Hasil untuk "Microscopy"

L. Schermelleh, R. Heintzmann, H. Leonhardt

For centuries, cell biology has been based on light microscopy and at the same time been limited by its optical resolution. However, several new technologies have been developed recently that bypass this limit. These new super-resolution technologies are either based on tailored illumination, nonlinear fluorophore responses, or the precise localization of single molecules. Overall, these new approaches have created unprecedented new possibilities to investigate the structure and function of cells.

G. Victora, T. Schwickert, David R Fooksman et al.

O. Krivanek, M. Chisholm, V. Nicolosi et al.

F. J. G. D. Abajo

This review discusses how low-energy, valence excitations created by swift electrons can render information on the optical response of structured materials with unmatched spatial resolution. Electron microscopes are capable of focusing electron beams on sub-nanometer spots and probing the target response either by analyzing electron energy losses or by detecting emitted radiation. Theoretical frameworks suited to calculate the probability of energy loss and light emission (cathodoluminescence) are revisited and compared with experimental results. More precisely, a quantum-mechanical description of the interaction between the electrons and the sample is discussed, followed by a powerful classical dielectric approach that can be in practice applied to more complex systems. We assess the conditions under which classical and quantum-mechanical formulations are equivalent. The excitation of collective modes such as plasmons is studied in bulk materials, planar surfaces, and nanoparticles. Light emission induced by the electrons is shown to constitute an excellent probe of plasmons, combining sub-nanometer resolution in the position of the electron beam with nanometer resolution in the emitted wavelength. Both electron energy-loss and cathodoluminescence spectroscopies performed in a scanning mode of operation yield snap shots of plasmon modes in nanostructures with fine spatial detail as compared to other existing imaging techniques, thus providing an ideal tool for nanophotonics studies.

P. Thibault, M. Dierolf, A. Menzel et al.

T. Vettenburg, H. Dalgarno, J. Nylk et al.

D. Rugar, R. Budakian, H. J. Mamin et al.

J. Lichtman, J. Conchello

S. Edition, C. J. Chen

The scanning tunnelling microscope (STM) was invented by Binnig and Rohrer and received a Nobel Prize of Physics in 1986. Together with the atomic force microscope (AFM), it enables non-destructive observing and mapping atoms and molecules on solid surfaces down to a picometer resolution. A recent development is the non-destructive observation of wavefunctions in individual atoms and molecules, including nodal structures inside the wavefunctions. STM and AFM have become indespensible instruments for scientists of various disciplines, including physicists, chemists, engineers, and biologists to visualize and utilize the microscopic world around us. Since the publication of the first edition in 1993, this book has been recognized as a standard introduction for everyone that starts working with scanning probe microscopes, and a useful reference book for those more advanced in the field. After an Overview chapter accessible for newcomers at an entry level presenting the basic design, scientific background, and illustrative applications, the book has three Parts. Part I, Principles, provides the most systematic and detailed theory of its scientific bases from basic quantum mechancis and condensed-metter physics in all available literature. Quantitative analysis of its imaging mechanism for atoms, molecules, and wavefunctions is detailed. Part II, Instrumentation, provides down to earth descriptions of its building components, including piezoelectric scanners, vibration isolation, electronics, software, probe tip preparation, etc. Part III, Related methods, presenting two of its most important siblings, scanning tunnelling specgroscopy and atomic force miscsoscopy. The book has five appendices for background topics, and 405 references for further readings.

P. Campagnola, L. Loew

By M. A. Hayat

J. Bozzola, L. Russell

E. Betzig, J. Trautman

G. Johnson, Gloria M. de C. Nogueira Araujo

B. Schuler, G. Meyer, D. Peña et al.

Juan Du, Wei Lü, Shenping Wu et al.

Das S, Satapathy BS, Pattnaik G et al.

