Influence of magnetite incorporation into chitosan on the adsorption of the methotrexate and in vitro cytotoxicity.

Emerging pollutants are a group of substances involved in environmental contamination resulting mostly from incomplete drug metabolism, associated with inadequate disposal and ineffective effluent treatment techniques. Methotrexate (MTX), for instance, is excreted at high concentrations in unchanged form through the urine. Although the MTX is still effective in cancer and autoimmune disease treatment, this drug shows the ability of bioaccumulation and toxicity to the organism. Thus, the present work aimed to evaluate the adsorption of the MTX drug onto magnetic nanocomposites containing different amounts of incorporated magnetite (1:1, 1:5, and 1:10 wt%), combining the theoretical-experimental study as well as the in vitro cytotoxicity. Moreover, equilibrium studies (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Hill, Redlich-Peterson, and Sips), kinetic (PFO, PSO, and IPD), and thermodynamic (ΔG°, ΔH°, and ΔS°) were used to describe the experimental data, and ab initio simulations were employed in the theoretical study. Magnetic nanocomposites were synthesized by the co-precipitation method using only FeCl2 as the iron precursor. Adsorbents were characterized by FTIR, XRD, Raman, SEM-EDS, BET, and VSM analysis. Meanwhile, cytotoxic effects on L929 and A375 cell lines were evaluated through MTT, NR, and LDH assays. The adsorption of the MTX was carried out in a typical batch system, exploring the different experimental conditions. The theoretical study suggests the occurrence of chemisorption between CS·Fe3O4-MTX. The maximum adsorption capacity of MTX was 285.92 mg g-1, using 0.125 g L-1 of CS·Fe3O4 1:1, with an initial concentration of the MTX (50 mg L-1), pH 4.0 at 293 ± 1.00 K. The best adjustment of equilibrium and kinetic data were the Sips (low values for statistical errors) and PSO (qe = 96.73 mg g-1) models, respectively. Thermodynamic study shows that the adsorption occurred spontaneously (ΔG° < 0), with exothermic (ΔH° = - 4698.89 kJ mol-1) and random at the solid-solution interface (ΔS° = 1,476,022.00 kJ mol-1 k-1) behavior. Finally, the in vitro study shows that magnetic nanomaterials exhibit higher cytotoxicity in melanoma cells. Therefore, the magnetic nanocomposite reveals to be not only an excellent tool for water remediation studies but also a promising platform for drug delivery.

Avaliação da interferência do plástico filme sobre a luminosidade de laser terapêutico de baixa potência / Evaluation of the interference of plastic film on the luminosity of low-power therapeutic laser

Objetivos: Avaliar a interferência do policloreto de vinil (plástico filme) sobre a luminosidade emitida pelos LASERs Hélio-Neônio e Arseneto-Gálio. Métodos: Estudo experimental desenvolvido em ambiente laboratorial controlado. A coleta de dados foi realizada por meio de fotosensor (DET36A). A luminosidade dos LASERs foi avaliada nas situações: controle, policloreto de vinil em contato direto com a caneta e policloreto de vinil a 1cm de distância da caneta. Em cada situação foram realizadas 30 emissões (1, 4 e 8 J/cm²). Resultados: O contato direto reduziu em 19% a luminosidade do Hélio-Neônio e a 1cm de distância esta redução foi de 17% (p < 0,001). No Arseneto-Gálio esta redução foi de 8 e 21% (p < 0,001), respectivamente. Conclusão: O policloreto de vinil (plástico filme) reduz a luminosidade em aproximadamente 15% das diferentes canetas dos LASERs terapêuticos de baixa potência. (AU)

Objectives: To evaluate the interference of polyvinyl chloride (plastic film) on the light emitted by LASER Helium-Neon and Gallium-Arsenide. Methods: This experimental study was developed in a controlled laboratory environment. Data collection was collected using a photodetector (DET36A). The luminosity of the LASERs was evaluated in the situations: control, polyvinyl chloride in direct contact with the pen and polyvinyl chloride at 1 cm away from the pen. Luminosity of the LASERs was evaluated in the situations: control, polyvinyl chloride in contact with the skin and pen and polyvinyl chloride with 1 cm distance between the skin and pen. In each situation, 30 emissions (1, 4 and 8 J/cm²) were performed. Results: Direct contact reduced by 19% the luminosity of the Helium-Neon and 1 cm from this reduction was 17% (p < 0.001). In Gallium-Arsenide the reductions were 8% and 21% (p < 0.001), respectively. Conclusion: The results indicated that the Polyvinyl chloride (plastic film) reduces the luminous emission by about 15% of the different pens of low-power therapeutic LASERs. (AU)