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| Sensing of heavy metal ions using nanostructured materials
(Faculty Mentor: Dr. Paresh C. Ray, Department of Chemistry) Developing nanomaterial based fluorescence energy transfer (NSET) probes 5-11 for screening toxic metal ions
in contaminated water and fish with excellent sensitivity (2 ppt) and selectivity over competing analytes.
The detection approach is based on the unique super quenching property of gold naoparticles and nanorods for
chromophores through both energy-transfer and electron-transfer processes.
The REU participant will learn how to synthesize these materials and how to design nanoprobes.
Participant will also approach problems in applications for sensing different toxic metal ions using NSET probe.
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Modeling of plasmon-enhanced nanoparticle based single molecule spectroscopy
(Faculty Mentor: Dr. Tigran V. Shahbazyan, Department of Physics) The project involves theoretical and numerical
studies of optical properties of metal nanoparticles with biomolecular adsorbates.
These systems are building blocks of biosensors capable of detecting changes in the chemical composition of the
environment.
The REU participant will be involved in development of a microscopic model for accurate evaluation of radiative and non-radiative lifetimes of
nanobiomolecular systems. Our calculations will be carried out using the time-dependent density-functional
theory methods. The results are expected to aid the engineering of
nanoparticle-based sensing devices which have potential applications as chemical and biological
defense sensing systems.
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Nanomaterials interactions with human skin cells
(Faculty Mentor: Dr. Hongtao Yu, Department of Chemistry) Whether or how nanomaterial affect the toxicity of the compounds from which they are derived is not known. This lack of data is remarkable given the use of the technology in high consumer-use products like clothes and sunscreens. We are using human skin keratinocyte cells to determine the cellular and molecular effects of metal nanoparticles including gold, silver, and others. We are considering the possible effects of size, agglomerate properties, composition, shape and surface composition, and determining how these parameters affect the ability of metal nanoparticles to damage DNA and induce genomic instability. The REU participant will learn the synthesis of gold and silver nanoparticles, cultivation of human keratinocytes, and treatment of human keratinocytes cells with nanomaterials. The participant also will involve in cell damage study using biological essays and TEM, SEM, and other techniques.
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Nanotube model for biological application
(Faculty Mentor: Dr. Jerzy R. Leszczynski, Department of Chemistry) Single-walled carbon nanotubes (SWNTs) that consist of a graphene sheet wrapped to form a cylinder are on the order of several nanometers in diameter but several microns in length. Because of their high aspect ratio, the tubes can be viewed as a quasi-one-dimensional system. SWNTs have interesting properties as building blocks of emergent nanotechnologies. Carbon nanotubes (CNTs) hold great promise for applications in biomedicine and biotechnology, in particular, as biosensors. In order to study biological applications of SWNT segments such as artificial molecular channels conducting water, protons, ions, or polymers, we are developing an efficient model for SWNTs that can be used in conjunction with molecular dynamics simulations. We have developed an accurate, yet computationally efficient, empirical method to model the electrostatics of finite-length single-walled armchair CNTs 41-43. These methodologies include density functional theory with Gaussian orbitals and periodic boundary conditions. The REU participant will learn how to use simple DFT calculation for predicting nanotobe structure and develop modeling which can be used for biological applications.
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Synthesis, characterization of Nanotubes for Sensor and Protective Technologies
(Faculty Mentor: Dr. Wilbur L. Walters Jr., Department of Civil and Environmental Engineering) Nanotube structures have a number of attributes that make them potential candidates for biomedical applications. First, nanotubes have inner voids that can be filled with species ranging from large proteins to small molecules. In addition, nanotubes have distinct inner and outer surfaces that can be differentially functionalized. The ability to control the dimensions allows for tailoring tube size to fit the biomedical problem at hand. Finally, the ability to make these nanotubes out of nearly any material creates the possibility of making nanotubes with a desired property such as ruggedness or biodegradability. Efforts are focused on understanding the physical properties of nanotubes as a function of their response to humidity, high temperature, ultraviolet radiation, corrosive environments and general weathering. Processed materials are tested using accelerated testing techniques. Sheet resistance, capacitance and structure are analyzed using SEM, AFM, STM, four-point probe and capacitance analysis techniques The REU student will learn how to synthesize these nanotubes using CVD technique and characterize them using SEM and TEM. The student will also approach problems in various applications such as biosensors, membrane transports, and electronic devices.
