Microscopy Images Research Articles

Optical characterization of molecular interaction strength in protein condensates.

Biomolecular condensates have been identified as a ubiquitous means of intracellular organization, exhibiting very diverse material properties. However, techniques to characterize these material properties and their underlying molecular interactions are scarce. Here, we introduce two optical techniques - Brillouin microscopy and quantitative phase imaging (QPI) - to address this scarcity. We establish Brillouin shift and linewidth as measures for average molecular interaction and dissipation strength, respectively, and we used QPI to obtain the protein concentration within the condensates. We monitored the response of condensates formed by FUS and by the low-complexity domain of hnRNPA1 (A1-LCD) to altering temperature and ion concentration. Conditions favoring phase separation increased Brillouin shift, linewidth, and protein concentration. In comparison to solidification by chemical crosslinking, the ion-dependent aging of FUS condensates had a small effect on the molecular interaction strength inside. Finally, we investigated how sequence variations of A1-LCD, that change the driving force for phase separation, alter the physical properties of the respective condensates. Our results provide a new experimental perspective on the material properties of protein condensates. Robust and quantitative experimental approaches such as the presented ones will be crucial for understanding how the physical properties of biological condensates determine their function and dysfunction.

A unique and biocompatible corneal collagen crosslinking in vivo

Corneal crosslinking (CXL) is a widely applied technique to halt the progression of ectatic diseases through increasing the thickness and mechanical stiffness of the cornea. This study investigated the biocompatibility and efficiency of a novel CXL procedure using ruthenium and blue light in rat corneas and evaluated parameters important for clinical application. To perform the CXL procedure, the corneal epithelium of rats was removed under anaesthesia, followed by the application of a solution containing ruthenium and sodium persulfate (SPS). The corneas were then exposed to blue light at 430 nm at 3 mW/cm2 for 5 min. Rat corneas were examined and evaluated for corneal opacity, corneal and limbal neovascularization, and corneal epithelial regeneration on days 0, 1, 3, 6, 8, and 14. On day 28, the corneas were isolated for subsequent tissue follow-up and analysis. CXL with ruthenium and blue light showed rapid epithelial healing, with 100% regeneration of the corneal epithelium and no corneal opacity on day 6. The ruthenium group also exhibited significantly reduced corneal (p < 0.01) and limbal neovascularization (p < 0.001). Histological analysis revealed no signs of cellular damage or apoptosis, which further confirms the biocompatibility and nontoxicity of our method. Confocal and scanning electron microscopy (SEM) images confirmed high density of collagen fibrils, indicating efficient crosslinking and enhanced structural integrity. This study is unique that demonstrates in vivo safety, biocompatibility, and functionality of ruthenium and blue light CXL. This approach can prevent toxicity caused by UV-A light and can be an immediate alternative compared to the existing crosslinking procedures that have side effects and clinical risks for the patients.

Target-specified reference-based deep learning network for joint image deblurring and resolution enhancement in surgical zoom lens camera calibration

Background and objectiveFor the augmented reality of surgical navigation, which overlays a 3D model of the surgical target on an image, accurate camera calibration is imperative. However, when the checkerboard images for calibration are captured using a surgical microscope having high magnification, blur owing to the narrow depth of focus and blocking artifacts caused by limited resolution around the fine edges occur. These artifacts strongly affect the localization of corner points of the checkerboard in these images, resulting in inaccurate calibration, which leads to a large displacement in augmented reality. To solve this problem, in this study, we proposed a novel target-specific deep learning network that simultaneously enhances both the blur and spatial resolution of an image for surgical zoom lens camera calibration. MethodsAs a scheme of an end-to-end convolutional deep neural network, the proposed network is specifically intended for the checkerboard image enhancement used in camera calibration. Through the symmetric architecture of the network, which consists of encoding and decoding layers, the distinctive spatial features of the encoding layers are transferred and merged with the output of the decoding layers. Additionally, by integrating a multi-frame framework including subpixel motion estimation and ideal reference image with the symmetric architecture, joint image deblurring and enhanced resolution were efficiently achieved. ResultsFrom experimental comparisons, we verified the capability of the proposed method to improve the subjective and objective performances of surgical microscope calibration. Furthermore, we confirmed that the augmented reality overlap ratio, which quantitatively indicates augmented reality accuracy, from calibration with the enhanced image of the proposed method is higher than that of the previous methods. ConclusionsThese findings suggest that the proposed network provides sharp high-resolution images from blurry low-resolution inputs. Furthermore, we demonstrate superior performance in camera calibration by using surgical microscopic images, thus showing its potential applications in the field of practical surgical navigation.

