpoisuuden ja veren mikrovirtauksen parantamiseen tähtäävien tehokkaiden lähestymistapojen kehittäm

Biosensors based on nanotechnology are developing rapidly and are widely applied in many fields including biomedicine, environmental monitoring, national defense and analytical chemistry, and have achieved vital positions in these fields. Novel nano-materials are intensively developed and manufactured for potential biosensing and theranostic applications while lacking comprehensive assessment of their potential health risks. The integration of diagnostic in vivo biosensors and the DDSs for delivery of therapeutic drugs holds an enormous potential in next-generation theranostic platforms. Controllable, precise, and safe delivery of diagnostic biosensing devices and therapeutic agents to the target tissues, organs, or cells is an important determinant in developing advanced nanobiosensor-based theranostic platforms. Particularly, inspired by the comprehensive biological investigations on the red blood cells (RBCs), advanced strategies of RBC-mediated in vivo delivery have been developed rapidly and are currently in different stages of transforming from research and design to pre-clinical and clinical investigations. In this review, the RBC-mediated delivery of in vivo nanobiosensors for applications of bio-imaging at the single-cell level, advanced medical diagnostics, and analytical detection of biomolecules and cellular activities are presented. A comprehensive perspective of the technical framework of the state-of-the-art RBC-mediated delivery systems is explained in detail to inspire the design and implementation of advanced nanobiosensor-based theranostic platforms taking advantage of RBC-delivery modalities.

Multiwavelength Stokes polarimetry imaging is used for screening fixed bulk mouse brain tissue blocks at different stages of Alzheimer’s disease, providing statistically significant difference sufficient for quantitative analysis of brain tissue.

The impairments of cerebral blood flow microcirculation brought on by cardiac and respiratory arrest were assessed with multi-modal diagnostic facilities, utilising laser speckle contrast imaging, fluorescence spectroscopy and diffuse reflectance spectroscopy. The results of laser speckle contrast imaging show a notable reduction of cerebral blood flow in small and medium size vessels during a few minutes of respiratory arrest, while the same effect was observed in large sinuses and their branches during the circulatory cessation. Concurrently, the redox ratio assessed with fluorescence spectroscopy indicates progressing hypoxia, NADH accumulation and increase of FAD consumption. The results of diffuse reflectance spectra measurements display a more rapid grow of the perfusion of deoxygenated blood in case of circulatory impairment. In addition, consequent histopathological analysis performed by using new tissue staining procedure developed in-house. It shows notably higher reduction of size of the neurons due to their wrinkling within brain tissues influenced by circulation impair. Whereas, the brain tissues altered with the respiratory arrest demonstrate focal perivascular oedema and mild hypoxic changes of neuronal morphology. Thus, the study suggests that consequences of a cessation of cerebral blood flow become more dramatic and dangerous compare to respiratory arrest.

The possibilities of using Mueller matrix (MM) imaging polarimetry to assess meat quality have not yet been sufficiently explored. In the current study, the fresh porcine muscles are imaged at room temperature with a wide-field MM imaging polarimeter over 26 hours to visualize dynamics of tissue optical properties through applying Lu-Chipman decomposition. The frequency distribution histograms (FDHs) and statistical analysis of the MM elements show prominent changes over time. The wavelength spectra of both total depolarization and scalar retardance have dips at 550 nm whereas their values continuously increase with time; the former is referred to the increase of number of scattering events and decrease of myoglobin absorption in the red part of visible spectra related to meat color and freshness, while the latter is associated with the increase in birefringence and meat tenderness. The obtained results are promising to develop a novel fast noncontact optical technique for monitoring of meat quality.