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Nanoparticle-enabled Chemiluminescence Detection for Capillary Electrophoresis
(Faculty Mentor: Dr. Yiming Liu, Department of Chemistry) Advances in nanotechnology allow the synthesis and fabrication of numerous novel nanoparticles (NPs) for different purposes, such as in electronics, as sensors, and as catalysts, because of the unique electronic, optical, and catalytic properties that result from their size. Capillary electrophoresis (CE) is a fast and efficient separation technique that can be used for the analysis of tryptic digests. It is a long-standing interest in our research group to study protein separation by CE in conjunction with laser-induced fluorescence (LIF) detection44-48. Chemiluminescence (CL) detection offers similar sensitivity like LIF and the experimental set-up for CL measurement is very simple. However, a big disadvantage of CL is the limited versatility. So far only a small number of analytes can be detected by CL detection. The development of a versatile CL detection scheme that can sensitively detect compounds of biomedical interest including peptides and DNA molecules will be highly significant, and will greatly extend the applicability of CE separations in areas such as toxicological, biomedical, and environmental research. Our recent study showed that gold nanoparticles eluted from CE capillary at trace levels (10-10 M Au3+ gold nanoparticle solution, ~10 nL injected) catalyzed luminol-H2O2 CL reaction producing neat CE peaks. We envisage that nanopaticles with surface functionalities will find wide applications to enhance CE in terms of both sensitive detection and efficient separation. The research plan for REU participants is comprised of three specific objectives: (a) synthesis of gold nanoparticles with various surface functionalities that enable CL detection in CE, (b) development of CE/CL methods based on nanoparticle-catalyzed CL reactions for the assay of neurotransmitters and peptides, and (c) development of CE/CL methods based on quantum dots-enabled CRET for immunoassay |
Photosensitizing nano-drugs for photodynamic therapy
(Faculty Mentor: Dr. Ruomei Gao, Department of Chemistry) Photodynamic therapy (PDT) for cancer treatment involves administration of a photosensitizer in targeted tissues followed by photogeneration of singlet oxygen (1O2) that destroys tumor cells. Based on the fact that nanoparticles are preferentially taken up by tumor tissues, a variety of approaches have been explored by using photosensitizing nanoparticles such as quantum dots, phthalocyanine-nanoparticle-conjugates, peptide-conjugates and silica nanoparticles. The combination of the nanoparticles with traditional photosensitizers offers promising future for PDT. We have reported49-51 1O2 production from TiO2 colloid solutions by time-resolved Nd:YAG laser at 1O2 luminescence emission of 1270 nm. The REU participants will involve (i) establishing the reliable analytical method for absolute quantum yield of 1O2 production; (ii) determining the quantum efficiency of 1O2 generation from different types of TiO2/SiO2 nanoparticles; (iii) clarifying the effects of pH, light intensity, electron donor and the chemical binding on electron transfer and energy transfer mechanisms.
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Nano-Catalyst Based Synthetic Organic Chemistry
(Faculty Mentor: Dr. Ashton T Hamme II, Department of Chemistry) The objective of the research is to synthesize novel heterocycles in a manner that is as "green" as possible. We propose to utilize the 1,3-dipolar cycloaddition reaction with a number of alkenes in order to synthesize isoxazoles,1 isoxazolines,2 pyrazoles, pyrazolines, and other heterocycles while using water as the solvent. These reactions will be performed with and without the aid of traditional and nao-Lewis acids as catalysts. The cycloaddition of a nitrile oxide with an alkene in water affords an isoxazoline in approximately 24 hours, depending upon the alkene that is used. However, when a Lewis acid added to the reaction mixture, the isoxazoline product can be detected by thin layer chromatography in approximately 4 hours, depending upon the Lewis acid that is used. REU participant will explore the role that a variety of Lewis acids and nanopartilces plays on the rate and isolated yields of the cycloadducts.
