Review. Fluorescence Microscopy Studies of Porous Silica Materials

2013 ◽  
Vol 68 (5-6) ◽  
pp. 423-444 ◽  
Author(s):  
Bastian Rühle ◽  
Melari Davies ◽  
Thomas Bein ◽  
Christoph Bräuchle

In this article, we discuss how fluorescence microscopy techniques are used to investigate important characteristics of porous silica materials. We start with a discussion of the synthesis, formation mechanism and functionalization of these materials. We then give an introduction to single molecule microscopy and show how this technique can be used to gain deeper insights into some defining properties of porous silica, such as pore structure, host-guest interactions and diffusion dynamics. We also provide examples from the literature demonstrating how fluorescence microscopy is used for elucidating important aspects of porous silica materials and heterogeneous catalysis, e. g. diffusion properties, reactivity, morphology, intergrowth, accessibility, and catalyst deactivation. Finally, a short outlook on the scope of porous silica hosts in drug delivery applications is given

ChemInform ◽  
2013 ◽  
Vol 44 (35) ◽  
pp. no-no
Author(s):  
Bastian Ruehle ◽  
Melari Davies ◽  
Thomas Bein ◽  
Christoph Braeuchle

2016 ◽  
Vol 09 (03) ◽  
pp. 1630008 ◽  
Author(s):  
Luchang Li ◽  
Mengting Li ◽  
Zhaoning Zhang ◽  
Zhen-Li Huang

Low-light camera is an indispensable component in various fluorescence microscopy techniques. However, choosing an appropriate low-light camera for a specific technique (for example, single molecule imaging) is always time-consuming and sometimes confusing, especially after the commercialization of a new type of camera called sCMOS camera, which is now receiving heavy demands and high praise from both academic and industrial users. In this tutorial, we try to provide a guide on how to fully access the performance of low-light cameras using a well-developed method called photon transfer curve (PTC). We first present a brief explanation on the key parameters for characterizing low-light cameras, then explain the experimental procedures on how to measure PTC. We also show the application of the PTC method in experimentally quantifying the performance of two representative low-light cameras. Finally, we extend the PTC method to provide offset map, read noise map, and gain map of individual pixels inside a camera.


2017 ◽  
Author(s):  
Anders S Hansen ◽  
Maxime Woringer ◽  
Jonathan B Grimm ◽  
Luke D Lavis ◽  
Robert Tjian ◽  
...  

ABSTRACTSingle-particle tracking (SPT) has become an important method to bridge biochemistry and cell biology since it allows direct observation of protein binding and diffusion dynamics in live cells. However, accurately inferring information from SPT studies is challenging due to biases in both data analysis and experimental design. To address analysis bias, we introduce “Spot-On”, an intuitive web-interface. Spot-On implements a kinetic modeling framework that accounts for known biases, including molecules moving out-of-focus, and robustly infers diffusion constants and subpopulations from pooled single-molecule trajectories. To minimize inherent experimental biases, we implement and validate stroboscopic photo-activation SPT (spaSPT), which minimizes motion-blur bias and tracking errors. We validate Spot-On using experimentally realistic simulations and show that Spot-On outperforms other methods. We then apply Spot-On to spaSPT data from live mammalian cells spanning a wide range of nuclear dynamics and demonstrate that Spot-On consistently and robustly infers subpopulation fractions and diffusion constants.IMPACT STATEMENTSpot-On is an easy-to-use website that makes a rigorous and bias-corrected modeling framework for analysis of single-molecule tracking experiments available to all.


Nano Letters ◽  
2009 ◽  
Vol 9 (8) ◽  
pp. 2877-2883 ◽  
Author(s):  
Timo Lebold ◽  
Christophe Jung ◽  
Jens Michaelis ◽  
Christoph Bräuchle

2019 ◽  
Vol 116 (43) ◽  
pp. 21563-21572 ◽  
Author(s):  
Laura Marchetti ◽  
Fulvio Bonsignore ◽  
Francesco Gobbo ◽  
Rosy Amodeo ◽  
Mariantonietta Calvello ◽  
...  