Revisiting the taxonomy of Korean Ischnochiton species (Polyplacophora, Ischnochitonidae) based on a combined analysis of morphological and molecular data.

Chiton species belonging to the genus Ischnochiton J. E. Gray, 1847 are commonly found in intertidal rocky shores worldwide, with the exception of the northern Atlantic and Arctic oceans. Ischnochiton species are characterised by imbricate girdle scales that are uniform in size, rounded, sculpted with striae or occasionally smooth. However, their species-level taxonomy is complicated due to the high variation in their shell microstructures. Despite more than a hundred species reported worldwide, taxonomic studies of this group remain relatively unexplored in Korean waters, with only a few species recorded to date. In this study, we compared the microstructural characteristics of tegmentum sculpture, girdle scales and radula amongst four Korean Ischnochiton species using high-resolution microscopic images and a scanning electron microscope (SEM). Along with mtDNA cox1 sequence comparison, a comprehensive analysis of their morphology revealed that I.hayamii Owada, 2018 was identified for the first time in Korean waters. This species is morphologically distinguished by its small body size of adults, smooth lateral areas on valves and small perinotum scales sculptured with weak longitudinal ribs. Phylogenetic analysis of the mtDNA cox1 sequence provides distinct resolution at the species level, but interrelationships amongst Ischnochiton species remain unresolved. Results from the morphological and molecular analyses presented in this study offer valuable taxonomic information for accurate species identification amongst closely-related Ischnochiton species.

Engineering sulfur doped flower-like BiOBrxI1-x solid solutions for strengthened photocatalytic activities

In this work, a series of S-doped BiOBrxI1-x solid solutions are fabricated via a simple and rapid solvothermal process. Various characterization techniques are used to thoroughly investigate the as-fabricated solid solutions. Interestingly, compared to BiOBrxI1-x, S-doped BiOBrxI1-x solid solutions exhibit a loose flower-like structure comprised of thinner nanosheets, which contributes to the enhanced specific surface area, as assessed by Brunauer-Emmett-Teller analysis. Furthermore, S-doped BiOBrxI1-x solid solutions reveal boosted visible-light response and rapid separation of photoinduced charge carriers, as verified by optical, photo-electrochemical, and electrochemical analysis. These lead to superior visible-light photocatalytic properties of S-doped BiOBrxI1-x solid solutions on pollutant removal, N2 fixation, and microplastic degradation. The crystal structure, morphology, and photocatalytic stability of the prepared samples are demonstrated by comparing their X-ray diffraction patterns, scanning electron microscopy images, and photocatalytic degradation as well as nitrogen reduction performance before and after six catalytic recycles. Furthermore, based on Density Functional Theory simulations, significant modifications in the band gap of BiOBrxI1-x solid solutions occur as iodine content increases while sulfur doping further refines the electronic features, which aligns with the results of Tauc plots. This research proves that S doping is a viable strategy for modulating the electronic structures of BiOBrxI1-x solid solutions for improving its photocatalytic performance, and provides a new route for optimizing the bandgaps of semiconductors via the non-metallic doping strategy.

A Dot-Blot Screening for Identifying the Temozolomide-Regulated Proteins as Potential Targets for Glioma Multi-OMICS Studies.

