Development of a Reagent-Less Sensor for Inhibitors of Acetylocholinesterase

Department of Physic

Porphyrins as Colorimetric Indicators for Detection and Identification of Chemical and Biological Agents

The objective of this study was to design sensor surfaces for rapid, real-time, optical detection of chemical/biological warfare agents and/or environmental pollutants that yield a minimum of false readings. Porphyrins were used as colorimetric indicators for transduction in surfaces using biological recognition elements such as enzymes and as combination recognition element/transducer in other surfaces. Immobilization protocols and assaying procedures were developed for each of the sensor surfaces. As a reversible, competitive inhibitor of enzymes, porphyrins can be used for identification and quantification of the presence of a substrate or another competitive inhibitor of the enzyme. This technique has been useful for development of glass surfaces for the detection of cholinesterase inhibitors such as organophosphate compounds and nerve agent simulants at parts per trillion levels using acetylcholinesterase, butyrylcholinesterase, and organophosphorous hydrolase as recognition elements. Evanescent wave aDepartment of Physic

Reduction of Non-Specific Protein Adsorption Using Poly(ethylene) Glycol (PEG) Modified Polyacrylate Hydrogels In Immunoassays for Staphylococcal Enterotoxin B Detection

Three PEG molecules (PEG-methacrylate, -diacrylate and -dimethacrylate) were incorporated into galactose-based polyacrylate hydrogels and their relative abilities to reduce non-specific protein adsorption in immunoassays were determined. Highly crosslinked hydrogels containing amine-terminated functionalities were formed and used to covalently attach antibodies specific for staphylococcal enterotoxin B (SEB). Patterned arrays of immobilized antibodies in the PEG-modified hydrogels were created with a PDMS template containing micro-channels for use in sandwich immunoassays to detect SEB. Different concentrations of the toxin were applied to the hydrogel arrays, followed with a Cy3-labeled tracer antibody specific for the two toxins. Fluorescence laser scanning confocal microscopy of the tracer molecules provided both qualitative and quantitative measurements on the detection sensitivity and the reduction in non-specific binding as a result of PEG incorporation. Results showed the PEG-modified hydrogel significantly reduced non-specific protein binding with a detection limit for SEB of 1 ng/mL. Fluorescence signals showed a 10-fold decrease in the non-specific binding and a 6-fold increase in specific binding of SEB

Fluorescent Silicate Materials for the Detection of Paraoxon

Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the semi-selective adsorption of small molecule contaminants. These structures offer high surface areas and large pore volumes within an organized framework. The organic bridging groups in the materials can be altered to provide varied binding characteristics. This effort seeks to utilize the tunable binding selectivity, high surface area, and low materials density of these highly ordered pore networks and to combine them with the unique spectrophotometric properties of porphyrins. In the porphyrin-embedded materials (PEMs), the organosilicate scaffold stabilizes the porphyrin and facilitates optimal orientation of porphyrin and target. The materials can be stored under ambient conditions and offer exceptional shelf-life. Here, we report on the design of PEMs with specificity for organophosphates and compounds of similar structure

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Structure of a VHH isolated from a naïve phage display library

Abstract Objective To determine the X-ray structure and biophysical properties of a Camelid VHH isolated from a naïve phage display library. Results Single domain antibodies (VHH) derived from the unique immune system of the Camelidae family have gained traction as useful tools for biotechnology as well as a source of potentially novel therapeutics. Here we report the structure and biophysical characterization of a VHH originally isolated from a naïve camelid phage display library. VHH R419 has a melting temperate of 66 °C and was found to be a monomer in solution. The protein crystallized in space group P6522 and the structure was solved by molecular replacement to a resolution of 1.5 Å. The structure revealed a flat paratope with CDR loops that could be classified into existing canonical loop structures. A combination of high expression yield, stability and rapid crystallization might make R419 into a candidate scaffold for CDR grafting and homology modeling

Path to Success: Examining a Multifaceted Retention Model for Major Pathways Students at a Large, Diverse Research University

This study examines a retention model designed for the understudied, at-risk, Major Pathways students, at a large, diverse, research university. Major Pathways students were defined as undergraduates who initially selected their major during the admission process and while they were accepted to the institution, they were not admitted into their desired major/college primarily due to their math test scores. The retention model included a strategic new student orientation, marketing/outreach, proactive academic advising, and a specialized first-year seminar. The fall-to-spring retention rate increased from 84.5% to 88.5% to 89.6% to 89.7% and increased the fall-to-fall retention rate by 12.9 percentage point