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Two photon microscopy

R Glenn Hepfer, Peng Chen, Kelvin G M Brockbank, Alyce L Jones, Amanda K Burnette, Zhen Chen, Elizabeth D Greene, Lia H Campbell, Hai Yao
The purpose of this study was to determine the impact of elevated temperature exposure in tissue banking on soft tissues. A secondary objective was to determine the relative ability of various assays to detect changes in soft tissues due to temperature deviations. Porcine pulmonary heart valve leaflets exposed to 37 °C were compared with those incubated at 52 and 67 °C for 10, 30 and 100 min. The analytical methods consisted of (1) viability assessment using the resazurin assay, (2) collagen content using the Sircol assay, and (3) permeability assessment using an electrical conductivity assay...
November 13, 2017: Cardiovascular Engineering and Technology
Tejapratap Bollu, Nathan R Cornelius, John Sunwoo, Nozomi Nishimura, Chris B Schaffer, Peter C Doerschuk
Computations are described which estimate flows in all branches of the cortical surface arteriole network from two-photon excited fluorescence (2PEF) microscopy images which provide the network topology and, in selected branches red blood cell (RBC) speeds and lumen diameters. Validation is done by comparing the flow predicted by the model with experimentally measured flows and by comparing the predicted flow redistribution in the network due to single-vessel strokes with experimental observations. The model predicts that tissue is protected from RBC flow decreases caused by multiple occlusions of surface arterioles but not penetrating arterioles...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
Yu-Jia Fu, Hui-Wen Yao, Xiao-Yan Zhu, Xiao-Feng Guo, Hong Wang
Hydrogen sulfide (H2S) is a new endogenously generated gasotransmitter and has implicated in many physiologies and pathologies closely related to its intracellular and intercellular signaling transduction. Although many fluorescent probes have been exploited to track and quantify H2S in living systems, none of them could be used for monitoring intercellular transmission of H2S. Herein, we developed a cell surface specific H2S probe, 4-azido-6-sulfo-N-hexadecyl-1,8-naphthalimide, sodium salt (ASNHN-N3), trying to investigate the behaviors of extracellular release of H2S...
November 22, 2017: Analytica Chimica Acta
F Bolze, S Jenni, A Sour, V Heitz
Two-photon excitation has attracted the attention of biologists, especially after the development of two-photon excited microscopy in the nineties. Since then, new applications have rapidly emerged such as the release of biologically active molecules and photodynamic therapy (PDT) using two-photon excitation. PDT, which requires a light-activated drug (photosensitiser), is a clinically approved and minimally invasive treatment for cancer and for non-malignant diseases. This feature article focuses on the engineering of molecular two-photon photosensitisers for PDT, which should bring important benefits to the treatment, increase the treatment penetration depth with near-infrared light excitation, improve the spatial selectivity and reduce the photodamage to healthy tissues...
November 8, 2017: Chemical Communications: Chem Comm
Minsoo Cho, Seulgi Han, Hyemin Kim, Ki Su Kim, Sei Kwang Hahn
Human parathyroid hormone 1-34 fragment (PTH1-34) has been used as a FDA-approved therapeutics to treat osteoporosis by daily subcutaneous injection. In this work, we successfully developed PTH1-34 conjugated hyaluronic acid (HA) for the transdermal treatment of osteoporosis with improved patient compliance. HA-PTH1-34 conjugate was synthesized by the coupling reaction between aldehyde group introduced to HA and amine group of PTH1-34. After characterization by gel permeation chromatography (GPC) and ELISA, the biological effect of HA-PTH1-34 conjugate on the proliferation of human osteoblast cells was confirmed by in vitro calcium colorimetric assay and cAMP assay...
November 8, 2017: Journal of Biomaterials Science. Polymer Edition
Lara G Freidus, Priyamvada Pradeep, Pradeep Kumar, Yahya E Choonara, Viness Pillay
Fluorescent molecular imaging has advanced drastically over the past decade. With the development of high-resolution microscopy techniques and the ability to visualize intracellular molecular events, there is a growing need for new fluorophores to accompany these fast-developing techniques. Therefore, there has been substantial development of alternative fluorophores for single-molecule detection and molecular imaging. These rationally designed fluorophores have infinite possibilities and novel fluorophores are constantly being produced for different applications...
October 27, 2017: Drug Discovery Today
Mohadeseh Hashemi, Meisam Omidi, Bharadwaj Muralidharan, Lobat Tayebi, Matthew J Herpin, Mohammad Ali Mohagheghi, Javad Mohammadi, Hugh D C Smyth, Thomas E Milner
Stimuli responsive polyelectrolyte nanoparticles have been developed for chemo-photothermal destruction of breast cancer cells. This novel system, called layer by layer Lipo-graph (LBL Lipo-graph), is composed of alternate layers of graphene oxide (GO) and graphene oxide conjugated poly (l-lysine) (GO-PLL) deposited on cationic liposomes encapsulating doxorubicin. Various concentrations of GO and GO-PLL were examined and the optimal LBL Lipo-graph was found to have a particle size of 267.9 ± 13 nm, zeta potential of +43...
