Browsing by Subject "Ricin"
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Item Development of the "NoSlip": a simple yet sophisticated paper analytical device for detection of proteins(2016-05) Cunningham, Josephine Carol; Crooks, Richard M. (Richard McConnell); Ellington, Andy; Richards, Ian; Anslyn, Eric; Hoffman, DavidThe two most successful commercial sensors in self-diagnostics are the pregnancy test and the blood glucose meter. Our opinion is that too much time has gone by without successful commercialization of more consumer operated sensors, despite there being a significant market opportunity. For that reason, we put together a team in 2012 with the objective to develop a sophisticated sensor that could use telemedicine to revolutionize individual’s involvement in their health monitoring. We chose paper as the sensor substrate because of it’s inherently low-cost and ease of fabrication, and electrochemistry as the detection method because the necessary equipment can be miniaturized into an inexpensive handheld reader while achieving sensitive and quantitative detection. The scientific journey that we have traveled thus far while working towards our stated objective is reported here. We’ve developed three different paper-based electrochemical sensors, where each new sensor is an improved version of the former. The first is a paper-based electrochemical sensor that uses conformational switching of DNA probes or aptamers for detection of thrombin and DNA at 16 nM and 30 nM, respectively. The second paper analytical device uses a magnetic microbead supported metalloimmunoassay for electrochemical detection of a model analyte and a biological warfare agent (ricin) at 767 fM and 34 pM, respectively. The concluding device is very similar to the second but with an alternative detection strategy involving galvanic exchange that makes the device a true point-of-need sensor while still maintaining the low-cost, ease of mass production, and dynamic range that is relevant for most biological markers. We’ve come a long way but the journey continues.Item Structure based design of a ricin antidote(2012-12) Jasheway, Karl Richard; Robertus, Jon D.; Hackert, Marvin LRicin is a potent cytotoxin easily purified in large quantities. It presents a significant public health concern due to its potential use as a bioterrorism agent. For this reason, extensive efforts have been underway to develop antidotes against this deadly poison. The catalytic A subunit of the heterodimeric toxin has been biochemically and structurally well characterized, and is an attractive target for structure-based drug design. Aided by computer docking simulations, several ricin toxin A chain (RTA) inhibitors have been identified; the most promising leads belonging to the pterin family. To date, the most potent RTA inhibitors developed using this approach are only modest inhibitors with apparent IC50 values in the 10-4 M range, leaving significant room for improvement. This thesis discusses the development of a subset of inhibitors belonging to the pterin family in which amino acids have been utilized as building blocks. Inhibitors in this family have achieved a significant increase in potency, and have provided valuable structural information for further development.Item Synthesis and optimization of a library of small molecule inhibitors of ricin toxin A(2012-05) Pruet, Jeffrey Michael; Anslyn, Eric V., 1960-Ricin is a potent cyctotoxin with no known antidote. Chapter 1 provides background and context for this thesis, which is primarily focused on probing the active site of Ricin toxin A (RTA). Relevant information about Ricin, its use, method of action, and noteworthy contributions towards the discovery of Ricin A chain inhibitors are provided. Furthermore, a brief description of the assays used by our collaborators to monitor RTA inhibition is provided. Additionally, a great deal of this thesis pertains to a particular heterocycle, pterin, and thus the remainder of Chapter 1 is dedicated to pterins, their physical properties, biological relevance, and selected reports of pterin chemistry. Chapter 2 details preliminary research focused on the use of nucleic acid-based platforms as RTA inhibitors. Two specific nucleic acids were chosen, adenine and guanine, and the chapter is split to address them individually. Rational for their use is provided, as well as the synthetic strategies investigated. Both platforms showed significant interference with the analysis assay, most pronounced for the adenine series. A primary goal throughout this thesis is the identification of a simple, rapid method to provide a library of new compounds. To this end, discussion of improved synthetic routes are provided within the section dedicated to guanines. Initial investigation into pterins as a platform for RTA inhibitors is provided in Chapter 3. Much of this chapter is concerned with hurtles encountered while dealing with the poor solubility of pterins, purification, and limits in reaction scope. Finally this chapter details a significant discovery in pterin's utility, both in terms of synthetic ease and preference towards one regioisomer over another. A variety of amides are initially used to probe the active site for significant interactions to the pterin pendents. Chapter 4 builds off the discoveries detailed within the previous chapter. Efforts to optimize the preliminary amide series from Chapter 3 are described, leading to a significant enhancement in activity. Additionally, Chapter 4 describes a synthetic breakthrough which greatly enhanced the speed of synthesis and complexity of the designed pterin inhibitors. Building upon the goal to map the RTA active site, a description of various peptide conjugated pterins is provided, as well as efforts to arrive at optimized isosteres of the most promising peptide derivatives.