Modification of Synthetic Polymeric Materials' Surface for Suppression of Biofilm Formation
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Date
2014-5-2
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Technická Univerzita v Liberci
Abstract
Nosokomiální infekce (NI) představují významný problém pro hospitalizované pacienty kde téměř polovina infekcí je zprostředkována nerůznějšími lékařskými nástroji. Tyto nástroje obsahují části nebo jsou celé z polymerních materiálů typu polyamidů (např. Nylon 6) a polyesterů (např. PET). Tyto polymery se běžně používají v řadě zavedených biomedicinských aplikací, jako jsou katetry, stenty, srdeční chlopně, krycí materiály pro popáleniny a řadu dalších pomocných materiálů. Modifikace povrchu těchto a dalších polymerů je jednou z možností jak upravovat vlastnosti a s nimi spojenou aplikovatelnost těchto biomedicinských materiálů. Vhodnou funkcionalizací povrchu lze dospět k matertiálům biokompatibilním, antibakteriálním, a/nebo rezistentním k tvorbě a ulpívání biofilmu. V první části byl rozpracován postup pro modifikaci povrchu polyesterů (konkretně PET) využívající reakci esterových funkcí s Grignardovými a organolitnými organokovovými činidly. Reakcí se do povrchové vrstvy vnáší hydroxylová skupina, ale zároveň i dva organické zbytky, odpovídající použitému organokovovém činidlu. Tím lze povrchovou vrstvu modifikovat v širokých mezích. Reakci lze monitorovat řadou technik, zde bylo využito měření kontaktního úhlu, volné povrchové energie, měření fluorescenční intenzity (po vhodném fluorescenčně aktivním označení účinkem dansyl chloridu). Vedle toho byly interpretována data SEM, AFM, i IČ analýz. Biologická aktivita modifikovaných povrchů byla testována na kmenech: Staphylococcus aureus, Escherichia coli, methicillin-resistentní Staphylococcus aureus (MRSA) a Pseudomonas aeruginosa. Biokompatibilita vyšší než 70 % byla zjištěna u některých materiálů s modifikovanou povrchovou vrstvou. Druhá část popisuje studii, jejíž podstatou je aplikace účinné redukce amidické funkce polyamidů (zde Nylon 6) účinkem diboranu a jeho komplexů. Tato reakce byla ihned následována funkcionalizací (alkylací) vznikajícího aminu. K tomu bylo využito benzyl chloridu (C6H5CH2Cl) a poly(ethylen glycol) methyl ether tosylátu (H3C-PEG-OTs). Volbou alkylačních činidel bylo možné měnit povrchové vlastnosti výchozích polyamidů v širokých mezích. Takto získaný modifikovaný Nylon 6 vykazoval zajímavé vlastnosti se silně potlačenou tvorbou biofilomu. Výsledné vlastnosti polymeru byly závislé nejen na použitém činidle, ale také na využitých reakčních podmínkách. Pro další funkcionalizaci byly využity i nanočástice Cu spontánně tvořící povlak na Nylonu 6. Byl vyzkoušen i jiný postup funkcionalizace redukovaného polyamidu účinkem N,N-disukcinimidyl karbonátu (DSC). Vlastnosti takto získaných modifikovaných povrchů byly testovány s využitím analogických metodik a postupů, které se osvědčily u polyesterů. Většina vzorků s modifikovanými povrchy byla shledána jako cytokompatibilní. Ve třetí části jsou popsány naše výsledky při syntéze Cu NPs, které byly využity pro funkcionalizace polyamidů. Vzniklé nanočastice byly charakterizovány s využitím běžných metod a postupů jako jsou: dynamický rozptyl světla (DLS), elektronová mikroskopie (SEM), UV-VIS a FT-IR spektroskopie.
