Recently, there is a need of alternatives to antibiotics due to increasing antibiotic-resistant microorganism. Promising classes of bioactive polymers are 6-deoxy-6-amino cellulose derivatives. The purpose of the stud...Recently, there is a need of alternatives to antibiotics due to increasing antibiotic-resistant microorganism. Promising classes of bioactive polymers are 6-deoxy-6-amino cellulose derivatives. The purpose of the study was the assessment of the biocompatibility of 6-deoxy-6-aminoethyleneamino cellulose (AEAC) with different degree of substitution (DS). HaCaT keratinocyte cell viability was analyzed by measuring the cellular ATP content. The antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae was examined by microplate laser nephelometry. Thus, the ratio of half-maximal lethal concentration (LC50) and half-maximal inhibitory concentration (IC50) was calculated and described as biocompatibility index. The study revealed that biocompatibility of AEAC depends on the DS. AEAC of low DS (0.3) showed the best biocompatibility.展开更多
Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Har...Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.展开更多
文摘Recently, there is a need of alternatives to antibiotics due to increasing antibiotic-resistant microorganism. Promising classes of bioactive polymers are 6-deoxy-6-amino cellulose derivatives. The purpose of the study was the assessment of the biocompatibility of 6-deoxy-6-aminoethyleneamino cellulose (AEAC) with different degree of substitution (DS). HaCaT keratinocyte cell viability was analyzed by measuring the cellular ATP content. The antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae was examined by microplate laser nephelometry. Thus, the ratio of half-maximal lethal concentration (LC50) and half-maximal inhibitory concentration (IC50) was calculated and described as biocompatibility index. The study revealed that biocompatibility of AEAC depends on the DS. AEAC of low DS (0.3) showed the best biocompatibility.
基金supported by the Fonds der Chemischen Industrie and Deutsche Forschungsgemeinschaft (Mu 1088/9-1)
文摘Expanded 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes with variable substitution pattern on the peripheral thiophene ring were synthesized in moderate to very good yields by Suzuki and Buchwald-Hartwig coupling of the corresponding brominated 3-ethynyl quinoxalines. Dumbbell-shaped bis(thienyl 3-ethynyl quinoxalines) are also accessible by the Suzuki protocol. The photophysical properties were investigated by UV and fluorescence spectroscopy. Most of the obtained compounds display fluorescence in solution and some of them also in the solid state. Additionally, tuning of the emission color of the quinoxaline based chromophores can be conveniently accomplished by the remote substituent group. The determined absorption and emission maximum as well as the Stokes shifts strongly correlate with Hammett σp+parameters. Besides,photophysical properties of selected derivatives in the solid state, biphasic solutions, and PMMA films, along with their relationships, are comparatively investigated. Moreover, two 5-(hetero)aryl-thien-2-yl substituted 3-ethynyl quinoxaline dyes are aggregation induced emission(AIE) chromophores indicated by restriction of molecular motions. A covalently restricted 3-ethynyl quinoxaline supports that the inhibition of molecular rotation is responsible for the significant enhancement of fluorescence in acetonitrile/water mixtures.