Gene therapy is a rapidly developing medical field, which focuses on the utilization of therapeutic delivery of recombinant nucleic acids into a patient’s cells to treat or prevent a broad spectrum of diseases. However, several important obstacles remain before its wide introduction into clinical application can be implemented. One of the biggest bottlenecks is a lack of efficient and safe delivery technologies, particularly, for in vivo distribution. Additionally, standard requirements for carriers are still an open question (safety, minimal/absent toxicity and immunogenicity, sufficient packaging capacity, targeting, straight and low-cost large-scale Good Manufacturing Practice (GMP) production). Therefore, a growing variety of non-viral delivery platforms represent a promising alternative. Nanotechnology opens new possibilities for resolving biomedical issues. Polymer and hybrid micro- and core–shell nanoparticles are currently under development as a platform for safe and efficient gene delivery. The present thesis describes the development of new safety gene delivery system based on polymer nanoparticles. The results show that nucleic acids (DNA/RNA) can be successfully imbedded into the nanoparticle structures and delivered to various types of cells. For the characterization of the biocompatibility of nanoparticles in vitro, two optical methods were considered. Compatibility with red blood cells (important for intravenous delivery) was assessed using optical tweezers. Capsule biodistribution in vivo was studied with fluorescence spectroscopy and a radiolabeling technique. The data and experience gained from this research open new prospects in the fields of delivery systems areas, gene therapy, and diagnostics in vivo and new possibilities for future clinical applications., Tiivistelmä Geeniterapia on nopeasti kehittyvä lääketieteellinen ala, joka keskittyy rekombinanttisten nukleiinihappojen terapeuttisen annon hyödyntämiseen potilaan soluihin laajan kirjon tautien hoitamiseksi tai ehkäisemiseksi. On kuitenkin olemassa useita tärkeitä esteitä, ennen kuin sen laajaa käyttöönottoa kliinisessä sovelluksessa voidaan toteuttaa. Yksi suurimmista pullonkauloista on tehokkaiden ja turvallisten jakelutekniikoiden puute etenkin in vivo -jakelussa. Myös kiistanalainen vakiovaatimukset operaattoreille ovat edelleen avoin ongelma (turvallisuus, vähäinen / puuttuva myrkyllisyys ja immunogeenisuus, riittävä pakkauskapasiteetti, kohdennus, suora ja edullinen laajamittainen GMP-tuotanto). Siksi kasvava valikoima ei-viraalisia jakelualustoja on lupaava vaihtoehto. Nanoteknologia avaa uuden mahdollisuuden ratkaista biolääketieteelliset kysymykset. Polymeerisiä ja hybridimikro- ja ydin-kuori-nanohiukkasia kehitetään parhaillaan turvallisen ja tehokkaan geeninsiirron alustana. Tässä opinnäytetyössä kuvataan polymeerisiin nanohiukkasiin perustuvan uuden turvallisuusgeenin kuljetusjärjestelmän kehittäminen. Tulokset osoittivat, että nukleiinihapot (DNA / RNA) voidaan upottaa onnistuneesti nanohiukkasten rakenteeseen ja toimittaa erityyppisiin soluihin. Nanohiukkasten biologisen yhteensopivuuden in vitro karakterisoimiseksi otettiin huomioon kaksi optista menetelmää. Yhteensopivuus punasolujen kanssa (tärkeä laskimoon annettaessa) arvioitiin optisilla pinseteillä. Kapselien biologinen jakautuminen in vivo mitattiin ja tutkittiin fluoresenssispektroskopialla ja radioleimaustekniikalla. Tästä tutkimuksesta saadut tiedot ja kokemukset avaavat uusia näkymiä jakelujärjestelmiin, geeniterapiaan ja diagnostiikkaan in vivo ja avaavat uusia mahdollisuuksia tulevassa kliinisessä sovelluksessa.