Malignant gliomas represent a heterogenous group of brain cancers that are characterized by infiltrative growth that lacks a clearly identifiable tumor border. The lack of the possibility of radical surgical resection and targeted therapy results in a poor prognosis. Although Temozolomide (TMZ) is still the leading chemotherapeutic agent in glioma treatment, its efficacy is limited due to the development of tumor resistance. Therefore, there an urgent need to improve the diagnosis and treatment of these tumors. Finding and developing biomarkers that are specific to glioma could be useful for both identifying therapy targets and monitoring treatment as well as for constructing a personalized therapy. However, there are still no reliable markers that would change the quality of glioma treatment. In this study, differences in the expression of 84 cancer-related proteins in three glioma cell lines were analyzed using the dot-blot method: commercial T98G cells and two patient-derived cell lines. The influence of TMZ on changes in protein expression, cell morphology, and migration was also investigated (Proteome Profiler Human XL Oncology Array, LeviCell System, Microscopic imaging). The lines that were analyzed were characterized by a remarkably different plasticity of protein expression and the proteomic alterations that were induced by TMZ. A dot-blot analysis revealed ten proteins that were common to all of the lines and five (Cathepsin b, FGF, Survivin, AXL, Osteopontin) that were modulated by the TMZ. As a result of the exposure of TMZ, the proteins that are involved in chemoresistance and invasion (TIE-2, Thrombospondin) were detected in both the HROG02 and T98G cell lines. In the control culture (not exposed to TMZ) of HROG17 cells, the proteins that are involved in metabolism were strongly suppressed. The presented data sheds new light on the modulatory effect of Temozolomide on the expression of a protein panel: Cathepsin b, fibroblast growth factor (FGF), Survivin, AXL, and Osteopontin that may suggest their potential as therapeutic targets or biomarkers to monitoring therapy effects. However, further high-throughput analysis and detection of the proteins in the body fluids are necessary.

Opto2P-FCM: A MEMS based miniature two-photon microscope with two-photon patterned optogenetic stimulation.

Multiphoton microscopy combined with optogenetic photostimulation is a powerful technique in neuroscience enabling precise control of cellular activity to determine the neural basis of behavior in a live animal. Two-photon patterned photostimulation has taken this further by allowing interrogation at the individual neuron level. However, it remains a challenge to implement imaging of neural activity with spatially patterned two-photon photostimulation in a freely moving animal. We developed a miniature microscope for high resolution two-photon fluorescence imaging with patterned two-photon optogenetic stimulation. The design incorporates a MEMS scanner for two-photon imaging and a second beam path for patterned two-photon excitation in a compact and lightweight design that can be head-attached to a freely moving animal. We demonstrate cell-specific optogenetics and high resolution MEMS based two-photon imaging in a freely moving mouse. The new capabilities of this miniature microscope design can enable cell-specific studies of behavior that can only be done in freely moving animals.

Effect of CTAB and NaBH4 Solutions on Ti and Cu Nanoparticles Prepared by Pulsed Laser Ablation

The effect of different media, including cetyltrimethylammonium bromide (CTAB) and sodium borohydride (NaBH4), on the size, shape, optical absorption, and stability of titanium (Ti) and copper (Cu) nanoparticles (NPs) synthesized by laser ablation in liquid, was investigated. Ti and Cu NPs were fabricated by irradiating Ti and Cu targets using a Nd:YAG pulsed laser with a wavelength of 1064 nm, an energy of 500 mJ, repetition rate of 1 Hz, and a number of pulses of 1000. Results showed the direct effect of the type of surfactant on the size and size distribution of Ti and Cu NPs under the same laser ablation parameters. Morphological properties were described by field emission scanning electron microscope (FESEM) images, which revealed the formation of semispherical particles. The EDS results confirmed the spike-induced synthesis of Ti and Cu in CTAB and NaBH4 solutions. The transmission electron microscopy (TEM) images showed the nanostructures of Ti and Cu with spherical particles. The UV-vis absorption spectra showed that the absorption peak of Ti was almost constant at 289 nm, while the peak of Cu disappeared for both solutions. Zeta potential analysis showed that NPs prepared in CTAB solution were more stable than those in NaBH4 solution.