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Application of thioamide receptors for the remediation of toxic nanomaterials
(Faculty Mentor: Dr. Alamgir Hossain, Department of Chemistry) Nanomaterials such as CdSe and ZnSe are thought to be toxic because of the presence of the heavy metal. We are interested in the remediation of Quantum dots (Qdots) that contain heavy metals such as Cd, Zn, Pb, Fe, and Hg. Although, ligands with thiomide functionalities (NHC=S) are known as excellent chelating agents for heavy metals, they have not been explored for nanoparticles. Thioamide receptor can be used to bind and separate heavy metal containing Qdots through the NHC=S group either in its free state or attached to MCM-type mesoporous silica nanosphere (MSN) materials. Once the Qdot is bound to MSN, they can be removed. Functionalized MSN is expected to be stable in aqueous, organic mediums, and can be recycled. MSN can be attached to a pendant thioamide to generate nanosized pores. Thioamide groups on MSN functionalized with NHC=S would coordinate with the aforementioned metal nanoparticle though a combination of covalent and coordination interactions with the metal nanoparticle. The thioamide groups were chosen as coordinating groups for metal species, due to the strong binding ability for transition metals. Removal and separation of the nanoparticle from the mesoporous channel of the MSN can be achieved by controlling the pH for MSN materials. REU students will be involved in the synthesis of the thioamide receptor and the MSN material and their ability to remediate QDots.
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Risk assessment of nanoparticles via in vitro cytotoxicity test on Pseudomonas sp. and E. Coli
(Faculty Mentor: Dr. Huey-Min Hwang, Department of Biology) Lack of toxicological data on nanomaterials makes it difficult to determine if there is a risk associated with exposure. Thus, there is an immediate need to develop rapid, relevant and efficient testing strategies to assess emerging materials of concern. In vitro techniques, such as cell line and microorganisms are preferred because they are rapid, efficient and cost effective. Therefore, the bacteria Pseudomonas sp. and E. coli strains are selected for the cytotoxicity determination of nanopaticles in this study. Expected outcomes include: (1) the scientific data of cytotoxicity of TiO2 and C60 using Pseudomonas sp. and E. Coli as experimental organisms; (2) development of a rapid and accurate method to evaluate the cytotoxicity of nanoparticles. REU students will be involved in the bacteria culture and test of the toxicity of various nanomaterials.
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Development of chemosensors for the detection of nerve agent using nanoparticle imprinted polymers
(Faculty Mentor: Dr. R. Venkatraman, Department of Chemistry) Noble metal nanoparticles provide an attractive scaffold for the attachment of multiple fluorescent labels. We are working on integrating molecular imprinting technology (MIP) of the lanthanide complexes with nano gold that can modulate the fluorescence of the lanthanide and aid in effective detection of the nerve agents. We propose to develop a novel sensor first by functionalizing HBAP-thiol units on Au/Ag nanoparticles and further complexing them with lanthanide metal ions such as Eu+3/Tb+3. This will be then bound in a polymer using MIP technology for use as a sensor. Molecular imprinting is a process for making selective binding sites in synthetic polymers. The process involves building a complex of the imprint molecule and complementary polymerizable ligands. By copolymerizing the complexes with a matrix monomer and an empirically determined level of cross-linking monomer, the imprint complex becomes bound in a polymeric network. The network is then chemically processed to liberate the imprinting species and create a binding site. Upon exposure to the template molecule the luminescence change (by a shift in wavelength, intensity or lifetime of luminescent emission) observed is used for the detection of the nerve agent. REU students will participate in the synthesis of the lanthanide complex and carry out spectroscopic studies.
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