In this thesis, light-tissue interaction was investigated through different experimental and analytical methodologies to analyze optical and polarization properties over time and the obtained results were utilized in biomedical and food science applications. In this thesis, soft biological tissues (pork samples) were selected as a biological tissue due to their similarity to human tissue. First, the relative spectral changes of absorbance were studied by applying two different custom-built configurations. A Monte Carlo modelling and principal component analysis (PCA) method were applied further to the absorbance dataset to provide thorough studies for a spectroscopic approach. Second, a novel application of Mueller matrix (MM) imaging polarimetry was pioneered to visualize the dynamics of the tissue polarization properties over time with a custom-built Mueller matrix imaging polarimeter (MMIP). Frequency distribution histograms (FDHs) and the changes in the statistical moments of the MM elements were analyzed over time to provide qualitative and quantitative information of the tissue polarization properties. Finally, a new Stokes-polarimetry was introduced to examine optically thin histological sections from optically anisotropic biological tissues with different morphological structures. In summary, in spectroscopic and imaging polarimetry approaches, prominent changes in optical properties of the examined soft biological tissues were discriminated over time. The obtained results are promising in the development of a novel non-destructive tool for monitoring biological tissues for application in biomedical applications and the food industry. The Stokes-polarimetry method can provide a comparative analysis of different polarimetric techniques and prove the diagnostic potential of Stokes correlometry of pathological changes in the orientation-phase structure of biological tissues., Tiivistelmä Tässä opinnäytetyössä valon ja kudoksen vuorovaikutusta tutkittiin erilaisilla kokeellisilla ja analyyttisillä menetelmillä, jotta voitiin tunnistaa optisten ja polarisaatio-ominaisuuksien alkuvaiheita ja hyödyntää saatuja tuloksia biolääketieteellisissä ja elintarviketieteellisissä sovelluksissa. Tässä työssä pehmeäksi biologiseksi kudokseksi valittiin sianlihanäytteet niiden ja ihmiskudoksen samankaltaisuuden vuoksi. Ensiksi pehmeiden biologisten kudosten absorbanssin suhteellisia spektrimuutoksia tutkittiin soveltamalla kahta erilaista räätälöityä kokoonpanoa, jotka yhdistettiin. Monte Carlon mallintamista ja pääkomponenttianalyysimenetelmää (PCA) sovellettiin edelleen absorbanssiaineistoon, jota voitiin perusteellisesti tutkia spektroskooppisesti. Toiseksi Mueller-matriisin (MM) kuvantamispolarimetrian uudella sovelluksella pyrittiin visualisoimaan kudosten polarisaatio-ominaisuuksien dynamiikkaa ajan suhteen räätälöidyllä Mueller-matriisikuvauspolarimetrillä (MMIP). Taajuusjakauman histogrammit (FDH) ja MM-elementtien tilastolliset momenttimuutokset analysoitiin ajan suhteen, jotta saataisiin kvalitatiivista ja kvantitatiivista tietoa kudosten polarisaatio-ominaisuuksista. Lopuksi otettiin käyttöön uusi Stokesin polarimetrinen menetelmä, jotta voitiin tutkia optisesti ohuita histologisia leikkauksia anisotrooppisista biologisista kudoksista, joilla on erilainen morfologinen rakenne. Yhteenvetona voidaan todeta, että spektroskooppisesti ja kuvantamispolarimetrillä tutkittujen pehmeiden biologisten kudosten optisten ominaisuuksien huomattavat muutokset erotettiin selvästi ajan suhteen. Saadut tulokset ovat lupaavia, kun kehitetään uutta ainetta rikkomatonta työkalua biologisten kudosten seurantaan biolääketieteellisissä sovelluksissa ja elintarviketeollisuudessa. Stokesin polarimetrisella menetelmällä voidaan tuottaa vertaileva analyysi erilaisista polarimetrisistä tekniikoista ja todistaa Stokesin korrelometrian diagnostinen potentiaali biologisten k

The laser has biomodulation effects on blood properties thus could regulate the microcirculation. The laser-RBC interaction mechanism is unclear, whereas most studies provide statistical results and lack detailed observations of laser irradiation effects on blood rheology. This study is designated to probe the in vitro effects of 520 nm diode laser irradiation on red blood cells (RBCs) mutual interaction properties in spontaneous aggregation process in autologous plasma by optical tweezers (OTs), with an attempt to reveal the laser-RBC interaction outcomes at a single-cell level. The results preliminarily show that though the laser irradiation statistically inhibited the increase of the size of RBC aggregates compared with the non-irradiating group, the aggregation force between single RBCs increased slightly with the time of irradiation.

