Author(s): Chen, Fanqing; Gerion, Daniele | Abstract: One of the biggest challenges in cell biology is the imaging of living cells. For this purpose, the most commonly used visualization tool is fluorescent markers. However, conventional labels, such as organic fluorescent dyes or green fluorescent proteins (GFP), lack the photostability to allow the tracking of cellular events that happen over minutes to days. In addition, they are either toxic to cells (dyes), or difficult to construct and manipulate (GFP). We report here the use of a new class of fluorescent labels, silanized CdSe/ZnS nanocrystal-peptide conjugates, for imaging the nuclei of living cells. CdSe/ZnS nanocrystals, or so called quantum dots (qdots), are extremely photostable, and have been used extensively in cellular imaging of fixed cells. However, most of the studies about living cells so far have been concerned only with particle entry into the cytoplasm or the localization of receptors on the cell membrane. Specific targeting of qdots to the nucleus of living cells has not been reported in previous studies, due to the lack of a targeting mechanism and proper particle size. Here we demonstrate for the first time the construction of a CdSe/ZnS nanocrystal-peptide conjugate that carries the SV40 large T antigen nuclear localization signal (NLS), and the transfection of the complex into living cells. By a novel adaptation of commonly used cell transfection techniques for qdots, we were able to introduce and retain the NLS-qdots conjugate in living cells for up to a week without detectable negative cellular effects. Moreover, we can visualize the movement of the CdSe/ZnS nanocrystal-peptide conjugates from cytoplasm to the nucleus, and the accumulation of the complex in the cell nucleus, over a long observation time period. This report opens the door for using qdots to visualize long-term biological events that happen in the cell nucleus, and provides a new nontoxic, long-term imaging platform for cell nuclear processes.

/pdf/fluorescent-cdse-zns-nanocrystal-peptide-conjugates-for-long-i96546wo0h.pdf

Fluorescent CdSe/ZnS nanocrystal-peptide conjugates for long-term, nontoxic imaging and

http://people.bu.edu/parkhs/Papers/eomPR2011.pdf

Nanomechanical resonators and their applications in biological/chemical detection: Nanomechanics principles

With the increasing requirements for microelectromechanical systems (MEMS) regarding stability, miniaturization and integration, novel materials such as wide band gap semiconductors are attracting more attention. Polycrystalline SiC has first been implemented into Si micromachining techniques, mainly as etch stop and protective layers. However, the outstanding properties of wide band gap semiconductors offer many more possibilities for the implementation of new functionalities. Now, a variety of technologies for SiC and group III nitrides exist to fabricate fully wide band gap semiconductor based MEMS. In this paper we first review the basic technology (deposition and etching) for group III nitrides and SiC with a special focus on the fabrication of three-dimensional microstructures relevant for MEMS. The basic operation principle for MEMS with wide band gap semiconductors is described. Finally, the first applications of SiC based MEMS are demonstrated, and innovative MEMS and NEMS devices are reviewed.

http://iopscience.iop.org/article/10.1088/0022-3727/40/20/S19/pdf

Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications

2.4. Temperature Effects 527 2.4.1. Effect on Material Properties 528 2.4.2. Effect on Geometry 528 3. Detection Schemes 528 3.1. Optical Lever 528 3.2. Interferometer 529 3.3. Piezoresistive 529 3.4. Capacitive 529 4. Design, Materials, and Fabrication 529 4.1. Design Considerations 530 4.2. Fabrication of Silicon-based Cantilevers 530 4.2.1. Film Deposition 530 4.2.2. Photolithography 530 4.2.3. Etching 530 4.2.4. Doping 530 4.3. Fabrication of Polymeric Cantilevers 531 5. Chemical Selectivity 531 6. Chemical Applications 533 6.1. Volatile Organics 533 6.2. Chemical Warfare Agents 534 6.3. Explosives 534 6.4. Toxic Metal Ions 534 7. Biological Applications 534 7.1. Cells 534 7.2. Viruses 534 7.3. Antigen−Antibody Interactions 535 7.4. DNA Hybridization 536 7.5. Enzymes 537 8. Recommendations for Future Work 538 8.1. Guidelines for Reporting Sensor Performance 538 8.2. Experimental Design Considerations 538 8.3. Fruitful Areas for Further Research 539 8.3.1. More Selective Coatings 539 8.3.2. Increased Sensitivity and Faster Response 539

Microcantilevers: Sensing Chemical Interactions via Mechanical Motion

Surface engineering of inorganic nanoparticles for imaging and therapy

Label free novel electrical detection using micromachined PZT monolithic thin film cantilever for the detection of C-reactive protein.

Purpose
Researchers have been studying the mechanisms by which metastasis can be prevented via blocking the hematogenous and the lymphatic routes for a long time now. However, metastasis is still the single most challenging obstacle for successful cancer management. In a new twist that may require some retooling of this established approach, we investigated the hypothesis that tumor metastases can occur via an independent fluid-conducting system called the primo-vascular system.

Evidence for an additional metastatic route: In vivo imaging of cancer cells in the primo-vascular system around tumors and organs

Bonghan ducts as possible pathways for cancer metastasis.

The effect of broadening the bandwidth with a dielectric load in a cylindrical gyrotron is investigated for a hollow electron beam. The linear dispersion relation for the azimuthally symmetric, transverse electric (TE) modes is obtained by the method of the wave impedance matching. It is found that the TE perturbations exhibit three unstable modes characterized by their phase velocities vph : one fast wave, the long wavelength mode (LWM, vph ≳c), and two slow waves, the intermediate (IWM, c≳vph ≳ce−1/2) and the short (SWM, vph <ce−1/2) wavelength modes. The optimum conditions for the wide band operation are obtained individually for each mode. Although the bandwidth in excess of 40% is possible for the slow waves (IWM, SWM) at a small axial momentum spread, it decreases rapidly as the spread increases. On the other hand, the LWM yields approximately 10% of the bandwidth insensitive to the spread. It is also shown that for a small spread (<5%), the slow wave (IWM) is preferable for the wide band operation,...

Analysis of the wide band gyrotron amplifier in a dielectric loaded waveguide

Solitary internal wave packets were observed in May 1999, propagating toward the east coast of Korea with thermocline displacements up to twentysix meters downward from the initial depth of twenty meters. High nonlinearity of these waves is represented by the second-order KdV model better than KdV equations. Regular occurrence of solitary internal wave packets with the period of about nineteen hours suggests the generation by near-inertial internal waves, which has not been reported in the literature yet.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2001GL013130

Saeyoung Ahn

Papers

Label free novel electrical detection using micromachined PZT monolithic thin film cantilever for the detection of C-reactive protein.

Evidence for an additional metastatic route: In vivo imaging of cancer cells in the primo-vascular system around tumors and organs

Bonghan ducts as possible pathways for cancer metastasis.

Analysis of the wide band gyrotron amplifier in a dielectric loaded waveguide

Observations of highly nonlinear internal solitons generated by near-inertial internal waves off the east coast of Korea