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Subcellular Localization of Thiol-Capped CdTe Quantum Dots in Living Cells  [cached]
Zhang Yu,Mi Lan,Xiong Rongling,Wang Pei-Nan
Nanoscale Research Letters , 2009,
Abstract: Internalization and dynamic subcellular distribution of thiol-capped CdTe quantum dots (QDs) in living cells were studied by means of laser scanning confocal microscopy. These unfunctionalized QDs were well internalized into human hepatocellular carcinoma and rat basophilic leukemia cells in vitro. Co-localizations of QDs with lysosomes and Golgi complexes were observed, indicating that in addition to the well-known endosome-lysosome endocytosis pathway, the Golgi complex is also a main destination of the endocytosed QDs. The movement of the endocytosed QDs toward the Golgi complex in the perinuclear region of the cell was demonstrated.
Fabrication of Silicon Carbide Quantum Dots via Chemical-Etching Approach and Fluorescent Imaging for Living Cells  [PDF]
Yuepeng Song, Dongsheng Gao, Hyoung Seop Kim, Cuiqin Qu, Jie Kang, Yanmin Zhu, Ziping Liu, Jing Guo, Lingfeng Xu, Chong Soo Lee
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.54022
Abstract:

A simple chemical-etching approach is used to prepare the silicon carbide quantum dots (QDs). The raw materials of silicon carbide (SiC) with homogeneous nanoparticles fabricated via self-propagating combustion synthesis are corroded in mixture etchants of nitric and hydrofluoric acid. After sonication and chromatography in the ultra-gravity field for the etched products, aqueous solution with QDs can be obtained. The microstructure evolution of raw particles and optical properties of QDs were measured. Different organophilic groups on the surface like carboxyl, oxygroup, and hyfroxy were produced in the process of etching. Fluorescent labeling and imaging for living cells of Aureobasidium pulluans were investigated. The results indicated that SiC QDs were not cytotoxic and could stably label due to the conjugation between organophilic groups of QDs and specific protein of cells, it can be utilized for fluorescent imaging and tracking cells with in vivo and long-term-distance. Moreover, mechanism and specificity of mark were also analyzed.

Single-Molecule Tracking in Living Cells Using Single Quantum Dot Applications  [cached]
Koichi Baba, Kohji Nishida
Theranostics , 2012,
Abstract: Revealing the behavior of single molecules in living cells is very useful for understanding cellular events. Quantum dot probes are particularly promising tools for revealing how biological events occur at the single molecule level both in vitro and in vivo. In this review, we will introduce how single quantum dot applications are used for single molecule tracking. We will discuss how single quantum dot tracking has been used in several examples of complex biological processes, including membrane dynamics, neuronal function, selective transport mechanisms of the nuclear pore complex, and in vivo real-time observation. We also briefly discuss the prospects for single molecule tracking using advanced probes.
Exploring Transduction Mechanisms of Protein Transduction Domains (PTDs) in Living Cells Utilizing Single-Quantum Dot Tracking (SQT) Technology  [PDF]
Yasuhiro Suzuki
Sensors , 2012, DOI: 10.3390/s120100549
Abstract: Specific protein domains known as protein transduction domains (PTDs) can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs), we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP) in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT), to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency.
Molecular fluctuation in living cells
Xiaowei Tang
Science China Life Sciences , 1997, DOI: 10.1007/BF02879104
Abstract: The concept of molecular fluctuation in living cells is introduced. Many apparently different experimental facts in living cells, including the velocity non-uniformity of organelle movement, the saltatory movement of transport vesicles in axoplasmic transport, the chromosome oscillation during metaphase in mitosis and the pauses in the chromosome movement during anaphase are explained using a unified viewpoint. A method of determination of average number of the attached motor protein molecules from the experimental data is also proposed.
Molecular fluctuation in living cells
TANG Xiaowei,
唐孝威