New methods for the functional characterization of biological tissues based on optical sensing and imaging techniques have been developed in recent decades. These advanced optical methods enable the quantitative scoring of tissue optical properties and give rise to the optical biopsy, which shows high potential for implementation in clinical practice in the near future. The present thesis describes the methods for the functional characterization of biological tissues based on the polarized light of the visible range and terahertz radiation. The considered approaches, enhanced by methods of mathematical and statistical analysis, were applied to differentiate various conditions of biological tissues that affect their morphological structure and water content. Polarized light imaging techniques, in particular, Stokes vector polarimetry based on circularly polarized illumination and multi-wavelength Mueller matrix imaging, were used for the label-free analysis of changes in tissue depolarization and anisotropy characteristics caused by different conditions such as cancer, beta-amyloidosis, tissue stretching, and dystrophic changes of fibrillary structures. Terahertz time-domain spectroscopy was utilized to non-invasively monitor tissue dehydration in transmission- and reflection-based measurement configurations. The fundamentals of the considered methods of optical tissue characterization, their limitations, and recent advances are overviewed. The present work aims for the improvement of the considered optical imaging and characterization techniques, as well as for discovering their potential to achieve better diagnostic efficiency and for facilitating their transfer from the laboratory to clinical use., Tiivistelmä Viime vuosikymmeninä biologisten kudosten toiminnalliseen karakterisointiin on kehitetty uusia menetelmiä, jotka perustuvat optisen tunnistamisen ja kuvantamisen tekniikoihin. Nämä kehittyneet optiset menetelmät mahdollistavat kudoksen optisten ominaisuuksien kvantitatiivisen pisteytyksen ja luovat siten pohjaa optiselle biopsialle, jolla on suuri potentiaali tulla kliiniseen käyttöön lähitulevaisuudessa. Opinnäyte kuvaa näkyvän alueen polarisoituun valoon ja terahertsisäteilyyn perustuvat biologisten kudosten toiminnallisen karakterisoinnin menetelmät. Näitä valikoituja, matemaattisilla ja tilastollisilla analyysimenetelmillä tehostettuja lähestymistapoja sovellettiin erottelemaan biologisten kudosten morfologiseen rakenteeseen ja vesipitoisuuteen vaikuttavia erilaisia olotiloja. Polarisoitua valoa hyödyntäviä kuvantamistekniikoita, erityisesti pyöröpolarisoituun valaistukseen perustuvaa Stokes-vektoripolarimetriaa ja monen aallonpituuden Mueller-matriisikuvantamista, käytettiin kudosten depolarisaatio- ja anisotropiapiirteissä tapahtuneiden erilaisten muutosten, joita aiheuttava esimerkiksi syöpä, beta-amyloidoosin, kudosvenymä ja lihasrakenteiden rappeumamuutokset, nimeämättömään analysointiin. Aikatason terahertsispektroskopiaa käytettiin kudoksen kuivumisen kajoamattomaan seurantaan mittauskokoonpanoilla, jotka perustuvat sekä läpäisyyn että heijastukseen. Työssä luodaan yleiskuva valittujen optisten kudoksen karakterisointimenetelmien perusteista, rajoitteista ja viimeaikaisesta kehityksestä. Työ tähtää näiden optisten kuvantamis- ja karakterisointitekniikoiden parantamiseen sekä niiden uuden potentiaalin löytämiseen, jotta saavutetaan parempi diagnostinen tehokkuus ja helpotetaan tekniikoiden siirtymistä laboratoriosta kliiniseen käyttöön.

