Macromolecular Substances Commons^™

Robert, Powers; Unl Chemistry; Nmr-Assisted Drug Discovery, Mark Griep, Robert Powers

UNL ORCA Interview Series

Dr. Robert Powers became a chemistry professor at the University of Nebraska-Lincoln in 2003 and is about to retire after 23 years. Prior to UNL, Bob was a drug discovery researcher for 11 years at American Cyanamid, which eventually became Wyeth and is now part of Pfizer. Bob was born in Jersey City, New Jersey. Something in his youth must have sparked an interest in chemistry because he earned a bachelor's in that subject from Rutgers University in New Brunswick. Then he traveled 1200 miles west to Purdue University in Indiana where he earned his doctorate. Next, he did postdoctoral …

Turning Zwitterions Into Toughening Agents: Salt-Activated Microdomains In Poly(Vinyl Alcohol) Double-Network Hydrogels, Louis D. Zhang, Jintao Yang, Si Yu Zheng

University Research

Zwitterionic hydrogels, although highly biocompatible, are widely regarded as mechanically fragile, with typical tensile strengths below 0.1 MPa, which restricts their use in load-bearing applications. Here, we address this limitation by integrating a polyzwitterionic network with a poly(vinyl alcohol) (PVA) network through high-speed pregelation agitation that enhances chain entanglement and induces flow orientation. By exploiting the salt-driven conformational transition of zwitterionic chains, a controlled salting-out step generates uniformly dispersed nanoscale microdomains that act as reversible energy-dissipating units. At the same time, balanced hydrogen bonding between the two networks moderates PVA crystallinity, limiting embrittlement while preserving elasticity. The resulting double-network hydrogel …

Exploring The Theoretical Foundation With Rupture And Delayed Rupture Experiments, Shi-Qing Wang, Junpeng Wang, Asal Y. Siavoshani, Cheng Liang

University Research

We carry out uniaxial continuous and step stretching of various cross-linked polymer networks to demonstrate how characteristics of rupture during continuous stretching and delayed rupture after step stretching can be used to probe the structure of the emergent kinetic activation theory of bond dissociation (KATBD) for elastomeric failure. Based on delayed rupture experiments, we show that the network lifetime tntw, taken as the incubation time tdel-rupt for delayed rupture, depends on temperature in an Arrhenius like manner and is exponentially sensitive to the degree of network stretching (depicted by the step-stretch ratio λss). Rupture at λb during continuous stretching for …

Nitroarene-Mediated Photo-Oxidative Deconstruction And Upcycling Of Unsaturated Rubber Waste, Junpeng Wang, Zefeng Wang, Roberto Obergon, Obed Fernando

University Research

Transforming waste polymers into materials with improved properties offers a compelling strategy for advancing the sustainable use of polymers, echoing the Chinese proverb: “Blue comes from indigo but surpasses it in blueness.” Herein, we report a photo-oxidative deconstruction and upcycling method for unsaturated rubber waste. Under 390 nm LED irradiation at room temperature, in the presence of a nitroarene oxidant, diverse unsaturated polymers─including natural rubber, polybutadiene, nitrile rubber, styrene–butadiene rubber, and even cross-linked nitrile gloves─are selectively converted into carbonyl-terminated oligomers. The aldehyde-functionalized products are cross-linked via dynamic imine chemistry with p-phenylenediamine to yield reprocessable elastomers with markedly improved tensile strength …

Scalable Biosynthesis And Recovery Of Poly-3-Hydroxybutyrate Produced From Cotton-Derived Glucose By Cupriavidus Necator, Ashley M. Clark, Lucia E. Gargano, Gabriella M. Fioravanti, Hannah M. Schapiro, Ron G. Kander

School of Design and Engineering Papers

To combat the growing issue of petroleum plastic waste, alternative bio-based polymers are being developed. Many of these biopolymers are made from bio-derived materials, or are biodegradable, but the most promising polymers fall in both categories. Polyhydroxyalkanoates (PHAs) are one such class of polymers, and poly-3-hydroxybutyrate (P3HB), the most popular PHA, has shown great potential. This study utilized two types of cotton-derived glucose, alongside commercial glucose, as a feedstock for the biosynthesis of P3HB by Cupriavidus necator (also known as Ralstonia eutropha). The fermentation took place in a 2-L bioreactor, showing potential for scale-up. A single-solvent extraction method was …