November 8, 2017: Acta Biomaterialia
Michael A Washington, Stephen C Balmert, Morgan V Fedorchak, Steven R Little, Simon C Watkins, Tara Y Meyer
Controlling the backbone architecture of poly(lactic-co-glycolic acid)s (PLGAs) is demonstrated to have a strong influence on the production and release of acidic degradation by-products in microparticle matrices. Previous efforts for controlling the internal and external accumulation of acidity for PLGA microparticles have focused on the addition of excipients including neutralization and anti-inflammatory agents. In this report, we utilize a sequence-control strategy to tailor the microstructure of PLGA. The internal acidic microclimate distributions within sequence-defined and random PLGA microparticles were monitored in vitro using a non-invasive ratiometric two-photon microscopy (TPM) methodology...
October 31, 2017: Acta Biomaterialia
Ruben Mercadé-Prieto, Luis Rodriguez-Rivera, Xiao Dong Chen
Rhodamine B (RhB) is a well known dye extensively used in thermometric studies, either considering the decrease in the fluorescence intensity or the lifetime (τ) with temperature. Lifetime measurements are preferred over intensity ones as they are more robust. In order to expand microscopy thermometry to complex food fluids, the effect of solutes on the τ of RhB was studied using fluorescence lifetime imaging microscopy (FLIM) in a two-photon microscope. Polysaccharides of different molecular weights (glucose, lactose, dextran, maltodextrin, and sodium alginate), as well as whey proteins, were considered as typical model food ingredients...
November 8, 2017: Photochemical & Photobiological Sciences
Marina V Shirmanova, Lubov' E Shimolina, Maria M Lukina, Elena V Zagaynova, Marina K Kuimova
Abnormal levels of viscosity in tissues and cells are known to be associated with disease and malfunction. While methods to measure bulk macroscopic viscosity of bio-tissues are well developed, imaging viscosity at the microscopic scale remains a challenge, especially in vivo. Molecular rotors are small synthetic viscosity-sensitive fluorophores in which fluorescence parameters are strongly correlated to the microviscosity of their immediate environment. Hence, molecular rotors represent a promising instrument for mapping of viscosity in living cells and tissues at the microscopic level...
2017: Advances in Experimental Medicine and Biology
Lingling Lu, Adam D Hogan-Cann, Andrea K Globa, Ping Lu, James I Nagy, Shernaz X Bamji, Christopher M Anderson
Astrocytes express neurotransmitter receptors that serve as sensors of synaptic activity and initiate signals leading to activity-dependent local vasodilation and increases in blood flow. We previously showed that arteriolar vasodilation produced by activation of cortical astrocytes is dependent on endothelial nitric oxide synthase (eNOS) and endogenous agonists of N-methyl-D-aspartate (NMDA) receptors. Here, we tested the hypothesis that these effects are mediated by NMDA receptors expressed by brain endothelial cells...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
Hai Li, Jiang-Bin Wu, Feirong Ran, Miao-Ling Lin, Xue-Lu Liu, Yanyuan Zhao, Xin Lu, Qihua Xiong, Jun Zhang, Wei Huang, Hua Zhang, Ping-Heng Tan
Interfacial coupling between neighboring layers of van der Waals heterostructures (vdWHs), formed by vertically stacking more than two types of two-dimensional materials (2DMs), greatly affects their physical properties and device performance. Although high-resolution cross-sectional scanning tunneling electron microscopy can directly image the atomically sharp interfaces in the vdWHs, the interfacial coupling and lattice dynamics of vdWHs formed by two different types of 2DMs, such as semimetal and semiconductor, are not clear so far...
October 25, 2017: ACS Nano
Danielle Tokarz, Richard Cisek, Marc N Wein, Raphaël Turcotte, Christa Haase, Shu-Chi A Yeh, Srinidhi Bharadwaj, Anthony P Raphael, Hari Paudel, Clemens Alt, Tzu-Ming Liu, Henry M Kronenberg, Charles P Lin
Osteocytes are the most abundant cell in the bone, and have multiple functions including mechanosensing and regulation of bone remodeling activities. Since osteocytes are embedded in the bone matrix, their inaccessibility makes in vivo studies problematic. Therefore, a non-invasive technique with high spatial resolution is desired. The purpose of this study is to investigate the use of third harmonic generation (THG) microscopy as a noninvasive technique for high-resolution imaging of the lacunar-canalicular network (LCN) in live mice...
