Hasil untuk "Microscopy"

Pengcheng Fu, Xiao Liu, Siming Wang et al.

Label-free optical microscopy through absorption or scattering spectroscopy provides fundamental insights across biology and materials science, yet its sensitivity remains fundamentally limited by photon shot noise. While recent demonstrations of quantum nonlinear microscopy show sub-shot-limited sensitivity, they are intrinsically limited by availability of high peak-power squeezed light sources. Here, we introduce squeezing-enhanced photothermal (SEPT) microscopy, a quantum imaging technique that leverages twin-beam quantum correlations to detect absorption induced signals with unprecedented sensitivity. SEPT achieves 3.5 dB noise suppression beyond the standard quantum limit, enabling a 2.5-fold increase in imaging throughput or 31% reduction in pump power, while providing an unmatched versatility through the intrinsic compatibility between continuous-wave squeezing and photothermal modulation. We showcase SEPT applications by providing high-precision characterization of nanoparticles and revealing subcellular structures, such as cytochrome c, that remain undetectable under shot-noise-limited imaging. By combining label-free contrast, quantum-enhanced sensitivity, and compatibility with existing microscopy platforms, SEPT establishes a new paradigm for molecular absorption imaging with far-reaching implications in cellular biology, nanoscience, and materials characterization.

Franciele Floriani, Bayaan Jabr, Silvia Rojas-Rueda et al.

Background: This study evaluated the effect of charcoal-containing toothpaste on the surface roughness of CAD/CAM lithium disilicate ceramic (e.max CAD) after simulated toothbrushing. Methods: Forty-eight e.max CAD ceramic specimens were divided into four groups (n = 12) and subjected to 18,000 brushing cycles using a toothbrushing simulator. The groups included Crest 3D White Charcoal, Colgate Optic White with Charcoal, Arm & Hammer Charcoal White, and a control group (conventional toothpaste). Surface roughness was measured with a profilometer before and after brushing, and scanning electron microscopy (SEM) was used for topographical analysis. Statistical analysis was performed using the Kruskal–Wallis test and post hoc comparisons. Results: Significant differences in surface roughness were found among the groups (<i>p</i> < 0.001). The mean roughness values were 540.70 ± 21.68 µm (Control), 294.88 ± 11.49 µm (Crest 3D White Charcoal), 1157.00 ± 52.85 µm (Colgate Optic White with Charcoal), and 593.37 ± 37.69 µm (Arm & Hammer Charcoal White). Post hoc analysis showed that Colgate Optic White with Charcoal had the highest roughness, which was significantly different from all other groups (<i>p</i> < 0.001). SEM analysis revealed severe surface degradation with Colgate Optic White with Charcoal, while Crest 3D White Charcoal caused minimal changes. Conclusions: Charcoal-containing toothpastes vary in abrasiveness, with Colgate Optic White with Charcoal causing the most significant surface roughness and damage to lithium disilicate ceramics.

Mingqian Chen, Wen Li, Taoyu Hu et al.

Abstract Quantitative, label-free monitoring of dynamic cell adhesion remains challenging. Meta-Surface Plasmon Resonance Microscopy (Meta-SPRM) is a novel platform integrating bright-field microscopy with engineered Meta-SPR nanocup arrays. This system simultaneously acquires bright-field images and Meta-SPRM signals, enabling their computational separation and co-analysis to provide multifaceted insights into cell-substrate interactions. Meta-SPRM offers sensitive, high-throughput, and long-term label-free quantification of cell adhesion strength and distribution. It captures dynamic processes like cell spreading and migration at micrometer lateral resolution. Notably, Meta-SPRM signals spatially correlate with key focal adhesion proteins (Integrin-β1, Vinculin), and an intrinsic intracellular signal polarity correlates with cell migration direction. Meta-SPRM provides a powerful, label-free tool for dynamic cell adhesion studies, overcoming limitations of traditional methods. Graphical abstract

Karl D. Briegel, Nick R. von Grafenstein, Julia C. Draeger et al.

