Biomedical subjects

Charles H Patterson

Publications and source records attributed to Charles H Patterson.

9 recordsLinked to original sources

PubMed2006

Detection of organics using porphyrin embedded nanoporous organosilicas.

Molecularly imprinted polymers and silica have been studied as receptor binding site mimics for use in a wide range of separation, catalysis, and detection applications employing transduction mechanisms including conductometric, amperometric, and capacitance. Porphyrins are also well known as sensor components due to the extreme sensitivity of their spectrophotometric characteristics to changes in their immediate environment. We have developed periodic mesoporous organosilicas (PMO) which incorporate a porphyrin into the material for use as an optical indicator of target binding. This material combines the stability, selectivity, and high density of binding sites characteristic of the molecularly imprinted PMO with the sensitivity and selectivity of the porphyrin. We demonstrate binding of p-nitrophenol, p-cresol, 2,4,6-trinitrotoluene, and RDX by the porphyrin-embedded PMOs with selective adsorption of TNT over the other analytes. In addition, the binding of each of the organics by the PMO results in unique changes in the spectrophotometric characteristics of the incorporated porphyrin. These changes can be observed by visual inspection or through the use of fluorescence spectra collected in 96-well format.

Nanostructures↗

PubMed2005

Immobilization and hybridization of DNA in a sugar polyacrylate hydrogel.

Using a non-contact microarrayer, amine-terminated probe oligonucleotides representing 20-, 50-, and 70-mer fragments of the fliC gene were covalently coupled into three-dimensional regions in a "sugar polyacrylate" hydrogel based on poly(6-acryloyl-beta-O-methyl galactopyranoside-co-aminopropyl methacrylamide). The arrayer deposited the solution containing ssDNA probes in discrete regions on the surface of the gel (i.e. as a droplet with a ca. 450 microm diameter), allowing penetration and attachment of the ss DNA within the three dimensional region of the gel. The attachment was mediated by the homobifunctional crosslinker bis-succinimidyl suberate. Confocal microscopy showed the density of attached probe DNA was greatest in the interior-most regions of the gel volume. Target ssDNA (20- and 70-mer) was able to diffuse through the gel and undergo successful hybridization with the probes. For target ssDNA in the concentration range 0.19 microM to 6.0 microM, there was a linear correlation between DNA concentration and the fluorescence of the gel region where hybridization occurred.

Acrylic Resins↗

PubMed2005

Molecularly inherent voltage-controlled conductance switching.

Molecular electronics has been proposed as a pathway for high-density nanoelectronic devices. This pathway involves the development of a molecular memory device based on reversible switching of a molecule between two conducting states in response to a trigger, such as an applied voltage. Here we demonstrate that voltage-triggered switching is indeed a molecular phenomenon by carrying out studies on the same molecule using three different experimental configurations-scanning tunnelling microscopy, crossed-wire junction, and magnetic-bead junction. We also demonstrate that voltage-triggered switching is distinctly different from stochastic switching, essentially a transient (time-dependent) phenomenon that is independent of the applied voltage.

Journal Article↗

PubMed2004

Detection of proteins cross-linked within galactoside polyacrylate-based hydrogels by means of a quantum dot fluororeagent.

Protein toxins have been immobilized in a galactoside polyacrylate hydrogel in a microarray format. The large pore size and solution-like environment of these novel hydrogels allow for easy penetration of large proteins and detection reagents. Confocal microscopy provided three-dimensional visualization of dye-labeled toxins cross-linked within the gel and of streptavidin-coated quantum dot (QD) fluorophores used to visualize the toxins after incubation with biotinylated anti-toxin antibodies. Fluorescence microscopy was utilized to visualize arrays of toxins detected by a biotinylated antibody and then exposure to streptavidin-conjugated QDs. The intensity of the QD fluorescence was quantified, and binding to two toxins on three types of hydrogels was examined.

Acrylic Resins↗

PubMed2004

Characterization and performance evaluation of in vivo and in vitro produced monoclonal anti-TNT antibodies for the detection of TNT.