Aging and diabetes lead to protein glycation and cause dysfunction of collagen-containing tissues. The accompanying structural and functional changes of collagen significantly contribute to the development of various pathological malformations affecting the skin, blood vessels, and nerves, causing a number of complications, increasing disability risks and threat to life. In fact, no methods of non-invasive assessment of glycation and associated metabolic processes in biotissues or prediction of possible skin complications, e.g., ulcers, currently exist for endocrinologists and clinical diagnosis. In this publication, utilizing emerging photonics-based technology, innovative solutions in machine learning, and definitive physiological characteristics, we introduce a diagnostic approach capable of evaluating the skin complications of diabetes mellitus at the very earlier stage. The results of the feasibility studies, as well as the actual tests on patients with diabetes and healthy volunteers, clearly show the ability of the approach to differentiate diabetic and control groups. Furthermore, the developed in-house polarization-based hyperspectral imaging technique accomplished with the implementation of the artificial neural network provides new horizons in the study and diagnosis of age-related diseases.

We applied the wide-field Mueller imaging polarimetry for the screening of formalin-fixed paraffin-embedded samples of mouse brain tissue at different stages of brain β-amyloidosis in Alzheimer’s disease (AD). The accumulation of amyloid-beta (Aβ) deposits throughout the brain tissue is one of the key pathological hallmarks observed with the AD progression. We demonstrate that the presence of Aβ plaques influences the properties of backscattered polarized light, in particular, its degree of depolarization. By means of statistical analysis, we demonstrate that the high-order statistical moments of depolarization distributions, acquired with the multi-spectral Mueller imaging polarimetry, can be used as sensitive markers of the growing presence of Aβ plaques. The introduced label-free polarimetric approach has a potential to facilitate the current practice of the histopathology screening in terms of diagnosis accuracy, time and cost efficiency.

Alzheimer’s disease, being a major societal burden, demands improvement of current techniques for its treatment and diagnostics. Currently only autopsy histology is able to provide the definite diagnosis for Alzheimer’s disease. However, the procedure is rather time consuming and costly. In the current study, we utilized Stokes and Mueller polarimetry techniques to screen for amyloid-β (Aβ) deposits in formalin-fixed, paraffin-embedded mouse brain tissue at different stages of Alzheimer’s disease. The study has shown that the presence of Aβ plaques influences the properties of scattered polarized light. The Poincaré sphere was used as a graphical tool for the visualization of the alterations of the Stokes vector, obtained with Stokes polarimetry, whereas statistical moments were used for the analysis of depolarization distributions that were acquired with Mueller polarimetry. We demonstrate the sensitivity of the last component of the Stokes vector, the degree of polarization and high-order statistical moments of depolarization to the structural alterations in brain tissue, which correspond to the disease progression. The described approach has a potential to improve the existing pathology screening methods and facilitates Aβ detection in AD research.

The peculiarity of red blood cell interaction was studied by optical tweezers. The intercellular interaction force in cell pairs and the role of cell deformation and adhesion time in interaction dynamics were evaluated and discussed.

This work is dedicated to the diagnosis and grading of colon cancer by a combined use of Poincaré sphere and 2D Stokes vector polarimetry mapping approaches. The major challenge consists in exploring the applicability of polarized light for noninvasive screening of the histological abnormalities within the samples of biological tissues. Experimental studies were conducted in ex vivo colon sample, excised after surgical procedure for colon tumor removal of G2‐adenocarcinoma lesion. Polarimetric measurements in linear and circular regime were carried via personally developed polarimetric, optical set‐up, using supercontinuous fiber laser with irradiation fixed at 635 nm. We apply the Poincaré sphere and two‐dimensional Stokes vector scanning approach for screening the corresponding tissue samples. A comparison between linear and circular polarization states is made both for quantitative and qualitative evaluations. It is shown that circular polarization has better diagnostic capabilities than linear polarization, with higher dynamic ranges of the polarimetric parameters and better values of the diagnostic quantities. In addition to the standard polarimetry parameters, utilized as essential diagnostic markers, we apply statistical analysis to obtain more detailed information in frame of the applied diagnostic.