Hydrothermal Growth Zinc Oxide Nanorods for pH Sensor Application

The aim of this work is to apply synthesized zinc oxide (ZnO) Nanorods using hydrothermal (HTL) growth technique for pH sensor application. The highly crystallite of ZnO Nanorods was obtained by anneal the growth ZnO Nanorods in furnace at 200 °C for 2 hours. Besides that, XRD analysis shows the produced ZnO Nanorods belonged to the (002) plane. Furthermore, Scanning Electron Microscope (SEM) images confirm that the ZnO Nanorods with hexagonal-faceted structural were successfully produced by HTL growth technique. In addition, Ultraviolet–visible (UV-Vis) spectrophotometer analysis shows that the synthesized ZnO belongs to the wide band gap semiconductor material. The growing ZnO Nanorods were then subjected to electrical measurement with various pH levels. The outcome demonstrates that the current rises as the solution changes from acidic to alkaline. Overall, our study shows a relationship between the electrical as well as the structural characteristics of ZnO Nanorods at various pH levels.

Femto-Laser Processed Metasurface With Fano Response: Applications to a High Performance Refractometric Sensor

The practical development of compact modern nanophotonic devices relies on the availability of fast and low-cost fabrication techniques applicable to a wide variety of materials and designs. We have engraved a split grating geometry on stainless steel using femtosecond laser processing. This structure serves as a template to fabricate efficient plasmonic sensors, where a thick gold layer is grown conformally on it. The scanning electron microscope (SEM) images confirm the generation of the split laser-induced periodic spatial structures. The optical reflectance of our sensors shows two dips corresponding to the excitation of surface plasmon resonances (SPRs) at two different wavelengths. Furthermore, the asymmetric shape of these spectral responses reveals a strong and narrow Fano resonance. Our computational electromagnetism models accurately reproduce the reflectivity of the fabricated structure. The spectral responses of both the simulated and fabricated structures are fitted to the Fano model that coherently combines the narrow SPRs with the broad continuum background caused by diffraction. The parameters extracted from the fitting, such as the resonance wavelengths and line widths, are used to evaluate the performance of our device as a refractometric sensor for liquids. The maximum sensitivity and figure of merit are 880 nm/RIU and 80 RIU−1, respectively. Besides the compact design of our sensing device, its performance exceeds the theoretical maximum sensitivity of a classical Kretschmann setup.

Fabrication, Characterization and Release Profile of Aloe Vera Extracts/PVA Composite Electrospun Nanofiber

Aloe vera is a well-known remedy that carries many beneficial health effects such as painkiller, anti-inflammatory, promote skin growth and repair. The combination of bioactive natural product of aloe vera as a drug model and polyvinyl alcohol (PVA) as the base material or carrier in the electrospinning process were studied. Smooth straight and continues electrospun fibers were collected with the Field Effect Scanning Electron Microscope (FESEM) images show no formation of bead (defect signed) in the electrospun membrane when the concentration was set at 10% w/w of PVA nanofibre. The morphological structure of the electrospun membranes shows a smooth and longitudinal fiber when aloe vera is mixed with the PVA polymer with percentage ratio of aloe vera over PVA is less than 25%. The Fourier Transform Infrared Spectroscopy (FTIR) shows no reaction between PVA and aloe vera by not showing peaks other than the initial materials. The Differential Scanning Calorimetry (DSC) proves the presence of aloin indicating the presence of aloe vera in nanofiber. The release profile of the electrospun aloe vera in PVA shows a higher initial burst release at the 50% and 70% concentration levels indicating very little control of the release or none at all. These results show the potential of aloe vera – PVA electrospun nanofibers membrane as a promising material for wound dressing and topical drug delivery.