Shubhashree Das,1 Bhabani Sankar Satapathy,2 Gurudutta Pattnaik,1 Sovan Pattanaik,3 Yahya Alhamhoom,4 Mohamed Rahamathulla,4 Mohammed Muqtader Ahmed,5 Ismail Pasha6 1Department of Pharmaceutics, School of Pharmacy and Life Sciences, Centurion University of Technology and Management, Odisha, India; 2Department of Pharmaceutics, GITAM School of Pharmacy, GITAM Deemed to Be University, Hyderabad Campus, Telangana, India; 3Department of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Siksha O Anusandhan Deemed to be University, Bhubaneswar, Odisha, India; 4Department of Pharmaceutics, College of Pharmacy, King Khalid University, Al Faraa, Abha, 62223, Saudi Arabia; 5Department of Pharmaceutics, College of Pharmacy, Prince Sattam bin Abdul Aziz University, Al Kharj, 11942, Saudi Arabia; 6Department of Pharmacology, Orotta College of Medicine and Health Science, Asmara, EritreaCorrespondence: Gurudutta Pattnaik, School of Pharmacy and Life Sciences, Centurion University of Technology and Management, Odisha, India, Email gurudutta.pattnaik@cutm.ac.in Ismail Pasha, Department of Pharmacology, Orotta college of medicine and Health Science, Asmara, Eritrea, Email ismail.orotta@gmail.comBackground: Breast cancer remains a leading cause of cancer-related mortality in women globally. The main purpose of the research to develop, optimise and characterise a trastuzumab (TZ)-functionalized nanolipid carrier (NCs) encapsulating capecitabine, as a targeted strategy to breast cancer cells, to enhance therapeutic efficacy and reduce the severe side effects associated with conventional chemotherapy.Methods: Capecitabine encapsulated NCs (CBNCs) were prepared by thin-film hydration technique, optimized by Box-Behnken design. The optimized formulation CBNCs were subsequently conjugated with TZ by using EDC-NHS chemistry. The prepared formulations of NCs were evaluated by FTIR, DSC, XRD, FESEM, TEM, AFM, drug loading, entrapment efficiency, average particle size, PDI, zeta potential, in vitro drug release. The successful surface conjugation of TZ was tested by BCA assay and SDS-PAGE analysis. In vitro targeting efficiency and cytotoxicity initially tested in MCF-7 cells (HER2-low expressing) and subsequently validated in SKBR3 cells (HER2-overexpressing) to confirm receptor-mediated uptake and specificity.Results: Optimized CBNCs were found spherical, nanosized (194.6 nm), with a zeta potential − 25.55 mV for CBNCs, which increased to – 57.76 mV upon TZ conjugation. The formulation showed 8.5% drug loading capacity and 84.26% drug release over 72 h. FTIR and DSC showed compatibility of drug and lipid components with no major shifting in characteristic peaks. TEM and AFM confirmed formation of stable, spherical discrete nanostructures. TZ conjugation showed minor alternation in average size/surface charge/morphology/texture. Successful TZ conjugation onto CBNCs was confirmed by BCA assay and SDS-PAGE. Fluorescence microscopy confirmed successful cellular internalization. MTT assay on SKBR3 cells demonstrated significantly higher cytotoxicity for TZ-CBNCs compared to CBNCs and free drug, thereby validating the HER2-specific targeting effect beyond preliminary results obtained in MCF-7 cells.Conclusion: In view of the desired physicochemical properties, controlled drug release, and in vitro anticancer effectiveness, further in vivo investigations should be prioritized to validate its clinical application in HER2-positive breast cancer treatment. Nonetheless, the use of HER2-low MCF-7 cells in early assays highlights the importance of complementary validation in HER2-overexpressing models, as addressed by SKBR3 testing in this study. Keywords: nanolipid carrier, trastuzumab, capecitabine, breast cancer, MTT assay

Lía Hoz Rodríguez, Maricela Santana Vázquez, Luis Fernando Ramírez González et al.

Abstract A pentapeptide AVIFM (CAP‐p5) derived from the carboxy‐terminus end of cementum attachment protein was examined for its role on proliferation, differentiation, and mineralization of human periodontal ligament cells (HPLC), and for its potential to induce cementum deposition in vivo. CAP‐p5 capability to induce hydroxyapatite crystal formation on demineralized dentin blocks was characterized by scanning electron microscopy, μRAMAN, and high‐resolution transmission electron microscopy. The results revealed that CAP‐p5 promoted cell proliferation and cell differentiation and increases alkaline phosphatase activity of HPLC and mineralization at an optimal concentration of 10 μg/mL. It induced the expression of cementum molecular markers BSP, CAP, CEMP1, and ALP at the protein level. In a cell‐free system, human demineralized dentin blocks coated with CAP‐p5 induced the deposition of a homogeneous and continuous mineralized layer, intimately integrated with the underlying dentin indicating new cementum formation. Physicochemical characterization of this mineral layer showed that it is composed of hydroxyapatite crystals. Demineralized dentin blocks coated with CAP‐p5 implanted subcutaneously in BALB/cAnNCrl were analyzed histologically; the results disclosed that CAP‐p5 could induce the deposition of a cementum layer intimately integrated with the subjacent dentin with cementocytes embedded into the cementum matrix. Immunostaining showed the expression of cementum molecular markers; v.gr. BSP, CAP, CEMP1 and ALP, validating the molecular identity of the newly deposited cementum. We conclude that CAP‐p5 is a new biomolecule with the potential of therapeutic application to contribute to the regeneration of cementum and periodontal structures lost in periodontal disease.

Vladimir Vinarsky, Stefania Pagliari, Bacel Aldabash et al.

Abstract Cardiac diseases are fueled by extracellular matrix (ECM) remodelling. Together with the altered ECM chemical composition, the mechanical turmoil associated with ECM maladaptive remodelling in the pathological heart drives the shuttling of Yes Associated Protein 1 (YAP1) into cardiomyocyte (CM) nuclei that results either in cell cycle re-entry or cardiomyocyte hypertrophy. The mechanism of YAP1 reactivation and factors driving qualitatively different cellular outcomes is not well understood. Here we employed mechanical actuation as a proxy reproducing ECM remodelling in vitro to trigger YAP1 nuclear shuttling in contractile cardiomyocytes derived from human embryonic and induced pluripotent stem cells (hPSCs). By using hPSC lines in which YAP1 expression has been genetically depleted, super-resolution microscopy and electrophysiological measurements, we show that ECM-triggered nuclear presence of endogenous YAP1 contributes to cardiomyocyte maturation, participates in the formation and alignment of myofibrils, as well as in the maturation of their electrophysiological properties and calcium dynamics. We eventually exploit engineered heart tissues (EHTs) to demonstrate that the net effect of YAP1 deficiency in cardiomyocytes is the inability to respond to physiological stimuli by compensatory growth that results in reduced force development. These results suggest that the re-activation of endogenous YAP1 following ECM maladaptive remodelling promotes cardiomyocyte contractility by restructuring the sarcomere apparatus and the maturation of electrophysiological properties via transcriptionally dependent and independent mechanisms.