Research

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309 KiB

Open AccessArticle

Synthesis and Characterization of New Thieno[3,2-b]thiophene Derivatives

by Moawia O. Ahmed, Wojciech Pisula and Subodh G. Mhaisalkar

Molecules 2012, 17(10), 12163-12171; https://doi.org/10.3390/molecules171012163 - 16 Oct 2012

Cited by 16 | Viewed by 7330

Three derivatives of thieno[3,2-b]thiophene end-capped with phenyl units have been synthesized and characterized by MALDI TOF mass spectroscopy, elemental analysis, UV-vis absorption spectroscopy and thermogravimetric analysis (TGA). All compounds were prepared using Pd-catalyzed Stille or Suzuki coupling reactions. Optical measurements and [...] Read more.

Three derivatives of thieno[3,2-b]thiophene end-capped with phenyl units have been synthesized and characterized by MALDI TOF mass spectroscopy, elemental analysis, UV-vis absorption spectroscopy and thermogravimetric analysis (TGA). All compounds were prepared using Pd-catalyzed Stille or Suzuki coupling reactions. Optical measurements and thermal analysis revealed that these compounds are promising candidates for p-type organic semiconductor applications. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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508 KiB

Open AccessArticle

Artificial Self-Sufficient P450 in Reversed Micelles

by Hidehiko Hirakawa, Noriho Kamiya, Yutaka Kawarabayasi and Teruyuki Nagamune

Molecules 2010, 15(5), 2935-2948; https://doi.org/10.3390/molecules15052935 - 27 Apr 2010

Cited by 5 | Viewed by 9188

Abstract

Cytochrome P450s are heme-containing monooxygenases that require electron transfer proteins for their catalytic activities. They prefer hydrophobic compounds as substrates and it is, therefore, desirable to perform their reactions in non-aqueous media. Reversed micelles can stably encapsulate proteins in nano-scaled water pools in [...] Read more.

Cytochrome P450s are heme-containing monooxygenases that require electron transfer proteins for their catalytic activities. They prefer hydrophobic compounds as substrates and it is, therefore, desirable to perform their reactions in non-aqueous media. Reversed micelles can stably encapsulate proteins in nano-scaled water pools in organic solvents. However, in the reversed micellar system, when multiple proteins are involved in a reaction they can be separated into different micelles and it is then difficult to transfer electrons between proteins. We show here that an artificial self-sufficient cytochrome P450, which is an enzymatically crosslinked fusion protein composed of P450 and electron transfer proteins, showed micelle-size dependent catalytic activity in a reversed micellar system. Furthermore, the presence of thermostable alcohol dehydrogenase promoted the P450-catalyzed reaction due to cofactor regeneration. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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477 KiB

Open AccessArticle

Synthesis of a Novel Fluorescent Sensor Bearing Dansyl Fluorophores for the Highly Selective Detection of Mercury (II) Ions

by Nantanit Wanichacheva, Supranee Watpathomsub, Vannajan Sanghiran Lee and Kate Grudpan

Molecules 2010, 15(3), 1798-1810; https://doi.org/10.3390/molecules15031798 - 12 Mar 2010

Cited by 30 | Viewed by 8848

Abstract

A new macromolecule possessing two dansyl moieties and based on 2-[4-(2-aminoethylthio)butylthio]ethanamine was prepared as a fluorescent sensor and its mercury sensing properties toward various transition metal, alkali, and alkali earth ions were investigated. The designed compound exhibited pronounced Hg²⁺-selective ON-OFF type [...] Read more.

A new macromolecule possessing two dansyl moieties and based on 2-[4-(2-aminoethylthio)butylthio]ethanamine was prepared as a fluorescent sensor and its mercury sensing properties toward various transition metal, alkali, and alkali earth ions were investigated. The designed compound exhibited pronounced Hg²⁺-selective ON-OFF type fluorescence switching upon binding. The new compoundprovided highly selective sensing to Hg²⁺in acetonitrile-water solvent mixtures with a detection limit of 2.49 x 10^{-7 M or 50 ppb.}The molecular modeling results indicated that ions-recognition of the sensor originated from a self assembly process of the reagentand Hg²⁺ to form a helical wrapping structure with the favorable electrostatic interactions of Hg²⁺coordinated with sulfur, oxygen, nitrogen atoms and aromatic moieties. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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906 KiB

