Iskanje po katalogu digitalne knjižnice

Opis: In this study, we explored the development of cationized 2-hydroxyethyl cellulose (HEC) and succinylated polyallylamine (PAA) in conjunction with polyvinyl alcohol (PVA) for potential applications as antimicrobial wound dressings. Quaternary ammonium compounds are known for their broad-spectrum antimicrobial properties against both Gram-negative and Gram-positive bacteria, but their non-selectivity can lead to high cytotoxicity. To improve the biocompatibility of the cationic materials investigates two distinct approaches. The first approach involves reducing the cationic nature of protonated PAA at a pH below 8.3 through amidation reaction with succinic anhydride. Gradual reduction of the cationic charge is achieved by varying the molar ratios of succinic anhydride during the reaction process. Notably, this reaction can be carried out in an aqueous solution, eliminating potential issues associated with solvent removal. The second part of this thesis focuses on introducing cationic charge by covalently binding naturally occurring quaternary ammonium compounds, such as betaine hydrochloride (BET HCl), choline chloride (ChCl), and carnitine hydrochloride (carnitine). Using 1,1′-carbonyldiimidazole (CDI), we quaternized HEC in anhydrous DMSO, with a detailed investigation of the reaction mechanism by isolating and characterizing intermediate products. This same procedure was applied to form a cationic dimer between BET HCl and ChCl. The chemical structures of the resulting materials were characterized using attenuated total reflectance infrared spectroscopy (ATR-IR) and nuclear magnetic resonance (NMR). The quantification of cationic and total charge was determined through polyelectrolyte and potentiometric titration, respectively. While succinylated PAA exhibited the anticipated biological properties associated with the reduction of cationic characteristics, the same behaviour was not observed for quaternized materials. High cytotoxicity and low antimicrobial properties in the derivatized HEC may be attributed to inadequate purification and the sensitivity of fibroblasts. We produced electrospun non-woven mats incorporating PVA and these derived materials using a single-needle electrospinning machine. The average diameter of the fibres was determined through scanning electron microscopy (SEM) images. Despite the cytotoxicity and the absence of significant antimicrobial properties in these materials, they exhibit potential as effective cationic flocculants for wastewater treatment. Further investigations are pending to address purification issues and make slight adjustments to the procedure to potentially scale up production. These materials still hold promise for applications in both biomedical and environmental chemistry.
Ključne besede: cellulose, quaternary ammonium compounds, antimicrobial, cytotoxicity, electrospinning
Objavljeno v DKUM: 11.07.2024; Ogledov: 127; Prenosov: 28
Celotno besedilo (16,36 MB)

Opis: Electrospinning is a method based on the use of electrostatic forces for producing continuous fibres with the diameter from between ten nanometres to some micrometres. Such fine fibres cannot be produced with conventional methods for the production of nonwovens. The nanofibres formed with electrospinning have an exceptionally large active surface area per mass unit (fibre surface at diameter of 100 nm equals 40 $m^2$/g) and the spinning process itself enables a planned formation of the web structure (e.g. planned size of pores in the web by adjusting the nanofibre diameter and fibre thickness). Nanofibres can be electrospun from synthetic or natural polymers and their blends, from polymers with various nanoparticles (metal, ceramic etc), active substances etc. We can fabricate individual fibres, as well as webs with a random or planned fibre arrangement. Fibres with a complex structure, e.g. core shell or hollow fibres, can be produced with a special electrospinning method. Regarding the advantages demonstrated by the nanofibres fabricated with electrospinning, this procedure has become an important part of research in seve ral fields of use of technical textiles, e.g. shielding materials, air and oil filters in the car industry, agrotextiles and most of all medical textiles. The method can also be used in the production of batteries and photovoltaic cells. Apart from the apparatus designed for the research purpose in laboratories, pilot devices and the devices designed for the use in the industry can be found on the market. The paper comprises the introduction of the preparation procedure of nanofibres on an electrospinning apparatus, the morphological characteristics of fibres and the characteristics of electrospun webs in dependence of the conditions when forming fibres.
Ključne besede: nanotechnology, nanofibres, electrospinning, 3D-structure
Objavljeno v DKUM: 10.07.2015; Ogledov: 1941; Prenosov: 100
Celotno besedilo (290,78 KB)
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