Emilia Choińska

Fabrication and characterization of electrospun bionanocomposites of poly (vinyl alcohol)/nanohydroxyapatite/cellulose nanofibers

ABSTRACT The aim of the present study was preparation, optimization, and systematic characterization of electrospun bionanocomposite fibers based on polyvinyl alcohol (PVA) as matrix and nanohydroxy apatite (nHAp) and cellulose nanofibers (CNF) as nanoreinforcements. The presence of nHAp and nHAp-CNF affected the morphology of electrospun mats and reduced fiber diameter, particularly at a higher content of nanofillers. The obtained results of FTIR, DSC, and WAXS proved the crystallinity reduction of electrospun nancomposites. Both nHAp and nHAp-CNF addition led to a significant increase of Young modulus with the highest stiffness for nanocomposite fibers at 10 wt% of nHAp and 3 wt% of CNF. GRAPHICAL ABSTRACT

Biodegradable fiducial markers for X-ray imaging – soft tissue integration and biocompatibility

This study aims at the development of materials for biodegradable fiducial markers for X-ray based medical imaging and their anchorage in soft tissue. Towards this goal a degradable polymer matrix of poly(l-lactide-co-ε-caprolactone) (P[LAcoCL]) was combined with barium sulfate (BaSO4) and hydroxyapatite (HAp) as radio-opaque fillers. Low pressure plasma treatment was applied to the composite materials to improve cell adhesion and subsequent tissue integration. In particular, the effects of oxygen and ammonia plasmas were evaluated and compared using X-ray photoelectron spectroscopy, atomic force microscopy and dynamic water contact angle measurements as well as in vitro studies using the murine fibroblast cell line L929. To exclude the cytotoxic effects of degradation products of P[LAcoCL] and released BaSO4 or HAp cytotoxicity assays with the degradation products of the composite materials were conducted. The results obtained by this broad range of analytical techniques suggest the application of composites of P[LAcoCL] with BaSO4 and HAp as promising material systems for innovative fiducial markers for soft tissue in X-ray based medical imaging.

Effect of TiN Coating on Functional Properties of Implant Titanium Alloy

Surface engineering is considered a very prospective method of improving functional properties of implant alloys. Many publications reported the excellent influence of TiN coating on wear resistance as well as corrosion properties of titanium alloys. However, some authors pointed the danger of delamination of thin coating during exploitation. The aim of presented work was research of effect of TiN coating obtained by the RF-PCVD method on tribological and corrosion properties of Ti6Al4V alloy. Investigations performed by the simulator of hip joint friction as well as corrosion tests carried out at various temperatures showed adverse influence of TiN coating on wear and corrosion resistance. Analysis of presented date demonstrate that results strongly depend on test conditions.

Multi-scale characterization and biological evaluation of composite surface layers produced under glow discharge conditions on NiTi shape memory alloy for potential cardiological application

NiTi shape memory alloys are characterized by relatively good biocompatibility primarily thanks to their ability to self-passivate. However, before they can be used as medical implants for long term use, they need to undergo treatment aimed at producing layers on their surface that are superior to spontaneously formed oxide layers and that would increase their resistance to corrosion, limit nickel ion release from the surface (metallosis) and have the capability to shape their biological properties depending on the application. Furthermore, cardiac implants require addressing the issue of blood clotting on the surface. Treatment in glow-discharge low temperature plasma makes it possible to produce titanium layers with a structure and properties that are controlled via process parameters. In addition, antithrombogenic properties can be improved by depositing a carbon coating via the RFCVD process. The aim of the study was to investigate the structure, surface topography, adhesive properties, wettability, surface free energy and evaluate metallosis after producing TiO2 and a-C:N:H + TiO2 composite layers on NiTi alloy. The capabilities of AFM microscopes in studying the adhesive properties of a surface were also highlighted in the study. The study shows that the produced surface layers are capable of significantly reducing metallosis. Furthermore, in contrast to NiTi in its initial state, layers of nanocrystalline TiO2 titanium oxide (rutile) with a homogeneous structure demonstrate greater adhesion strength and more developed surface in the microscale, which facilitates the formation of an a-C:N:H coating. Therefore the formation of a coating of a-C:N:H amorphous carbon on NiTi alloy that has previously been oxidised in low-temperature plasma may prove to be a favourable solution in terms of using NiTi alloy to produce cardiac implants.

Micro and nanoscale characterization of poly(DL-lactic-co-glycolic acid) films subjected to the L929 cells and the cyclic mechanical load

In this paper, the effect of the presence of L929 fibroblast cells and a cyclic load application on the kinetics of the degradation of amorphous PLGA films was examined. Complex micro and nano morphological, mechanical and physico-chemical studies were performed to assess the degradation of the tested material. For this purpose, molecular weight, glass transition temperature, specimen morphology (SEM, μCT) and topography (AFM) as well as the stiffness of the material were measured. The study showed that the presence of living cells along with a mechanical load accelerates the PLGA degradation in comparison to the degradation occurring in acellular media: PBS and DMEM. The drop in molecular weight observed was accompanied by a distinct increase in the tensile modulus and surface roughness, especially in the case of the film degradation in the presence of cells. The suspected cause of the rise in stiffness during the degradation of PLGA films is a reduction in the molecular mobility of the distinctive superficial layer resulting from severe structural changes caused by the surface degradation. In conclusion, all the micro and nanoscale properties of amorphous PLGA considered in the study are sensitive to the presence of L929 cells, as well as to a cyclic load applied during the degradation process.