Open AccessArticle

Polysaccharides Coatings on Medical-Grade PVC: A Probe into Surface Characteristics and the Extent of Bacterial Adhesion

by Ahmad Asadinezhad, Igor Novák, Marián Lehocký, František Bílek, Alenka Vesel, Ita Junkar, Petr Sáha and Anton Popelka

Molecules 2010, 15(2), 1007-1027; https://doi.org/10.3390/molecules15021007 - 23 Feb 2010

Cited by 78 | Viewed by 12781

Abstract

Medical-grade polyvinyl chloride was coated by polysaccharides through a novel physicochemical approach. An initial surface activation was performed foremost via diffuse coplanar surface barrier discharge plasma in air at ambient temperature and pressure. Then, radical graft copolymerization of acrylic acid through grafting-from pathway [...] Read more.

Medical-grade polyvinyl chloride was coated by polysaccharides through a novel physicochemical approach. An initial surface activation was performed foremost via diffuse coplanar surface barrier discharge plasma in air at ambient temperature and pressure. Then, radical graft copolymerization of acrylic acid through grafting-from pathway was directed to render a well-defined brush of high density, and finally a chitosan monolayer and chitosan/pectin alternating multilayer were bound onto the functionalized surfaces. Surface characteristics were systematically investigated using several probe techniques. In vitro bacterial adhesion and biofilm formation assays indicated that a single chitosan layer was incapable of hindering the adhesion of a Staphylococcus aureus bacterial strain, while up to 30% reduction was achieved by the chitosan/pectin layered assembly. On the other hand, chitosan and chitosan/pectin multilayer could retard Escherichia coli adhesion by 50% and 20%, respectively. Furthermore, plasma treated and graft copolymerized samples were also found effective to diminish the degree of adherence of Escherichia coli. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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266 KiB

Open AccessArticle

Mechanism of Introduction of Exogenous Genes into Cultured Cells Using DEAE-Dextran-MMA Graft Copolymer as Non-Viral Gene Carrier

by Yuki Eshita, Junko Higashihara, Masayasu Onishi, Masaaki Mizuno, Jun Yoshida, Tomohiko Takasaki, Naoji Kubota and Yasuhiko Onishi

Molecules 2009, 14(7), 2669-2683; https://doi.org/10.3390/molecules14072669 - 23 Jul 2009

Cited by 18 | Viewed by 17012

Abstract

Comparative investigations were carried out regarding the efficiency of introduction of exogenous genes into cultured cells using a cationic polysaccharide DEAE-dextran-MMA (methyl methacrylate ester) graft copolymer (2-diethylaminoethyl-dextran-methyl methacrylate graft copolymer; DDMC) as a nonviral carrier for gene introduction. The results confirmed that the [...] Read more.

Comparative investigations were carried out regarding the efficiency of introduction of exogenous genes into cultured cells using a cationic polysaccharide DEAE-dextran-MMA (methyl methacrylate ester) graft copolymer (2-diethylaminoethyl-dextran-methyl methacrylate graft copolymer; DDMC) as a nonviral carrier for gene introduction. The results confirmed that the gene introduction efficiency was improved with DDMC relative to DEAE-dextran. Comparative investigations were carried out using various concentrations of DDMC and DNA in the introduction of DNA encoding luciferase (pGL3 control vector; Promega) into COS-7 cells derived from African green monkey kidney cells. The complex formation reaction is thought to be directly proportional to the transformation rate, but the complex formation reaction between DDMC and DNA is significantly influenced by hydrophobic bonding strength along with hydrogen bonding strength and Coulomb forces due to the hydrophobicity of the grafted MMA sections. It is thought that the reaction is a Michaelis-Menten type complex formation reaction described by the following equation: Complex amount = K1 (DNA concentration)(DDMC concentration). In support of this equation, it was confirmed that the amount of formed complex was proportional to the RLU value. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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323 KiB

Open AccessArticle

Electronic Structure of the Azide Group in 3¢-Azido-3¢-deoxythymidine (AZT) Compared to Small Azide Compounds

by Fang-Fang Chen and Feng Wang

Molecules 2009, 14(7), 2656-2668; https://doi.org/10.3390/molecules14072656 - 22 Jul 2009

Cited by 36 | Viewed by 18493

Abstract

Theoretical calculations for some structural and electronic properties of the azide moiety in the nucleoside reverse transcriptase (RT) inhibitor 3¢-azido-3¢-deoxythymidine (AZT) are reported. These properties, which include geometrical properties in three dimensional space, Hirshfeld charges, electrostatic potential (MEP), vibrational frequencies, and core and [...] Read more.

