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27 Aug 2012

Volume 101, Issue 9, Articles (09xxxx)

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Appl. Phys. Lett. 101, 091102 (2012); http://dx.doi.org/10.1063/1.4747168 (3 pages)

Hagay Shpaisman, Bhaskar Jyoti Krishnatreya, and David G. Grier
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Non-destructive imaging of an individual protein

J.-N. Longchamp, T. Latychevskaia, C. Escher, and H.-W. Fink

Appl. Phys. Lett. 101, 093701 (2012); http://dx.doi.org/10.1063/1.4748113 (4 pages) | Cited 1 time

Online Publication Date: 27 August 2012

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Imaging a single biomolecule at atomic resolution without averaging over different conformations is the ultimate goal in structural biology. We report recordings of a protein at nanometer resolution obtained from one individual ferritin by means of low-energy electron holography. One single protein could be imaged for an extended period of time without any sign of radiation damage. Since the fragile protein shell encloses a robust iron cluster, the holographic reconstructions could also be cross-validated against transmission electron microscopy images of the very same molecule by imaging its iron core.
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87.80.-y Biophysical techniques (research methods)
87.64.Ee Electron microscopy
42.40.My Applications
36.20.Ey Conformation (statistics and dynamics)
36.20.Hb Configuration (bonds, dimensions)
87.15.B- Structure of biomolecules
87.15.hp Conformational changes
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Plasma-assisted atomic layer deposition of Al2O3 and parylene C bi-layer encapsulation for chronic implantable electronics

Xianzong Xie, Loren Rieth, Srinivas Merugu, Prashant Tathireddy, and Florian Solzbacher

Appl. Phys. Lett. 101, 093702 (2012); http://dx.doi.org/10.1063/1.4748322 (5 pages) | Cited 1 time

Online Publication Date: 27 August 2012

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Encapsulation of biomedical implants with complex three dimensional geometries is one of the greatest challenges achieving long-term functionality and stability. This report presents an encapsulation scheme that combines Al2O3 by atomic layer deposition with parylene C for implantable electronic systems. The Al2O3-parylene C bi-layer was used to encapsulate interdigitated electrodes, which were tested invitro by soak testing in phosphate buffered saline solution at body temperature (37 °C) and elevated temperatures (57 °C and 67 °C) for accelerated lifetime testing up to 5 months. Leakage current and electrochemical impedance spectroscopy were measured for evaluating the integrity and insulation performance of the coating. Leakage current was stably about 15 pA at 5 V dc, and impedance was constantly about 3.5 MΩ at 1 kHz by using electrochemical impedance spectroscopy for samples under 67 °C about 5 months (approximately equivalent to 40 months at 37 °C). Alumina and parylene coating lasted at least 3 times longer than parylene coated samples tested at 80 °C. The excellent insulation performance of the encapsulation shows its potential usefulness for chronic implants.
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87.85.F- Smart prosthetics
87.85.J- Biomaterials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Electrical characterization of deoxyribonucleic acid hybridization in metal-oxide-semiconductor-like structures

S. Libertino, G. Cannella, V. Aiello, A. Busacca, and S. Lombardo

Appl. Phys. Lett. 101, 093703 (2012); http://dx.doi.org/10.1063/1.4747452 (4 pages) | Cited 1 time

Online Publication Date: 27 August 2012

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In this work, metal-oxide-semiconductor (MOS)-like sensors in which deoxyribonucleic acid (DNA) strands are covalently immobilized either on Si oxide or on a gold surface were electrically characterized. Si oxide fabrication process allowed us to have a surface insensitive to the solution pH. A significant shift in the flat band voltage was measured after single strand DNA immobilization (+0.47 ± 0.04 V) and after the complementary strand binding (+0.07 ± 0.02 V). The results show that DNA sensing can be performed using a MOS structure which can be easily integrated in a more complex design, thus avoiding the problems related to the integration of micro-electrochemical cells.
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87.85.fk Biosensors
87.14.gk DNA
FREE

Noise spectroscopy as an equilibrium analysis tool for highly sensitive electrical biosensing

Qiushi Guo, Tao Kong, Ruigong Su, Qi Zhang, and Guosheng Cheng

Appl. Phys. Lett. 101, 093704 (2012); http://dx.doi.org/10.1063/1.4748931 (5 pages)