Fabrication of drug loaded polylactic acid/keratin/polyethylene glycol GTR membrane for periodontal application

This study proposes the fabrication of, amoxicillin-loaded composite GTR membranes from polylactic acid (PLA), wool keratin (WK), and polyethylene glycol (PEG) for periodontal therapy. Deep eutectic solvents were employed for the extraction of keratin from wool fibers. For the preparation of the control (C), PLA and PEG were dissolved in a ratio of 60:40 in chloroform. While the experimental groups K2 and K3 were prepared by adding, 2% and 3% WK powder, respectively, to the control mixture. To prepare the experimental groups K2-D and K3-D, 1% AMOX-treated WK powder was mixed with the previously mentioned groups. The prepared GTR membrane was characterized using various analytical techniques. The treatment of sheep wool and the presence of AMOX in the experimental groups were confirmed using FTIR analysis. The Scanning electron microscope (SEM) images of the prepared GTR membranes showed voids and presented a conglomerated appearance. The K2 had the highest tensile strength, whereas K2-D and K3-D which contained drugs had lower tensile strengths but significant antibacterial activity. K2 experienced the greatest mass change after 1 h, while K2-D and K3-D experienced the least. Each membrane was found to be hydrophilic. The Alamar Blue Assay revealed good biocompatibility.

3-D Visualization of Atlantic salmon skin through Ultrasound and Photoacoustic Microscopy.

Three-dimensional photoacoustic imaging (PAM) has emerged as a promising technique for non-invasive label-free visualization and characterization of biological tissues with high spatial resolution and functional contrast. The application of PAM and ultrasound as a microscopy technique of study for Atlantic salmon skin is presented here. A custom ultrasound and photoacoustic experimental setup was used for conducting this experiment with a sample preparation method where the salmon skin is embedded in agarose and lifted from the bottom of the petridish. The results of C-scan, B-scan, and overlayed images of ultrasound and photoacoustic are presented. The results are then analyzed for understanding the pigment map and its relation to salmon behavior to external stimuli. The photoacoustic images are compared with the optical images and analyzed further. A custom colormap and alpha map is designed and the matrices responsible for PAM and ultrasound are inserted together to overlay the ultrasound image and PAM image on top of each other. In this study, we propose an approach that combines scanning acoustic microscopy (SAM) images with PAM images for providing a comprehensive understanding of the salmon skin tissue. Overlaying acoustic and photoacoustic images enabled unique visualization of tissue morphology, with respect to identification of structural features in the context of their pigment distribution.

Insight into structural changes in heat-induced whey protein-fucoidan hydrogel by SR-IR and molecular docking techniques

This study aimed to investigate the structural changes in heat-induced polymerized whey protein (PWP)-fucoidan (FCN) hydrogels with different FCN concentration (0 % to 0.75 %, w/v). The interaction of PWP and FCN were traced by simultaneous rheology and Fourier transform infrared spectroscopy spectra (SR-IR) technology. The particle size and absolute zeta potential of PWP-FCN increased significantly (p < 0.05) with higher FCN concentrations, indicating that the formation of PWP-FCN enhanced the stability of the system. The gelation time of PWP-FCN was shortened from 1328 s to 881 s as the FCN concentration increased from 0 to 0.75 % (w/v) paralleled the increased apparent viscosity. The endothermic peak temperature of the hydrogels increased from 95.28 °C to 102.26 °C demonstrating the improved thermal stability due to FCN. The intrinsic fluorescence, surface hydrophobicity, and free thiol groups of PWP-FCN all indicated that FCN could interact with PWP through hydrophobic interactions, which changed the tertiary structure of PWP, and increased the density of PWP-FCN network. Cryogenic scanning electron microscopy (Cryo-SEM) and SEM images showed that the interactions between PWP and FCN resulted to rough and wrinkled microstructure of samples. Results of SR-IR and molecular docking assay both indicated that FCN could also interact with PWP through hydrogen bonds. In summary, FCN could promote the gelation process and the physicochemical properties of PWP-FCN hydrogel. Results of this study could provide theoretical basis for the application of protein–polysaccharide hydrogels in food field.

