Hasil untuk "Microscopy"

Y. Martin, H. K. Wickramasinghe

A. Bard, F. Fan, Juhyoun Kwak et al.

McDowell Em, Trump Bf

B. Knoll, F. Keilmann

D. Croft, G. Shedd, S. Devasia

J. Korlach, P. Schwille, W. Webb et al.

Shaohui Huang, A. Heikal, W. Webb

J. Alcaraz, L. Buscemi, Mireia Grabulosa et al.

R. Colton, D. R. Baselt, Y. Dufrêne et al.

Thai V. Truong, Willy Supatto, D. Koos et al.

Vidit Agrawal, John Peters, Tyler N. Thompson et al.

Quantifying cell morphology using images and machine learning has proven to be a powerful tool to study the response of cells to treatments. However, models used to quantify cellular morphology are typically trained with a single microscopy imaging type. This results in specialized models that cannot be reused across biological studies because the technical specifications do not match (e.g., different number of channels). Here, we present CHAMMI-75, an open access dataset of heterogeneous, multi-channel microscopy images from 75 diverse biological studies. We curated this resource from publicly available sources to investigate cellular morphology models that are channel-adaptive and can process any microscopy image type. Our experiments show that training with CHAMMI-75 can improve performance in multi-channel bioimaging tasks primarily because of its high diversity in microscopy modalities. This work paves the way to create the next generation of cellular morphology models for biological studies.

Tommaso A. Salamone, Sofia Marotta, Stella Mrmić et al.

Abstract Background Trastuzumab (TZ) resistance remains a significant challenge in the treatment of human epidermal growth factor receptor 2 (HER2)-positive epithelial ovarian cancer (EOC), necessitating novel therapeutic strategies to improve treatment efficacy. Functionalized gold nanoparticles (AuNPs) constitute a promising platform for drug delivery and the ability to enhance tumor targeting via the enhanced permeability and retention (EPR) effect. miR-200c, a well-established tumor suppressor microRNA (miRNA), plays a crucial role in inhibiting epithelial-mesenchymal transition (EMT). However, its role in modulating HER2 signaling pathways and sensitizing ovarian cancer cells to TZ remains largely unexplored. Here, we investigate for the first time the combinatorial effect of miR-200c and thiol-functionalized AuNPs (< 10 nm) loaded with TZ (AuNPs-TZ) in overcoming TZ resistance and enhancing treatment efficacy in ovarian cancer cells. Results Pristine AuNPs were not cytotoxic, confirming their biocompatibility as a nanocarrier for TZ delivery. AuNPs were loaded noncovalently with TZ and maintained colloidal stability to prevent aggregation while facilitating effective cellular uptake. Treatment of ovarian cancer cells overexpressing miR-200c with AuNPs-TZ significantly reduced cell viability and increased apoptosis. Immunoblot analysis showed a reduction of phosphorylated HER2 and downstream Kirsten Rat Sarcoma Virus (KRAS) signaling. Furthermore, transmission electron microscopy (TEM) demonstrated morphological changes in miR-200c-transfected ovarian cancer cells and confirmed the localization of AuNPs carrying TZs on the cell membrane and in the cytoplasm. Conclusions These findings highlight the potential of AuNPs-TZ delivery combined with miR-200c as a promising therapeutic strategy to improve the response of HER2-positive EOC to TZ treatment. These results imply the need to further develop AuNP/miRNA-based combinatorial therapies as a viable nanomedicine approach for drug-resistant cancers. Graphical Abstract

E. Mudry, K. Belkebir, J. Girard et al.

Jabez J. McClelland, Evgheni Strelcov, Ami Chand

We present measurements comparing scanning thermal microscopy in air and vacuum. Signal levels are compared and resolution is probed by scanning over the edge of a nanofabricated Ag square embedded in SiO2. Signals measured in air were seen to be 2.5 to 40 times larger than in vacuum. Furthermore, the air signals were stable while the vacuum signals varied significantly. Edge widths measured in air were approximately 39 % larger than those measured in vacuum. Our observations are consistent with the air measurements experiencing heat transfer from the surrounding sample via conduction and convection as well as the formation of a water-related meniscus at the tip-sample junction. These results contribute to the understanding of the complex heat exchange effects that can occur in scanning thermal microscopy when it is conducted in an ambient atmosphere.

Aymerick Bazin, Amaury Badon

Achieving fast, large-scale volumetric imaging with micrometer resolution has been a persistent challenge in the field of biological microscopy. To address this challenge, we report an augmented version of light field microscopy, incorporating a motorized tilting mirror upstream the camera. Depending on the scanning pattern, the field of view and/or the lateral resolution can be greatly improved. Our microscope technique is simple, versatile and configured for both bright-field and epifluorescence modes. We demonstrate its performances with imaging of multi-cellular aggregates of various shape and sizes.

Stephanie N. Kramer, Jeanpun Antarasen, Cole R. Reinholt et al.

We present a comprehensive guide to light-sheet microscopy (LSM) to assist scientists in navigating the practical implementation of this microscopy technique. Emphasizing the applicability of LSM to image both static microscale and nanoscale features, as well as diffusion dynamics, we present the fundamental concepts of microscopy, progressing through beam profile considerations, to image reconstruction. We outline key practical decisions in constructing a home-built system and provide insight into the alignment and calibration processes. We briefly discuss the conditions necessary for constructing a continuous 3D image and introduce our home-built code for data analysis. By providing this guide, we aim to alleviate the challenges associated with designing and constructing LSM systems and offer scientists new to LSM a valuable resource in navigating this complex field.

