Thomas J. Manning

Synthesis of exfoliated graphite from fluorinated graphite using an atmospheric-pressure argon plasma

Abstract Synthesis of a stable form of exfoliated graphite (EG) is described. EG was prepared from the Graphite Intercalation Compound (GIC) fluorine–graphite using an atmospheric-pressure 27.12 MHz inductively coupled argon plasma. The fluorinated graphite dust is continuously injected into the argon plasma (5000–8000 K), and collected. Raman spectroscopy and scanning electron microscopy (SEM) images are used to identify nanotubular structures at the terminals of the EG graphite sheets.

Aggregation studies of humic acid using multiangle laser light scattering.

An aqueous phase study of the naturally occurring dissolved organic carbon humic acid (HA) is performed using multiangle laser light scattering (MALLS) to measure its RMS radius and average molecular weight. A Zimm plot using Berry Formulism and a second-order fit gave an average molar mass of 1.164 x 10(8) g/mol and an average RMS radius (Rz) of 436.0 +/- 36 nm at 25 degrees C.

Production Of Ozone in an Electrical Discharge Using Inert Gases as Catalysts

Abstract The catalytic role of using inert gases to increase the efficiency and lower the power cost of producing ozone (O3) from high purity oxygen (O2) in a process incorporating an electrical discharge is demonstrated. Three inert gases (Ar, Ne, He) and N2 are individually mixed with O2 and the results presented. The increase in ozone production is partially attributed to the increase in electron density provided by the ionization of the inert gas in the discharge.

Iron chelators in medicinal applications - chemical equilibrium considerations in pharmaceutical activity.

Iron chelators are being examined as a potential class of pharmaceutical agents to battle different types of cancer as well as iron overload diseases. In recent studies, iron binding species such as desferrioxamine, triapine, tachpyridine, Dp44Mt, and PIH have been tested in cell line tests and clinical trials. Using published chemical equilibrium values (stability constants, equilibrium constants), it is argued that an iron chelator cannot competitively remove iron from a heme-containing biomolecule (i.e. hemoglobin (Hb), myoglobin) causing a cancerous cell to die. This type of reaction (DFO(aq) + [Fe(2+,3+)-Hb] --> [Fe(2+,3+)-DFO] + Hb) has been proposed in a number of published studies using circumstantial evidence. It is argued that iron chelators can potentially interact with iron from ferritin or iron that has precipitated or flocculated as oxyhydroxide under physiological pHs. It is argued that chelators can interfere with various physiological processes by binding cations such as Ca(2+), Zn(2+) or K(+). A number of siderophores and natural products that have the ability to bind Fe(3+)/Fe(2+) as well as other cations are discussed in terms of their potential pharmaceutical activity as chelators. Chemical equilibria between cations and pharmaceutical agents, which are rarely quantitated in explaining medicinal mechanisms, are used to show that chelators can bind and remove iron and other cations from physiologically important systems required for cell survival and propagation.

Gas mixtures and ozone production in an electrical discharge

Abstract The quantitative production of ozone (O3) with N2, O2, and Ar gas mixtures in an atmospheric pressure corona discharge (CD) is investigated. A five-part model is presented that explores the discharge conditions needed for optimum ozone production. One part of the model is the well-known relationship that correlates the discharges voltage, frequency, gap, dielectric material, etc with the generators yield. The four other parameters revolve around the correct selection of the gas mixture, which subsequently effects the discharges ionization potential, continuum background, excitation of atomic and molecular species, and gas cooling efficiency. Varying the ratios of the three basic components of air (N2, O2) and Ar) is demonstrated to have a pronounced effect on ozone production in a modified CD.

The copper (II) ion as a carrier for the antibiotic capreomycin against Mycobacterium tuberculosis.

In recent years, the bacterium responsible for tuberculosis has been increasing its resistance to antibiotics resulting in new multidrug resistant Mycobacterium tuberculosis (MR-TB) and extensively drug-resistant tuberculosis (XDR-TB). In this study we use several analytical techniques including NMR, FT-ICR, TOF-MS, LC-MS and UV/Vis to study the copper-capreomycin complex. The copper (II) cation is used as a carrier for the antibiotic capreomycin. Once this structure was studied using NMR, FT-ICR, and MALDI-TOF-MS, the NIH-NIAID tuberculosis cell line for several Tb strains (including antibiotic resistant strains) were tested against up to seven variations of the copper-capreomycin complex. Different variations of copper improved the efficacy of capreomycin against Tb up to 250 fold against drug resistant strains of Tb.