Emerging biomedical instrumentation for imaging and diagnostics requires tissue-mimicking phantoms with optical properties close to those of real biological tissues. Many such tissues and organs consist of several layers with different physical properties, e.g. the head includes the brain, skull, and skin, which in turn also comprise several layers. Structure, optical and mechanical properties depend on the purpose of phantoms and studied materials and technologies. In this paper, we present both plain single-, multi-layered phantoms, and complex opto-mechanical phantoms that imitate parts of the body, in particular, the head. We describe the procedure, materials, internal structure, and tuning of the optical properties of two different phantom manufacturing methods as well as show examples of tissue-mimicking phantoms for different biomedical applications.

Light in the range of 700—1100 nm has many proven diagnostics and therapeutic medical applications. In this study, we demonstrate another potential application of light. We implemented a testbed to transmit data wirelessly through a human skull and biological phantoms mimicking skin tissues properties using near-infrared (NIR) light. Currently, radio frequency (RF) is widely used to transmit data wirelessly through biological tissues, example includes implants communications. However, RF communications contain interference and security challenges. In this study, we present a novel use of NIR light for wireless data transfer, for which a phantom is exposed to an externally modulated light source and the transmitted light through phantom is captured with a receiver. Initially, a high-resolution picture is successfully transmitted through skin phantom of 2 cm in depth. In the second phase, we successfully communicated through a human skull. Due to hardware limitations, we are able to achieve data rates in tens of kilobits per second. The minimum power applied to the phantoms measured during the data transmission from 810 nm light-emitting-diode (LED) is 0.098 W/cm2. The measured optical power values are within the safe limit set by ANSI.Z136.1—2007 standard on laser safety, which is 2 W/cm2 for 1 sec exposure of 830 nm wavelength. Initial results are encouraging and there are many possible applications for a system using light to transmit data wirelessly through biological tissues, including communication with brain implants and performing brain therapies.

We introduce a method of azimuthally invariant 3D Mueller-matrix (MM) layer-by-layer mapping of the phase and amplitude parameters of anisotropy of the partially depolarizing layers of benign (adenoma) and malignant (carcinoma) prostate tumours. The technique is based on the analysis of spatial variations of Mueller matrix invariant (MMI) of histological sections of benign (adenoma) and malignant (carcinoma) tissue samples. The phase dependence of magnitudes of the first-to-fourth order statistical moments is applied to characterize 3D spatial distributions of MMI of linear and circular birefringence and dichroism of prostate tumours. The high order statistical moments and phase sections of the optimal differentiation of the polycrystalline structure of tissue samples are revealed. The obtained results are compared with the results obtained by conventional methods utilizing polarized light, including 2D and 3D Mueller matrix imaging.

The prevalence of diabetes complications is a significant public health problem with a considerable economic cost. Thus, the timely diagnosis of complications and prevention of their development will contribute to increasing the length and quality of patient life, and reducing the economic costs of their treatment. This article aims to review the current state‐of‐the‐art biophotonics technologies used to identify the complications of diabetes mellitus and assess the quality of their treatment. Additionally, these technologies assess the structural and functional properties of biological tissues, and they include capillaroscopy, laser Doppler flowmetry and hyperspectral imaging, laser speckle contrast imaging, diffuse reflectance spectroscopy and imaging, fluorescence spectroscopy and imaging, optical coherence tomography, optoacoustic imaging and confocal microscopy. Recent advances in the field of optical noninvasive diagnosis suggest a wider introduction of biophotonics technologies into clinical practice and, in particular, in diabetes care units.