中国科学C辑(英文版) , 1997,
Abstract: The concept of molecular fluctuation in living cells is introduced. Many apparently different experi-mental facts in living cells, including the velocity non-uniformity of organelle movement, the saltatory movement of transport vesicles in axoplasmic transport, the chromosome oscillation during metaphase in mitosis and the pauses in the chromosome movement during anaphase are explained using a unified viewpoint. A method of determination of average number of the attached motor protein molecules from the experimental data is also proposed.
Comparison of the photoluminescence properties of semiconductor quantum dots and non-blinking diamond nanoparticles. Observation of the diffusion of diamond nanoparticles in living cells  [PDF]
Orestis Faklaris,Damien Garrot,Fran?ois Treussart,Vandana Joshi,Patrick Curmi,Jean-Paul Boudou,Thierry Sauvage
Physics , 2009,
Abstract: Long-term observations of photoluminescence at the single-molecule level were until recently very diffcult, due to the photobleaching of organic ?uorophore molecules. Although inorganic semiconductor nanocrystals can overcome this diffculty showing very low photobleaching yield, they suffer from photoblinking. A new marker has been recently introduced, relying on diamond nanoparticles containing photoluminescent color centers. In this work we compare the photoluminescence of single quantum dots (QDs) to the one of nanodiamonds containing a single-color center. Contrary to other markers, photoluminescent nanodiamonds present a perfect photostability and no photoblinking. At saturation of their excitation, nanodiamonds photoluminescence intensity is only three times smaller than the one of QDs. Moreover, the bright and stable photoluminescence of nanodiamonds allows wide ?eld observations of single nanoparticles motion. We demonstrate the possibility of recording the tra jectory of such single particle in culture cells.
Formation of Toxic Oligomeric α-Synuclein Species in Living Cells  [PDF]
Tiago Fleming Outeiro, Preeti Putcha, Julie E. Tetzlaff, Robert Spoelgen, Mirjam Koker, Filipe Carvalho, Bradley T. Hyman, Pamela J. McLean
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0001867
Abstract: Background Misfolding, oligomerization, and fibrillization of α-synuclein are thought to be central events in the onset and progression of Parkinson's disease (PD) and related disorders. Although fibrillar α-synuclein is a major component of Lewy bodies (LBs), recent data implicate prefibrillar, oligomeric intermediates as the toxic species. However, to date, oligomeric species have not been identified in living cells. Methodology/Principal Findings Here we used bimolecular fluorescence complementation (BiFC) to directly visualize α-synuclein oligomerization in living cells, allowing us to study the initial events leading to α-synuclein oligomerization, the precursor to aggregate formation. This novel assay provides us with a tool with which to investigate how manipulations affecting α-synuclein aggregation affect the process over time. Stabilization of α-synuclein oligomers via BiFC results in increased cytotoxicity, which can be rescued by Hsp70 in a process that reduces the formation of α-synuclein oligomers. Introduction of PD-associated mutations in α-synuclein did not affect oligomer formation but the biochemical properties of the mutant α-synuclein oligomers differ from those of wild type α-synuclein. Conclusions/Significance This novel application of the BiFC assay to the study of the molecular basis of neurodegenerative disorders enabled the direct visualization of α-synuclein oligomeric species in living cells and its modulation by Hsp70, constituting a novel important tool in the search for therapeutics for synucleinopathies.
Brownian motion and temperament of living cells  [PDF]
R. Tsekov,M. C. Lensen
Quantitative Biology , 2009, DOI: 10.1088/0256-307X/30/7/070501
Abstract: The migration of living cells obeys usually the Einstein law of Brownian motion. While the latter is due to the thermal motion of surrounding matter, the cells locomotion is generally associated to their vitality. In the present paper the concept of cell temperament is introduced, being analogous to thermodynamic temperature and related to the cell entropy production. A heuristic expression for the diffusion coefficient of cell on structured surfaces is derived as well. The cell locomemory is also studied via the generalized Langevin equation.
mRNA analysis of single living cells
Toshiya Osada, Hironori Uehara, Hyonchol Kim, Atsushi Ikai
Journal of Nanobiotechnology , 2003, DOI: 10.1186/1477-3155-1-2
Abstract: The properties of individual cells depend on molecules that constitute them. The different combinations of protein expression result in structural and functional changes of individual cells. Although most of these events depend on differences in gene expression, no method is available to examine time dependent gene expression of individual living cells. There are other methods to analyze mRNA from single cells. For example, the cellular content may be aspirated into a fine capillary and mRNAs could be analyzed with PCR [1], differential display [2], or amplified antisense RNA procedure using T7 RNA polymerase [3]. These techniques did not allow examining time dependent gene expression of individual living cells because their mRNA harvesting procedures resulted in partial or complete disruption of the cells. The goal of our study is a time dependent measurement of gene expression of a single living cell, as defined by mRNA expression. The change of gene expression in a single living cell may determine its uniqueness, function, and biochemical activities. We refer to this field as single cell biology and believe it will provide exciting new opportunities to better understand new biochemical processes of cell biology.Recent progress in the field of nanotechnology has enabled us to perform direct manipulations of biological material containing proteins [4-6], DNA molecules [7,8], organelles and cells [9-13]. The AFM has been considered to be an important tool in the study of nanotechnology. Since its invention in 1986 by Binnig et al. [14], the AFM has been increasingly used in biological systems [15-21] because it can be operated in a liquid environment as well as under ambient conditions. The AFM has the ability not only to produce high-resolution images of biological samples, but also to manipulate the sample because the AFM tip makes direct contact with the sample surface with high positional accuracy. In this paper, we developed a method to examine mRNA expression
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