Theoretical calculations for some structural and electronic properties of the azide moiety in the nucleoside reverse transcriptase (RT) inhibitor 3¢-azido-3¢-deoxythymidine (AZT) are reported. These properties, which include geometrical properties in three dimensional space, Hirshfeld charges, electrostatic potential (MEP), vibrational frequencies, and core and valence ionization spectra, are employed to study how the azide group is affected by the presence of a larger fragment. For this purpose, two small but important organic azides, hydrazoic acid and methyl azide, are also considered. The general features of trans Cs configuration for RNNN fragments[1] is distorted in the large AZT bio-molecule. Hirshfeld charge analysis shows charges are reallocated more evenly on azide when the donor group R is not a single atom. Infrared and photoelectron spectra reveal different aspects of the compounds. In conclusion, the electronic structural properties of the compounds depend on the specific property, the local structure and chemical environment of a species. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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137 KiB

Open AccessArticle

Synthesis of a Diamino Substituted Terphenyldivinyl Chromophore

by Zhen-Ting Du, Ru Liu, Jun-Ru Wang and An-Pai Li

Molecules 2009, 14(6), 2111-2117; https://doi.org/10.3390/molecules14062111 - 10 Jun 2009

Cited by 3 | Viewed by 11695

Abstract

(E,E)-1,4-bis(4'-aminostyryl)-2,5-bis(octyloxy)-benzene (6) and its derivative (E,E)-1,4-bis(4'-acetamidostyryl)-2,5-bis(octyloxy)-benzene (7) were synthesized and characterized after alkylation, bromomethylation, Horner-Emmons reaction and reduction from hydroquinone. In order to gain more molecular electronic data, HOMO and LUMO of compound 6 have been calculated by Gaussian 03 W. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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Review

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244 KiB

Open AccessReview

Processing of Polymer Nanocomposites Reinforced with Polysaccharide Nanocrystals

by Alain Dufresne

Molecules 2010, 15(6), 4111-4128; https://doi.org/10.3390/molecules15064111 - 08 Jun 2010

Cited by 246 | Viewed by 16845

Abstract

Aqueous suspensions of polysaccharide (cellulose, chitin or starch) nanocrystals can be prepared by acid hydrolysis of biomass. The main problem with their practical use is related to the homogeneous dispersion of these nanoparticles within a polymeric matrix. Water is the preferred processing medium. [...] Read more.

Aqueous suspensions of polysaccharide (cellulose, chitin or starch) nanocrystals can be prepared by acid hydrolysis of biomass. The main problem with their practical use is related to the homogeneous dispersion of these nanoparticles within a polymeric matrix. Water is the preferred processing medium. A new and interesting way for the processing of polysaccharide nanocrystals-based nanocomposites is their transformation into a co-continuous material through long chain surface chemical modification. It involves the surface chemical modification of the nanoparticles based on the use of grafting agents bearing a reactive end group and a long compatibilizing tail. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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333 KiB

Open AccessReview

Bacterial Extracellular Polysaccharides Involved in Biofilm Formation

by Barbara Vu, Miao Chen, Russell J. Crawford and Elena P. Ivanova

Molecules 2009, 14(7), 2535-2554; https://doi.org/10.3390/molecules14072535 - 13 Jul 2009

Cited by 848 | Viewed by 45858

Abstract

Extracellular polymeric substances (EPS) produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids and humic substances. EPS make up the intercellular space of microbial aggregates and form the structure and architecture of [...] Read more.

Extracellular polymeric substances (EPS) produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids and humic substances. EPS make up the intercellular space of microbial aggregates and form the structure and architecture of the biofilm matrix. The key functions of EPS comprise the mediation of the initial attachment of cells to different substrata and protection against environmental stress and dehydration. The aim of this review is to present a summary of the current status of the research into the role of EPS in bacterial attachment followed by biofilm formation. The latter has a profound impact on an array of biomedical, biotechnology and industrial fields including pharmaceutical and surgical applications, food engineering, bioremediation and biohydrometallurgy. The diverse structural variations of EPS produced by bacteria of different taxonomic lineages, together with examples of biotechnological applications, are discussed. Finally, a range of novel techniques that can be used in studies involving biofilm-specific polysaccharides is discussed. Full article

(This article belongs to the Special Issue Macromolecules: Chemistry, Medicinal and Functional Materials)

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