Emeritus Faculty
D. Allan Cadenhead
Professor Emeritus
827 Natural Sciences Complex
Phone: (716) 645-4315
Fax: (716) 645-6963
E-mail: checaden@buffalo.edu
Dr. Cadenhead retired in 2008 after 48 years of research on surfaces. These include the surfaces of catalysts, carbons, lunar (Apollo) materials as well as a wide range of biological membrane lipids. With regard to the latter the behavior of phospholipids and their interaction with cholesterol and the effects of chain branching with both polar and non-polar substitutes was examined. Other interests include the effects of local anesthetics on lipid packing. Currently he is consulting on the preparation and effects of pulmonary surfactants on neonatal lungs. He was awarded the Alexander von Humboldt Senior US award in 1983 for his work with ultra-thin films.
Education:
- B. S., St. Andrews University, Scotland (1954)
- Ph.D., Bristol University, England (1957)
- Alexander von Humbold Senior U.S. Scientist Award (1983)
Specializations:
Surface chemistry monomolecular model membranes, sterol/lipid interactions, branched-chain lipids Langmuir-Blodgett multilayers of selected polymers. Local anesthetic biomembrane interactions
Research Summary:
Current studies include film characteristic determinations of glycerides, vitamin related and carotenoid films with a particular regard being paid to pressure and oxidation stability. A new technique is being employed in examining a wide variety of systems. This involves locating a biphasic monomolecular film in the objective stage of an optical microscope and observing both fluid and microcrystalline condensed phases by means of a lipid fluorescent probe that is miscible in the fluid phase only. These studies provide valuable information on a wide variety of systems and problems. These include alkane chain order/disorder and other conformational transitions, cholesterol/lipid and drug membrane interactions and two-dimensional polymerization.
Analysis of the lipid components of the inner membrane of strains of the bacteria B. acidocaldarius, that exist in hot springs, shows that up to 70% of these are diacylglycerols with monoglucosyl polar head-groups and w-cyclohexyl alkyl chains. Comparative film studies of synthetic lipids having either phosphatidylcholine or monoglucosyl head-groups and either straight, methyl iso-branched or w-cyclohexyl chains, indicates that the monoglucosyl head-groups can provide a thermal stability up to about 70°C, whereas the phosphatidylcholine head-groups are unstable at temperatures in excess of 40°C. In addition the w-cyclohexyl alkyl chains create a highly condensed, but still liquid-crystalline-like state which provides low permeability and resists the effects of high acidity.
Recent studies have focused on the ability of molecules such as ethanol and procaine to penetrate biological membranes and the profound differences of one to the other as well as to their local anesthetic action. A totally different study looks at membrane formation on solids, edge effects and the wetting of edged solids.
Selected Recent Publications:
"Monomolecular Films", McGraw Hill Encyclopedia of Science and Technology, pp. 403-406 (2006).
"Effect of the Hydroxy Group Position on the Monolayer Characteristics of Hydroxypalmitic Acids" (with S. Siegel, D. Vollhardt), Colloids and Surfaces A: Physicochem. Eng. Aspects 2005, 256, 9-15.
"The Wetting of Edged Solids" (with B. Spencer and N. Tumavitch), Langmuir 2005, In Press.
"Effect of Hydroxyl-Group Position and System Parameters on the Features of Hydroxystearic Monolayers" (with S. Siegel and D. Vollhardt), Langmuir 2004, 20, 7670-7677.
"Characteristic Features of Hydroxystearic Acid Monolayers at the Air/Water Interface" (with S. Siegel and D. Vollhardt), J. Phys. Chem. B 2004, 108, 17448-17456.
"Temperature Dependent Domain Growth in 9-Hydroxypalmitic Acid" (with S. Siegal and D. Vollhardt), Progress in Colloid and Polymer Science 2002, 121, 67-71.
"Model Membrane/Substrate Interactions: Ethanol and Procaine Interactions", Colloid and Surfaces B Biointerfaces 2001, 22, 63-68.
"A Comparative Monomolecular Film Study of Monoglucosyl Diacylglycerols Containing Linear, Methyl Iso- and w-Cyclohexyl Fatty Acids" (with B. Asgharian, D. Mannock and R. N. McElhaney), Langmuir 2000, 16, 7315-7317.
"Monolayer/Membrane Substrate Interactions: Thermodynamic and Molecular Aspects", Progress in Anesthetic Mechanisms 2000, 6, 69-78.
"The Thermodynamics of Meniscus Formation on Wilhelmy Plate Immersion at the Air/Water Interface and the Mechanics of Initial Film Deposition", in Proceedings of the Space Technology and Applications International Forum, pp. 854-860 (2000), American Institute of Physics publication # 504 (Springer Verlag, Ed. M. El-Genk), Nicholas J. Tumavitch, D. A. Cadenhead and B. J. Spencer.
"Bipolar/Monopolar Conformational Transitions of Selected Hydroxy Octadecanoic Acids and Esters: A Fluorescence Microscopy Study", B. Asgharian and D. A. Cadenhead, Langmui
