This research presents an innovative fiber optic dosimetry sensor tailored for radiation measurement in biological environments. The aim is to achieve a two-dimensional (2D) spatial distribution of radiation by using an array of sensors that are arranged in a custom-designed holder. In this investigation, the FLIXCAT™ FlexHD1 Fiber-Optic Dosimeter (FOD) was irradiated using a ¹³⁷Cs γ-ray source, highlighting a discrepancy of up to 61% between the actual irradiated dose and the reconstructed dose inside animal subjects. Employing the FOD as a novel dosimeter, specifically in in vivo biological systems, necessitated biocompatibility studies to assess their interaction with real tissue and their influence on inflammatory markers in the blood.

This study initiated with the surgical implantation of three cylindrical FODs, along with three standard TLD_100 dosimeters at various in vivo points (behind the neck, right femur, and abdomen). Subsequent to implantation, both FOD and TLD_100 samples were subjected to gamma radiation and analyzed post-extraction. The observed discrepancy between the actual irradiation dose and the reconstructed dose within the animal is due to the dosimeter directly receiving the unimpeded true dose in open air, unlike within the animal’s body, where various tissues attenuate radiation from its point of entry to the dosimeter’s location. This attenuation is influenced by factors like tissue thickness and type and the depth of the dosimeter from the body surface.

For implant validation, Magnetic Resonance Imaging (MRI) was performed to detect the dosimeters at three different points in the animal’s body. MRI confirmed that implants (dosimeters) were present at all three locations without signs of oedema or inflammation. Additionally, there was no cell infiltration, confirming the sterility and biocompatibility of the dosimeters. Our results underscore the potential of the novel FOD in accurately measuring effective radiation doses for various organs in vivo, without inducing adverse effects.

Photodynamic therapy (PDT) is an emerging cancer treatment in which a specific wavelength (laser) is used to activate a molecule that is sensitive to light (photosensitizer) and damages cancer cells. Prior to treating a patient with PDT, a reliable dosimetric verification method is required, since the success of the treatment depends on the accurate delivery of the photodynamic dose. The present study evaluates the response of a possible dosimeter based on porcine gel with dispersion properties (intralipid emulsion to mimic human skin) doped with the photosensitizer PpIX (absorbent property) under different radiation doses of a 635 nm laser (PpIX excitation). The porcine gel was synthesized both with and without PpIX. To determine the effect of the radiation dose on both porcine gels, the dose enhancement factor was quantified. For this, IR thermography measurements were taken on doped and non-doped gels. The radiation-induced temperature (ΔT) changes of the PpIX-loaded gel samples compared to the control samples (without PpIX) after red laser irradiation at different doses (15, 30, 45, 60, and 100 J/cm²) showed a significant dose enhancement that was greater than unity, except for 45 J/cm². Our findings show that porcine gels respond to a range of radiation doses that include the standard dose (37 J/cm²) used for skin treatments, making them attractive for use as dosimeters that are capable of being read by a thermal imaging camera.

In the physical world, patterns of different sizes and forms are ubiquitous, from the nanoworld to the macroworld and, ultimately, gigantic like galaxies and the universe itself. At the atomic level, various geometric forms, such as the angles between atomic bonds and the spatial distribution of electronic density, fix the system's configuration and, therefore, its reactivity. On a larger scale, the helical spirals of DNA, the lattice patterns of crystals and supramolecular assemblies, the shapes of cells, and various assemblies of cells within tissues are examples of the most common patterns exhibited by nature. Nanostructured materials possess properties that depend on size and shape, distinctly differing from their bulk counterparts. These nanopatterns and morphologies influence biological organisms' thermal and optical management, which is essential for life. This management is often interwoven with the size and geometry of patterns. Elucidating its properties and occurrence is of high importance for understanding our world. In this study, we reveal, on a phenomenological level, the effect of the nanoscale patterns on thermal management. Besides the fundamental importance of exposing the structural constraints that are responsible for unusual thermodynamic response, the presented study offers the concept of shaping heat capacity on command by controlling the geometry without changing the system's chemistry.

Digital pathology images often suffer from a low resolution due to limitations in acquisition and storage, which severely affects diagnosis and machine analysis. To address the issue of low-resolution pulmonary H&E-stained sections, we propose a deep learning network model, the lung cytopathological images super-resolution and segmentation network (LCSr-SeNet), which aims to simultaneously enhance image resolution and achieve cell segmentation. LCSr-SeNet consists of two modules: a super-resolution module and a segmentation module. The super-resolution module, through progressive feature extraction and reconstruction, significantly enhances the details and clarity of pathology images. The segmentation module then precisely segments the enhanced high-resolution images, distinguishing cancer cells from normal cells. In quantitative evaluations, LCSr-SeNet demonstrates significant advantages in both image resolution enhancement and cell segmentation tasks. In terms of its peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM), LCSr-SeNet significantly outperforms traditional methods. Additionally, in cell segmentation tasks, the model exhibits excellent performance in metrics such as the Dice coefficient and intersection over union (IoU), greatly improving the segmentation accuracy and robustness. LCSr-SeNet successfully overcomes the challenges posed by low-resolution sections, achieving precise segmentation and localization of cells in pulmonary tissues. This innovative method provides a new solution for pulmonary pathology image analysis and holds promise for significant contributions to the diagnosis and treatment of lung cancer.