2017: PloS One
Beibei Hou, Mengran Xie, Ruoyu He, Minbiao Ji, Sonja Trummer, Rainer H Fink, Luning Zhang
Conventional far-field microscopy cannot directly resolve the sub-diffraction spatial distribution of localized surface plasmons in metal nanostructures. Using BaTiO3 microspheres as far-field superlenses by collecting the near-field signal, we can map the origin of enhanced two-photon photoluminescence signal from the gap region of gold nanosphere dimers and gold nanorod dimers beyond the diffraction limit, on a conventional far-field microscope. As the angle θ between dimer's structural axis and laser polarisation changes, photoluminescence intensity varies with a cos(4)θ function, which agrees quantitatively with numerical simulations...
October 23, 2017: Scientific Reports
Rohan Gala, Daniel Lebrecht, Daniela A Sahlender, Anne Jorstad, Graham Knott, Anthony Holtmaat, Armen Stepanyants
The ability to measure minute structural changes in neural circuits is essential for long-term in vivo imaging studies. Here, we propose a methodology for detection and measurement of structural changes in axonal boutons imaged with time-lapse two-photon laser scanning microscopy (2PLSM). Correlative 2PLSM and 3D electron microscopy (EM) analysis, performed in mouse barrel cortex, showed that the proposed method has low fractions of false positive/negative bouton detections (2/0 out of 18), and that 2PLSM-based bouton weights are correlated with their volumes measured in EM (r = 0...
October 23, 2017: ELife
Barbara Lykke Lind, Sanne Barsballe Jessen, Micael Lønstrup, Charlène Joséphine, Gilles Bonvento, Martin Lauritzen
Cerebral blood flow (CBF) is regulated by the activity of neurons and astrocytes. Understanding how these cells control activity-dependent increases in CBF is crucial to interpreting functional neuroimaging signals. The relative importance of neurons and astrocytes is debated, as are the functional implications of fast Ca(2+) changes in astrocytes versus neurons. Here, we used two-photon microscopy to assess Ca(2+) changes in neuropil, astrocyte processes, and astrocyte end-feet in response to whisker pad stimulation in mice...
October 23, 2017: Glia
Janna L Morrison, Alexandra Sorvina, Jack R T Darby, Christie A Bader, Mitchell C Lock, Mike Seed, Tim Kuchel, Sally E Plush, Douglas A Brooks
The heart has high metabolic demand to maintain function. The primary source of energy supply to support correct contractile muscle function differs between a fetus and an adult. In fetal life, ATP is primarily generated by glycolysis and lactate oxidation, whereas following birth there is a shift towards a reliance on mitochondrial metabolism and fatty acid oxidation. This change in metabolic status is an adaptation to different fuel availability, oxygenation and growth patterns. Here, we have employed two-photon excitation fluorescence microscopy to define the relationship between two critical metabolic co-factors NAD(P)H and FAD, effectively utilising a redox ratio to differentiate between the metabolic status in fetal (proliferative) and adult (quiescent/hypertrophic) hearts...
October 23, 2017: Journal of Biophotonics
Ryan Beams, Jeremiah W Woodcock, Jeffrey W Gilman, Stephan J Stranick
We demonstrate a multimodal superresolution microscopy technique based on a phase masked excitation beam in combination with spatially filtered detection. The theoretical foundation for calculating the focus from a non-paraxial beam with an arbitrary azimuthally symmetric phase mask is presented for linear and two-photon excitation processes as well as the theoretical resolution limitations. Experimentally this technique is demonstrated using two-photon luminescence from 80 nm gold particle as well as two-photon fluorescence lifetime imaging of fluorescent polystyrene beads...
2017: Photonics
Weiwei Fan, Dengning Xia, Quanlei Zhu, Xiuying Li, Shufang He, Chunliu Zhu, Shiyan Guo, Lars Hovgaard, Mingshi Yang, Yong Gan
Oral absorption of protein/peptide-loaded nanoparticles is often limited by multiple barriers of the intestinal epithelium. In addition to mucus translocation and apical endocytosis, highly efficient transepithelial absorption of nanoparticles requires successful intracellular trafficking, especially to avoid lysosomal degradation, and basolateral release. Here, the functional material, deoxycholic acid-conjugated chitosan, is synthesized and loaded with the model protein drug insulin into deoxycholic acid-modified nanoparticles (DNPs)...
October 13, 2017: Biomaterials
M Rutkauskas, D T Reid, J Garduño-Mejía, M Rosete-Aguilar
We show that in a nonlinear microscopy system the effects of chromatic and spherical aberrations are revealed by a difference in the focal positions corresponding to the shortest pulse duration and the minimum lateral resolution. By interpreting experimental results from a high-numerical-aperture two-photon microscope using a previously reported spatio-temporal model, we conclude that the two-photon autocorrelation of the pulses at the focal plane can be used to minimize both the chromatic and spherical aberrations of the system...
June 10, 2017: Applied Optics
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