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Results: 11 to 15 of 15

Publication Record


Photonic crystal slab sensor with enhanced surface area.
Kang C, Phare CT, Vlasov YA, Assefa S, Weiss SM
(2010) Opt Express 18: 27930-7
MeSH Terms: Equipment Design, Equipment Failure Analysis, Photons, Refractometry, Silanes, Transducers
Show Abstract · Added April 27, 2017
In this work, we demonstrate improved molecular detection sensitivity for silicon slab photonic crystal cavities by introducing multiple-hole defects (MHDs), which increase the surface area available for label-free detection without degrading the quality factor. Compared to photonic crystals with L3 defects, adding MHDs into photonic crystal cavities enabled a 44% increase in detection sensitivity towards small refractive index perturbations due to surface monolayer attachment of a small aminosilane molecule. Also, photonic crystals with MHDs exhibited 18% higher detection sensitivity for bulk refractive index changes.
0 Communities
1 Members
0 Resources
6 MeSH Terms
Direct imprinting of porous substrates: a rapid and low-cost approach for patterning porous nanomaterials.
Ryckman JD, Liscidini M, Sipe JE, Weiss SM
(2011) Nano Lett 11: 1857-62
MeSH Terms: Biocompatible Materials, Drug Delivery Systems, Microscopy, Electron, Scanning, Nanostructures, Nanotechnology, Photons, Polymers, Porosity, Silicon, Spectrum Analysis, Raman, Static Electricity, Surface Properties
Show Abstract · Added April 27, 2017
This work describes a technique for one-step, direct patterning of porous nanomaterials, including insulators, semiconductors, and metals without the need for intermediate polymer processing or dry etching steps. Our process, which we call "direct imprinting of porous substrates (DIPS)", utilizes reusable stamps with micro- and nanoscale features that are applied directly to a porous material to selectively compress or crush the porous network. The stamp pattern is transferred to the porous material with high fidelity, vertical resolution below 5 nm, and lateral resolution below 100 nm. The process is performed in less than one minute at room temperature and at standard atmospheric pressure. We have demonstrated structures ranging from subwavelength optical components to microparticles and present exciting avenues for applications including surface-enhanced Raman spectroscopy (SERS), label-free biosensors, and drug delivery.
0 Communities
1 Members
0 Resources
12 MeSH Terms
Diffusion of the second messengers in the cytoplasm acts as a variability suppressor of the single photon response in vertebrate phototransduction.
Bisegna P, Caruso G, Andreucci D, Shen L, Gurevich VV, Hamm HE, DiBenedetto E
(2008) Biophys J 94: 3363-83
MeSH Terms: Animals, Calcium Signaling, Calibration, Catalysis, Cyclic GMP, Cytoplasm, Diffusion, Humans, Kinetics, Models, Biological, Photons, Second Messenger Systems, Time Factors, Vision, Ocular
Show Abstract · Added December 10, 2013
The single photon response in vertebrate phototransduction is highly reproducible despite a number of random components of the activation cascade, including the random activation site, the random walk of an activated receptor, and its quenching in a random number of steps. Here we use a previously generated and tested spatiotemporal mathematical and computational model to identify possible mechanisms of variability reduction. The model permits one to separate the process into modules, and to analyze their impact separately. We show that the activation cascade is responsible for generation of variability, whereas diffusion of the second messengers is responsible for its suppression. Randomness of the activation site contributes at early times to the coefficient of variation of the photoresponse, whereas the Brownian path of a photoisomerized rhodopsin (Rh*) has a negligible effect. The major driver of variability is the turnoff mechanism of Rh*, which occurs essentially within the first 2-4 phosphorylated states of Rh*. Theoretically increasing the number of steps to quenching does not significantly decrease the corresponding coefficient of variation of the effector, in agreement with the biochemical limitations on the phosphorylated states of the receptor. Diffusion of the second messengers in the cytosol acts as a suppressor of the variability generated by the activation cascade. Calcium feedback has a negligible regulatory effect on the photocurrent variability. A comparative variability analysis has been conducted for the phototransduction in mouse and salamander, including a study of the effects of their anatomical differences such as incisures and photoreceptors geometry on variability generation and suppression.
0 Communities
1 Members
0 Resources
14 MeSH Terms
Structural changes in bacteriorhodopsin during ion transport at 2 angstrom resolution.
Luecke H, Schobert B, Richter HT, Cartailler JP, Lanyi JK
(1999) Science 286: 255-61
MeSH Terms: Bacteriorhodopsins, Binding Sites, Crystallography, X-Ray, Cytoplasm, Hydrogen Bonding, Hydrogen-Ion Concentration, Ion Transport, Isomerism, Light, Models, Molecular, Photolysis, Photons, Point Mutation, Protein Conformation, Protein Structure, Secondary, Proton Pumps, Protons, Retinaldehyde, Schiff Bases, Thermodynamics, Water
Show Abstract · Added May 7, 2010
Crystal structures of the Asp96 to Asn mutant of the light-driven proton pump bacteriorhodopsin and its M photointermediate produced by illumination at ambient temperature have been determined to 1.8 and 2.0 angstroms resolution, respectively. The trapped photoproduct corresponds to the late M state in the transport cycle-that is, after proton transfer to Asp85 and release of a proton to the extracellular membrane surface, but before reprotonation of the deprotonated retinal Schiff base. Its density map describes displacements of side chains near the retinal induced by its photoisomerization to 13-cis,15-anti and an extensive rearrangement of the three-dimensional network of hydrogen-bonded residues and bound water that accounts for the changed pKa values (where Ka is the acid constant) of the Schiff base and Asp85. The structural changes detected suggest the means for conserving energy at the active site and for ensuring the directionality of proton translocation.
1 Communities
1 Members
0 Resources
21 MeSH Terms
Quantitative imaging of metabolism by two-photon excitation microscopy.
Piston DW, Knobel SM
(1999) Methods Enzymol 307: 351-68
MeSH Terms: Animals, Cells, Cultured, Glucose, Hexokinase, Image Processing, Computer-Assisted, Islets of Langerhans, Lasers, Mice, Microscopy, Confocal, Microscopy, Fluorescence, Muscles, NAD, NADP, Pancreas, Photons
Added May 5, 2017
0 Communities
1 Members
0 Resources
15 MeSH Terms