Low-power, high-fidelity optical excitation and the effective suppression of uncoordinated heartbeats are major challenges in cardiac optogenetics. Recently, a red-shifted, cation-conducting channelrhodopsin known as ChRmine, derived from the Rhodomonas lens (also attributed to the marine ciliate Tiarina fusus), has been discovered. ChRmine exhibits high light sensitivity and generates a large photocurrent for optical excitation. In addition, a potassium (K⁺)-conducting channelrhodopsin from Hyphochytrium catenoids (HcKCR1) has also been discovered. HcKCR1 exhibits a reversal potential close to the resting membrane potential of the targeted cardiac cells, making it suitable for optical suppression. In this paper, we present a theoretical model and a detailed analysis of optogenetic excitation and the suppression of cardiac activity using ChRmine and HcKCR1 in human ventricular cardiomyocytes (HVCMs). The present study shows that in ChRmine-expressing HVCMs, action potential (AP) can be triggered at 6 μW/mm² on illuminatation with 10 ms light pulse, which enables deeper excitation up to ~ 8 mm from the pericardial surface at safe light irradiances. High-fidelity optical pacing with ChRmine-expressing HVCMs is achievable up to 2.5 Hz at 0.7 ms light pulse and 0.58 mW/mm², which is an order of magnitude lower than the previously used opsins. HcKCR1 effectively suppresses action potentials by shunting the cell membrane potential to the resting state at a light irradiance of 1 mW/mm². Furthermore, HcKCR1 enables precise shortening of the AP duration at a very low irradiance of 1 µW/mm² on illuminating the cell during the repolarization phase. The present study highlights the advantages of the newly discovered ChRmine and HcKCR1 opsins for low-intensity optogenetic pacing and complete suppression of uncoordinated heartbeats. The results are useful for designing energy-efficient, light-induced cardiac pacemakers and for the effective treatment of cardioversion and tachycardia, as well as for extending the scale of cardiac optogenetics.

It is known that lipids of different compositions play a fundamental role in the organization of cell membranes. Membranes consist of highly mobile individual molecules (mainly lipids and proteins) in dynamic equilibrium undergoing transient interactions organized into a three-dimensional supramolecular structure. The lipid and protein components of the membrane are not held together by covalent interactions. Recent studies showed that a lipid membrane has specific domains containing sphingolipids (SM) and cholesterol (Ch) known as lipid rafts. The latter have a liquid ordering phase (dense phase) organized in the environment of liquid-crystalline or fluidic liquid disordering phase. Changes in lipid composition caused by the nonspecific influence of various amphiphilic and hydrophobic drugs, viruses, etc., are supposed to modify the plasma membrane, which in turn affects the membrane receptors.

Here, we investigated a model of lipid raft formation and the influence on its lipid compositions of the antiviral drug remdesivir which is used for the treatment of severe cases of COVID-19 disease. FTIR molecular bands were chosen as spectral markers. With FTIR spectroscopy, the marker spectral regions for the lipid rafts were 1) the region of C=O vibrations of 1670-1640 cm^-1, 2)1570-1520 cm^-1 corresponding to C=C vibrations, and 3) the region of 1400-1364 cm^-1 assigned to C -H bending vibrations. In the case of the liquid-ordered phase, the IR absorption bands centered at 1644 cm^-1 and 1548 cm^-1 shift towards the high frequency, and the band at 1400 cm^-1 towards the low frequency, which indicates a decrease in the raft domain integrity in the membrane.

In addition to DOPC, changes in the ratio of lipids (SM and Ch) and remdesivir are able to disrupt the structure of the lipid rafts. Following the changes in the structure of the lipid rafts, we could clear up the mechanism of the influence of environmental factors including drugs and propose an additional test.

The recently much-noticed Far-UVC spectral range offers the possibility of inactivating pathogens without necessarily posing a major danger to humans. Unfortunately, there are various Far-UVC sources that differ significantly in their longer wavelength UVC emission and, subsequently, in their risk potential. Therefore, a simple assessment method for Far-UVC sources is presented here. In addition, the temporal intensity stability of Far-UVC sources was examined in order to reduce possible errors in irradiation measurements. For this purpose, four far-UVC sources and a conventional Hg lamp were each spectrally measured over 60 h and mathematically evaluated for their antimicrobial effect and hazard potential using available standard data. Only two filtered KrCl lamps were found to emit at stable intensity after a warm-up time of 10 min. With regard to the antimicrobial effect, the radiation efficiencies of all examined (Far-) UVC sources were more or less similar. However, the calculated differences in the potential human hazard to eyes and skin were more than one order of magnitude. The two filtered KrCl lamps were the safest, followed by an unfiltered KrCl lamp, a Far-UVC LED and, finally, the Hg lamp. When experimenting with these Far-UVC radiation sources, the irradiance should be checked more than once. If UVC radiation is to be or could be applied in the presence of humans, filtered KrCl lamps are a much better choice than any other available Far-UVC sources.

