Influence of the type of substrate on the properties of carbon nanotubes layer studied by Raman spectroscopy.

The development of nanomaterials technology allows to design a novel medical strategies, and could also be useful in the field of regenerative medicine. The paper presents a study on the functionalized multi-walled carbon nanotubes (MWCNTs-f) layers deposited by electrophoretic method (EPD) on the surfaces of two types of substrates: titanium (Ti) and stainless steel. SEM and EDS analyses confirm that incubation in a simulated body fluid (SBF) caused a formation of hydroxyapatite on the surface of the Ti/MWCNTs-f. Raman micro-spectroscopy was a method of choice to study presented materials. The MWCNTs-f layer on the surface of the titanium plate shows better layer order than the corresponding layer deposited on the stainless steel. The structure and ordering of the nanocarbon layer play a key role in the biological activity of the materials. This was confirmed by the incubation of the plates with deposited layer of carbon nanotubes in SBF. A titanium substrate with a MWCNTs-f layer supports the deposition of some components from the environment, while a stainless steel substrate promotes the formation of a carbon film that inhibits the deposition of certain components from the environment. A two-trace two-dimensional (2T2D) analysis confirmed a different effect of SBF on the MWCNTs-f layer depending on the type of substrate. The MWCNTs-f layer on titanium substrate seems to represent an interesting proposition for novel bioactive strategies.

A study of the interactions between human osteoblast-like cells and polymer composites with functionalized graphene derivatives using 2D correlation spectroscopy (2D-COS).

In response to the growing need for development of modern biomaterials for applications in regenerative medicine strategies, the research presented here investigated the biological potential of two types of polymer nanocomposites. Graphene oxide (GO) and partially reduced graphene oxide (rGO) were incorporated into a poly(ε-caprolactone) (PCL) matrix, creating PCL/GO and PCL/rGO nanocomposites in the form of membranes. Proliferation of osteoblast-like cells (human U-2 OS cell line) on the surface of the studied materials confirmed their biological activity. Fluorescence microscopy was able to distinguish the different patterns of interaction between cells (depending on the type of material) after 15 days of the test run. Raman micro-spectroscopy and two-dimensional correlation spectroscopy (2D-COS) applied to Raman spectra distinguished the nature of cell-material interactions after only 8 days. Combination of these two techniques (Raman micro-spectroscopy and 2D-COS analysis) facilitated identification of a much more complex cellular response (especially from proteins) on the surface of PCL/GO. The presented approach can be regarded as a method for early study of the bioactivity of membrane materials.

Corrosion Resistance and Electrical Conductivity of Hybrid Coatings Obtained from Polysiloxane and Carbon Nanotubes by Electrophoretic Co-Deposition.

Nanocomposites developed based on siloxanes modified with carbon nanoforms are materials with great application potential in the electronics industry, medicine and environmental protection. This follows from the fact that such nanocomposites can be endowed with biocompatibility characteristics, electric conductivity and a high mechanical durability. Moreover, their surface, depending on the type and the amount of carbon nanoparticles, may exhibit antifouling properties, as well as those that limit bacterial adhesion. The paper reports on the properties of polysiloxane (PS) and carbon nanotubes (CNT) nanocomposite coatings on metal surfaces produced by the electrophoretic deposition (EPD). A comparison with coatings made of pure PS or pure CNT on the same substrates using the same deposition method (EPD) is provided. The coatings were examined for morphology and elemental composition (SEM, EDS), structural characteristics (confocal Raman spectroscopy), electrical conductivity and were tested for corrosion (electrochemical impedance spectroscopy-EIS, potentiodynamic polarization-PDP). The results obtained in this study clearly evidenced that such hybrid coatings conduct electricity and protect the metal from corrosion. However, their corrosion resistance differs slightly from that of a pure polymeric coating.

Early Recognition of the PCL/Fibrous Carbon Nanocomposites Interaction with Osteoblast-like Cells by Raman Spectroscopy.

Poly(ε-caprolactone) (PCL) is a biocompatible resorbable material, but its use is limited due to the fact that it is characterized by the lack of cell adhesion to its surface. Various chemical and physical methods are described in the literature, as well as modifications with various nanoparticles aimed at giving it such surface properties that would positively affect cell adhesion. Nanomaterials, in the form of membranes, were obtained by the introduction of multi-walled carbon nanotubes (MWCNTs and functionalized nanotubes, MWCNTs-f) as well as electro-spun carbon nanofibers (ESCNFs, and functionalized nanofibers, ESCNFs-f) into a PCL matrix. Their properties were compared with that of reference, unmodified PCL membrane. Human osteoblast-like cell line, U-2 OS (expressing green fluorescent protein, GFP) was seeded on the evaluated nanomaterial membranes at relatively low confluency and cultured in the standard cell culture conditions. The attachment and the growth of the cell populations on the polymer and nanocomposite samples were monitored throughout the first week of culture with fluorescence microscopy. Simultaneously, Raman microspectroscopy was also used to track the dependence of U-2 OS cell development on the type of nanomaterial, and it has proven to be the best method for the early detection of nanomaterial/cell interactions. The differentiation of interactions depending on the type of nanoadditive is indicated by the ν(COC) vibration range, which indicates the interaction with PCL membranes with carbon nanotubes, while it is irrelevant for PCL with carbon nanofibers, for which no changes are observed. The vibration range ω(CH2) indicates the interaction for PCL with carbon nanofibers with seeded cells. The crystallinity of the area ν(C=O) increases for PCL/MWCNTs and for PCL/MWCNTs-f, while it decreases for PCL/ESCNFs and for PCL/ESCNFs-f with seeded cells. The crystallinity of the membranes, which is determined by Raman microspectroscopy, allows for the assessment of polymer structure changes and their degradability caused by the secretion of cell products into the ECM and the differentiation of interactions depending on the carbon nanostructure. The obtained nanocomposite membranes are promising bioactive materials.

