Stokes polarization imaging applied for monitoring dynamic tissue optical clearing

Mueller matrix polarimetry for quantitative evaluation of the Achilles tendon injury recovery

Achilles tendon injuries, as a widely existing disease, have attracted a lot of research interest. Mueller matrix polarimetry, as a novel label-free quantitative imaging method, has been widely used in various applications of lesion identification and pathological diagnosis. However, focusing on the recovery process of Achilles tendon injuries, current optical imaging methods have not yet achieved the label-free precise identification and quantitative evaluation. In this study, using Mueller matrix polarimetry, various Achilles tendon injury samples were characterized specifically, and the efficacy of different recovery schemes was evaluated accordingly. Experiments indicate that injured Achilles tendons show less phase retardance, larger diattenuation, and relatively disordered orientation. The combination of experiments with Monte Carlo simulation results illustrate the microscopic mechanism of the Achilles tendon recovery process from three aspects, that is, the increased fiber diameter, a more consistent fiber orientation, and greater birefringence induced by more collagen protein. Finally, based on the statistical distribution of polarization measurements, a polarization specific characterization parameter was extracted to construct a label-free image, which cannot only intuitively show the injury and recovery of Achilles tendon samples, but also give a quantitative evaluation of the treatment.

Stereoscopic spatial graphical method of Mueller matrix: Global-Polarization Stokes Ellipsoid

A Mueller matrix covers all the polarization information of the measured sample, however the combination of its 16 elements is sometimes not intuitive enough to describe and identify the key characteristics of polarization changes. Within the Poincaré sphere system, this study achieves a spatial representation of the Mueller matrix: the Global-Polarization Stokes Ellipsoid (GPSE). With the help of Monte Carlo simulations combined with anisotropic tissue models, three basic characteristic parameters of GPSE are proposed and explained, where the V parameter represents polarization maintenance ability, and the E and D† parameters represent the degree of anisotropy. Furthermore, based on GPSE system, a dynamic analysis of skeletal muscle dehydration process demonstrates the monitoring effect of GPSE from an application perspective, while confirming its robustness and accuracy.

Clearing Properties Between Coconut Oil and Xylene in Histological Tissue Processing

Xylene is the commonest clearing agent even though it is hazardous and costly. This study evaluated the clearing properties of coconut oil as an alternative cost-effective clearing agent for histological processes. Ten (10) prostate samples fixed in formalin were taken and each one was cut into 4 before randomly separating them into four groups (A, B, C and D). Tissues were subjected to ascending grades of alcohol for dehydration. Group A was cleared in xylene and Groups B, C, and D were cleared at varying times of 1hr 30mins, 3hrs, and 4hrs in coconut oil respectively before embedding, sectioning, and staining were carried out. Gross and histological features were compared. Results indicated a significant shrinkage in coconut oil-treated specimen compared with the xylene-treated specimen and only the tissues cleared in coconut oil for 4hrs were as rigid as the tissues cleared in xylene (p > 0.05). No significant difference was found in either of the sections when checked for cellular details and staining quality (p > 0.999). Coconut oil is an efficient substitute for xylene in prostate tissues with a minimum clearing time of 4hrs, as it is environmentally friendly and less expensive, but causes significant shrinkage to prostate tissue.

Mechanical stability of polarization signatures in biological tissue characterization

Mueller matrix imaging polarimetry (MMIP) is a promising technique for investigating structural abnormalities in pathological diagnosis. The characterization stability of polarization signatures, described by Mueller matrix parameters (MMPs), correlates with the mechanical state of the biological medium. In this study, we developed an MMIP system capable of applying quantitative forces to samples and measuring the resulting polarization signatures. Mechanical stretching experiments were conducted on a mimicking phantom and a tissue sample at different force scales. We analyzed the textural features and data distribution of MMP images and evaluated the force effect on the characterization of MMPs using the structural similarity index. The results demonstrate that changes in the mechanical microenvironment (CMM) can cause textural fluctuations in MMP images, interfering with the stability of polarization signatures. Specifically, parameters of anisotropic orientation, retardance, and optical rotation are the most sensitive to CMM, inducing a dramatic change in the overall image texture, while other parameters (e.g., polarization, diattenuation, and depolarization) exhibit locality in their response to CMM. For some MMPs, CMM can enhance regional textural contrasts. This study elucidates the mechanical stability of polarization signatures in biological tissue characterization and provides a valuable reference for further research toward minimizing CMM influence.

Multispectral polarization microscopy of different stages of human oral tissue: A polarization study

Many optical techniques have been used in various diagnostics and biomedical applications since a decade and polarization imaging is one of the non-invasive and label free optical technique to investigate biological samples making it an important tool in diagnostics, biomedical applications. We report a multispectral polarization-based imaging of oral tissue by utilizing a polarization microscope system with a broadband-light source. Experiments were performed on oral tissue samples and multispectral Stokes mapping was done by recording a set of intensity images. Polarization-based parameters like degree of polarization, angle of fast axis, retardation and linear birefringence have been retrieved. The statistical moments of these polarization components have also been reported at multiples wavelengths. The polarimetric properties of oral tissue at different stages of cancer have been analyzed and significant changes from normal to pre-cancerous lesions to the cancerous are observed in linear birefringence quantification as (1.7 ± 0.1) × 10-3 , (2.5 ± 0.2) × 10-3 and (3.3 ± 0.2) × 10-3 respectively.