Microscopy enables detailed visualization and understanding of minute structures or processes. While cameras have significantly advanced optical, infrared, and electron microscopy, imaging nuclear magnetic resonance (NMR) signals on a camera has remained elusive. Here, we employ nitrogen-vacancy (NV) centers in diamond as a quantum sensor, which converts NMR signals into optical signals that are subsequently captured by a high-speed camera. Unlike traditional magnetic resonance imaging (MRI), our method records the NMR signal over a wide field of view in real space. We demonstrate that our optical widefield NMR microscopy (OMRM) can image NMR signals in microfluidic structures with a $\sim 10\,μm$ resolution across a $\sim 235 \times 150\,μm^2$ area. Crucially, each camera pixel records an NMR spectrum providing multicomponent information about the signal's amplitude, phase, local magnetic field strengths, and gradients. The fusion of optical microscopy and NMR techniques enables multifaceted imaging applications in the physical and life sciences.

Trygve Magnus Ræder, Urko Petralanda, Thomas Olsen et al.

The properties of semiconductors and functional dielectrics are defined by their response in electric fields, which may be perturbed by defects and the strain they generate. In this work, we demonstrate how diffraction-based X-ray microscopy techniques may be utilized to image the electric field in insulating crystalline materials. By analysing a prototypical ferro- and piezoelectric material, BaTiO$_{3}$, we identify trends that can guide experimental design towards imaging the electric field using any diffraction-based X-ray microscopy technique. We explain these trends in the context of dark-field X-ray microscopy, but the framework is also valid for Bragg scanning probe X-ray microscopy, Bragg coherent diffraction imaging and Bragg X-ray ptychography. The ability to quantify electric field distributions alongside the defects and strain already accessible via these techniques offers a more comprehensive picture of the often complex structure-property relationships that exist in many insulating and semiconducting materials.

Khalil Ahmad, Hafiz Muhammad Asif, Taimoor Afzal et al.

Introduction: The area of “Green Synthesis of Nano-medicine,” as compared to its synthetic counterparts, is a relatively safer research technology for various biomedical applications, including identification, therapeutic application, and prevention of pathological conditions, pain control, safety, and development of human wellness. The present study explored the synthesis and characterization of AgNPs using the ethanolic extract of Piper cubeba fruit as a reducing and stabilizing agent and its potential as an enzyme inhibitory agent. Urease inhibitors are helpful against many severe diseases, including gastric ulcers induced by Helicobacter pylori.Method: The fruits of the Piper cubeba plant were taken and ground to a fine powder. Plant material was added to 500 ml ethanol, and the mixture was filtered. The solvent of the filtrate was evaporated, and a thick, gummy extract was obtained and stored at 4°C in the refrigerator. AgNPs were green synthesized from solutions of AgNO3 using the P. cubeba extract, which was indicated by a change in the color from light brown to deep brown. The synthesized AgNPs were characterized via Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM).Results and Discussion: Analysis showed the reduction of Ag+ to Ag0 at room temperature (25°C), and the average particle size of AgNPs was in the range of 40–80 nm. Consequently, the synthesized AgNPs were evaluated for their anti-urease activity. The maximum urease inhibition of the Piper cubeba ethanolic extract was 88.5% at 5 mg conc., and of derived nanoparticles was 78.6% at 0.05 mg conc. The results were nearly similar to the control drug, i.e., thiourea (0.5 and 0.6 mM conc., respectively).Conclusion: The study concluded that the P. cubeba extract, as well as its green-derived AgNPs, might prove to be a better and safer substitute for their enzyme inhibitory potential in emerging medicine and novel drug delivery techniques to improve and maintain human health.

Irina O. Dzhun, Andrey V. Gerasimenko, Alexander A. Ezhov et al.