The p75 neurotrophin (NT) receptor (p75NTR) plays a crucial role in balancing survival-versus-death decisions in the nervous system. Yet, despite 2 decades of structural and biochemical studies, a comprehensive, accepted model for p75NTR activation by NT ligands is still missing. Here, we present a single-molecule study of membrane p75NTR in living cells, demonstrating that the vast majority of receptors are monomers before and after NT activation. Interestingly, the stoichiometry and diffusion properties of the wild-type (wt) p75NTR are almost identical to those of a receptor mutant lacking residues previously believed to induce oligomerization. The wt p75NTR and mutated (mut) p75NTR differ in their partitioning in cholesterol-rich membrane regions upon nerve growth factor (NGF) stimulation: We argue that this is the origin of the ability of wt p75NTR , but not of mut p75NTR, to mediate immature NT (proNT)-induced apoptosis. Both p75NTR forms support proNT-induced growth cone retraction: We show that receptor surface accumulation is the driving force for cone collapse. Overall, our data unveil the multifaceted activity of the p75NTR monomer and let us provide a coherent interpretative frame of existing conflicting data in the literature.


2020 ◽  
Vol 42 (4) ◽  
pp. 52-56
Author(s):  
Ilijana Vojnovic ◽  
Ulrike Endesfelder

The development of super-resolution microscopy techniques, which are able to achieve resolutions in the nanometre range and as such allow the visualization of subcellular structures and dynamics, has considerably expanded the possibilities of fluorescence microscopy in the life sciences. While a majority of these techniques require highly specialized hardware, single-molecule localization microscopy (SMLM) can be implemented on conventional widefield fluorescence microscopes. Here, we describe what technical upgrades are necessary and discuss some of the difficulties that can be encountered during sample preparation and imaging.


eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Sukrit Suksombat ◽  
Rustem Khafizov ◽  
Alexander G Kozlov ◽  
Timothy M Lohman ◽  
Yann R Chemla

Escherichia coli single-stranded (ss)DNA binding (SSB) protein mediates genome maintenance processes by regulating access to ssDNA. This homotetrameric protein wraps ssDNA in multiple distinct binding modes that may be used selectively in different DNA processes, and whose detailed wrapping topologies remain speculative. Here, we used single-molecule force and fluorescence spectroscopy to investigate E. coli SSB binding to ssDNA. Stretching a single ssDNA-SSB complex reveals discrete states that correlate with known binding modes, the likely ssDNA conformations and diffusion dynamics in each, and the kinetic pathways by which the protein wraps ssDNA and is dissociated. The data allow us to construct an energy landscape for the ssDNA-SSB complex, revealing that unwrapping energy costs increase the more ssDNA is unraveled. Our findings provide insights into the mechanism by which proteins gain access to ssDNA bound by SSB, as demonstrated by experiments in which SSB is displaced by the E. coli recombinase RecA.


Chaotic systems behavior attracts many researchers in the field of image encryption. The major advantage of using chaos as the basis for developing a crypto-system is due to its sensitivity to initial conditions and parameter tunning as well as the random-like behavior which resembles the main ingredients of a good cipher namely the confusion and diffusion properties. In this article, we present a new scheme based on the synchronization of dual chaotic systems namely Lorenz and Chen chaotic systems and prove that those chaotic maps can be completely synchronized with other under suitable conditions and specific parameters that make a new addition to the chaotic based encryption systems. This addition provides a master-slave configuration that is utilized to construct the proposed dual synchronized chaos-based cipher scheme. The common security analyses are performed to validate the effectiveness of the proposed scheme. Based on all experiments and analyses, we can conclude that this scheme is secure, efficient, robust, reliable, and can be directly applied successfully for many practical security applications in insecure network channels such as the Internet


2013 ◽  
Vol 10 (4) ◽  
pp. 654-657 ◽  
Author(s):  
Simonpietro Agnello ◽  
Marco Cannas ◽  
Giuseppe Iovino ◽  
Lavinia Vaccaro ◽  
Franco Mario Gelardi

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