Increasing concerns about adulterated meat encouraged industry looking for new non-invasive methods for rapid accurate meat quality assessment. Main meat chromophores (myoglobin, oxy-myoglobin, fat, water, collagen) are characterized by close comparable absorption in visible to near-infrared (NIR) spectral region. Therefore, structural and compositional variations in meat may lead to relative differences in the absorption of light. Utilizing typical fiber-optic probes and integrating sphere, a degradation of pork samples freshness was observed at room temperature referring to the relative changes in absorbance of main meat chromophores. The application of principal component analysis (PCA) used for examination of measured absorbance spectra revealed more detailed sub-stages of freshness, which are not observed by the conventional analysis of the reflectance spectra. The results show a great potential of the combined application of optical-NIR spectroscopy with complementary use of PCA approach for assessing meat quality and monitoring relative absorbance alternation of oxymyoglobin and myoglobin in visible, and fat, water, collagen in NIR spectral ranges.

Demonstration of the light radiation pressure on a microscopic level by A. Ashkin led to the invention of optical tweezers (OT). Applied in the studies of living systems, OT have become a preferable instrument for the noninvasive study of microobjects, allowing manipulation and measurement of the mechanical properties of molecules, organelles, and cells. In the present paper, we overview OT applications in hemorheological research, placing emphasis on red blood cells but also discussing OT applications for the investigation of the biomechanics of leukocytes and platelets. Blood properties have always served as a primary parameter in medical diagnostics due to the interconnection with the physiological state of an organism. Despite blood testing being a well-established procedure of conventional medicine, there are still many complex processes that must be unraveled to improve our understanding and contribute to future medicine. OT are advancing single-cell research, promising new insights into individual cell characteristics compared to the traditional approaches. We review the fundamental and practical findings revealed in blood research through the optical manipulation, stretching, guiding, immobilization, and inter-/intracellular force measurements of single blood cells.

The purpose of the study is to demonstrate a new method of Stokes-correlometric evaluation of polarization-inhomogeneous images of optically thin (optical thickness smaller than 0.01) histological sections from optically anisotropic biological tissues of different morphological structure. This method is based on a correlation (“two-point”) generalization of traditional optical methods for analyzing “one-point” distributions of polarization states of microscopic images of biological tissues. Analytical algorithms are obtained for describing the “two-point” complex parameters of the Stokes vector image of a birefringent biological tissue. An experimental technique has been developed for measuring polarization-correlation maps, i.e. the coordinate distributions of the magnitude and phase of the “two-point” Stokes vector parameters. Within the framework of the statistical and correlation analysis of the obtained data, new quantitative criteria for the differentiation of the optical properties of biological tissues of various morphological structures are found. A comparative analysis of the distribution of the “single-point” and “two-point” parameters of the Stokes vector of polarizationally inhomogeneous images was performed. It revealed a higher sensitivity (2–5 times) of the Stokes-correlometry method to variations in orientation-phase structure of biological tissues compared to the single-point approach.

Optical tweezers (OTs) are innovative instruments utilized for the manipulation of microscopic biological objects of interest. Rapid improvements in precision and degree of freedom of multichannel and multifunctional OTs have ushered in a new era of studies in basic physical and chemical properties of living tissues and unknown biomechanics in biological processes. Nowadays, OTs are used extensively for studying living cells and have initiated far-reaching influence in various fundamental studies in life sciences. There is also a high potential for using OTs in haemorheology, investigations of blood microcirculation and the mutual interplay of blood cells. In fact, in spite of their great promise in the application of OTs-based approaches for the study of blood, cell formation and maturation in erythropoiesis have not been fully explored. In this review, the background of OTs, their state-of-the-art applications in exploring single-cell level characteristics and bio-rheological properties of mature red blood cells (RBCs) as well as the OTs-assisted studies on erythropoiesis are summarized and presented. The advance developments and future perspectives of the OTs’ application in haemorheology both for fundamental and practical in-depth studies of RBCs formation, functional diagnostics and therapeutic needs are highlighted.