Thin film ferromagnet/antiferromagnet (F/AF) exchange biased structures that are widely used in GMR spin valves are considered nowadays as promising systems for antiferromagnetic spintronic and spin-orbitronic devices. Here, the temperature dependences of magnetization dynamics in Co/IrMn and Co/FeMn F/AF structures are investigated using ferromagnetic resonance (FMR) in comparison to a free Co layer. A strong additional decrease in the resonance field was observed in Co/IrMn with a temperature decrease attributed to the rotatable anisotropy increase, which almost vanished at room temperature. In contrast to Co/IrMn, the contribution of the rotatable anisotropy in Co/FeMn is much weaker, even though it exists at RT, it is negative, and slightly varies with the temperature and resonance field shift in Co/FeMn. This is mainly due to unidirectional exchange anisotropy. FMR linewidth for the free Co layer increases with decreasing temperature and is accompanied with a slow relaxation process, while the additional contribution to FMR line broadening in Co/IrMn and Co/FeMn structures is correlated with variation in the exchange anisotropy. The observed results are discussed based on structural and surface morphology and magnetization reversal characterization using X-ray diffraction, atomic force microscopy, and vibrating sample magnetometry data.

Zunyu Liu, Chaoyu Zhao, Shuangfeng Jia et al.

Abstract Multi-dimensional heterojunction materials have attracted much attention due to their intriguing properties, such as high efficiency, wide band gap regulation, low dimensional limitation, versatility and scalability. To further improve the performance of materials, researchers have combined materials with various dimensions using a wide variety of techniques. However, research on growth mechanism of such composite materials is still lacking. In this paper, the growth mechanism of multi-dimensional heterojunction composite material is studied using quasi-two-dimensional (quasi-2D) antimonene and quasi-one-dimensional (quasi-1D) antimony sulfide as examples. These are synthesized by a simple thermal injection method. It is observed that the consequent nanorods are oriented along six-fold symmetric directions on the nanoplate, forming ordered quasi-1D/quasi-2D heterostructures. Comprehensive transmission electron microscopy (TEM) characterizations confirm the chemical information and reveal orientational relationship between Sb2S3 nanorods and the Sb nanoplate as substrate. Further density functional theory calculations indicate that interfacial binding energy is the primary deciding factor for the self-assembly of ordered structures. These details may fill the gaps in the research on multi-dimensional composite materials with ordered structures, and promote their future versatile applications. Graphical Abstract

Simone Dilaria, Caterina Previato, Jacopo Bonetto et al.

In this paper, we discuss the presence of volcanic pozzolans in the structural mortars of the Roman Temple of Nora in Sardinia (3rd c. AD), represented by pyroclastic rocks (pumices and tuffs) employed as coarse and fine aggregates. The provenance of these materials from the Phlegraean Fields was highlighted through a multi-analytical approach, involving Polarized Light Microscopy on thin sections (PLM), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Quantitative Phase Analysis by X-ray Powder Diffraction (QPA-XRPD), and X-ray Fluorescence (XRF) investigations. These volcanic pozzolans, outcropping in the Bay of Naples between Pozzuoli and the Vesuvius, are traditionally associated with the <i>pulvis puteolana</i>, the famous pozzolanic ash prescribed by Vitruvius and Pliny in order to confer strength and waterproofing capabilities to ancient concretes. This is the first evidence of the trade of this volcanic material from the Neapolitan area to Sardinia, starting at least by the Middle Imperial Age. The use of the <i>pulvis puteolana</i> in the Roman Temple of Nora seems primarily targeted to strengthen above-ground masonries, while waterproofing capabilities were not strictly pursued. This opens new questions about the construction reasons for which the demand and commercialization for this product was intended.

Stefan G. Stanciu, Radu Hristu, George A. Stanciu et al.