Online Publication Date: 28 August 2012

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We demonstrate an approach for highly sensitive bio-detection based on silicon nanowire field-effect transistors by employing low frequency noise spectroscopy analysis. The inverse of noise amplitude of the device exhibits an enhanced gate coupling effect in strong inversion regime when measured in buffer solution than that in air. The approach was further validated by the detection of cardiac troponin I of 0.23 ng/ml in fetal bovine serum, in which 2 orders of change in noise amplitude was characterized. The selectivity of the proposed approach was also assessed by the addition of 10 μg/ml bovine serum albumin solution.
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87.80.Dj Spectroscopies
85.30.Tv Field effect devices
87.14.E- Proteins

Mid-infrared (λ = 8.4–9.9 μm) light scattering from porcine tissue

Sabbir Liakat, Anna P. M. Michel, Kevin A. Bors, and Claire F. Gmachl

Appl. Phys. Lett. 101, 093705 (2012); http://dx.doi.org/10.1063/1.4748331 (4 pages) | Cited 1 time

Online Publication Date: 28 August 2012

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Back-scattering of mid-infrared light from porcine skin is studied versus wavelength and angle for a Quantum Cascade laser and a broadband infrared light source. Scattering is detected over 30° away from the specular angle for both sources, and modulation patterns with angle are seen when using the laser. A nonlinear increase in scattered light intensity versus input power indicates that directional scattering from within the skin is dominant. Collagen fibers in the dermis layer, over 200 μm deep into the skin, are conducive to such scattering. We conclude that mid-infrared light penetrates deep enough for potential glucose detection in dermal interstitial fluid.
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87.63.lt Laser imaging
87.64.Cc Scattering of visible, uv, and infrared radiation
42.72.Ai Infrared sources

Efficacy of an AC sinusoidal electric field for apoptosis induction in lung carcinoma cells (A549)

Hyoun-Hyang Park, Seung S. Lee, and Dae Hoon Lee

Appl. Phys. Lett. 101, 093706 (2012); http://dx.doi.org/10.1063/1.4748871 (4 pages)

Online Publication Date: 28 August 2012

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An AC sinusoidal electric field was applied to lung carcinoma cells for the induction of apoptosis. The occurrence of apoptosis was determined by analysis of Annexin V/PI and DNA fragmentation. Additional evidence of apoptosis was confirmed by caspase-3 cleavage and disruption of mitochondrial membrane potential. These results demonstrated that the expression of apoptosis can be controlled by varying the magnitude and the duration of the field, and that the application of an AC electric field can stimulate the apoptosis via mitochondria-mediated pathway.
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87.50.cf Biophysical mechanisms of interaction
87.19.xj Cancer
87.14.gk DNA
87.16.Tb Mitochondria and other organelles
87.16.D- Membranes, bilayers, and vesicles
87.14.ej Enzymes

Microheater platform for selective detachment of DNA

Annas Javed, Samir M. Iqbal, and Ankur Jain

Appl. Phys. Lett. 101, 093707 (2012); http://dx.doi.org/10.1063/1.4748308 (5 pages)

Online Publication Date: 30 August 2012

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Despite deoxyribonucleic acid (DNA)’s well-known temperature sensitivity, not much work has been reported on leveraging temperature to manipulate the interaction of DNA with surfaces. This paper describes a microheater device that enables the application of a temperature field on a glass surface, thereby enabling the study of temperature-dependence of DNA-surface interactions. Experimental data for thermal performance of the device agree well with finite-element simulation results. Experiments demonstrate the capability of spatially selective detachment of DNA from a glass surface using the device. The integration of thermal-based capabilities described here with analysis tools such as polymerase chain reaction may help improve DNA detection and separation capabilities.
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87.80.Qk Biochemical separation processes
87.14.gk DNA
87.10.Kn Finite element calculations

A shear lag analysis predicts the strong size effect on the persistence length of microtubules

Bin Chen

Appl. Phys. Lett. 101, 093708 (2012); http://dx.doi.org/10.1063/1.4748908 (4 pages)

Online Publication Date: 31 August 2012

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As one essential component in cytoskeleton, the persistence length of a microtubule was reported to strongly depend on its contour length. To understand this intriguing size effect, here we develop a composite model for a microtubule with an adapted shear lag analysis. A characteristic length is identified, over which the persistence length of a microtubule monotonously increases with its contour length until it saturates, in consistency with the experimental data. This work clearly shows that shear lag between neighboring protofilaments due to the highly anisotropy leads to the strong size effect on the persistence lengths of microtubules.
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87.17.Rt Cell adhesion and cell mechanics
87.16.Ka Filaments, microtubules, their networks, and supramolecular assemblies
87.14.em Fibrils (amyloids, collagen, etc.)
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