1. Effect of peptides' binding on the antimicrobial activity and biocompatibility of protein-based substrates Maja Kaisersberger Vincek, 2017, doktorska disertacija Opis: This work reveals the effect of coupling approach (chemical by using carbodiimide chemistry and grafting-to vs. grafting-from synthesis routes, and enzymatic by using transglutaminase) of a hydrophilic ε-poly-L-lysine (εPL) and an amphiphilic oligo-acyl-lysyl (OAK) derivative (K-7α12-OH) to wool fibers and gelatine (GEL) macromolecules, respectively, and substrates antibacterial activity against Gram-negative E. coli and Gram-positive S. aureus bacteria after 1–24 h of exposure, as well as their cytotoxicity. Different spectroscopic (ultraviolet-visible, infrared, fluorescence and electron paramagnetic resonance) and separation techniques (size-exclusion chromatography and capillary zone electrophoresis) as well as zeta potential and potentiometric titration analysis, were performed to confirm the covalent coupling of εPL/OAK, and to determine the amount and orientation of its immobilisation.
The highest and kinetically the fastest level of bacterial reduction was achieved with wool/GEL functionalised with εPL/OAK by chemical grafting-to approach. This effect correlated with both the highest grafting yield and conformationally the highly-flexible (brush-like) orientation linkage of εPL/OAK, implicating on the highest amount of accessible amino groups interacting with bacterial membrane. However, OAK`s amphipathic structure, the cationic charge and the hydrophobic moieties, resulted to relatively high reduction of S. aureus for grafting-from and the enzymatic coupling approaches using OAK-functionalised GEL.
The εPL/OAK-functionalised GEL did not induce toxicity in human osteoblast cells, even at ~25-fold higher concentration than bacterial minimum inhibitory (MIC) concentration of εPL/OAK, supporting their potential usage in biomedical applications.
It was also shown that non-ionic surfactant adsorbs strongly onto the wool surface during the process of washing, thereby blocking the functional sites of immobilized εPL and decreases its antibacterial efficiency.
Ključne besede: wool, gelatine, antimicrobial peptides, ε-poly-L-lysine, oligo-acyl-lysyl, grafting chemistry, grafting approach, peptide orientation, antibacterial activity, cytotoxicity
Objavljeno v DKUM: 17.08.2017; Ogledov: 1931; Prenosov: 178
 Celotno besedilo (3,98 MB) |
2. Grafting of ethylcellulose microcapsules onto cotton fibresRoxana Badulescu, Vera Vivod, Darja Jaušovec, Bojana Vončina, 2008, izvirni znanstveni članek Opis: In this paper a treatment of cotton with ethylcellulose (EC) microcapsules wasinvestigated. EC microcapsules containing Rosemary oil were obtained by phase separation method. The surface and morphology of microcapsules were characterized by scanning electron microscopy (SEM). Microcapsules with a regular spherical shape in the 10-90 m size range were prepared and grafted onto cotton using the crosslinking reagent 1,2,3,4-butanetetracarboxylic acid (BTCA) in the presence of catalysts. The influence of the two catalysts, cyanamide (CA) and N,N'-dicyclohexylcarbodiimide (DCC) on curing efficiency (grafting) was investigated. SEM and Fourier transform infrared spectroscopy (FT-IR) were used to study the formation of ester bonds between BTCA and hydroxyl groups of cotton and/or hydroxyl groups of EC. When DCC was used as acatalyst, the esterification took place slowly at room temperature. In the case of CA, the cotton was cured at 110 °C for several minutes. After 2 min curing, the microcapsules, which kept their original shape, were bonded to thecotton fibers. Increasing the curing time altered the microcapsule shell. Grafting and crosslinking reactions of the thermofixed EC microcapsules onto cotton were proposed.
Ključne besede: textiles, chemical modification, cotton fibres, ethylcellulose, microcapsules, BTCA, SEM, FT-IR, grafting
Objavljeno v DKUM: 01.06.2012; Ogledov: 2211; Prenosov: 43
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4. Tyrosinase catalysed coupling of functional molecules onto protein fibresSuzana Jus, Vanja Kokol, Georg M. Gübitz, 2008, izvirni znanstveni članek Opis: Grafting, using oxidative enzymes shows a high potential for wool fibres funktionalisation. In this work we attempt to graft on wool fibres with phenolic antioxidants order to introduce and improve the properties of the fibre. The approach of tyrosinase to oxidize tyrosine residues in wool proteins to quinones, which can further react with free sulfhydryl (thiol), amino or phenolic groups of different substrates was exploited to couple different phenolic antioxidants (caffeic acid and chlorogenic acid) onto the wool fibre proteins. Tyrosinase catalysed reactions were followed by different analytical methods like oxygen consumption, FT-NIR Raman and UV/VIS spectroscopy. It was proved that phenolic compounds used are strongly cross-linked on the wool fibre resulting to an improved antioxidant activity.
Ključne besede: textile fibres, wool fibers, tyrosinase, caffeic acid, chlorogenic acid, grafting, chemical modification of fibres
Objavljeno v DKUM: 31.05.2012; Ogledov: 2100; Prenosov: 101
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