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Antibacterial electrospun membrane prepared from poly(vinylidene fluoride)-co-hexafluoropropylene with lauric acid monoacylglycerol
Zelenková, Jana ; Peer, Petra ; Pleva, P. ; Janalíková, M. ; Sedlaříková, J. ; Filip, Petr
The aim of this study was to prepare an antibacterial nanofibrous membrane using electrospinning technique. The nanofibrous membranes were spun from polymer solution of poly(vinylidne fluoride)-co-hexafluoropropylene (PVDF-co-HFP) dissolved in N,N´-dimethylformamide. Monoacylglycerol of lauric acid (MAG C12) was used as an antimicrobial agent at the concentrations ranging from 1 to 3 wt%. The impact of MAG C12 incorporation on the rheological, structural and antibacterial properties was investigated. The rheological tests of polymer solutions, as steady shear and oscillatory shear, proved that addition of MAG C12 changed marginally rheological quantities such as viscosity, elastic (storage) and viscous (loss) moduli. Measurement of mean nanofibres diameter indicated a slight decrease with increasing MAG C12 concentration. Antimicrobial activity of PVDF-co-HFP nanofibre membranes with incorporated MAG C12 against Gram-positive bacteria Staphylococcus aureus and Gram-negative Escherichia coli was studied. An antibacterial activity was revealed for the samples containing MAG C12 at all concentrations against Gram-positive bacteria Staphylococcus aureus by the disk diffusion method.
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Studies towards the Preparation of Organic-Inorganic Hybrid Silica Fibers via Electrospinning
Koukolová, Anna ; Dzik, Petr (referee) ; Hüsing, Nicola (advisor)
Polyorganosilany spadají do skupiny hybridních materiálů třídy II, které nabízejí nové možnosti materiálových funkcí a jejich vlastností. Ačkoliv byly v této kategorii již některé materiály zkoumány a stejně tak i jejich aplikace, nebyly doposud vlákna na základě polyorganosilanu v mikro a nano rozměru popsány což bylo motivací pro tuto práci. Předkládaná diplomová práce se zabývá podrobným zkoumáním poly(vinylmethyldimethoxysilanu) jako možného prekurzoru pro elektrostatické zvlákňování. Za účelem přípravy polymeru na bázi vinylmethylsilanu byla provedena radikálová polymerace a podmínky reakce byly modifikovány se záměrem změny molekulové hmotnosti získaného polymeru. Stupeň polymerace byl upravován na základě změny koncentrace iniciátoru a byl stanovován dynamickým rozptylem světla v roztoku polymeru a spektroskopickou metodou nukleární magnetické rezonance. Elektrostatické zvlákňování je velkou měrou spojeno s vlastnostmi roztoku a důraz byl proto kladen právě na zjištění těchto vlastností. Na základě experimentů bylo zjištěno, že syntetizovaný polymer je na přípravu vláken vhodný. Nicméně byly získány i fragmenty vláken a to s využitím polymeru v roztoku methanolu. Předpokladem zvlákňování je dostatek propojení mezi polymerními řetězci. Tento přístup byl studován se zapojením sol-gel postupu a bylo zjištěno, že fáze sol-gel procesu je velmi významná s ohledem na tvorbu vláken. Dalším využitým postupem pro získání vláken bylo začlenění dalšího polymeru do směsi jako nosiče a tímto postupem byla získána vlákna s různým průměrem.
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Magnetic properties of electrospun polyvinyl butyral/Fe2O3 nanofibrous membranes
Peer, Petra ; Cvek, M. ; Urbánek, M. ; Sedlačík, M.
In this contribution, magnetic Fe2O3 nanoparticles (MNPs) were successfully incorporated into the polyvinyl butyral (PVB) nanofibrous membranes using the electrospinning process. The effects of the MNP concentration on the morphology of the nanofibres and their magnetic properties were investigated. Scanning electron microscopy and transmission electron microscopy confirmed their concentration-dependent, yet uniform diameter, and the presence of well-embedded MNPs inside the PVB nanofibres. The magnetic properties of the PVB/MNP membranes were studied using the vibrating-sample magnetometry. The saturation magnetization increased from 6.4 to 45.5 emu/g as the MNP concentration in the feedstock solution increased from 1 to 15 wt%. The fabricated PVB/MNP nanofibrous membranes possessed the ability to respond to the external magnetic fields, which determines their potential in the development of the advanced smart textiles.