In this paper are the experimental results used to characterize four distinct monoclonal anti-TNT antibodies (in vivo and in vitro cloned) for potential use in a field-portable immunosensor. Direct and competitive enzyme-linked immunosorbent assays (ELISA) were performed to determine their affinity for TNT and a fluorescently labeled analog of TNT for use in an immunosensor. Effective concentrations (EC(50)), inhibition concentration (IC(50)) and cross-reactivity measurements to related nitroaromatics (e.g., 2,4,6-trinitrobenzene [TNB], methyl-2,4,6-trinitrophenyl nitramine [tetryl], 2-amino-4,6-dinitrotoluene [2A-4,6-DNT], 2,4-dinitrotoluene [2,4-DNT] and 1,3-dinitrotoluene [1,3-DNT]) were measured. Final characterization of the monoclonal antibodies was based on performance (measured by fluorescence dose response) using a fluorescence-based microcapillary displacement assay. Analytical techniques showed a high degree of affinity for TNT and varying degrees of cross-reactivity with each respective monoclonal antibody. Microcapillary displacement immunoassays with each of the antibodies resulted in detection capabilities at the lowest applied TNT concentration (10 ng/ml).

Animals↗

PubMed2003

Detection of 2,4,6-trinitrotoluene in environmental samples using a homogeneous fluoroimmunoassay.

We have tested both soil and water environmental samples for 2,4,6-trinitrotoluene (TNT) using a simple homogeneous assay. This assay is based on changes in fluorescence emission intensity when a fluorescently labeled TNT analogue, bound to an anti-TNT antibody, is competitively displaced by TNT. Fluoroimmunoassay results for TNT concentrations in diluted acetone extracts prepared from archived soils were in good agreement with the results from high-performance liquid chromatography analysis of the same sample extracts. In addition, assays of TNT-spiked environmental well water gave results essentially identical with assays conducted in a TNT-spiked laboratory buffer. The homogeneous fluoroimmunoassay, which is rapid, simple, sensitive, and amenable to high throughput screening, shows promise for near real-time evaluation of TNT contamination in environmental samples.

Chromatography, High Pressure Liquid↗

PubMed2003

Ligand effects on charge transport in platinum(II) acetylides.

To investigate the electrical characteristics of organometallic complexes as molecular conductors, organometallic pi-conjugated molecules of the type trans-[PtL2(CCC6H4SAc-4)2], where L = PCy3, PBu3, PPh3, P(OEt)3, P(OPh)3, were synthesized and characterized by NMR, IR, UV, and X-ray spectroscopies. For the three complexes (L = PCy3, PPh3, and P(OEt)3) that could be measured using a cross-wire junction technique, the current-voltage (I-V) characteristics of a molecular monolayer of these complexes showed no ligand effect, despite spectroscopic evidence that electronic interaction between the phosphine ligands and the pi-system does occur. It was concluded that the tunneling efficiency across the molecule is the determining factor for conduction in this metal-molecule-metal system. It was also shown that the incorporation of a transition metal in pi-conjugated molecular wires does not adversely affect charge transport compared to all-carbon pi-conjugated molecular wires.

Journal Article↗

PubMed2003

Analysis of aqueous 2,4,6-trinitrotoluene (TNT) using a fluorescent displacement immunoassay.

We report a rapid, simple, and sensitive assay that is potentially amenable to high throughput screening for analysis of 2,4,6-trinitrotoluene (TNT) present in aqueous solutions. The assay is based on the change in fluorescence emission intensity of a fluorescently labeled TNT analogue pre-bound to an anti-TNT antibody that occurs upon its competitive displacement by TNT. The assay can be performed in both cuvette- and 96-well plate-based formats. TNT at a level of 0.5 micro g L(-1) (0.5 ppb) was detected in phosphate buffered saline; detection improved to 0.05 micro g L(-1) (0.05 ppb) for TNT dissolved in artificial seawater.

Antibodies↗

PubMed2002

Demonstration of four immunoassay formats using the array biosensor.

The ability of a fluorescence-based array biosensor to measure and quantify the binding of an antigen to an immobilized antibody has been demonstrated using the four different immunoassay formats: direct, competitive, displacement, and sandwich. A patterned array of antibodies specific for 2,4,6-trinitrotoluene (TNT) immobilized onto the surface of a planar waveguide and used to measure signals from different antigen concentrations simultaneously. For direct, competitive, and displacement assays, which are one-step assays, measurements were obtained in real time. Dose-response curves were calculated for all four assay formats, demonstrating the array biosensor's ability to quantify the amount of antigen present in solution.

Antibodies↗