Browsing by Subject "nanotechnology"
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Item Design, simulation and analysis of a molecular nano-sensor operating at terahertz frequencies for energetic materials.(Texas A&M University, 2007-09-17) Shenoy, SukeshNano-sensors, as an application of nanotechnology, are extremely important for environmental, medical and security applications. Terahertz science is an exciting new field that is set to impact the field of sensing to a large extent. I proposed to combine the fields of nanotechnology and terahertz science and develop a molecular nano-sensor that operates at terahertz frequencies. I focused our sensing on energetic materials, particularly nitromethane, and conducted an extensive analysis on its frequency spectrum. The study also focused on designing the nano-sensor and determining its terahertz operation characteristics. I subjected it to various conditions through the use of molecular dynamics simulations. Finally we analyzed the simulation results and provided a proof of the concept that we had a working molecular nano-sensor that operates at terahertz frequencies and senses energetic materials. The results from the frequency analysis of nitromethane showed that the frequency characteristics determined from our simulations were in close agreement with the ones determined experimentally. In addition to this we also successfully demonstrated the use of a Lennard Jones potential to model the CN bond scission of nitromethane. Finally, the results from the interactions between the nano-sensor and nitromethane showed that the presence of nitromethane causes sufficient change in the terahertz frequency characteristics of the nano-sensor providing a means to detect nitromethane.Item Development of a Surface Enhanced Raman Spectroscopy Platform Technology to Detect Cardiac Biomarkers of Myocardial Infarction(2013-04-24) Benford, Melodie ElaneThe clinical evaluation of people with possible myocardial infarction (MI) is often limited by atypical symptoms and inconclusive initial electrocardiograms. A recent consensus from the American College of Cardiology has redefined acute MI to include cardiac markers as central to diagnosis. To address this clinical need, a sensitive microfluidic surface-enhanced Raman spectroscopy (SERS) nanochannel-based optical device is being developed for ultimate use as a point-of-care device for the simultaneous measurement of MI blood biomarkers. The device can provide enhancements of the Raman signal of the analyte measured of up to 1013 using a mechanical aggregation technique at the interface of nanofluidic structures enabling repeatable SERS measurements. Specifically in this research iterations of a sensitive, low volume SERS platform technology were designed that provided quantitative information across a specific range. With the SERS platforms studied, not only were SERS enhancements of up to 1013 achieved but also imprecision values of less than 10% across the 10-50 pM range using a ratiometric approach and qualitative detection down to 100 aM was achieved. Beyond assessment of SERS substrates, assay designs were investigated and characterized including, label-free techniques and competitive immunoassay formats. Lastly, detecting the SERS signal of multiplexed reporter molecules was investigated. By identifying the analyte and assay constraints the design and optimization of future assays will be aided using this SERS platform technology.Item Dreamhome: A Personal Space of Core Human Desire and Ambition(2012-08-15) Tanna, Hemali 1980-Dreamhome is a creative exploration of a prototype house designed with creative freedom using possible future technologies that may not be currently feasible. New and forthcoming technology in various scientific branches that could be applicable to architecture will be presented, and the applications discussed. Limitations of application to architecture of the reviewed technologies will be discussed. Prior works by architects and engineers who push boundaries to innovatively overcome technological limitations will be explored, as will examples in which advanced technology is applied to create unique architectural designs. Together these references will evoke inspirations to be translated into an architectural design and a virtual home. The house is desired to boast of a unique design with various aesthetic and functional features that are not usually seen in present day architecture. This visualization could be a glimpse of possible home design of the future.Item Engineering functionalized gold nanoparticles as a molecular-specific contrast agent to enhance optoacoustic detection of breast cancer cells(2008-12-02) Mohammad Eghtedari; Massoud Motamedi; Vicente Resto; Nicholas A Kotov; Malcolm Brodwick; Gracie VargasMolecular targeting of malignant tumors is a promising field of research that could potentially revolutionize the diagnosis and treatment of many types of cancer including breast. Delivering molecular specific contrast agents to breast cancer cells would enhance the sensitivity and specificity of imaging methods to detect cancer foci at earlier stages, when complete cure is possible. Optoacoustic tomography (OAT) is a non-invasive imaging modality that can be used to produce an image of the distribution of light absorbing components deep within a turbid medium such as human breast. OAT could potentially be used to image breast tumors based on their enhanced angiogenesis; however, its sensitivity and specificity would be limited due to the lack of abnormal angiogenesis at the early stages of tumor growth.\r\nGold nanoparticles generate strong acoustic signal upon pulse laser irradiation and thus are detectable at low concentrations using optoacoustic technique. The goal of this dissertation is to engineer functionalized gold nanoparticles and employ them as a contrast agent for optoacoustic detection of cancer cells.\r\nTo achieve this goal: 1) gold nanoparticles were fabricated in different shape and sizes and their physicochemical properties were optimized for both tumor targeting and optoacoustic detection; 2) the biological properties of fabricated gold nanoparticles were evaluated in vitro and in vivo by determining their stability, toxicity, biodistribution, and molecular targeting properties; 3) the performance of gold nanoparticles to target cancer cells and function as a contrast agent for OAT were assessed in vitro using breast phantoms and then in vivo using animal models.