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Electrospinning of bioglass and glass-ceramic fibers
Kozáková, Zdenka ; Šťastná, Eva (referee) ; Částková, Klára (advisor)
Bachelor thesis is focused on the preparation of fibers based on bioglass and glass ceramics. The theoretical part of the work summarizes the division and description of biomaterials and their use in biomedical applications. The main part of the work deals with the preparation of bioglass with a focus on the preparation by electrospinning. Experimental part is focused on the preparation of fibers based on bioglass by electrospinning. Different types of bioglass precursors were studied and their spinnability, morphology and bioactivity of the prepared fibers were assessed. The fibers were analyzed by scanning electron microscopy and interactions in simulated body fluid. Fibers prepared from bioglass 45S5 and polyvinylalcohol precursor were evaluated as promising for biomedical applications.
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Electrical characterization of flexible nanofiber piezoelectric materials
Pokorná, Romana ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This bacherol thesis is focused on piezoelectric nanofibrous materials. The first part describes the formation, use and possible aplications of nanofibers. It further analyze the principle of piezoelectric effect. It is a conversion of mechanical energy into electric energy and conversely. The second part is focused on design of experimental workplace for measurement of functional material properties. The last section of the thesis is dedicated to the electrical characterization of PVDF nanofibers and to the measurement of the piezoelectric charge constant.
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Release of active substances from porous structures based on poly(3-hydroxybutyrate) (PHB)
Černeková, Nicole ; Veselá, Mária (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deals with the study of the release of active substances from porous structures based on poly(3-hydroxybutyrate) (P3HB). The theoretical part describes the basic characteristics of polyhydroxyalkanoates, their effect on the organism and method of electrospinning. In the experimental part, solutions of poly(3-hydroxybutyrate) in a solvent mixture of dichloromethane and chloroform were electrospun in three different ratios. The morphology of the formed fibrous porous structures was assessed by scanning electron microscopy, based on which the active substance, the antibiotic Levofloxacin, was incorporated into suitable structures. Antimicrobial activity of the antibiotic released from prepared porous structures was tested by the agar diffusion method against gram-negative bacteria Escherichia coli and Serratia marcescens, the gram-positive bacterium Micrococcus luteus and against the yeast Candida glabrata. The results showed a significant antimicrobial effect of the prepared samples against all bacterial cultures, in the case of the culture of yeasts, no zones of inhibition occurred. Next, the course of the active substance release from the prepared electrospun meshes was studied spectrophotometrically depending on the morphological structure. It was found that the active substance was successfully incorporated into electrospun fibers and the course of the drug release depended on the morphology of P3HB electrospun meshes.
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Electrospinning of composite fiberous structures for piezoapplications
Schifferová, Zuzana ; Kaštyl, Jaroslav (referee) ; Částková, Klára (advisor)
Polymer and composite polymer-ceramic nanofibers were prepared by electrospinning process. Solution of 20 wt.% polyvinylidene fluoride (PVDF) in a mixture of dimethyl sulfoxide (DMSO) and acetone in the ratio of 7:3 was chosen as the most suitable precursor. When preparing composite nanofibers, 20 wt.% of barium calcium zirconate titanate (BCZT) or barium titanate (BT) nanoparticles was added to this PVDF solution. Given parameters were defined as the most suitable for the process of electrospinning: voltage of 50 kV, feeding rate of 30 l/min, distance between emitter and collector of 20 cm and needle diameter of 17 G. The effect of polymer molecular weight and the rotation speed of collector was also studied. Various properties of prepared samples were studied: morphology and fiber diameter, phase composition with the use of x-ray diffraction and Fourier transform infrared spectroscopy and also chosen electrical properties. Lower fiber diameters appeared with lower polymer molecular weight and higher rotation speed of the collector. These parameters resulted in higher percentage of the piezoelectric phase as well. The smallest achieved fiber diameter was around 300 nm, the highest percentage of phase was 92 % and the highest piezoelectric constant had a value of 16 pC/N. Composite fibers filled with BT particles showed better properties that the ones filled with BCZT particles.
