Controlled release of an antimicrobial substance from polymeric matrices

Diedericks, Hanneke (2016-03)

Thesis (MSc)--Stellenbosch University, 2016

Thesis

ENGLISH ABSTRACT : The main goal of this study was to develop polymeric artifacts (nanofibers and films) infused with an antimicrobial agent, 2,3-dihydroxybenzoic acid and study the release of DHBA as a function of the structure and properties of selected polymers. The effect of hydrophilic and hydrophobic polymers on the release behavior was the main focus of this study. Four different polymers, poly (vinyl alcohol) (PVA), chitosan, poly (ethylene-co-vinyl alcohol) (EVOH) and poly (styrene-co-maleic anhydride) (SMA); all different in their hydrophilic-hydrophobic nature were used. Controlling the release of DHBA from these polymers have however not been investigated to our knowledge. Various parameters can influence the release of an agent from a matrix, which includes the type of polymer used and interactions between the polymer and the agent. To effectively study the release of DHBA from electrospun nanofibers, it was important for the different polymer nanofibers to have similar average fiber diameters. This was done by investigating the effect different electrospinning parameters has on the fiber diameter. Incorporation of DHBA into the polymer artifacts (films and nanofibers) was successful with minimum loss of the agent. Interaction between polymer and agent was confirmed using FTIR. The interaction can be ascribed to the size of the molecular structure of the polymers, the smaller molecules showed hydrogen bonding with the agent with the larger molecules, limited interaction was observed. Thermal analysis of the matrices was studied using techniques such as DSC and TGA. These results revealed changes in the stability of the DHBA-loaded matrices compared to the pure polymer matrix. These changes can be attributed to the interaction between the polymer and the agent. The release of DHBA from the films and nanofibers was investigated using UV spectroscopy. A burst release was observed which is explained by the type of polymer used. Although the burst release of this agent has been documented, the ability to control the release of DHBA has not been done. Controlling the release of DHBA from the films and nanofibers was done by a coating process. SEM and FTIR were used to confirm the successful coating of these nanofibers. These coated nanofibers showed retardation of the release of DHBA. The more hydrophilic polymer used showed the greatest effect on the release behavior. These results confirmed the effect the type of polymer used has on the release of DHBA.

AFRIKAANSE OPSOMMING : Die hoofdoel van hierdie studie was die ontwikkeling van polimeriese artifakte (films and nanovesels) gekombineer met ‗n antimikrobiese agent, 2,3-dihidroksibenzoësuur (DHBA) en die vrystelling van DHBA as ‗n funksie van die struktuur en eienskappe van gekiesde polimere. Die effek van hidrofiliese and hidrofobiese polimere op die vrystelling gedrag was die hooffokus van hierdie studie. Vier verskillende polimere, poliviniel alkohol (PVA), chitosan, poliëtileen (ko-viniel alkohol) (EVOH) en poli (stireen-ko-maleïen anhidried) (SMA), almal verskillend in hidrofiliese-hidrofobiese natuur is gebruik. Om die vrystelling van DHBA van die polimere te beheer was nog nie volgens ons kennis al gedoen nie. Verskeie parameters kan die vrystelling van die agent van ‗n matriks beïnvloed, dit sluit in die tipe polimeer en interaksies tussen die polimeer en die agent. Om die vrystelling van DHBA van die elektro-gespinde vesels effektief te bestudeer, is dit belangrik vir die verskillende polimeer vesels om soortgelyke gemiddelde vesel diameters te hê. Dit is gedoen deur die effek van verskillende elektrospin parameters op die vesel diameter te ondersoek. Inkorporasie van DHBA binne-in die polimeer artefakte was suksesvol met minimale verlies van die agent. Die interaksie tussen die polimeer en die agent is bevestig met fourier-transform infrarooi spektroskopie (FTIR). Die interaksie kan toegeskryf word aan die grootte van die molekulêre struktuur van die polimeer. Die kleiner molekules was deur waterstofbindings in interaksie met die agent, waar die interaksie beperk was met die groter molekules. Termiese analise van die matrikse is uitgevoer d.m.v. tegnieke soos differensieëlskandeerkalorimetrie (DSC) and termiese-gravimetriese analise (TGA). Die resultate wat verkry is het bewys dat daar verandering in die stabiliteit van die DHBA-gelaaide matrikse was in vergelyking met die skoon polimeer matriks. Die verandering kan toegeskryf word aan die interaksie tusen die polimeer en die agent. Die vrystelling van DHBA van die films en nanovesels is bestudeer d.m.v. ‗n UV spektroskoop. ‗n Gebarste vrystelling is opgemerk wat verduidelik is deur die tipe polimeer wat gebruik was. Alhoewel die gebarste vrystelling van hierdie agent al gedokumenteer is, is die vermoë om die vrystelling van DHBA te beheer nog nie gedoen nie. Die beheer van DHBA van die films en nanovesels is gedoen deur ‗n bedekking proses. Skandeerelektron spektroskopie (SEM) en FTIR is gebruik om die suksesvolle bedekking van die nanovesels te bevestig. Die bedekte nanovesels het retardasie van die vrystelling van DHBA getoon. Die meer hidrofiliese polimeer het die grootste effek op die vrystelling gedrag getoon. Hierdie resultate bevestig die effek wat die tipe polimeer op die vrystelling van DHBA het.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98759
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