Vladimir Sedlarik

Amphiphilic chitosan-grafted-functionalized polylactic acid based nanoparticles as a delivery system for doxorubicin and temozolomide co-therapy

The aim of this work was to investigate the potential of an amphiphilic system comprising chitosan-grafted polylactide and carboxyl-functionalized polylactide acid as a carrier for the controlled release and co-release of two DNA alkylating drugs: doxorubicin and temozolomide. Polylactide and carboxyl-functionalized polylactide acid were obtained through direct melt polycondensation reaction, using methanesulfonic acid as a non-toxic initiator, and subsequently these were grafted to the chitosan backbone through a coupling reaction, utilizing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a condensing agent. ATR-FTIR analysis and conductometric titration confirmed that a reaction between CS and PLA, PLACA2% and PLACA5% occurred. Chitosan-grafted-polylactide and polylactide-citric acid nanoparticles were prepared via the polyelectrolyte complex technique, applying dextran sulphate as a polyanion, and loaded with doxorubicin and temozolomide. The diameter of particles, ζ-potential and their relationship to temperature and pH were analysed in all formulations. Encapsulation, co-encapsulation efficiency and release studies were conducted in different physiological simulated environments and human serum. Results showed the continuous release of drugs without an initial burst in different physiological media.

Correlation of Morphology and Viscoelastic Properties of Partially Biodegradable Polymer Blends Based on Polyamide 6 and Polylactide Copolyester

The morphology and viscoelastic properties of newly prepared partially biodegradable polymeric blend based on polyamide 6 and commercially available co-polyester of polylactide, BioFlex®, were studied in this work. Observations by scanning electron microscopy and solvent extraction method, and rheological measurements were carried out for structural studies. Experimental data were compared with several semi-empirical models for determination of phase inversion concentration. The correlation between experimental data and models reveals the significant contribution of elasticity effect to interfacial adhesion between polyamide 6 and BioFlex, which seems to have influence on the phase inversion composition of the blends and co-continuous morphology formation.

Low molecular weight poly(lactic acid) microparticles for controlled release of the herbicide metazachlor: preparation, morphology, and release kinetics.

The preemergence chloroacetamide herbicide metazachlor was encapsulated in biodegradable low molecular weight poly(lactic acid) micro- and submicroparticles, and its release to the water environment was investigated. Three series of particles, S, M, and L, varying in their size (from 0.6 to 8 μm) and with various initial amounts of the active agent (5%, 10%, 20%, 30% w/w) were prepared by the oil-in-water solvent evaporation technique with gelatin as biodegradable surfactant. The encapsulation efficiencies reached were about 60% and appeared to be lower for smaller particles. Generally, it was found that the rate of herbicide release decreased with increasing size of particles. After 30 days the portions of the herbicide released for its highest loading (30% w/w) were 92%, 56%, and 34% for about 0.6, 0.8, and 8 μm particles, respectively. The release rates were also lower for lower herbicide loadings. Metazachlor release from larger particles tended to be a diffusion-controlled process, while for smaller particles the kinetics was strongly influenced by an initial burst release.

Characterization of Antibacterial Polymeric Films Based on Poly(vinyl alcohol) and Zinc Nitrate for Biomedical Applications

Abstract Poly(vinyl alcohol) (PVA) was modified by zinc nitrate in the concentration range from 0 to 22.29 wt.% using the solvent cast technique. The resulting material was characterized by optical microscopy, stress-strain analysis, differential scanning calorimetry, UV-visible spectroscopy, and Fourier transform-infrared spectroscopy. In addition, the antibacterial properties of the prepared films were tested against the both gram positive and gram negative bacterial strains. The results show the uniform distribution of the modifier within the PVA matrix, enhanced mechanical properties (up to 8.24 wt.%), and good antibacterial activity against gram negative bacteria at low modifier content.

Application of extremely non-equilibrium plasmas in the processing of nano and biomedical materials

Some applications of extremely non-equilibrium oxygen plasma for tailoring the surface properties of organic as well as inorganic materials are presented. Plasma of low or moderate ionization fraction and very high dissociation fraction is created by high frequency electrodeless discharges created in chambers made from a material of low recombination coefficient. The O atom density often exceeds 1021 m−3 which allows for rapid functionalization of carbon-containing materials. Surface saturation with polar oxygen-rich groups is achieved in a fraction of a second and further exposure leads to etching. The etching is often non-uniform and results in nano-structuring of surface morphology. A combination of rich morphology and saturation with polar functional groups allows for a super-hydrophilic character of originally hydrophobic materials. Polymer composites are etched selectively so the polymer component is removed from the sample surface, leading to modified surface properties. Furthermore, such a treatment allows for distinguishing the distribution and orientation of fillers inside the polymer matrix. The exposure of inorganic materials to non-equilibrium oxygen plasma causes one-dimensional growth of metal oxide nanoparticles, thus representing a unique technique for the rapid catalyser-free growth of nanowires.

