Surface nano-structured materials to control bacterial contamination
The spread of bacteria and infections, initially associated with an increased number of hospital-acquired infections, has now extended into the community causing severe and difficult to treat diseases. Additionally, many of those diseases are evoked by bacteria that have become resistant to antibiot...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/398122 |
| Acceso en línea: | http://hdl.handle.net/10803/398122 https://dx.doi.org/10.5821/dissertation-2117-98108 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria química 615 66 |
| Sumario: | The spread of bacteria and infections, initially associated with an increased number of hospital-acquired infections, has now extended into the community causing severe and difficult to treat diseases. Additionally, many of those diseases are evoked by bacteria that have become resistant to antibiotics. Overcoming the ability of bacteria to develop resistance will potentially reduce the burden of these infections on the healthcare systems worldwide and prevent thousands of deaths each year. The nano-scale particles are promising candidates to fight bacteria, since developing of resistance to their action is less likely to occur. Nanoparticles (NPs) can be incorporated into polymeric matrices to design a wide variety of nanocomposites. Such nano-structures consisting of inorganic and inorganic/organic NPs represent a novel class of materials with a broad range of applications. This thesis is about the development of antibacterial nano-structured materials aimed at preventing the spread of bacteria. To achieve this, two versatile physicochemical and biotechnological tools, namely sonochemistry and biocatalysis were innovatively combined. Ultrasound irradiation used for the generation of various nano-structures and its combination with biocatalysts (enzymes) opens new perspectives in materials processing, here illustrated by the production of NPs coated medical textiles, water treatment membranes and chronic wound dressings. The first part of the thesis aims at the development of antibacterial medical textiles to prevent the bacteria transmission and proliferation using two single step approaches for antibacterial NPs coating of textiles. In the first approach antibacterial zinc oxide NPs (ZnO NPs) and chitosan (CS) were deposited simultaneously on cotton fabric by ultrasound irradiation. The obtained hybrid NPs coatings demonstrated durable antibacterial properties after multiple washing cycles. Moreover, the presence of biopolymer in the NP hybrids improved the biocompatibility of the material in comparison with ZnO NPs coating alone. In the second approach, a simultaneous sonochemical/enzymatic process for durable antibacterial coating of cotton with ZnO NPs was carried out. The enzymatic treatment provides better adhesion of the ZnO NPs and, as a consequence, enhanced coating stability during exploitation. Likewise to the antibacterial coatings obtained in the first approach, the antibacterial efficiency of these textiles was maintained after multiple intensive laundry regimes used in hospitals. The NPs-coated cotton fabrics inhibited the growth of the most medically relevant bacteria species. In the second part of the thesis, hybrid antibacterial biopolymer/silver NPs and cork matrices, were enzymatically assembled into an antimicrobial material with potential for water remediation. Intrinsically antibacterial amino-functional biopolymers, namely CS and aminocellulose were used as doping agents to stabilize colloidal dispersions of silver NPs (AgNPs), additionally providing the particles with functionalities for covalent immobilization on cork to impart durable antibacterial effect. The biopolymers promoted the antibacterial efficacy of the obtained nanocomposites in conditions simulating a real situation in constructed wetlands. In the last, third part of the thesis, a bioactive nanocomposite hydrogel for wound treatment was developed. Sonochemically synthesized epigallocatechin gallate nanospheres (EGCG NSs) were incorporated and simultaneously crosslinked enzymatically into a thiolated chitosan hydrogel. The potential of the generated material for chronic wound treatment was evaluated by assessing its antibacterial properties and inhibitory effect on myeloperoxidase and collagenase biomarkers of chronic wound infection. Sustained release of the EGCG NSs from the biopolymer matrix was achieved. The latter, coupled with the good biocompatibility of the hydrogel, suggested its potential for chronic wound management. |
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