Browsing by Author "Musselman, Inga H."
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Item A Carbon Nanotube-based Raman-imaging Immunoassay For Evaluating Tumor Targeting Ligands(Royal Society of Chemistry, 2014-04-16) Bajaj, Pooja; Mikoryak, Carole; Wang, Ruhung; Bushdiecker II, David K.; Memon, Pauras; Draper, Rockford K.; Dieckmann, Gregg R.; Pantano, Paul; Musselman, Inga H.; Pantano, Paul; Musselman, Inga H.Herein, we describe a versatile immunoassay that uses biotinylated single-walled carbon nanotubes (SWNTs) as a Raman label, avidin-biotin chemistry to link targeting ligands to the label, and confocal Raman microscopy to image whole cells. Using a breast tumor cell model, we demonstrate the usefulness of the method to assess membrane receptor/ligand systems by evaluating a monoclonal antibody, Her-66, known to target the Her2 receptors that are overexpressed on these cells. We present two-dimensional Raman images of the cellular distribution of the SWNT labels corresponding to the distribution of the Her2 receptors in different focal planes through the cell with validation of the method using immunofluorescence microscopy, demonstrating that the Her-66-SWNT complexes were targeted to Her2 cell receptors.;Item Fabrication and Characterization of Aging Resistant Carbon Molecular Sieve Membranes for C₃ Separation Using High Molecular Weight Crosslinkable Polyimide, 6FDA-DABA(Elsevier B.V.) Karunaweera, Chamaal; Musselman, Inga H.; Balkus, Kenneth J.; Ferraris, John P.; Karunaweera, C.; Musselman, Inga H.; Balkus, Kenneth J.; Ferraris, John P.Although propylene/propane separation remains a challenge for industrial processes, carbon molecular sieve membranes (CMSMs) have the potential to replace traditional separation methods. A high molecular weight crosslinkable polyimide was utilized to fabricate CMSMs, which showed pure gas permeabilities in excess of 400 barrers with propylene/propane selectivities as high as 25. Mixed gas (C₃H₈:C₃H₆ 50:50) measurements yielded a propylene permeability of 257 barrers and a selectivity of 20. CMSMs from thermally precrosslinked polymer precursors demonstrated a 98% propylene permeability retention after aging for 20 days under vacuum. Active gas flow conditions resulted in slightly lower permeability retention (92.5%) after 15 days of testing. ©2019 Elsevier B.V.Item Modifying the Electronic Properties of Single-Walled Carbon Nanotubes using Designed Surfactant Peptides(2012-05-25) Samarajeewa, D. R.; Dieckmann, Gregg R.; Nielsen, Steven O.; Musselman, Inga H.; Nielsen, Steven O.; Musselman, Inga H.The electronic properties of carbon nanotubes can be altered significantly by modifying the nanotube surface. In this study, single-walled carbon nanotubes (SWCNTs) were functionalized noncovalently using designed surfactant peptides, and the resultant SWCNT electronic properties were investigated. These peptides have a common amino acid sequence of X(Valine) 5(Lysine) 2, where X indicates an aromatic amino acid containing either an electron-donating or electron-withdrawing functional group (i.e. p-amino-phenylalanine or p-cyano-phenylalanine). Circular dichroism spectra showed that the surfactant peptides primarily have random coil structures in an aqueous medium, both alone and in the presence of SWCNTs, simplifying analysis of the peptide/SWCNT interaction. The ability of the surfactant peptides to disperse individual SWCNTs in solution was verified using atomic force microscopy and ultraviolet-visible-near-infrared spectroscopy. The electronic properties of the surfactant peptide/SWCNT composites were examined using the observed nanotube Raman tangential band shifts and the observed additional features near the Fermi level in the scanning tunneling spectroscopy dI/dV spectra. The results revealed that SWCNTs functionalized with surfactant peptides containing electron-donor or electron-acceptor functional groups showed n-doped or p-doped altered electronic properties, respectively. This work unveils a facile and versatile approach to modify the intrinsic electronic properties of SWCNTs using a simple peptide structure, which is easily adaptable to obtain peptide/SWCNT composites for the design of tunable nanoscale electronic devices.Item Prevention of Physical Aging within Carbon Molecular Sieve Membranes for Gas Separations(2020-08) Cosey, Whitney; Musselman, Inga H.Carbon molecular sieve membranes (CMSMs) are a subclass of porous materials with the ability to perform molecular sieving. Controlling the jump lengths from one pore to another allows for enhanced permselectivity of such membranes. This control makes CMS materials extraordinarily attractive for gas separations, in comparison to state-of-the-art polymeric membranes that separate molecules based primarily on sorption-diffusion. This work considers the recent progress in the development of carbon membranes as well as limitations that prevent their commercialization, in particular the rapid onset of aging that occurs with CMSMs. Various aspects of how properties of a CMSM may change over time and how important it is to find the optimum starting materials and process conditions to minimize aging are addressed within. Conditions which affect the performance of CMSMs and current preparation methods are explored and aligned with future research needed to achieve commercially viable CMSMs. Chapter 1 summarizes the history and applicability of CMSMs along with their ability to surpass commercially used polymeric membranes for gas separations. A focus on their limitations, primarily physical aging, is addressed along with current endeavors to mitigate it. Chapter 2 explicates the novel use of metal nanoparticles in CMSMs to scaffold membranes’ inherent pore structure to minimize aging. The in-situ formation of copper nanoparticles within polymer of intrinsic microporosity-1 (PIM-1) was studied via transmission electron microscopy and gas permeation. Chapter 3 describes the synthesis of tailored metal pillars which can be used for various polymeric precursors, including Matrimid® 5218 and PIM-1. The tunability of the size of the metal nanoparticles provides a more universal approach to reduce physical aging within CMSMs that can be monitored by means of gas permeation.