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Dependence of morphology of electrospun PVB nanofibres containing fumed silica on elasticity of the processed solutions
Peer, Petra ; Polášková, M. ; Filip, Petr
Application of various types of fumed silica gives a possibility to tailor a degree of hydrophilicity or hydrophobicity of the resulting electrospun nanofibrous mats where as a basic polymeric material is taken poly(vinyl butyral) (PVB) solved in methanol. Presence of fumed silica substantially changes viscoelastic attributes in comparison with the neat PVB solution.\nThe aim of this contribution is to compare morphological structures of the resulting electrospun mats generated from the solutions with presence and absence of various types of fumed silica differing in surface morphology, size and the specific surface area. This comparison is based on the rheological characteristics with the emphasis to elasticity of the pre-processed solutions. The differences in elasticity among fumed silica based solutions are indeed remarkable. The obtained results show that elasticity does not play a crucial role in creation and morphological aspects of the corresponding nanofibrous mats including fibres diameter.
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A COMPARISON OF THE CENTRIFUGAL FORCE SPINNING AND ELECTROSPINNING OF COLLAGEN UNDER DIFFERENT CONDITIONS
Hlavatá, J. ; Suchý, Tomáš ; Šupová, Monika ; Pokorný, M. ; Košťáková, E.
Collagen makes up one of the most important parts of the extracellular matrix and connective tissue. Collagen type I accounts for up to 90% of the collagen found in the body and it can be isolated and purified in large quantities and processed into a variety of forms. With respect to the process of the treatment of collagen into the nano-fibrous and submicron-fibrous forms, severe conditions leading to the denaturation of the collagen and thus the gelatin content should be avoided. Centrifugal force spinning and electrospinning processes appear to present promising methods for the spinning of collagen solutions. This paper deals with a comparison of the various methods applied in the processing of collagen, i.e. principally needle and needleless centrifugal spinning technology and electrospinning technology. In addition, the effect of process parameters and collagen solution conditions on the final form of the material was analyzed. Spun layers were prepared based on collagen type I isolated from calf skin. Nano-structured layers were prepared employing the spinning of 4-16 wt% collagen solutions in phosphate buffer saline and ethanol. The layers thus prepared were characterized by means of scanning electron microscopy and Fourier transform infrared spectroscopy.
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Intelligent nanofibres functionalized with growth factors and blood derivatives for dermatology applications
Vocetková, Karolína ; Amler, Evžen (advisor) ; Rosina, Jozef (referee) ; Arenberger, Petr (referee)
Platelet derivatives are an attractive source of natural growth factors and they are widely used in various tissue engineering and regenerative medicine applications. The aim of this study was to optimize cell culture conditions using platelet lysate and to develop platelet-functionalized fibrous scaffolds as a controlled drug delivery system for native growth factors. Fibrous scaffolds were prepared by electrostatic and centrifugal spinning of PCL and they were functionalized by the platelets by surface adhesion or their encapsulation using emulsion spinning techniques. The cell culture study determined the 7% platelet lysate to be the optimum concentration as a medium supplement in keratinocyte and fibroblast culture. Additionally, following surface adhesion of the platelets to PCL electrospun nanofibres, the platelets were activated due to their contact with the nanofibre nanotopography, resulting in formation of fibrin network. Fibrin served as a reservoir of the growth factors, prolonging the half-time of EGF release to 1.7 days. Such platelet-functionalized samples fostered proliferation of keratinocytes, fibroblasts and melanocytes. Furthermore, adhesion of platelets to centrifugally spun nanofibrous scaffolds resulted in almost two-fold increase in the amount of immobilized platelet-derived...
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