Synthesis and properties of tailored β‐tricalcium phosphate for bone filler applications

AbstractThe present work reports the synthesis of highly phase pure (&gt; 95%) β‐TCP and its subsequent conversion into granules for bone graft applications, using an industrial scale proprietary manufacturing route. Following the wet chemical approach, several process parameters, were adjusted for large volume synthesis, including pH, precursor concentration, and ripening time. The granulation process is tailored to facilitate the scalibility and control over morphology, porosity, and pore size. X‐ray diffraction analysis confirms the presence of pure β‐TCP phase where as Ca/P molar ratio of 1.497 was determined using ICP‐OES. Fourier transform infrared spectroscopy depicts the presence of PO43− as a major molecular group. Scanning electron microscopy (SEM) images of the β‐TCP powders reveal necking features, a characteristic morphology of β‐TCP. SEM images of the β‐TCP granules reveal microporosity, which aids in triggering a biological response. The TGA‐DTA curve suggests that the weight loss in pure β‐TCP is twice as compared with β‐TCP containing hydroxyapatite. Furthermore, these β‐TCP granules were clinically tested in a few orthopedic and spine surgeries. In all the treated patients, β‐TCP granules did not induce any pus formation or infection at the surgical sites, thereby establishing clinically relevant biocompatibility properties.

Directing Charge Carriers and Ferroelectric Domains at Lateral Interfaces in van der Waals Heterostructures.

Emergent phenomena in traditional ferroelectrics are frequently observed at heterointerfaces. Accessing such functionalities in van der Waals ferroelectrics requires the formation of layered heterostructures, either vertically stacked (similar to oxide ferroelectrics) or laterally stitched (without equivalent in 3D-crystals). Here, we investigate lateral heterostructures of the ferroelectric van der Waals semiconductors SnSe and SnS. A two-step process produces ultrathin crystals comprising an SnSe core laterally joined to an SnS edge-band, as confirmed by Raman spectroscopy, transmission electron microscopy (TEM) imaging, and electron diffraction. TEM shows a moiré pattern across the SnSe core due to coverage by an ultrathin SnS layer. The ability of the lateral interface (IF) to direct excited carriers, probed by cathodoluminescence, shows electron transfer over 560 nm diffusion length from the SnS edge-band. Large, thin flakes supporting ferroelectricity allow investigating domains and domain wall interactions in uniform crystals and lateral heterostructures. Polarized optical microscopy of sub-20 nm flakes consistently shows ⟨110⟩ oriented stripe domains with mirror-twin domain walls. Heterostructures adopt two domain configurations, with domains either constrained to the SnSe core or propagating across the entire SnSe-SnS flakes. The combined results demonstrate multifunctional van der Waals heterostructures with high-quality IFs presenting extraordinary opportunities for manipulating carrier flows and ferroelectric domain patterns.

Nanoscale chirality generated in zinc(II) orthophosphate clusters: evidence by vibrational circular dichroism.

Layered zinc(II) hydroxides (LZH) intercalating the deprotonated forms of R-(-) or S-(+)-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (denoted as R- or S-BNDHPH, respectively) were prepared from Zn(NO3)2 at pH 5 and 60 °C by the mixing method. The obtained hybrid compounds (denoted as R- or S-BNDHP-/LZH, respectively) were heated from room temperature up to 800 °C under nitrogen atmosphere. According to the thermal gravimetric/differential thermal analysis measurements, hydroxyl groups were dehydrated at 270-400 °C, followed by the decomposition of organic components at 420-600 °C. X-ray diffraction patterns and scanning electron microscopy images indicated that the final products were a mixture of α-Zn3(PO4)2, ZnO crystals and non-crystalline zinc(II) orthophosphates. Vibrational circular dichroism (VCD) spectra were recorded before and after calcination. Before calcination, R- or S-BNDHP-/LZH exhibited VCD peaks assigned to intercalated R- or S-BNDHP-. The calcined products exhibited several VCD peaks in the range of 900-1200 cm-1, maintaining the mirror-image relationship between R-BNDHP-/LZH and S-BNDHP-/LZH used as starting materials. The observed peaks were assigned to the PO (symmetric), -POO-, and PO (asymmetric) stretching vibrations of the PO43- groups. According to theoretical simulations, the observed VCD activity can be rationalised in terms of vibrational coupling between two PO43- groups in a generated chiral zinc(II) orthophosphate cluster.