Second Harmonic Generation Microscopy (SHG) is generally acknowledged as a powerful tool for the label-free 3D visualization of tissues and advanced materials, with one of its most popular applications being collagen imaging. Although the great need, progress in super-resolved SHG imaging lags behind the developments reported over the past years in fluorescence-based optical nanoscopy. In this work, we quantitatively show on collagenous tissues that by combining SHG imaging with re-scan microscopy resolutions that surpass the diffraction limit with ~1.4x become available. Besides Re-scan Second Harmonic Generation Microscopy (rSHG), we demonstrate as well super-resolved Re-scan Two-Photon Excited Fluorescence Microscopy (rTPEF). These two techniques are implemented by modifying a Re-scan Confocal Microscope (RCM), retaining its initial function, resulting thus in a multimodal rSHG/rTPEF/RCM system. Given the simplicity and flexibility of re-scan microscopy, we consider that the reported results are likely to augment the number and nature of applications relying on super-resolved non-linear optical imaging.

Kithmini Herath, Hasindu Kariyawasam, Ramith Hettiarachchi et al.

Designing new optical systems from the ground up for microscopy imaging tasks such as phase retrieval, requires substantial scientific expertise and creativity. To augment the traditional design process, we propose differentiable microscopy ($\partialμ$), which introduces a top-down design approach. Using all optical phase retrieval as an illustrative example, we demonstrate the effectiveness of data-driven microscopy design through $\partialμ$. Furthermore, we conduct comprehensive comparisons with existing all-optical phase retrieval methods, showcasing the consistent superiority of our learned designs across multiple datasets, including biological samples. To substantiate our ideas, we experimentally validate the functionality of one of the learned designs, providing a proof of concept. The proposed differentiable microscopy framework supplements the creative process of designing new phase microscopy systems and may be extended to other similar applications in optical design.

Amany M. Fekry

A new electrochemical sensor for the detection of levofloxacin (LV) was efficiently realized. The aim was to develop a new, cheap, and simple sensor for the detection of LV, which is used in various infections due to its pharmacological importance. It consists of carbon paste (CP) enhanced with nano-sized fumed silica (NFS). NFS has a very low bulk density and a large surface area. The carbon paste-enhanced NFS electrode (NFS/CPE) showed great electrocatalytic activity in the oxidation of 1.0 mM LV in Britton–Robinson buffer (BR) at pH values ranging from 3.0 to 8.0. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used; the peak current value (I_p) of the NFS/CPE sensor was 2.7 times that of the bare electrode, ensuring its high electrocatalytic activity. Electrochemical impedance spectroscopy (EIS) was performed at a peak potential (E_p) of +1066 mV, yielding a resistance of 10 kΩ for the designed NFS/CPE sensor compared to 2461 kΩ for the bare electrode, indicating the high conductivity of the modified sensor and verifying the data observed using the CV technique. Surface descriptions were determined by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The variation in the concentration of LV (2.0 to 1000 µM) was considered in BR buffer (pH = 5.0) at a scan rate (SR) of 10 mV/s by the NFS/CPE. The detection and quantification limits were 0.09 µM and 0.30 µM, respectively. To evaluate the application of LV in real samples, this procedure was established on Quinostarmax 500 mg tablets and human plasma samples. Reasonable results were obtained for the detection of LV.

Lindsay C. C. Elliott, Adam L. Pintar, Craig R. Copeland et al.

Gravimetry typically lacks the resolution to measure single microdroplets, whereas microscopy is often inaccurate beyond the resolution limit. To address these issues, we advance and integrate these complementary methods, introducing simultaneous measurements of the same microdroplets, comprehensive calibrations that are independently traceable to the International System of Units (SI), and Monte-Carlo evaluations of volumetric uncertainty. We achieve sub-picoliter agreement of measurements of microdroplets in flight with volumes of approximately 70 pL, with ensemble gravimetry and optical microscopy both yielding 95% coverage intervals of +/- 0.6 pL, or relative uncertainties of +/- 0.9%, and root-mean-square deviations of mean values between the two methods of 0.2 pL or 0.3%. These uncertainties match previous gravimetry results and improve upon previous microscopy results by an order of magnitude. Gravimetry precision depends on the continuity of droplet formation, whereas microscopy accuracy requires that optical diffraction from an edge reference matches that from a microdroplet. Applying our microscopy method, we jet and image water microdroplets suspending fluorescent nanoplastics, count nanoplastic particles after deposition and evaporation, and transfer volumetric traceability to number concentration. We expect that our methods will impact diverse fields involving dimensional metrology and volumetric analysis of microdroplets, including inkjet microfabrication, disease transmission, and industrial sprays.

