I. Michaljaničová

Poly- l - lactic acid modified by etching and grafting with gold nanoparticles

This work is focused on characterization of plasma treated and consequently etched and grafted biocompatible polymer poly(l-lactide acid) (PLLA). The interaction of biodegradable polymers with cold plasma is of a great importance in a tissue engineering and surface science. Cold plasma exposure, grafting with gold nanoparticles and etching processes were successfully applied to biopolymer substrate. A method for biopolymer nanostructuring as combination of cold plasma treatment and Au nanoparticle grafting for biocompatibility improvement is introduced. Surface roughness, morphology and surface chemistry was determined. The plasma modification leads to significant increase in surface roughness of PLLA and appearance of sharp spikes and ridges on the PLLA surface. Modification by grafting and etching leads to significant changes in PLLA surface morphology and chemistry. The surface ablation of PLLA has been proved to be significant. In etching of plasma-modified PLLA, methanol proves to be stronger etching agent than water. The grafting of PLLA with gold nanoparticles improved mouse embryonic fibroblasts (NIH 3T3) adhesion and proliferation significantly.

Cytocompatibility of plasma and thermally treated biopolymers

This paper is focused on the surface characterization of plasma and consequently thermally treated biocompatible polymers. PLLA (poly(L-lactide acid) and PMP (poly-4-methyl-1-pentene) are studied. The influence of Ar plasma treatment on the surface polarity of substrate measured immediately after treatment and during the polymer surface aging is studied. Surface roughness, morphology, wettability, and surface chemistry were determined. Plasma treatment leads to significant changes in PLLA surface morphology and chemistry, with the PMP being slightly affected. The higher resistance to plasma fluence results in smaller ablation of PMP than that of PLLA. The plasma treatment improves cell adhesion and proliferation on the PMP. Plasma treatment of PLLA influences mostly the homogeneity of adhered and proliferated VSMC.

A novel method for biopolymer surface nanostructuring by platinum deposition and subsequent thermal annealing

A novel procedure for biopolymer surface nanostructuring with defined surface roughness and pattern dimension is presented. The surface properties of sputtered platinum layers on the biocompatible polymer poly(l-lactic acid) (PLLA) are presented. The influence of thermal treatment on surface morphology and electrical resistance and Pt distribution in ca. 100 nm of altered surface is described. The thickness, roughness and morphology of Pt structures were determined by atomic force microscopy. Surface sheet resistance was studied by a two-point technique. It was the sequence of Pt layer sputtering followed by thermal treatment that dramatically changed the structure of the PLLA’s surface. Depending on the Pt thickness, the ripple-like and worm-like patterns appeared on the surface for thinner and thicker Pt layers, respectively. Electrokinetic analysis confirmed the Pt coverage of PLLA and the slightly different behaviour of non-annealed and annealed surfaces. The amount and distribution of platinum on the PLLA is significantly altered by thermal annealing.

High power plasma as an efficient tool for polymethylpentene cytocompatibility enhancement

High power plasma was successfully used as an efficient and inexpensive tool for polymethylpentene (PMP) cytocompatibility enhancement. Proper surface roughness and morphology as well as the surface chemistry of a material are essential factors for successful utilization of a substrate intended for tissue engineering applications. Plasma treatment is an inexpensive, simple and highly effective method for optimization of surface properties, as a result of which enhancement of cell adhesion, growth and migration occurs. Oxygen and argon plasma treatments were applied to activate the PMP surface. The research was focused on the investigation of the changed properties. The AFM and FIB-SEM study demonstrated that plasma treatments of PMP induced structured surfaces which depended on the applied plasma setting. Measurement of the goniometry, and chemical changes (functional groups by FTIR, element concentration by XPS and RBS/ERDA) was included. Experiments on treated substrates with mouse fibroblasts (NIH 3T3) have shown a significant increase in cell adhesion and proliferation on treated PMP substrates when compared to the untreated polymer. Similarly, cell morphology and adhesion sites were carefully examined using fluorescence and scanning electron microscopy; results of both techniques confirmed the suitability of treated PMP samples for cell cultivation. This study demonstrates how to easily improve cytocompatibility of a very inert and resistant polymer for tissue engineering applications.

Efficient nanostructure construction on polymer substrates by plasma treatment for tissue engineering

Nanostructured polymers assume an important role in many applications, especially if they are prepared by an economical and effective process. The aim of this work is the construction and characterization of new surface structures induced by an inexpensive and easy method with a potential application in tissue engineering. Diverse surface structures and patterns on several polymer substrates were created by oxygen and argon plasma modification, while maintaining the identical properties of the bulk. The study was conducted on the foils of the following polymers: polyetheretherketone (PEEK), polyethersulfone (PES), polyhydroxybutyrate (PHB) and polymethylpentene (PMP). The shape and size of created structures are related to the choice of the treated polymer, applied plasma power, time exposure, and working atmosphere. The AFM and FIB-SEM images declare that the most interesting surface patterns were created on PMP and PHB by the longest time exposure (240 s). Goniometric measurement was also included and discussed.