Vladimir Pimonov, Said Tahir, Vincent Jourdain

This study addresses the challenge of analyzing the growth kinetics of carbon nanotubes using in-situ homodyne polarization microscopy (HPM) by developing an automated deep learning (DL) approach. A Mask-RCNN architecture, enhanced with a ResNet-50 backbone, was employed to recognize and track individual nanotubes in microscopy videos, significantly improving the efficiency and reproducibility of kinetic data extraction. The method involves a series of video processing steps to enhance contrast and used differential treatment techniques to manage low signal and fast kinetics. The DL model demonstrates consistency with manual measurements and increased throughput, laying the foundation for statistical studies of nanotube growth. The approach can be adapted for other types of in-situ microscopy studies, emphasizing the importance of automation in high-throughput data acquisition for research on individual nano-objects.

Marcel Reutzel, G. S. Matthijs Jansen, Stefan Mathias

Excitons -- two-particle correlated electron-hole pairs -- are the dominant low-energy optical excitation in the broad class of semiconductor materials, which range from classical silicon to perovskites, and from two-dimensional to organic materials. Recently, the study of excitons has been brought on a new level of detail by the application of photoemission momentum microscopy -- a technique that has dramatically extended the experimental capabilities of time- and angle-resolved photoemission spectroscopy (trARPES). Here, we review how the energy- and momentum-resolved photoelectron detection scheme enables direct access to the energy landscape of bright and dark excitons, and, more generally, to the momentum-coordinate of the exciton that is fundamental to its wavefunction. Focusing on two-dimensional materials and organic semiconductors as two tuneable platforms for exciton physics, we first discuss the typical photoemission fingerprint of excitons in momentum microscopy and highlight that is is possible to obtain information not only on the electron- but also hole-component of the former exciton. Second, we focus on the recent application of photoemission orbital tomography to such excitons, and discuss how this provides a unique access to the real-space properties of the exciton wavefunction. Throughout the review, we detail how studies performed on two-dimensional transition metal dichalcogenides and organic semiconductors lead to very similar conclusions, and, in this manner, highlight the strength of time-resolved momentum microscopy for the study of optical excitations in semiconductors.

Bibhu P. Sahu, Mohsen T. Andani, Arkajit Ghosh et al.

The crystallography of the eutectic Al-Si microstructure in both unmodified and Sr (0.2 wt.%)-modified hypereutectic Al-20 wt.% Si alloys, processed via arc-melting and laser surface remelting, has been comprehensively characterized using transmission electron microscopy and electron diffraction. Although, under as-cast conditions, specific orientations between different planes of Al and Si, satisfying defined orientation relationships (ORs), have been investigated within the flake morphology, the rapid solidification induced by laser surface remelting results in a notable transformation from a flake morphology to nanocrystalline Si fibers dispersed in an Al matrix. Consequently, this transformation results in a mis-orientation of the interface between the eutectic Al and Si phases, preventing the formation of orientation relationships, thus promoting the formation of faceted interfaces exhibiting substantial lattice disregistry.

Hany M. El-Naggar, Shimaa M. Ali, Amira R. Osman

Abstract The postharvest life of cut flowers is limited, which is a major challenge and varies greatly depending on plant varieties, cut flower stage, flower length of the harvested shoots, and storage conditions including postharvest treatments. As a result, improving the vase life and quality of cut flowers in regulating postharvest characteristics and overcoming these challenges is critical to the horticulture business. Novel engineered nanocomposites were created and tested for possible impacts on flower bud opening, postharvest life extension, longevity regulation, and preservation and enhancement of the strength and appearance of cut flowers. The experiment was conducted as a factorial experiment using a completely randomized design (CRD) with two factors. The first factor was two holding solutions (without or with sucrose at 20 gL−1). The second factor was 12 pulsing treatments for 24 h; distilled water as a control, 75 ppm GA3, multi-walled carbon nanotubes MWCNTs at 10, 20, 30, 40, and 50 ppm, and MWCNTs (10, 20, 30, 40, and 50 ppm)/GA3 (75 ppm) composites; each treatment had 3 replicates, for a total of 72 experimental units. In the present study, gibberellic acid (GA3) was synthesized in functionalized (MWCNT/GA3 composites) as a novel antisenescence agent, and their effect on the vase life quality of cut rose flowers Rosa hybrida cv. ‘Moonstone’ was compared by assaying several parameters critical for vase life. The adsorption of GA3 on MWCNTs was proven by performing FTIR spectroscopy which ensures that the formation of the MWCNTs/GA3 composite preserves the nanostructure and was examined by high-resolution transmission electron microscopy (HR-TEM). The results revealed that sucrose in the holding solution showed a significant increase in fresh weight, flower diameter, and vase life by 10.5, 10.6, and 3.3% respectively. Applying sucrose with MWCNTs 20 ppm/GA3 75 ppm composites or MWCNTs 20 ppm alone, was critical for the significant increase in flower opening by 39.7 and 28.7%, and longevity by 34.4 and 23.2%, respectively, and significantly increased chlorophyll a, b, total chlorophyll, anthocyanin, total phenolic content, and 2,2-Diphenyl-1-picrylhydrazyl scavenging activity as compared to the control.