Aghil Asadi, Mohsen Najafi, Hossien Bouhnedi et al.

Hypothesis: The volume of studies conducted on biopolymeric materials emphasizes the high-consumption of polymers in biomaterial fields, especially in cosmetics industry which must be resistant to different kinds of microorganisms and bacteria. Polymers in this category include acrylate polymers, which are generally made by precipitation polymerization. Carbopol is a brand of acrylic polymer, based on poly(acrylic acid). This polymer is highly used as thickening and gelling agents for its rheological features. By chemically induced antimicrobial agents into the carbopol structure, microgels of inherently antimicrobial properties are obtained with effective applications in personal and public health applications, including combating and controlling corona epidemics (Covid 19). Methods: In this study, it has been tried to improve the antibacterial nature of Carbopol by its bonding and surface modification with different amounts of cationic monomer acryloyl oxyethyl trimethyl ammonium chloride (A.Etac). In this work, for the first time, we attempted to modify the surface of carbopol by ultrasound. We also studied the swelling rate of the sample before and after surface modification in aqueous, alcoholic and salt solutions. Infrared spectroscopy (IR), scanning electron microscopy (SEM) with energy dispersive X-Ray analysis (SEM-EDX), antibacterial, rheometry and swelling tests were used to evaluate the chemical surface modification of Carbopol microparticles to achieve the stated goals. Antibacterial properties of the samples were evaluated by gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureu) by plate count agar method. Findings: Experimental results showed that the modified carbopol was significantly resistant to the bacteria. It should be noted that the samples showed more resistance to gram-positive bacteria than gram-negative bacteria. The results of rheological analysis also showed that the gel strength significantly increased after surface chemical modification. In addition, modified samples showed higher swelling in water and biological media (0.9% brine)

Giuseppe De Vito, Paola Parlanti, Roberta Cecchi et al.

When live imaging is not feasible, sample fixation allows preserving the ultrastructure of biological samples for subsequent microscopy analysis. This process could be performed with various methods, each one affecting differently the biological structure of the sample. While these alterations were well-characterized using traditional microscopy, little information is available about the effects of the fixatives on the spatial molecular orientation of the biological tissue. We tackled this issue by employing Rotating-Polarization Coherent Anti-Stokes Raman Scattering (RP-CARS) microscopy to study the effects of different fixatives on the myelin sub-micrometric molecular order and micrometric morphology. RP-CARS is a novel technique derived from CARS microscopy that allows probing spatial orientation of molecular bonds while maintaining the intrinsic chemical selectivity of CARS microscopy. By characterizing the effects of the fixation procedures, the present work represents a useful guide for the choice of the best fixation technique(s), in particular for polarisation-resolved CARS microscopy. Finally, we show that the combination of paraformaldehyde and glutaraldehyde can be effectively employed as a fixative for RP-CARS microscopy, as long as the effects on the molecular spatial distribution, here characterized, are taken into account.

Jack W Shepherd, Mark C Leake

Here, we report analysis and summary of research in the field of localization microscopy for optical imaging. We introduce the basic elements of super-resolved localization microscopy methods for PALM and STORM, commonly used both in vivo and in vitro, discussing the core essentials of background theory, instrumentation and computational algorithms. We discuss the resolution limit of light microscopy and the mathematical framework for localizing fluorescent dyes in space beyond this limit, including the precision obtainable as a function of the amount of light emitted from a dye, and how it leads to a fundamental compromise between spatial and temporal precision. The properties of a "good dye" are outlined, as are the features of PALM and STORM super-resolution microscopy and adaptations that may need to be made to experimental protocols to perform localization determination. We analyse briefly some of the methods of modern super-resolved optical imaging that work through reshaping point spread functions and how they utilize aspects of localization microscopy, such as stimulated depletion (STED) methods and MINFLUX, and summarize modern methods that push localization into 3D using non-Gaussian point spread functions. We report on current methods for analyzing localization data including determination of 2D and 3D diffusion constants, molecular stoichiometries, and performing cluster analysis with cutting-edge techniques, and finally discuss how these techniques may be used to enable important insight into a range of biological processes.

