David Pavliňák

Wound Dressing based on Chitosan/hyaluronan/Nonwoven Fabrics: Preparation, Characterization and Medical Applications

Thin layers of chitosan (positively charged)/sodium hyaluronate (negatively charged)/nonwoven fabrics were constructed by polyelectrolyte multilayer pad-dry-cure technique. Pure chitosan (CS) was isolated from shrimp shell and immobilized onto nonwoven fabrics (NWFs) using citric acid (CTA) as cross linker and solvent agents through a pad-dry-cure method. The prepared thin layer of chitosan citrate/nonwoven fabrics (CSCTA/NWFs) were consequently impregnated with hyaluronan (CSCTA/HA/NWFs) in the second path through a pad-dry-cure method. Chitosan/hyaluronan/nonwoven fabrics wound dressing was characterized by different techniques such as FTIR-ATR, TGA and SEM. The antibacterial activity and the cytotoxicity of the dressing sheets were evaluated against Escherichia coli (E. coli) and Streptococcus aureus (S. aureus), mouse fibroblast (NIH-3T3) and keratinocytes (HaCaT) cell lines, respectively. The cell-fabrics interaction was also investigated using fluorescence microscope, based on live/dead staining assay of 3T3 cells. The healing properties of the new wound dressing were evaluated and compared with the control sample.

Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

Novel electrospun gelatin/oxycellulose nanofibers as a suitable platform for lung disease modeling

Novel hydrolytically stable gelatin nanofibers modified with sodium or calcium salt of oxycellulose were prepared by electrospinning method. The unique inhibitory effect of these nanofibers against Escherichia coli bacteria was examined by luminometric method. Biocompatibility of these gelatin/oxycellulose nanofibers with eukaryotic cells was tested using human lung adenocarcinoma cell line NCI-H441. Cells firmly adhered to nanofiber surface, as determined by scanning electron microscopy, and no signs of cell dying were detected by fluorescent live/dead assay. We propose that the newly developed gelatin/oxycellulose nanofibers could be used as promising scaffold for lung disease modeling and anti-cancer drug testing.

Plasma-chemical modifications of cellulose for biomedical applications

Abstract A 6-carboxycellulose (in medicine known as “oxidized cellulose” or “oxycellulose”) is one of the cellulose derivatives popular in the field of surgery. Health products based on oxidized cellulose are great local hemostatics with unique bactericidal and fully bioabsorbable effects. Traditional process of native cellulose oxidation is described as a complex radical reaction in strong acidic liquid medium doped by toxic nitrous radicals (NO*). Our plasma-chemical reaction demonstrates a new synthesis method of oxidized cellulose with unique bactericidal effect. This plasma-chemical treatment is based on atmospheric plasma discharge in liquid medium leading to the oxidation of polysaccharide molecules resulting in oxycellulose. Final oxycellulose properties were evaluated by infrared spectroscopy and carboxyl content determination. The biological impact showed a strong germicidal effect. Graphical Abstract

Versatile low-pressure plasma-enhanced process for synthesis of iron and iron-based magnetic nanopowders

Using microwave low-pressure discharge, we synthesised magnetic iron-oxide nanopowder from the iron pentacarbonyl precursor. We were able to vary the size and chemical composition (especially the ratio between various iron oxides) by careful control of the process parameters. The nanoparticulate product was analysed by X-ray diffraction (XRD) and Raman spectroscopy. However, the XRD cannot reliably distinguish between the size-broadened peaks of γ-Fe2O3 (maghemite) and Fe3O4 (magnetite) due to their nearly identical crystalline structure. Hence we used a chemical method to determine the presence of Fe(II) and Fe(III) ions in the nanopowder samples. The results agree with those from the Raman spectroscopy.

Biodegradable poly (ε-caprolactone)/gelatin nanofibers: Effect of tubular halloysite on structure and properties

The work explores preparation of new advanced nanofibers based on biodegradable polymers and biocompatible tubular halloysite (HNT). Electrospun nanofibers comprising 8 wt% gelatin (Gel) and 8 wt% poly (-caprolactone) (PCL) have been prepared by using eco-friendly solvent – acetic acid. The content of HNT in PCL/Gel nanofibers was 0.5, 1.0, 3.0, 6.0 and 9.0 wt%. It was found that the addition of HNT significantly affected the polymer mixture spinnability and the fiber diameter. SEM observations revealed that the structure of nanofibers depends on nanofiber composition. Whilst in nanofibers with lower HNT content uniform morphology with HNTs located merely inside the individual nanofibers has been observed, in nanofibers with 6 and 9 wt% HNT individual particles as well as the agglomerates of HNT have been detected in both, the inner part as well as outside part of nanofiber. Important reinforcing effect has been achieved in whole HNT content. The highest improvement has been reached when the HNT content ...

Plasma treatment of polyethylene tubes in continuous regime using surface dielectric barrier discharge with water electrodes

Combining the surface dielectric barrier discharges generated in contact with water based electrolytes, as the discharge electrodes, we have designed a new type of surface electric discharge, generating thin layers of plasma which propagate along the treated polymer surfaces. The technique was aimed to achieve uniform atmospheric pressure plasma treatment of polymeric tubes and other hollow bodies. The results presented in this work show the possibility of such system to treat outer surface of polymer materials in a continuous mode. The technical details of experimental setup are discussed as well as results of treatment of polyethylene tubes are shown.

Magnetic halloysite reinforced biodegradable nanofibres: New challenge for medical applications

The work explores preparation of new biocompatible magnetic halloysite nanotubes (MHNTs) reinforced polycaprolactone/gelatine nanofibres. MHNTs were prepared by mixing halloysite nanotubes (HNTs) with microwave-synthesized magnetic iron oxide particles suspension. Electrospun nanofibres comprising 8 wt % poly ɛ-caprolactone (PCL) and 8 wt % gelatine (Gel) have been prepared by using eco-friendly solvent – acetic acid suitable for medical applications. The content of MHNT in PCL/Gel nanofibres was 6.0 and 9.0 wt %. SEM observations revealed that the addition of both, unmodified and magnetic halloysite, significantly affected the polymer mixture spinnability and fibre diameter; however the uniformity and homogeneity of nanofibres were much better in nanofibres with magnetic halloysite. In addition of improved structure, application of MHNTs to PCL/Gel nanofibres resulted in the formation of soft ferromagnetic materials with good response to magnetic field.