Detecting Early Changes In Cartilage Collagen And Proteoglycans Distribution Gradients In Mice Harboring The R992c Collagen Ii Mutant Using 2d Correlation Infrared Spectroscopy, Jolanta Fertala, Andrzej Steplewski, Andrzej Fertala

Department of Orthopaedic Surgery Faculty Papers

Collagen II is a vital structural component in developing bones and mature cartilage. Muta- tions in this protein cause spondyloepiphyseal dysplasia, a disease characterized primarily by altered skeletal growth and manifesting with a range of phenotypes, from lethal to mild. This study examined transgenic mice harboring the R992C (p.R1124C) substitution in colla- gen II. Previous research demonstrated significant growth abnormalities and disorganized growth plate structure in these mice, and histological signs of osteoarthritic changes in the knee joints of 9-month-old mice with the R992C mutation. Our study focuses on detecting early structural changes in the articular cartilage that occur before …

Bilateral Carotid Body Paragangliomas With Succinate Dehydrogenase Complex Subunit D Gene Mutation, Abdul R. Khan, Kelvin Li, Neel D. Gupta, Jagan D. Gupta, Mohammed M. Ansari, Triet M. Do, Enrique Palacios

School of Medicine Faculty Publications

No abstract provided.

Molecular Architecture Of Chitin And Chitosan-Dominated Cell Walls In Zygomycetous Fungal Pathogens By Solid-State Nmr, Qinghui Cheng, Malitha C. Dickwella Widanage, Jayasubba Reddy Yarava, Ankur Ankur, Jean Paul Latgé, Ping Wang, Tuo Wang

School of Medicine Faculty Publications

Zygomycetous fungal infections pose an emerging medical threat among individuals with compromised immunity and metabolic abnormalities. Our pathophysiological understanding of these infections, particularly the role of fungal cell walls in growth and immune response, remains limited. Here we conducted multidimensional solid-state NMR analysis to examine cell walls in five Mucorales species, including key mucormycosis causative agents like Rhizopus and Mucor species. We show that the rigid core of the cell wall primarily comprises highly polymorphic chitin and chitosan, with minimal quantities of β-glucans linked to a specific chitin subtype. Chitosan emerges as a pivotal molecule preserving hydration and dynamics. Some …

Factors Associated With Recanalization And Reintervention Following Below Knee Polidocanol Endovenous Microfoam Ablation For Great Saphenous And Small Saphenous Veins, John Fang, Christian Fang, Andy Moyal, Enrico Ascher, Anil Hingorani, Natalie Marks

Rowan-Virtua School of Osteopathic Medicine Departmental Research

BACKGROUND: Polidocanol endovenous microfoam (PEM) has been used to treat lower extremity venous reflux for almost one decade with specific advantages for below knee (BK) truncal veins where thermal ablation poses a risk of injury to adjacent nerves. The current literature of the BK segment often examines short-term outcomes with modest sample sizes. We aim to identify factors associated with recanalization and reintervention in this subset of patients.

METHODS: We performed a retrospective study of a prospectively maintained database of patients from a single institution who underwent 1% PEM ablation for BK great saphenous vein (GSV) and small saphenous vein …

The Developing Effects Of Potassium Ferricyanide On Tetrahymena, Katelyn Coronell

Whittier Scholars Program

Potassium Cyanide is a highly toxic chemical asphyxiant that interferes with the body's ability to use oxygen, typically by directly affecting the body by ingestion, inhalation, skin contact, or eye contact(CDC, 2011). Due to its high toxicity, the main effect that leads to the downfall of the organism begins with the cessation of aerobic metabolism; it does this by cyanide binding to the ferric ions and inhibiting cytochrome oxidase within the mitochondria (Zhang, 2015). There are no physical dangers the substance causes. Although, there are many chemical dangers. If used at temperatures higher than 70℉ The substance may produce toxic …

Anatomy And Physiology Preparatory Course Textbook (2nd Edition), Carlos Liachovitzky

Open Educational Resources

The goal of this preparatory textbook is to give students a chance to become familiar with some terms and some basic concepts they will find later on in the Anatomy and Physiology course, especially during the first few weeks of the course.

