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A short description of approaches for carbon nanostructures synthesis is made and the advantages of using plasma during the growth are presented. As a particular example of a plasma based technique we detail the process of downstream carbon nanowall (CNW) synthesis by a radiofrequency expanding plasma beam. The technique combines magnetron sputtering for catalyst deposition and plasma enhanced chemical vapor deposition (main gas: argon, active gas: hydrogen, precursor gas: acetylene) for carbon growth in a single reactor. The analysis focuses on the correlation between the material properties and the plasma characteristics measured at different points along the flow axis, aiming to reveal the importance of plasma species in the growth process. The material properties were investigated by scanning and transmission electron microscopy, whereas the plasma data were obtained by optical emission spectroscopy, Langmuir probes and mass spectrometry. CNWs with a large area and well isolated from each other are obtained at an optimum distance from the precursor injection point where the plasma presents an enhanced content of carbon nanoclusters. The possible processes responsible for the growth are discussed.

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We found that the cationic polysaccharide chitosan is an efficient dispersion agent for single-walled carbon nanotubes (SWNTs). The spectroscopic properties of chitosan–SWNTs dispersion are different from sodium dodecyl sulfate (SDS)–SWNTs dispersion in acidic conditions. It has been revealed that chitosan is efficiently protective against the protonation of SWNTs. The dispersion behavior of SWNTs in chitosan solutions will be discussed.

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Chitosan/biomimetic apatite thin films were grown in mild conditions of temperature and pressure by Combinatorial Matrix-Assisted Pulsed Laser Evaporation on Ti, Si or glass substrates. Compositional gradients were obtained by simultaneous laser vaporization of the two distinct material targets. A KrF* excimer (λ=248nm, τFWHM=25ns) laser source was used in all experiments. The nature and surface composition of deposited materials and the spatial distribution of constituents were studied by SEM, EDS, AFM, GIXRD, FTIR, micro-Raman, and XPS. The antimicrobial efficiency of the chitosan/biomimetic apatite layers against Staphylococcus aureus and Escherichia coli strains was interrogated by viable cell count assay. The obtained thin films were XRD amorphous and exhibited a morphology characteristic to the laser deposited structures composed of nanometric round shaped grains. The surface roughness has progressively increased with chitosan concentration. FTIR, EDS and XPS analyses indicated that the composition of the BmAp-CHT C-MAPLE composite films gradually modified from pure apatite to chitosan. The bioevaluation tests indicated that S. aureus biofilm is more susceptible to the action of chitosan-rich areas of the films, whilst the E. coli biofilm proved more sensible to areas containing less chitosan. The best compromise should therefore go, in our opinion, to zones with intermediate-to-high chitosan concentration which can assure a large spectrum of antimicrobial protection concomitantly with a significant enhancement of osseointegration, favored by the presence of biomimetic hydroxyapatite.

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