RETRACTION: Boroxine Nanotubes: Moisture‐Sensitive Morphological Transformation and Guest Release

AbstractRETRACTION: K. Ishikawa, N. Kameta, M. Masuda, M. Asakawa, T. Shimizu, “Boroxine Nanotubes: Moisture‐Sensitive Morphological Transformation and Guest Release,” Advanced Functional Materials 24, no. 5 (2013): 603–609, https://doi.org/10.1002/adfm.201302005.The above article, published online on 16 September 2013 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors; the journal Editor‐in‐Chief, Jörn Ritterbusch; and Wiley‐VCH GmbH, Weinheim. The retraction has been agreed upon authors' request and following an investigation by the National Institute of Advanced Industrial Science and Technology (AIST) due to image falsification in electron microscopy images in Figures 1g, 1h, 1i, 2a, 2b, 2c, S1a, S1b, and S1c, where the second author falsified incorrect scale bars; all affecting the interpretation of the data and research results presented.

Electrochemical Immunosensors on Laser-Induced Graphene Platforms for Monitoring of Anti-RBD Antibodies After SARS-CoV-2 Infection

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has posed a major challenge to global health. The development of fast, accurate, and accessible diagnostic methods is essential in controlling the disease and mitigating its impacts. In this context, electrochemical biosensors present themselves as promising tools for the efficient monitoring of SARS-CoV-2 infection. We have developed a highly specific biosensor for the detection of anti-SARS-CoV-2 antibodies in patient sera. The use of the RBD-S region as an antigen, although purified to minimize cross-linking, poses a specific challenge. The structural similarity between SARS-CoV-2 and other respiratory viruses, as well as the complexity of the serum matrix, hinders robust analytical strategies to ensure diagnostic accuracy. This work presents a novel immunosensor for COVID-19 diagnosis using laser-induced graphene (LIG) electrodes subjected to electrochemical reduction with graphene (named rGraphene-LIG). In the present study, we chose an initial approach focused on demonstrating the concept and evaluating the feasibility of the rGraphene-LIG sensor for SARS-CoV-2 detection. The rGraphene-LIG electrodes presented a notable current increase for the redox probe in the aqueous solution of a mixture of 5 mmol L−1 potassium ferricyanide/ferrocyanide ([Fe(CN)6]3−/[Fe(CN)6]4−) in 0.1 mol L−1 KCl (pH set at 7.4). As a proof of concept, the rGraphene-LIG electrode was applied for antibody determination in real samples using cyclic voltammetry, and a limit of detection (LOD) of 0.032 μg L−1 was achieved. When determining antigens in commercial samples, we obtained an LOD of 560 ηg mL−1 and a limit of quantification of 1677 ηg mL−1. The results of the electrochemical experiments were in accordance with the surface roughness obtained from atomic force microscopy images. Based on these results, the rGraphene-LIG electrode is shown to be an excellent platform for immunoglobulin detection when present in individuals after antigenic exposure caused by SARS-CoV-2.

Halamphorahampyeongensis sp. nov. (Amphipleuraceae, Bacillariophyceae), a new marine benthic diatom from a tidal mudflat in Hampyeong Bay, South Korea.

The abundance and variety of benthic diatoms inhabiting tidal flats is widely acknowledged, although it has received relatively less attention than other research areas. In this investigation, we provide a formal description of a benthic diatom found in the tidal mudflat of South Korea, based on morphological and molecular characteristics and the similarities and differences between Halamphorahampyeongensis sp. nov., with morphologically similar Halamphora species are also discussed. Morphological characteristics are described from light and electron microscopy images. H.hampyeongensis is distinguished by its wide ventral sides of the valve, small and rounded areolae present across the whole valve face, and dense dorsal striae biseriate (34-38 in 10 μm). Phylogenetic analysis based on 18S rDNA and rbcL sequence data revealed that H.hampyeongensis is related to H.montana, H.mosensis, and H.specensa. The results (morphometric and molecular) provide sufficient elements to support and propose this taxon as a new species.