\r\nItem Synthesis and characterization of carbon nanotubes using scanning probe based nano-lithographic techniques(2009-05-15) Gargate, Rohit VasantA novel process which does not require the traditional Chemical Vapor Deposition (CVD) synthesis techniques and which works at temperatures lower than the conventional techniques was developed for synthesis of carbon nanotubes (CNT). The substrates used for this study involved MEMS (Micro Electrical Mechanical Systems) elements and passive elements. These were coated with Fullerene using Physical Vapor Deposition or through a solution in an organic solvent. Catalyst precursors were deposited on these Fullerene coated substrates using ?wet processes?. These substrates were then heated using either the integrated microheaters or external heaters in an inert atmosphere to obtain CNT. Thus, in this process we tried to obviate the Chemical Vapor Deposition (CVD) process for synthesis of CNT (SWCNT and MWCNT). The synthesized CNT will be characterized using Scanning Electron Microscopy and Raman spectroscopy techniques. Also, conductivity measurements were carried out for the synthesized tubes using Dry (contact based) and Wet (electro-chemical) methods. This work also proves the concept for the feasibility for a portable hand held instrument for synthesis of CNT with tunable ?on demand? chirality.Item Synthesis and characterization of covalently-linked dendrimer bioconjugates and the non-covalent self-assembly of streptavidin-based megamers(Texas A&M University, 2005-02-17) McLean, Megan ElizabethThis work details the attachment of dendrimers to proteins, peptides and single stranded DNA (ssDNA). Dendrimers based on melamine satisfy many of the synthetic demands in the field of bioconjugate chemistry including: monodispersity, synthetic flexibility and scalability. The solution-phase syntheses of both ssDNA-dendrimer and peptide-dendrimer bioconjugates is described, and thorough characterization by matrix-assisted laser desorption ionization/ time-of-flight (MALDI-TOF) mass spectrometry, UV-vis spectroscopy, fluorescence spectroscopy, and polyacrylamide gel electrophoresis is discussed. Non-covalent DNA-dendrimer complexes have been shown to facilitate antisense gene delivery, but are vulnerable to dissociation and subsequent enzymatic degradation within the cell. In an effort to prepare biocompatible antisense agents capable of effectively shielding ssDNA from intracellular nuclease digestion, disulfide-linked ssDNA-dendrimers were prepared and rigorously characterized to rule out the possibility of an electrostatic-based interaction. Hybridization assays were performed to determine if the covalently-attached dendrimer affected the ability of the attached ssDNA strand to anneal with a complementary sequence to form double-stranded DNA (dsDNA)-dendrimers. Results indicate that ssDNA-dendrimer conjugates readily anneal to complementary ssDNA strands either in solution or attached to gold surfaces. Nuclease digestions of conjugates in solution suggested that enzymatic manipulation of dsDNA-dendrimers is possible, offering promise for DNA-based computation and other fields of DNA-nanotechnology. Much larger bioconjugates consisting of dendrimers, proteins and peptides were prepared with the goal of obtaining molecular weights sufficient for enhanced permeability and retention (EPR) in tumors. While the dendrimer provides the advantages of a purely synthetic route for drug delivery, the protein portion of the bioconjugate provides a monodisperse, macromolecular scaffold for the non-covalent self-assembly of the dendrimers. The strategy presented herein is based on the strong interaction between biotin and the 60 kD tetrameric protein streptavidin. Each monomer of streptavidin is capable of binding 1 biotin molecule, thus when biotin functionalized peptide-dendrimers are added to streptavidin they bind to form a cluster of dendrimers, or a megamer. The biotinylated peptides that link the dendrimers to the streptavidin core provide a way to actively target specific cell types for drug delivery. Megamer formation through the addition of tetrameric streptavidin was successful as indicated by MALDI-TOF, UV-vis titration and gel electrophoresis assays.Item Theoretical-Experimental Molecular Engineering to Develop Nanodevices for Sensing Science(2012-07-16) Rangel, Norma LuciaMolecular electrostatic potentials (MEPs) and vibrational electronics (?vibronics?) have developed into novel scenarios proposed by our group to process information at the molecular level. They along with the traditional current-voltage scenario can be used to design and develop molecular devices for the next generation electronics. Control and communication features of these scenarios strongly help in the production of ?smart? devices able to take decisions and act autonomously in aggressive environments. In sensor science, the ultimate detector of an agent molecule is another molecule that can respond quickly and selectively among several agents. The purpose of this project is the design and development of molecular sensors based on the MEPs and vibronics scenarios to feature two different and distinguishable states of conductance, including a nano-micro interface to address and interconnect the output from the molecular world to standard micro-technologies. In this dissertation, theoretical calculations of the electrical properties such as the electron transport on molecular junctions are performed for the components of the sensor system. Proofs of concept experiments complement our analysis, which includes an electrical characterization of the devices and measurement of conductance states that may be useful for the sensing mechanism. In order to focus this work within the very broad array between nanoelectronic and molecular electronics, we define the new field of Molecular Engineering, which will have the mission to design molecular and atomistic devices and set them into useful systems. Our molecular engineering approach begins with a search for an optimum fit material to achieve the proposed goals; our published results suggest graphene as the best material to read signals from molecules, amplify the communication between molecular scenarios, and develop sensors of molecular agents with high sensitivity and selectivity. Specifically, this is possible in the case of sensors, thanks to the graphene atomic cross section (morphology), plasmonic surface (delocalized charge) and exceptional mechanical and electrical properties. Deliverables from this work are molecular devices and amplifiers able to read information encoded and processed at the molecular level and to amplify those signals to levels compatible with standard microelectronics. This design of molecular devices is a primordial step in the development of devices at the nanometer scale, which promises the next generation of sensors of chemical and biological agents molecularly sensitive, selective and intelligent.