Properties enhancement of partially biodegradable polyamide/polylactide blends through compatibilization with novel polyalkenyl-poly-maleic-anhydride-amide/imide-based additives

This work is dedicated to compatibilization process investigation between polyamide 6 and biodegradable polylactide. The process was conducted by newly developed polyalkenyl-poly-maleic-anhydride-imide/amide agents over a selected range of composition to identify morphologies and properties of these blends. The properties of resulted blends were studied by scanning electron microscopy, solvent extraction techniques, mechanical testing, Fourier transform infrared spectroscopy, and differential scanning calorimetry measurements. Results show that blending of the two polymers without compatibilizers produced multiphase blends. It was shown by scanning electron microscopy imaging that addition of prepared compatibilizers reduced a domain size of a dispersed phase and also changes in nearly co-continuous state occurred. Static and dynamic mechanical properties were improved, and especially impact strength and tensile strength were the most sensitive on the presence of compatibilizers.

Effect of Phase Arrangement on Solid State Mechanical and Thermal Properties of Polyamide 6/Polylactide Based Co-polyester Blends

The main goal of this work is to correlate morphological parameters of the binary blend of polyamide 6 (PA6) and a polylactide (PLA) based biodegradable co-polyester blend (BioFlex) (scanning electron microscopy, solvent extraction method) with the solid-state mechanical properties (stress strain analysis) as well as thermal (differential scanning calorimetry) and selected physico-chemical characteristics (Fourier transform infrared spectroscopy and water uptake analysis). The blends of PA6/BioFlex were prepared in ratios of 100/0, 90/10, 75/25, 60/40, 50/50, 40/60, 25/75, 10/90 and 0/100 in wt.%. The occurrence of co-continuous morphology was observed within the range of 40 to 60 wt.% of BioFlex. Furthermore, the results show that the co-continuous morphology of PA6/BioFlex blends significantly affected both tensile (E modulus) and thermal properties (melting enthalpy) of the blends. In the case of the tensile properties, the effect of the morphological arrangement was strongly dependent on the deformation range. The presence of BioFlex in the blends reduced the crystallizability of PA6 noticeably. Co-continuous structure formation was observed to have a significant effect on the melting enthalpy of the blend. Composition morphology dependent responses were observed in the case of the FTIR and water uptake studies.

Modification of poly(vinyl alcohol) with lactose and calcium lactate: potential filler from dairy industry

Abstract Characteristics of a newly developed environmentally friendly biocomposite material, poly(vinyl alcohol) (PVA) modified with lactose and calcium lactate, potential fillers, byproduct of dairy industry, are reported in the present paper. Sample films containing 0, 10, 20, 33 and 42 wt-% of filler were prepared by conventional solvent casting into acrylic plates. Morphological, mechanical and thermal properties of PVA, PVA–lactose and PVA–calcium lactate composites were studied by optical microscopy, stress–strain analysis, Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR), differential scanning calorimetry, thermogravimetric analysis (TGA), and also the biodegradability was tested. The films were thin and transparent, and became gradually white with increasing concentration of the filler. Optical microscopy and FTIR–ATR analysis of PVA–lactose and PVA–calcium lactate confirmed that they are composite materials. Their mechanical properties increased up to 33 wt-% filler. The glass transition temperature also decreased with rising content of filler, which indicates the influence of moisture absorbed by the composites (confirmed by TGA measurements). Poly(vinyl alcohol) modification with lactose showed that the biodegradability is improved in aqueous environment.

Chitosan grafted low molecular weight polylactic acid for protein encapsulation and burst effect reduction

Chitosan and chitosan-grafted polylactic acid as a matrix for BSA encapsulation in a nanoparticle structure were prepared through a polyelectrolyte complexation method with dextran sulfate. Polylactic acid was synthetized via a polycondensation reaction using the non-metal-based initiator methanesulfonic acid and grafted to the chitosan backbone by a coupling reaction, with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide as the condensing agent. The effect of concentration of the polymer matrix utilized herein on particle diameter, ζ-potential, encapsulation efficiency, and the release kinetic of the model protein bovine serum albumin at differing pH levels was investigated. The influence of pH and ionic strength on the behavior of the nanoparticles prepared was also researched. Results showed that grafting polylactic acid to chitosan chains reduced the initial burst effect in the kinetics of BSA release from the structure of the nanoparticles. Furthermore, a rise in encapsulation efficiency of the bovine serum albumin and diminishment in nanoparticle diameter were observed due to chitosan modification. The results suggest that both polymers actually show appreciable encapsulation efficiency; and release rate of BSA. CS-g-PLA is more suitable than unmodified CS as a carrier for controlled protein delivery.

Construction of antibacterial poly(ethylene terephthalate) films via layer by layer assembly of chitosan and hyaluronic acid

Polyelectrolytic multilayers (PEMs) with enhanced antibacterial properties were built up onto commercial poly(ethylene terephthalate) (PET) films based on the layer by layer assembling of bacterial contact killing chitosan and bacterial repelling highly hydrated hyaluronic acid. The optimization of the aminolysis modification reaction of PET was carried out by the study of the mechanical properties and the surface characterization of the modified polymers. The layer by layer assembly was successfully monitored by TEM microscopy, surface zeta-potential, contact angle measurements and, after labeling with fluorescein isothiocyanate (FTIC) by absorption spectroscopy and confocal fluorescent microscopy. Beside, the stability of the PEMs was studied at physiological conditions in absence and in the presence of lysozyme and hyaluronidase enzymes. Antibacterial properties of the obtained PEMs against Escherichia coli were compared with original commercial PET.