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Medical Applications. (medical + applications)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Iron(III) Chelation: Tuning of the pH Dependence by Mixed Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2003
Anne-Marie Albrecht-Gary
Abstract The iron(III) chelating properties of two heteropodands with 8-hydroxyquinoline and catechol binding groups were examined and compared to those of the corresponding homopodal analogues, O-TRENSOX and TRENCAMS. Like the parent homopodands, the two heteropodands are based on the TREN scaffold and the chelating units are connected by amide groups, TRENSOX2CAMS having two 8-hydroxyquinoline and one catechol arms and TRENSOXCAMS2 one 8-hydroxyquinoline and two catechol moieties. The aqueous coordination chemistry of these ligands was examined by potentiometric and spectrophotometric methods in combination with 1H NMR spectroscopy. The respective pFeIII values showed a cooperative effect of the mixed chelating units. Moreover, the pFeIII dependence on pH showed that the mixed ligands exhibit a higher complexing ability than the parent ligands over the pH range 5,9 which is of biological relevance. This result could be of great interest for medical applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

The Synthesis of the Dimethyl Ester of Quino[4,4a,5,6- efg]-Annulated 7-Demethyl-8-deethylmesoporphyrin and Three of Its Isomers with Unprecedented peri -Condensed Quinoline Porphyrin Structures.

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2004
Molecules with Outstanding Properties as Sensitizers for Photodynamic Therapy in the Far-Red Region of the Visible Spectrum
Abstract The mesoporphyrin dimethyl ester nickel complex has been formylated via the Vilsmeier method. The four possible mono meso-formyl derivatives were isolated and characterized. Wadsworth,Emmons coupling with the anion of (diethylphosphono)acetonitrile converted these aldehydes into the four novel meso acrylonitriles. Brief treatment of these acrylonitrile systems in hot trichloroacetic acid resulted in the formation of four achiral porphyrin derivatives with unprecedented nickel complexes of quino-fused porphyrins. Subsequent removal of the nickel gave four quino-porphyrin free bases: quino[4,4a,5,6- efg]-annulated 7-demethyl-8-deethylmesoporphyrin dimethyl ester 6a, 2,-(methoxycarbonyl)quino[4,4a,5,6- jkl]-annulated 12-demethyl-13-de[2,-(methoxycarbonyl)ethyl]mesoporphyrin dimethyl ester 6b, 2,-(methoxycarbonyl)quino[4,4a,5,6- qrs]-annulated 18-demethyl-17-de(2,-methoxycarbonylethyl)mesoporphyrin dimethyl ester 6c and quino[4,5,6,7- abt]-annulated 2-demethyl-3-deethylmesoporphyrin dimethyl ester 6d. The structures of these systems were unambiguously determined via mass spectroscopy and a plethora of NMR techniques. In the same way, etioporphyrin and octaethylporphyrin were converted into the corresponding peri -condensed quinoporphyrins as products, which shows that the formation of novel pericondensed quino-porphyrins is a general reaction in the porphyrin series and will have a wide scope in this field. Also, a plausible reaction mechanism for the formation of the quinoporphyrin systems was derived. As a first test for the use of these systems as sensitizers in far-red phototherapy, the quantum yield of singlet oxygen generation by 6a in toluene was studied. This quantum yield is 0.77, which is even higher than the singlet oxygen generation by sensitized meso-tetraphenylporphyrin. Secondly, when Chinese Hamster ovary (CHO) cells were incubated in medium which contained up to 15 ,g/ml of 6a, the survival rate of the cells in the dark is complete within experimental error, showing that under these conditions, 6a is not toxic to CHO cells. When CHO cells incubated in medium containing 6a in concentrations of 1 ,g/ml and higher were treated with white light of intensity 30 mW/cm2 for 15 minutes, complete cell death was observed. Based on these facts, we expect that all four achiral systems will show very promising properties to form the basis of a photodynamic therapy in far-red light. The fact that these systems are achiral is an additional bonus for medical applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Novel interpenetrating networks with shape-memory properties

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2007
Shifeng Zhang
Abstract Novel polyesterurethane/poly(ethylene glycol) dimethacrylate (PEGDMA) interpenetrating networks (IPNs) with good shape-memory properties were synthesized using solvent casting method. The star-shaped oligo[(rac -lactide)- co -glycolide] was coupled with isophorone diisocyanate to form a polyesterurethane network (PULG), and PEGDMA was photopolymerized to form another polyetheracrylate network. IPNs were transparent and gel content exceeded 92%. The values of strain fixity rate and strain recovery rate were above 93%. PULG and PEGDMA networks in IPNs were amorphous and did not show any characteristic diffraction peaks in X-ray diffraction spectra. Only one glass transition temperature (Tg) of the IPNs between Tg of PEGDMA and PULG was observed, which was proportional to PEGDMA content. PULG and PEGDMA networks were miscible when PEGDMA content was below 50 wt %. The hydrophilicity, transition temperatures, and mechanical properties of IPNs could be conveniently adjusted through variation of network compositions to match the promising potential clinical or medical applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 768,775, 2007 [source]

Soyprotein fibers with high strength and water stability for potential medical applications

BIOTECHNOLOGY PROGRESS, Issue 6 2009
Narendra Reddy
Abstract Fibers with mechanical properties and water stability suitable for tissue engineering have been developed from soyproteins. Proteins are biocompatible and biodegradable and are preferred over synthetic polymers for medical applications. Although plant proteins are abundant and inexpensive and can be made into various types of scaffolds, very few attempts have been made to understand the suitability of using plant proteins for medical applications, especially as fibrous substrates for tissue engineering. So far, it has not been able to obtain good quality soyprotein fibers without using toxic crosslinking agents or blending soyprotein with synthetic polymers. In this research, we have developed 100% soyprotein fibers with good strength and water stability without using any external crosslinking agents. The soyprotein fibers have better wet strength than collagen fibers and are conducive to the attachment, growth, and proliferation of mouse fibroblasts. Fibers are better substrates than films for growth and orientation of cells and are therefore preferable for tissue engineering applications. Soyprotein fibers show good potential to be novel biomaterials with properties suitable for tissue engineering and other medical applications. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]