Identifying bryostatins and potential precursors from the bryozoan Bugula neritina

The bryozoan species Bugula neritina contains the anticancer agent bryostatin. Bryostatin has been extracted from these sessile marine invertebrates since the late 1960s from the Gulf of California, Gulf of Mexico, as well as various locations on the eastern and western rims of the Pacific Ocean. In this work we are focusing on animals harvested in the Gulf of Mexico near Alligator Point (Florida). Using Inductively Coupled Plasma-Mass Spectrometry (ICP–MS) we measure the concentration of 70 elements in B. neritina, a sea squirt, and the sediment from the point of harvesting. This data has helped us generate an extraction process for marine natural products. Combining UV/VIS absorbance measurements with Matrix Assisted Laser Desorption Ionization–Time of Flight-Mass Spectrometer (MALDI–TOF-MS), we demonstrated that the specific form of bryostatin extracted is a function of the solvent. A 9.4 T Fourier Transform-Ion Cyclotron Resonance (FT-ICR) mass spectrometer, whose sensitivity, mass accuracy, and resolving power allowed the exact empirical formulas of potential precursors of bryostatin to be identified, was employed. Finally we examine extracts of 14 marine species of the Gulf of Mexico, from the sand trout (Cynoscion arenarius) to chicken liver sponge (Chrondrilla nucula), all recently collected, which had shown some medicinal activity thirty years ago in a National Cancer Institute study. By the MALDI–TOF-MS, we were able to identify mass spectral features that correspond to different variations of the basic bryostatin structure, which raises the question if the bryozoans are the original source of bryostatin.

Impact of environmental conditions on the marine natural product bryostatin 1

Marine Natural Products (MNPs), such as bryostatin 1, are exposed to a range of physical and chemical conditions through the life cycle of the host organism. These include exposure to sunlight, oxidizing and reducing agents, cation binding, and adsorption to reactive metal oxide surfaces. Using Fourier Transform-Ion Cyclotron Resonance (FT–ICR), Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS), UV/Vis absorbance spectroscopy, and molecular modeling, we studied the impact of UV light, TiO2, I2, and reaction with FeCl3 on the structure of bryostatin 1. Our results demonstrate that natural conditions transform bryostatin to a number of structures, including one with a molar mass of 806 Da, which we have previously identified in the sediment collected from the Gulf of Mexico. To date, at least 20 different structures of bryostatin have been reported in the literature. This work suggests that these variations may be products of the chemical environment in which the bryozoa Bugula neritina resides and are not the result of genetic variations within Bugula.

Copper ion as a delivery platform for taxanes and taxane complexes.

A number of delivery agents, such as proteins, liposomes, micelles, and nanoparticles, are utilized for transporting pharmaceutical agents in a physiological environment. This Letter focuses on the use of the copper(II) ion and its potential role as a delivery agent for the taxanes and taxol couple to a malaria drug. Nuclear magnetic resonance (NMR, (1)H, (13)C, (15)N), Mass Spectrometry (LC-MS, MALDI-TOF, FT-ICR) and computational methods are used to examine the structure of the complex. The National Cancer Institutes benchmark 60 cell line panel is used to compare the efficacy of the copper-taxol and copper-taxol-hydroxychloroquin complexes to that of iron-taxol and pure taxol.

Naturally occurring organic matter as a chemical trap to scan an ecosystem for natural products

A model is proposed that tests an ecosystem for natural products (NPs) using a nonpolar extract of naturally occurring organic matter (NOM), which we demonstrate to be an efficient chemical trap for relatively nonpolar organic molecules. To test the model we collected twenty-six samples of NOM from various locations on the Suwannee River, from its headwaters in the Okeefenokee Swamp to the Gulf of Mexico. We have tentatively identified stearic acid, DDT, chincodine, and a potential precursor to bryostatin. Our data provide evidence that NOM can trap, hold for several decades, concentrate, and transport NP in the environment.