Jun Jiang, Warren S. Warren, Martin C. Fischer

We present a new imaging method for pump-probe microscopy that explores non-collinear excitation. This method (crossed-beam pump-probe microscopy, or CBPM) can significantly improve the axial resolution when imaging through low-NA lenses, providing an alternative way for depth resolved, large field-of-view imaging. We performed a proof-of-concept demonstration, characterized CBPM's resolution using different imaging lenses, and measured an enhanced axial resolution for certain types of low-NA lenses.

Montse Lopez-Martinez, Gwenael Mercier, Kamran Sadiq et al.

Single molecule localization microscopy is a recently developed superresolution imaging technique to visualize structural properties of single cells. The basic principle consists in chemically attaching fluorescent dyes to the molecules, which after excitation with a strong laser may emit light. To achieve superresolution, signals of individual fluorophores are separated in time. In this paper we follow the physical and chemical literature and derive mathematical models describing the propagation of light emitted from dyes in single molecule localization microscopy experiments via Maxwell's equations. This forms the basis of formulating inverse problems related to single molecule localization microscopy. We also show that the current status of reconstruction methods is a simplification of more general inverse problems for Maxwell's equations as discussed here.

Deepak R. Lakshmipathy, BS, Cornelia D. Cudrici, MD, Frederick Dyda, PhD et al.

A 54-year old female patient with the genetic disease of arterial calcification due to deficiency of CD73 was studied under the Undiagnosed Disease Program of the National Institutes of Health. She presented with symptoms of claudication in her 40s and later developed arthritic symptoms, ectopic calcification in her left hand and severe arterial calcifications of the lower extremities. Since little was known about the composition of the calcifications in arterial calcification due to deficiency of CD73, we investigated their chemical identity and microscopic morphology in this patient with imaging and x-ray diffraction analysis. We found that, microscopically, the bulk calcifications consisted of fragments of either solid or porous internal structure. Both periarticular and arterial calcifications were primarily hydroxyapatite crystals of the same crystalline anisotropy, but different crystalline grain sizes. This was consistent with the presence of hydroxyapatite crystals along with birefringent calcium pyrophosphate dihydrate crystals in the synovial fluid of the patients by polarized light microscopy. The result suggests that tissue calcification in both locations follow a similar biochemical mechanism caused by an increase in extracellular tissue-nonspecific alkaline phosphatase activity.

Yayuan He, Pian Wu, Wen Xiao et al.

It is vital to understand the adsorption mechanisms and identify the adsorption kinetics when applying an adsorbent to remove heavy metals from aqueous solution. A Pb(II) imprinted magnetic biosorbent (Pb(II)-IMB) was developed for the removal of Pb2+ via lead ion imprinting technology and crosslinking reactions among chitosan (CTS), Serratia marcescens and Fe3O4. The effect of different parameters such as solution pH, adsorbent dosage, selectivity sorption and desorption were investigated on the absorption of lead ion by Pb(II)-IMB. The adsorbent was characterized by a Brunauer-Emmett Teller (BET) analysis, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The adsorption kinetics, equilibrium and thermodynamics of Pb(II)-IMB for Pb(II) were studied. The results of the abovementioned analyses showed that the adsorption kinetic process fit well with the second-order equation. The adsorption isotherm process of Pb(II) on the Pb(II)-IMB was closely related to the Langmuir model. Thermodynamic studies suggested the spontaneous and endothermic nature of adsorption of Pb(II) by Pb(II)-IMB. The adsorption mechanism of Pb(II)-IMB was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the nitrogen in the amino group and the oxygen in the hydroxyl group of Pb(II)-IMB were coordination atoms.