RESUMO
The high degree of chemical modification of the chitosan chains due to protonated amine groups allows them to react with many negatively charged surfaces as anionic polymers and cell membranes, resulting in an attractive material for medical and pharmaceutics applications. Incorporating ionic iodine (I- and IO3 -) on chitosan chains is a direct way to successfully obtain chitosan-iodine nanoparticles (CSNPs-I and CSNPs-IO3) through ionic gelation. The nanoparticles (NPs) present a hemispherical morphology with sizes around 30-70 nm for CSNPs-I and CSNPs-IO3, similar to chitosan NPs, in accordance with SEM and DLS techniques. The XRD characterization did not show noticeable differences in the crystallinity index (CI) for CSNPs and CSNPs-I, 48.4 and 49.3%, respectively, but for CSNPs-IO3, the CI decreased to 43.85%. The cytotoxic effects on human tumor cells of chitosan and iodine-modified chitosan nanoparticles (CSNPs-I and CSNPs-IO3) were evaluated for 24 h in a range from 0.15 mg/mL to 0.95 mg/mL concentrations, where CSNPs-IO3 presented the lower viability for lung cancer A549, followed by cervical cancer HeLa cell and finally breast cancer MDA-MB-231, with a weight content of iodate ion in a range of 8.7 to 15 µg. This work presents the possibility of exploring chitosan-iodine NPs in medical applications.
RESUMO
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.