Macromonomers as a Novel Way to Investigate and Tailor Silicon-Oxycarbide-Based Materials Obtained from Polymeric Preceramic Precursors.

It has been shown that bifunctional monomers (D units), which are used to increase the carbon content in silicon oxycarbide precursors, can form volatile oligomers, thus affecting the amount of carbon available during the transition into the final material in the annealing process. Additionally, an uneven distribution of carbon-rich mers may lead to the formation of a free-carbon phase, instead of the incorporation of carbon atoms into the silicon matrix. In this study, a novel two-step approach was utilized. Firstly, a macromonomer containing a number of structural units with precise structure was synthesized, which was later polycondensed into a ceramic precursor. Chlorodimethylsilane modified 2,4,6,8-tetramethylcyclotetrasiloxane was used as a silicon oxycarbide precursor monomer containing both T and D structural units (i.e., silicon atoms bonded to three and two oxygen atoms, respectively), with well-defined interconnections between structural units. Such a macromonomer prevents the formation of small siloxane rings, and has a very limited number of possible combinations of structural units neighboring each silicon atom. This, after investigation using IR, XRD, TG and elemental analysis, gave insight into the effect of "anchoring" silicon atoms bonded to two methyl groups, as well as the impact of their distribution in comparison to the materials obtained using simple monomers containing a single silicon atom (structural unit).

Raman studies of the interactions of fibrous carbon nanomaterials with albumin.

Adsorption or immobilization of proteins on synthetic surfaces is a key issue in the context of the biocompatibility of implant materials, especially those intended for the needs of cardiac surgery but also for the construction of biosensors or nanomaterials used as drug carriers. The subject of research was the analysis of Raman spectra of two types of fibrous carbon nanomaterials, of great potential for biomedical applications, incubated with human serum albumin (HSA). The first nanomaterial has been created on the layer of MWCNTs deposited by electrophoretic method (EPD) and then covered by thin film of pyrolytic carbon introduced by chemical vapor deposition process (CVD). The second material was formed from carbonized nanofibers prepared via electrospinning (ESCNFs) of polyacrylonitrile (PAN) precursor and then covered with pyrolytic carbon (CVD). The G-band blue-shift towards the position of about 1600cm-1, observed for both studied surfaces, clearly indicates the albumin (HSA) adhesion to the surface. The G and G' (2D) peak shift was employed to assess the stress build up on the carbon nanomaterials. The surface nano- and micro-topography as well as the method of ordering the carbon nanomaterial has a significant influence on the mode of surface-protein interaction.

The FTIR studies of gels and thin films of Al2O3-TiO2 and Al2O3-TiO2-SiO2 systems.

In this work, samples in form of bulk ones and thin films were obtained using the sol-gel method. The bulk samples were heated at different temperatures (500 °C, 850 °C and 1100 °C) corresponding to the annealing process of coatings, deposited on different substrates by dipping and pulling out samples from the proper sol with the stable speed. Thin films of both Al2O3-TiO2 and Al2O3-TiO2-SiO2 systems were deposited on carbon, steel and titanium substrates in two different ways: as single layers obtained from Al2O3 sol, TiO2 sol and Al2O3 sol or deposited as mixed coatings from Al2O3-TiO2 sol as well as Al2O3-TiO2-SiO2 one. All bulk samples were studied by the FTIR spectroscopy and the X-ray diffractometry while thin films were also investigated by the electron microscopy. In the IR spectra of Al2O3-TiO2 samples, as well as gels and coatings, bands due to the vibrations of AlO bonds of the octahedrally and tetrahedrally coordinated aluminum were observed. The IR spectra of samples of Al2O3-TiO2-SiO2 system differ from that of Al2O3-TiO2 ones in presence of bands assigned to the SiO bond vibrations and in positions of bands due to AlO bond vibrations. In all spectra of bulk samples and coatings, the positions of TiO bond vibrations were ascribed basing on the IR spectra of the pure anatase and rutile.