Zdenka Capáková

Chitosan-based nanocomplexes for simultaneous loading, burst reduction and controlled release of doxorubicin and 5-fluorouracil

In this work, nanocomplexes based on chitosan grafted by carboxy-modified polylactic acid (SPLA) were prepared with the aim of loading simultaneously two anticancer drugs - doxorubicin and 5-fluorouracil, as well as to control their release, reduce the initial burst and boost cytotoxicity. The SPLA was prepared by a polycondensation reaction, using pentetic acid as the core molecule, and linked to the chitosan backbone through a coupling reaction. Nanocomplexes loaded with both drugs were formulated by the polyelectrolyte complexation method. The structure of the SPLA was characterized by 1H NMR, while the product CS-SPLA was analyzed by FTIR-ATR to prove the occurrence of the reaction. Results showed that the diameters and ζ-potential of the nanocomplexes fall in the range 120-200nm and 20-37mV, respectively. SEM and TEM analysis confirmed the spherical shape and dimensions of the nanocomplexes. The presence of hydrophobic side chain SPLA did not influence the encapsulation efficiency of the drugs but strongly reduced the initial burst and prolonged release over time compared to unmodified chitosan. MS analysis showed that no degradation or interactions between the drugs and carrier were exhibited after loading or 24h of release had taken place, confirming the protective role of the nanocomplexes. In vitro tests demonstrated an increase in the cytotoxicity of the drugs when loaded in the prepared carriers.

On the cytotoxicity of poly(4-aminodiphenylaniline) powders: Effect of acid dopant type and sample posttreatment

ABSTRACT Thanks to their unique properties, as intrinsic conductivity and simple preparation, conducting polymers are highly applicable in tissue engineering, regenerative medicine, and biosensors. Pristine polymers often include residual precursors or other low molecular impurities, which have a negative impact on their biocompatibility. Concerning poly(4-aminodiphenylaniline), its cytotoxicity and biocompatibility have not yet been investigated. Herein, the cytotoxicity of poly(4-aminodiphenylaniline), prepared by an innovative green approach, as well as the effect of samples’ posttreatment and kind of dopant acid used, are reported for the first time. The results show that not only the type of used dopant but also polymers’ washing in phosphate saline buffer and material’s morphology has a significant impact on materials’ cytotoxicity. After a proper posttreatment or when salicylic acid is used as the doping agent the cytotoxicity of poly(4-aminodiphenylaniline) seem to be lower than those obtained for traditional PANI. GRAPHICAL ABSTRACT

Interaction of nanostructured TiO2 biointerfaces with stem cells and biofilm-forming bacteria

Nanostructured TiO2 nanotubes (NTs) of diameters from 15 to 100nm were fabricated by an electrochemical anodization process. Biofilm-positive strains of Bacillus cereus and Pseudomonas aeruginosa behaved similarly on all TiO2 NTs as well as on native titanium (Ti) foil. The adhesion and growth of mesenchymal stem cells (MSc), embryonic stem cells (ESc), and pure cardiomyocytes derived from ESc exhibited significant differences. MSc as well as ESc were, in contrast to cardiomyocytes, able to adhere, and grow on TiO2 NTs. A correlation between NTs diameter and cell behaviour was however observed in the case of MSc and ESc. MSc were not in a physiological state in the case of 100nm TiO2 NTs, while ESc were not able to grow on 15nm TiO2 NTs. It can be stated that these differences can be assigned to different diameters of the NTs but not to the chemistry of the surface. This is the first study describing the comprehensive behaviour of both eukaryotic and prokaryotic cells on TiO2 NTs. On the basis of obtained results, it can be concluded that new generation of medical devices providing selective cell behaviour can be fabricated by optimizing the nanoscale morphology of TiO2.

Cell-compatible conducting polyaniline films prepared in colloidal dispersion mode

Conducting polyaniline can be prepared and modified using several procedures, all of which can significantly influence its applicability in different fields of biomedicine or biotechnology. The modifications of surface properties are crucial with respect to the possible applications of this polymer in tissue engineering or as biosensors. Innovative technique for preparing polyaniline films via in-situ polymerization in colloidal dispersion mode using four stabilizers (poly-N-vinylpyrrolidone; sodium dodecylsulfate; Tween 20 and Pluronic F108) was developed. The surface energy, conductivity, spectroscopic features, and cell compatibility of thin polyaniline films were determined using contact-angle measurement, the van der Pauw method, Fourier-transform infrared spectroscopy, and assay conducted on mouse fibroblasts, respectively. The stabilizers significantly influenced not only the surface and electrical properties of the films but also their cell compatibility. Sodium dodecylsulfate seems preferentially to combine both the high conductivity and good cell compatibility. Moreover, the films with sodium dodecylsulfate were non-irritant for skin, which was confirmed by their in-vitro exposure to the 3D-reconstructed human tissue model.

