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Carbon nanotubes have been used as scaffolds for tissue engineering. However, the identification of these nanomaterials disperses in biological solutions and their direct interaction with nerve cells is still controversial. The aim of this work is to characterize the topographic and ultra-structural distribution of the composite made of multi wall carbon nanotubes-polyvinylpyrrolidone MWCNTs-PVP, fixing it in paraformaldehyde at 4% and was observed with SEM and CM. Although the nanotubes were not labeled or stained with fluorescent compounds, the MWCNTs-PVP deposited on glass and on nerve cells, was observed by the confocal microscope in the reflection mode. In SEM studies, it was observed that MWCNTs-PVP was attached to the surface on neurons. Moreover, in CM studies, it was possible to observe that MWCNTs-PVP was attached to the neuronal membrane, crossing the cell membrane and getting into the cytoplasm. These results support the hypothesis that carbon nanotubes interact with the neuronal cell membrane and can be useful for neuronal tissue engineering. In addition, these results open new alternatives for toxicological studies, in order to elucidate the cytotoxicity of MWCNTs-PVP composite in neurons and other excitable cells.

In the present work, multiple-wall carbon nanotubes (MWCNTs) were surface modified in an environmentally friendly way, using low-frequency ultrasonic energy. This type of modification was carried-out using two different types of organic acids, citric acid (CA) and oxalic acid (OA). The modification of the MWCNTs was confirmed by Fourier-transform infrared spectroscopy (FTIR), where functional groups such as OH, C=O, O–C=O and COOH were detected. By means of Raman spectroscopy, an increase in carbon surface defects was found. On the other hand, using X-ray photoelectron spectroscopy (XPS), oxidation was evidenced on the surface of the modified MWCNT. In both Raman spectroscopy and XPS, the results indicate a greater modification when CA is used, possibly due to the fact that CA has a larger number of functional groups. MWCNT-CA showed good dispersion in methanol, while MWCNT-OA showed good stability in methanol and ethanol. Finally, a 20% removal of creatinine efficiency improvement was found with respect to the unmodified MWCNTs, while no improvement was found in the case of urea and uric acid.

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Polyaniline (PANI) composites have gained momentum as supercapacitive materials due to their high energy density and power density. However, some drawbacks in their performance remain, such as the low stability after hundreds of charge-discharge cycles and limitations in the synthesis scalability. Herein, we report for the first time PANI-Graphitic oxidized carbon nitride composites as potential supercapacitor material. The biomimetic polymerization of aniline assisted by hematin, supported by phosphorous and oxygen-modified carbon nitrides (g-POCN and g-OCN, respectively), achieved up to 89% yield. The obtained PAI/g-POCN and PANI/g-OCN show enhanced electrochemical properties, such as conductivity of up to 0.0375 S/cm, specific capacitances (Cs) of up to 294 F/g (at high current densities, 5 A/g) and a stable operation after 500 charge-discharge cycles (at 3 A/g). In contrast, the biomimetic synthesis of Free PANI, assisted by stabilized hematin in cosolvents, exhibited lower performance properties (65%). Due to their structural differences, the electrochemical properties of Free PANI (conductivity of 0.0045 S/cm and Cs of up to 82 F/g at 5 A/g) were lower than those of nanostructured PANI/g-POCN and g-OCN supports, which provide stability and improve the properties of biomimetically synthesized PANI. This work reveals the biomimetic synthesis of PANI, assisted by hematin supported by modified carbon nitrides, as a promising strategy to produce nanostructured supercapacitors with high performance.

Behavioral, electrophysiological and biochemical experiments were performed in order to establish the presence of a glutamate receptor in the ciliate Paramecium. It was found that an AMPA/KA receptor is functionally expressed in Paramecium and that this receptor is immunologically and fillogenetically related to the AMPA/KA receptor present in vertebrates.

The integration of carbon nanotubes (CNTs) into optical fibers allows the application of their unique properties in robust and versatile devices. Here, we present a laser-induced technique to obtain the deposition of CNTs onto the fiber optics tips of multimode interference (MMI) devices. An MMI device is constructed by splicing a section of no-core fiber (NCF) to a single-mode fiber (SMF). The tip of the MMI device is immersed into a liquid solution of CNTs and laser light is launched into the MMI device. CNTs solutions using water and methanol as solvents were tested. In addition, the use of a polymer dispersant polyvinylpyrrolidone (PVP) in the CNTs solutions was also studied. We found that the laser-induced deposition of CNTs performed in water-based solutions generates non-uniform deposits. On the other hand, the laser-induced deposition performed with methanol solutions generates uniform deposits over the fiber tip when no PVP is used and deposition at the center of the fiber when PVP is present in the CNTs solution. The results show the crucial role of the solvent on the spatial features of the laser-induced deposition process. Finally, we register and study the reflection spectra of the as-fabricated CNTs deposited MMI devices.