Nosocomial infections (NI) have been serious problems for hospitalized patients where almost half of all the infections are device related. Various polymeric materials including polyesters and polyamides such as polyethylene terephthalate PET and Nylon 6 are widely utilized for clinical devices. These polymers are commonly used in biomedical applications ranging from catheters to stents, vascular grafts, heart valves, wound dressings, sutures and scaffolds. Polymer surface modification is very essential factor to improve and impart desired properties for biomedical applications, making the polymers biocompatible, non-cytotoxic and antibacterial that can preferably resist biofilm formation caused by pathogenic bacteria. At first, novel approach to anti-corrosive wet chemical surface modification of PET by insertion of alkyl and hydroxyl groups was achieved by using different Grignard reagents and confirmed by several different characterization techniques including water contact angle (WCA) measurement, free surface energy (FSE) measurement, fluorescence intensity test after fluorescence labelling with dansyl chloride, scanning electron microscopy (SEM) and atomic force microscopy (AFM). High antibacterial efficiency against four different types of biofilm active, pathogenic bacterial strains namely: Staphylococcus aureus, Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa was established on the modified PET surface. Biocompatibility much higher than 70 % of the modified samples has been proved. Our second studies were focused on an efficient reduction of amide functional groups to secondary amine on Nylon 6 film surface with borane-tetrahydrofuran (BH3-THF) complex, followed by N-alkylation with benzyl chloride (C6H5CH2Cl) as well as grafting on reduced Nylon 6 surface by using poly(ethylene glycol) methyl ether tosylate (H3C-PEG-OTs). The different N-alkylation reactions allowed us to tune the surface properties of Nylon 6. Thus obtained modified Nylon 6 polyamide can be useful for many applications including antifouling biomaterials as the polyamide after functionalization was found to be biocompatible and resistant to pathogenic bacterial adhesion due to the presence of hydrophilic poly(ethylene glycol) methyl ether (H3C-PEG) chains after grafting. Not only that, the grafting intensity was regulated also by the duration of preceding lithiation reaction before grafting. The grafted Nylon 6 samples were further modified by physical assemblage of copper nanoparticles (Cu NPs) on the surface. Another modification route was also examined for PEG immobilization on reduced Nylon 6 surface via N,N-disuccinimidyl Carbonate (DSC) conjugation. The surface modifications were confirmed by different techniques. Water contact angle (WCA), free surface energy (FSE) analyses indicated the significant change in the surface morphology that were established by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The pathogenic bacterial strains: Gram positive Staphylococcus aureus and Gram negative Pseudomonas aeruginosa were used to depict the antibacterial efficacy. The resistance to bacterial adhesion has been established for the grafted and Cu NP deposited modified Nylon 6 samples. Most of the modified samples were established to be cytocompatible. Simultaneously, our focus was to synthesize the copper nanoparticles (Cu NPs) for the deposition on grafted Nylon 6 surface to examine the possibility of Cu NP physisorption on surface as well as to evaluate the antibacterial efficacy of prepared Cu NP deposited Nylon 6 samples. The synthesized Cu NPs were characterized by various methods including dynamic light scattering (DLS), scanning electron microscopy (SEM), UV-VIS spectroscopy and Fourier-transform infrared spectroscopy (FT-IR).
Nosocomial infections (NI) have been serious problems for hospitalized patients where almost half of all the infections are device related. Various polymeric materials including polyesters and polyamides such as polyethylene terephthalate PET and Nylon 6 are widely utilized for clinical devices. These polymers are commonly used in biomedical applications ranging from catheters to stents, vascular grafts, heart valves, wound dressings, sutures and scaffolds. Polymer surface modification is very essential factor to improve and impart desired properties for biomedical applications, making the polymers biocompatible, non-cytotoxic and antibacterial that can preferably resist biofilm formation caused by pathogenic bacteria. At first, novel approach to anti-corrosive wet chemical surface modification of PET by insertion of alkyl and hydroxyl groups was achieved by using different Grignard reagents and confirmed by several different characterization techniques including water contact angle (WCA) measurement, free surface energy (FSE) measurement, fluorescence intensity test after fluorescence labelling with dansyl chloride, scanning electron microscopy (SEM) and atomic force microscopy (AFM). High antibacterial efficiency against four different types of biofilm active, pathogenic bacterial strains namely: Staphylococcus aureus, Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa was established on the modified PET surface. Biocompatibility much higher than 70 % of the modified samples has been proved. Our second studies were focused on an efficient reduction of amide functional groups to secondary amine on Nylon 6 film surface with borane-tetrahydrofuran (BH3-THF) complex, followed by N-alkylation with benzyl chloride (C6H5CH2Cl) as well as grafting on reduced Nylon 6 surface by using poly(ethylene glycol) methyl ether tosylate (H3C-PEG-OTs). The different N-alkylation reactions allowed us to tune the surface properties of Nylon 6. Thus obtained modified Nylon 6 polyamide can be useful for many applications including antifouling biomaterials as the polyamide after functionalization was found to be biocompatible and resistant to pathogenic bacterial adhesion due to the presence of hydrophilic poly(ethylene glycol) methyl ether (H3C-PEG) chains after grafting. Not only that, the grafting intensity was regulated also by the duration of preceding lithiation reaction before grafting. The grafted Nylon 6 samples were further modified by physical assemblage of copper nanoparticles (Cu NPs) on the surface. Another modification route was also examined for PEG immobilization on reduced Nylon 6 surface via N,N-disuccinimidyl Carbonate (DSC) conjugation. The surface modifications were confirmed by different techniques. Water contact angle (WCA), free surface energy (FSE) analyses indicated the significant change in the surface morphology that were established by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The pathogenic bacterial strains: Gram positive Staphylococcus aureus and Gram negative Pseudomonas aeruginosa were used to depict the antibacterial efficacy. The resistance to bacterial adhesion has been established for the grafted and Cu NP deposited modified Nylon 6 samples. Most of the modified samples were established to be cytocompatible. Simultaneously, our focus was to synthesize the copper nanoparticles (Cu NPs) for the deposition on grafted Nylon 6 surface to examine the possibility of Cu NP physisorption on surface as well as to evaluate the antibacterial efficacy of prepared Cu NP deposited Nylon 6 samples. The synthesized Cu NPs were characterized by various methods including dynamic light scattering (DLS), scanning electron microscopy (SEM), UV-VIS spectroscopy and Fourier-transform infrared spectroscopy (FT-IR).
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Subject(s)
patogenní bakterie, polyethylentereftalát, Nylon 6, mesoporézní silika nanočástice, transport léčiv, pathogenic bacteria, polyethylene terephthalate, Nylon 6, mesoporous silica nanoparticles, drug delivery