Adhesion, Proliferation and Migration of NIH/3T3 Cells on Modified Polyaniline Surfaces.

Polyaniline shows great potential and promises wide application in the biomedical field thanks to its intrinsic conductivity and material properties, which closely resemble natural tissues. Surface properties are crucial, as these predetermine any interaction with biological fluids, proteins and cells. An advantage of polyaniline is the simple modification of its surface, e.g., by using various dopant acids. An investigation was made into the adhesion, proliferation and migration of mouse embryonic fibroblasts on pristine polyaniline films and films doped with sulfamic and phosphotungstic acids. In addition, polyaniline films supplemented with poly (2-acrylamido-2-methyl-1-propanesulfonic) acid at various ratios were tested. Results showed that the NIH/3T3 cell line was able to adhere, proliferate and migrate on the pristine polyaniline films as well as those films doped with sulfamic and phosphotungstic acids; thus, utilization of said forms in biomedicine appears promising. Nevertheless, incorporating poly (2-acrylamido-2-methyl-1-propanesulfonic) acid altered the surface properties of the polyaniline films and significantly affected cell behavior. In order to reveal the crucial factor influencing the surface/cell interaction, cell behavior is discussed in the context of the surface energy of individual samples. It was clearly demonstrated that the lesser the difference between the surface energy of the sample and cell, the more cyto-compatible the surface is.

Polyaniline cryogels: Biocompatibility of novel conducting macroporous material

Polyaniline cryogel is a new unique form of polyaniline combining intrinsic electrical conductivity and the material properties of hydrogels. It is prepared by the polymerization of aniline in frozen poly(vinyl alcohol) solutions. The biocompatibility of macroporous polyaniline cryogel was demonstrated by testing its cytotoxicity on mouse embryonic fibroblasts and via the test of embryotoxicity based on the formation of beating foci within spontaneous differentiating embryonic stem cells. Good biocompatibility was related to low contents of low-molecular-weight impurities in polyaniline cryogel, which was confirmed by liquid chromatography. The adhesion and growth of embryonic stem cells, embryoid bodies, cardiomyocytes, and neural progenitors prove that polyaniline cryogel has the potential to be used as a carrier for cells in tissue engineering or bio-sensing. The surface energy as well as the elasticity and porosity of cryogel mimic tissue properties. Polyaniline cryogel can therefore be applied in bio-sensing or regenerative medicine in general, and mainly in the tissue engineering of electrically excitable tissues.

The biocompatibility of polyaniline and polypyrrole: A comparative study of their cytotoxicity, embryotoxicity and impurity profile

Conducting polymers (CP), namely polyaniline (PANI) and polypyrrole (PPy), are promising materials applicable for the use as biointerfaces as they intrinsically combine electronic and ionic conductivity. Although a number of works have employed PANI or PPy in the preparation of copolymers, composites, and blends with other polymers, there is no systematic study dealing with the comparison of their fundamental biological properties. The present study, therefore, compares the biocompatibility of PANI and PPy in terms of cytotoxicity (using NIH/3T3 fibroblasts and embryonic stem cells) and embryotoxicity (their impact on erythropoiesis and cardiomyogenesis within embryonic bodies). The novelty of the study lies not only in the fact that embryotoxicity is presented for the first time for both studied polymers, but also in the elimination of inter-laboratory variations within the testing, such variation making the comparison of previously published works difficult. The results clearly show that there is a bigger difference between the biocompatibility of the respective polymers in their salt and base forms than between PANI and PPy as such. PANI and PPy can, therefore, be similarly applied in biomedicine when solely their biological properties are considered. Impurity content detected by mass spectroscopy is presented. These results can change the generally accepted opinion of the scientific community on better biocompatibility of PPy in comparison with PANI.

The effect of composition of a polymeric coating on the biofilm formation of bacteria and filamentous fungi

ABSTRACT Functionality of polymeric coating, especially in terms of anti-corrosive properties and stability, can be negatively influenced by formation of either bacterial or fungal biofilm on its surface. Herein, the epoxy-ester resin based polymeric coating was filled with pigments (natural silicon dioxide diatomite, natural wollastonite, tungstate and molybdate). Pigments was modified by conducting polymers (polyaniline phosphate, polypyrrole phosphate, poly(p-phenylenediamine) phosphate and ZnFe2O4). Impact of modified pigments on the surface energy and formation of biofilm were tested. The use of various biofilm forming species of both the bacteria and fungi filled a knowledge gap about their behavior on polymeric coatings. GRAPHICAL ABSTRACT