Public touchscreens, such as those used in ATMs or ticket payment systems, which are accessed by different people in a short period of time, could transmit pathogens and thus spread infections. Therefore, the aim of this study was to develop and test a prototype of a touchscreen system for the public sector that disinfects itself quickly and automatically between two users without harming any humans.

A quartz pane was installed in front of a commercial 19” monitor, into which 120 UVC LEDs emitted laterally. The quartz plate acted as a light guide and irradiated microorganisms on its surface, but—due to total reflection—not the user in front of the screen. A near-infrared touch frame was installed to recognize touch. The antibacterial effect was tested through intentional staphylococci contamination.

The prototype, composed of a Raspberry Pi microcomputer with a display, a touchscreen, and a touch frame was developed, as well as a simple game programmed that briefly switched on the UVC LEDs between two users. The antimicrobial effect was so strong that 1% of the maximum UVC LED current was sufficient for a 99.9% staphylococci reduction within 25 s. At 17.5% of the maximum current, no bacteria were observed after 5 s. The residual UVC irradiance at a distance of 100 mm in front of the screen was only 0.18 and 2.8 µW/cm² for both currents, respectively. This would allow users to stay in front of the system for 287 or 18 minutes, even if the LEDs would emit UVC continuously, and not be turned off after a few seconds as in the presented device.

Therefore, fast, automatic touchscreen disinfection with UVC LEDs is already possible today and with higher currents, disinfection durations below 1 s seems to be feasible, while the light guide approach virtually prevents the direct irradiation of the human user.

Electrospinning can be used to prepare nanofiber mats from diverse polymers and polymer blends with embedded metallic, ceramic, or other types of nanoparticles. Such nanofiber mats have been investigated for diverse applications, such as filtration, batteries, and supercapacitors; food packaging; or biomedicine and biotechnology. A large area of research is the application of nanofibrous membranes in tissue engineering. Typically, the cell adhesion and proliferation as well as the viability of mammalian cells are tested by seeding the cells on the substrates under examination, cultivating them for a defined period of time, and finally dyeing them to enable differentiation between cells and substrates under a white light or fluorescence microscope. While this procedure works well for cells cultivated in well plates or petri dishes, other substrates may undesirably also be colored by the dye. Here, we show investigations of the optical contrast between dyed CHO DP-12 (Chinese hamster ovary) cells and different nanofiber mats electrospun from pure poly(acrylonitrile) (PAN) as well as PAN/gelatin, PAN/keratin, and PAN/TiO₂. After cultivation for 5 days, the cells were fixed with glyoxal and afterwards dyed with haematoxylin–eosin (H&E), PromoFluor 488 premium, 4,6-diamidino-2-phenylindole (DAPI), or Hoechst 33342. Examination by white light or fluorescence microscopy, respectively, revealed that, in particular, the PAN/gelatin nanofiber mats—which were the most advantageous regarding cell growth—were also colored by the dyes. This paper reports the optimized dyeing parameters to maximize the optical contrast between CHO cells and nanofiber mats.

Yiran Wang, Gangshan Liu, Ziyang Li, Zhengjun Liu*

School of Physics, Harbin Institute of Technology, Harbin 150001, China

Structured illumination microscopy (SIM) is a mainstream super-resolution imaging technique that is applied in fluorescence microscopy, effectively doubling the lateral resolution compared to conventional methods. Compared to other popular fluorescence super-resolution techniques such as STORM and STED, SIM offers advantages through its reduced light exposure, faster imaging speeds, and, consequently, lower phototoxicity and photobleaching, making it particularly suitable for live cell imaging. However, traditional 2D-SIM requires nine sequentially captured raw structured illumination images to reconstruct a single super-resolution image. This results in a ninefold increase in acquisition time compared to standard wide-field imaging. Reducing the exposure time can mitigate motion artifacts but at the cost of image quality; conversely, increasing the exposure time can heighten phototoxicity, impacting the overall observation time and imaging efficiency.

To address these challenges, we propose a novel method called 4CSIM, which replaces sinusoidal illumination with a checkerboard-patterned structure, requiring only four raw images to achieve super-resolution imaging. In 4CSIM, instead of treating the entire image as a whole, we establish a point-wise relationship between the pixels in the reconstructed super-resolution image and the corresponding pixels in the original SIM images, reconstructing the Fourier spectrum of the super-resolution image pixel by pixel. The checkerboard illumination pattern enables this "point-wise reconstruction" method, with the reconstruction process involving only three-dimensional matrix operations. Compared to the existing 4SIM method, 4CSIM significantly accelerates image reconstruction due to its non-iterative nature and low memory usage, avoiding the trade-off between a high frame rate acquisition and reconstruction speed observed in 4SIM methods.

In summary, 4CSIM enhances both the acquisition frame rate and reconstruction speed of SIM technology, making real-time video imaging feasible.