Organization and functioning of the human organism are generally presented starting from the simplest building blocks, and then moving into levels of increasing complexity. This textbook follows the same presentation. It begins introducing the concept of homeostasis, then covers the chemical level, and later on a basic introduction to cellular level, organ level, and organ system level. This …

Distribution And Localization Of Novel Iodine Nanoparticles In The Human Glioma 1242 Growing In The Brains Of Mice, Benjamin Billings

Honors Scholar Theses

Observing and designing the in vivo distribution and localization of therapeutic nanoparticles is an essential aspect of developing and understanding novel nanoparticle- based medical treatments. This study investigates novel PEGylated Iodine-based nanoparticles (INPs), an alternate composition to the more widely researched gold nanoparticles (AuNPs), which may help avoid adverse effects associated with AuNPs, such as potential toxicity and skin discoloration, when used in similar applications. Determining the localization of the novel INPs within murine brains containing human glioma U-1242MG cells is critical in assisting the development of radiation dose enhancement therapy for this aggressive cancer. Radiation dose enhancement utilizes the …

Enhancing Clot Properties Through Fibrin-Specific Self-Cross-Linked Peg Side-Chain Microgels, Nicole Welsch, Ashley C. Brown, Thomas H. Barker, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Excessive bleeding and resulting complications are a major cause of death in both trauma and surgical settings. Recently, there have been a number of investigations into the design of synthetic hemostatic agents with platelet-mimicking activity to effectively treat patients suffering from severe hemorrhage. We developed platelet-like particles from microgels composed of polymers carrying polyethylene glycol (PEG) side-chains and fibrin-targeting single domain variable fragment antibodies (PEG-PLPs). Comparable to natural platelets, PEG-PLPs were found to enhance the fibrin network formation in vitro through strong adhesion to the emerging fibrin clot and physical, non-covalent cross-linking of nascent fibrin fibers. Furthermore, the mechanical reinforcement …

Synthesis Of Β-Triphosphotriester Pronucleotides, Yousef A. Beni, Chandravanu Dash, Keykavous Parang

Pharmacy Faculty Articles and Research

Dinucleoside phosphorochloridite were synthesized from phosphorus trichloride and three nucleoside analogues, 3-fluoro-2,3-dideoxythymidine (FLT), 2',3'-dideoxy-5-fluoro-3'- thiacytidine (FTC), and 2',3'-dideoxy-3'-thiacytidine (3TC), in a multistep synthesis. Polymerbound N-Boc p-acetoxybenzyl 5¢-O-2¢-deoxythymidine was reacted with dinucleoside phosphorochloridite in the presence of 2,6-lutidine, followed by the reaction with dodecyl alcohol and 5-(ethylthio)-1H-tetrazole, oxidation with tert-butyl hydroperoxide, and acidic cleavage, respectively, to afford the b-triphosphotriester derivatives containing three different nucleosides.

Biophysical Characterization Of A Riboflavin-Conjugated Dendrimer Platform For Targeted Drug Delivery, Amanda B. Witte, Christine M. Timmer, Jeremy J. Gam, Seok Ki Choi

University Faculty Publications and Creative Works

The present study describes the biophysical characterization of generation-five poly(amidoamine) (PAMAM) dendrimers conjugated with riboflavin (RF) as a cancer-targeting platform. Two new series of dendrimers were designed, each presenting the riboflavin ligand attached at a different site (isoalloxazine at N-3 and d-ribose at N-10) and at varying ligand valency. Isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC) were used to determine the binding activity for riboflavin binding protein (RfBP) in a cell-free solution. The ITC data shows dendrimer conjugates have K D values of ≥465 nM on a riboflavin basis, an affinity ∼93-fold lower than that of free riboflavin. …