Imaging and Non-imaging Analytical Techniques Used for Drug Nanosizing and their Patents: An Overview

BACKGROUND

Nanosizing is widely recognized as an effective technique for improving the solubility, dissolution rate, onset of action, and bioavailability of poorly water-soluble drugs. To control the execution and behavior of the output product, more advanced and valuable analytical techniques are required.

OBJECTIVE

The primary intent of this review manuscript was to furnish the understanding of imaging and non-imaging techniques related to nanosizing analysis by focusing on related patents. In addition, the study also aimed to collect and illustrate the information on various classical (laser diffractometry, photon correlation spectroscopy, zeta potential, laser Doppler electrophoresis, X-ray diffractometry, differential scanning calorimeter, scanning electron microscopy, transmission electron microscopy), new, and advanced analytical techniques (improved dynamic light scattering method, Brunauer-Emmett- Teller method, ultrasonic attenuation, biosensor), as well as commercial techniques, like inductively coupled plasma mass spectroscopy, aerodynamic particle sizer, scanning mobility particle sizer, and matrix- assisted laser desorption/ionization mass spectroscopy, which all relate to nano-sized particles.

METHODS

The present manuscript has taken a fresh look at the various aspects of the analytical techniques utilized in the process of nanosizing, and has achieved this through the analysis of a wide range of peer-reviewed literature. All summarized literature studies provide the information that can meet the basic needs of nanotechnology.

RESULTS

A variety of analytical techniques related to the nanosizing process have already been established and have great potential to weed out several issues. However, the current scenarios require more relevant, accurate, and advanced analytical techniques that can minimize the time and deviations associated with different instrumental and process parameters. To meet this requirement, some new and more advanced analytical techniques have recently been discovered, like ultrasonic attenuation technique, BET technique, biosensors, etc. Conclusion: The present overview certifies the significance of different analytical techniques utilized in the nanosizing process. The overview also provides information on various patents related to sophisticated analytical tools that can meet the needs of such an advanced field. The data show that the nanotechnology field will flourish in the coming future.

Polarization phase unwrapping by a dual-wavelength Mueller matrix imaging system

In this Letter, we report a dual-wavelength Mueller matrix imaging system for polarization phase unwrapping, allowing simultaneous acquisition of the polarization images at 633 nm and 870 nm. After phase unwrapping, the relative error of linear retardance is controlled to be 3% and the absolute error of birefringence orientation is about 6°. We first show that polarization phase wrapping occurs when the samples are thick or present obvious birefringence effects, and further analyze the effect of phase wrapping on anisotropy parameters via Monte Carlo simulations. Then, experiments on porous alumina with different thicknesses and multilayer tapes are performed to verify the feasibility of phase unwrapping by a dual-wavelength Mueller matrix system. Finally, by comparing the temporal characteristics of linear retardance during tissue dehydration before and after phase unwrapping, we emphasize the significance of the dual-wavelength Mueller matrix imaging system not only for anisotropy analysis in static samples, but also for determining the trend in polarization properties of dynamic samples.

Probing Dynamic Variation of Layered Microstructure Using Backscattering Polarization Imaging

Polarization imaging can quantitatively probe the microscopic structure of biological tissues which can be complex and consist of layered structures. In this paper, we established a fast-backscattering Mueller matrix imaging system to characterize the dynamic variation in the microstructure of single-layer and double-layer tissues as glycerin solution penetrated into the samples. The characteristic response of Mueller matrix elements, as well as polarization parameters with clearer physics meanings, show that polarization imaging can capture the dynamic variation in the layered microstructure. The experimental results are confirmed by Monte Carlo simulations. Further examination on the accuracy of Mueller matrix measurements also shows that much faster speed has to be considered when backscattering Mueller matrix imaging is applied to living samples.

Detection Methods of Nanoparticles Synthesized by Gas-Phase Method: A Review

The detection of nanoparticles is the basis of the study of synthesis mechanism, active regulation of the synthesis process, and the study of nanoparticle properties after synthesis. It is significantly meaningful to the academia and engineering industry. Although there are many relevant detection methods at present, each method has its own advantages and disadvantages, and their measurement quantity and application conditions are also different. There is a lack of unified sorting and generalization. In this paper, the significance of detection of nanoparticles synthesized by a gas-phase method is introduced, the development of detection technology is reviewed, and the future is prospected. It is hoped that this paper will provide a reference for the detection of nanoparticles under various conditions and for the development of new detection methods.

Polarization and Orbital Angular Momentum of Light in Biomedical Applications: feature issue introduction

In the last decade, consistent and successful innovations have been achieved in the field of lasers and optics, collectively known as 'photonics', founding new applications in biomedicine, including clinical biopsy. Non-invasive photonics-based diagnostic modalities are rapidly expanding, and with their exponential improvement, there is a great potential to develop practical instrumentation for automatic detection and identification of different types and/or sub-types of diseases at a very early stage. While using conventional light for the studies of different properties of objects in materials science, astrophysics and biomedicine already has a long history, the interaction of polarized light and optical angular momentum with turbid tissue-like scattering media has not yet been ultimately explored. Since recently this research area became a hot topic. This feature issue is a first attempt to summarize the recognitions achieved in this emerging research field of polarized light and optical angular momentum for practical biomedical applications during the last years.