Iskanje po katalogu digitalne knjižnice

Opis: The aim of this dissertation was to develop a novel medical tampon for alternative gynaecological treatment using chitosan nanoparticles as an antimicrobial agent or as a drug delivery system. For this purpose viscose tampon band was used and functionalized with chitosan and trimethyl chitosan nanoparticles. A comprehensive of interactions between chitosan and cellulose as well as characterization of prepared materials were done. At the beginning, chitosan (CS) and trimethyl chitosan (TMC) solutions, as well as nanoparticles synthesised by ionic gelation were studied. Their characterization was focused on determining the charge and antimicrobial properties against common pathogenic microorganism. The influence of cationic charge on the inhibition of microbial growth was confirmed. Since CS and TMC solutions and nanoparticles dispersions exhibited antibacterial activity against Lactobacillus, a detailed investigation in chitosan’s antimicrobial mode of action was performed using a novel diffusion nuclear magnetic resonance (D-NMR). D-NMR allowed the monitoring of intra- and extracellular water exchange from the cells indicating the membrane alteration and leakage of intracellular constituencies. Further, in order to study the adsorption phenomena and molecular interactions between CS/TMC (solution or nanoparticles) and cellulose material, model cellulose surfaces were used, and adsorption was studied by quartz crystal microbalance with dissipation. CS and TMC were favourably deposited onto cellulose model surface at higher ionic strength, higher pH values, i.e. factors causing lower solubility, where the presence of electrostatic interactions was negligible and non-electrostatic interactions were dominant. The knowledge gained from the model surfaces was extremely helpful in characterization of real systems, i.e. functionalized cellulose fibres and for understanding the obtained results. Immobilization of CS and TMC (in the form of solution and/or nanoparticles) onto cellulose viscose fibres was confirmed with several analytical methods. The attachment of chitosan onto fibres was reversible, as endorsed with desorption studies mimicking the conditions of vaginal usage. Evaluation of antimicrobial properties was performed using two different techniques, both revealing a high inhibition of the tested microorganism. In addition, Lactobacillus susceptibility testing has shown that chitosan-coated fibres do not have any negative influence on the resident microbiota. Assessment of in-vitro cytotoxicity demonstrated that samples do not cause a cytotoxic effect in direct contact. Additionally, model drug was incorporated into chitosan nanoparticles and subsequently attached onto fibres in order to create modern, vaginal drug delivery systems. Antimicrobial medical textiles investigated in the scope of this dissertation show the potential for their exploitation in gynaecological field as preventive or curative treatment without triggering any adverse effects for the user.
Ključne besede: chitosan, N, N, N-trimethyl chitosan, nanoparticles, antimicrobial activity, cellulose model films, regenerated cellulose fibres, diffusion nuclear magnetic resonance, quartz crystal microbalance, vaginal infections, drug delivery systems, cytotoxicity
Objavljeno v DKUM: 13.02.2014; Ogledov: 3877; Prenosov: 194
Povezava na celotno besedilo

Opis: This chapter presents an overview of methods for cellulose fibres functionalization in order to introduce antimicrobial activity. In view the need for ecologically friendly textiles antimicrobial finishing is introduced, together with some strategies for the functionalization of fibres using biodegradable polysaccharides such as the use of chitosan. Additionally,the methods used for the microbiological testing of these fibres are discussed and the current disadvantages of these methods indicated. Moreover, a new strategy for a reliable methodology regarding the antimicrobial testing of oriented fibre-based polymers such as cellulose is discussed, which could also be useful within several other polymer industrial fields.
Ključne besede: anitmicrobial agents, medical textiles, cellulose fibres, microbiological test, antimicrobial efficiency
Objavljeno v DKUM: 01.06.2012; Ogledov: 2636; Prenosov: 54
Povezava na celotno besedilo

Opis: Trend pri razvoju inovativnih sanitetnih materialov ter medicinskih tekstilij je v funkcionalizaciji površine tekstilij z namenom pridobitve protimikrobnih lastnosti. Pri večini funkcionalizacijskih metod se še zmeraj uporabljajo reagenti, ki so človeku in okolju neprijazni. Zato iz dneva v dan narašča zanimanje za funkcionalizacijske postopke, pri katerih se uporabljajo okolju prijazni in biorazgradljivi reagenti. Eden izmed najperspektivnejših je hitozan, derivat hitina, ki je za celulozo drugi najbolj razširjen biopolimer na Zemlji. Žal pa ima hitozan, kljub številnim prednostim, tudi slabosti kot so omejena stabilnost in učinkovitost vezana na kisli pH medij. Zato je izrednega pomena poiskati ustrezen substitut za hitozan. Med številnimi polisaharidi je primeren kandidat derivat celuloze, aminoceluloza, ki vsebuje aminske skupine vzdolž polimerne verige. V diplomski nalogi smo tako površino viskoznih vlaken protimikrobno funkcionalizirali z uporabo hitozana in aminoceluloze. Pri tem smo uporabili dva mehanizma nanosa, klasično impregnacijo in depozicijo (vezavo koloidne raztopine polisaharida). Uspešnost funkcionalizacije smo spremljali s potenciometrično titracijo in spektrofotometrično metodo C.I. Acid Orange 7, kakor tudi z mikrobiološkim testiranjem. Rezultati obeh analiznih metod za določanje aminskih skupin dobro sovpadajo; korelacijski koeficient med njima znaša 0,949. Uporaba aminoceluloze, ne glede na princip nanosa, doprinese na površino vlaken znatno večjo količino aminskih skupin v primerjavi s hitozanom. Poleg tega je aminoceluloza pokazala učinkovito zatiranje patogene bakterije Escherichia coli, medtem ko je bil hitozan proti tej bakteriji popolnoma neučinkovit. Na podlagi dobljenih rezultatov smo potrdili našo hipotezo, da je aminoceluloza ustrezen substitut za hitozan. Postopek depozicije se je v primerjavi z impregnacijo izkazal kot učinkovitejši, v smislu doprinosa števila aminskih skupin in posledično boljše inhibicije patogenih mikroorganizmov.
Ključne besede: viskozna vlakna, hitozan, aminoceluloza, impregnacija, depozicija, protimikrobne lastnosti, potenciometrična titracija
Objavljeno v DKUM: 08.10.2009; Ogledov: 3729; Prenosov: 383
Celotno besedilo (1,62 MB)