In this study, we utilize the properties of polarized light for the analysis of paraffin-embedded breast cancer samples. We perform the measurements of the full Stokes vector of back-reflected radiation and calculate the degree of polarization as a diagnostic criterion for the separation of healthy and cancer sample sections. We show that circularly polarized light scattered within the breast sample is sensitive to the presence of cancer cells. The degree of the polarization of the reflected light was found to be the most sensitive parameter for the reliable differentiation of tissue. We show that circularly polarized light scattered within the breast sample is sensitive to the presence of cancer cells. The highest contrast between cancerous and normal regions was observed for the probing wavelength of 450 nm. The degree of the polarization of the reflected light was found to be the most sensitive parameter. Mapping the Stokes vectors of backscattered light on a Poincaré sphere helps to highlight the changes of polarization state.

Significance: Biological tissues are typically characterized by high anisotropic scattering and may also exhibit linear form birefringence. Both scattering and birefringence bias the phase shift between transverse electric field components of polarized light. These phase alterations are associated with particular structural malformations in the tissue. In fact, the majority of polarization-based techniques are unable to distinguish the nature of the phase shift induced by birefringence or scattering of light. Aim: We explore the distinct contributions of scattering and birefringence in the phase retardation of circularly polarized light propagated in turbid tissue-like scattering medium. Approach: The circularly polarized light in frame of Stokes polarimetry approach is used for the screening of biotissue phantoms and chicken skin samples. The change of optical properties in chicken skin is accomplished by optical clearing, which reduces scattering, and mechanical stretch, which induces birefringence. The change of optical properties of skin tissue is confirmed by spectrophotometric measurements and second-harmonic generation imaging. Results: The contributions of scattering and birefringence in the phase retardation of circularly polarized light propagated in biological tissues are distinguished by the locus of the Stokes vector mapped on the Poincaré sphere. The phase retardation of circularly polarized light due to scattering alterations is assessed. The value of birefringence in chicken skin is estimated as 0.3 × 10− 3, which agrees with alternative studies. The change of birefringence of skin tissue due to mechanical stretch in the order of 10− 6 is detected. Conclusions: While the polarimetric parameters on their own do not allow distinguishing the contributions of scattering and birefringence, the resultant Stokes vector trajectory on the Poincaré sphere reveals the role of scattering and birefringence in the total phase retardation. The described

In the framework of novel medical paradigm the red blood cells (RBCs) have a great potential to be used as drug delivery carriers. This approach requires an ultimate understanding of the peculiarities of mutual interaction of RBC influenced by nano-materials composed the drugs. Optical tweezers (OT) is widely used to explore mechanisms of cells’ interaction with the ability to trap non-invasively, manipulate and displace living cells with a notably high accuracy. In the current study, the mutual interaction of RBC with polymeric nano-capsules (NCs) is investigated utilizing a two-channel OT system. The obtained results suggest that, in the presence of NCs, the RBC aggregation in plasma satisfies the ’cross-bridges’ model. Complementarily, the allocation of NCs on the RBC membrane was observed by scanning electron microscopy (SEM), while for assessment of NCs-induced morphological changes the tests with the human mesenchymal stem cells (hMSC) was performed. The combined application of OT and advanced microscopy approaches brings new insights into the conception of direct observation of cells interaction influenced by NCs for the estimation of possible cytotoxic effects.

Efficient delivery of genetic material to primary cells remains challenging. Here, efficient transfer of genetic material is presented using synthetic biodegradable nanocarriers, resembling extracellular vesicles in their biomechanical properties. This is based on two main technological achievements: generation of soft biodegradable polyelectrolyte capsules in nanosize and efficient application of the nanocapsules for co‐transfer of different RNAs to tumor cell lines and primary cells, including hematopoietic progenitor cells and primary T cells. Near to 100% efficiency is reached using only 2.5 × 10–4 pmol of siRNA, and 1 × 10–3 nmol of mRNA per cell, which is several magnitude orders below the amounts reported for any of methods published so far. The data show that biodegradable nanocapsules represent a universal and highly efficient biomimetic platform for the transfer of genetic material with the utmost potential to revolutionize gene transfer technology in vitro and in vivo.