John S. Harwood

Crystallization and textural porosity of synthetic clay minerals

The crystallization of synthetic layered magnesium silicate hectorite clays from both silica sol and organosilane sources is compared. For the silica sol-derived clays, a templating method is employed wherein organic or polymeric molecules are included during clay crystallization that are then removed from the composites via calcination. The mechanism of silane-derived hectorite formation is followed by XRD, TGA, 29Si MAS NMR, and small angle X-ray scattering (SAXS), and results are compared to those obtained for the sol-derived hectorite. The mechanism appears to be similar but the rate is approximately doubled when the silane is used rather than silica sol. Analytical transmission electron microscopy (TEM) is exploited to glean structural morphology information towards resolving the nature of the resulting pore network structures. Results are compared with nitrogen adsorption–desorption isotherm behavior; dominant hysteresis loops are present in the type IV isotherms. Pore size distributions based on both the adsorption and desorption isotherms are compared. Small angle neutron scattering (SANS) experiments reveal that the average particle size increases as synthetic laponite < sol-derived hectorite < silane-derived hectorite < natural hectorite. Contrast matching SANS studies in aqueous and organic solvents are carried out to extract information about pore accessibility.

Dual Targeting of Intracellular Pathogenic Bacteria with a Cleavable Conjugate of Kanamycin and an Antibacterial Cell-Penetrating Peptide

Bacterial infection caused by intracellular pathogens, such as Mycobacterium, Salmonella, and Brucella, is a burgeoning global health epidemic that necessitates urgent action. However, the therapeutic value of a number of antibiotics, including aminoglycosides, against intracellular pathogenic bacteria is compromised due to their inability to traverse eukaryotic membranes. For this significant problem to be addressed, a cleavable conjugate of the antibiotic kanamycin and a nonmembrane lytic, broad-spectrum antimicrobial peptide with efficient mammalian cell penetration, P14LRR, was prepared. This approach allows kanamycin to enter mammalian cells as a conjugate linked via a tether that breaks down in the reducing environment within cells. Potent antimicrobial activity of the P14KanS conjugate was demonstrated in vitro, and this reducible conjugate effectively cleared intracellular pathogenic bacteria within macrophages more potently than that of a conjugate lacking the disulfide moiety. Notably, successful clearance of Mycobacterium tuberculosis within macrophages was observed with the dual antibiotic conjugate, and Salmonella levels were significantly reduced in an in vivo Caenorhabditis elegans model.

Structure and solution-state conformation of botcinolide, a new biologically active metabolite from the fungus Botrytis cinerea

Abstract The structure of botcinolide, a new, phytotoxic, trihydroxlated nona-lactone, esterified with 4-hydroxy-2-octenoic acid, has been elucidated using both spectroscopic and chemical techniques. Botcinolide is a metabolite of the mould Botrytis cinerea (UK185RRC)

NITRATION OF CYCLOPENTENECARBOXALDEHYDE : STUDIES TOWARD 1-AMINO-2-NITROCYCLOPENTANECARBOXYLIC ACID

Abstract The formation of 2,2-dinitrocyclopentanone oxime is described during an attempted nitroacetamidation of cyclopentenecarboxaldehyde using ceric ammonium nitrate and sodium nitrite in acetonitrile. Progress towards the total synthesis of 1-amino-2-nitrocyclopentanecarboxylic acid is also discussed.