The main objective of this work was to develop a nanoemulsion based on linseed oil and betulinic acid, stabilized with Pluronic F127 and polyglycerol polyricinoleate, for anticancer applications. The nanoemulsions were synthesized by ultrasound and evaluated for in vitro cytotoxicity, particle size, polydispersity index, zeta potential, morphology, encapsulation efficiency, storage stability, rheology and in vitro release kinetics. In vitro cytotoxicity assays were performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (72 h) against HCT-116 (colorectal carcinoma), SNB-19 (glioblastoma), NCI-H460 (lung carcinoma) and L-929 (normal fibroblasts) cells. The determination of 50% inhibitory concentration (IC50) showed an increased selectivity for the emulsified betulinic acid when compared to its free form for the HCT-116 cells. The IC50 values for the synthesized nanoemulsions showed a range from 3.2 to 3.7 µM (HCT-116), 5.6 and 11.5 µM (NCI-H460), 5.8 and 7.3 µM (SNB-19) and > 16.5 µM for normal fibroblasts. In the 48 h in vitro release assays, it presented controlled release explained by the Korsmeyer-Peppas model, releasing 572.25 and 619.95 µg of betulinic acid in a controlled way, generating promising perspectives for the prolonged release of betulinic acid in anticancer applications.

Descreve-se a determinação de ácido giberélico em promotores de crescimento usados na agricultura, por análise de injecção sequencial e detecção potentiométrica. Os detectores potentiométricos com características melhoradas usam uma membrana de PVC preparada com Mn(III)tetrafenilporfirina-Cl ([(Mn(TPP)Cl]). Formularam-se diferentes membranas comparando-se aditivos iónicos com o objectivo de se seleccionar as unidades com as melhores características de declive, tempo de resposta, reprodutibilidade e selectividade. Para fins analíticos foi seleccionada uma membrana com 6% de [(Mn(TPP)Cl], 27% de PVC, 66% de dibutilftalato (DBP), como solvente mediador, e 1% de tetrafenilborato de sódio, como aditivo aniónico. Quando inserido num sistema SIA o eléctrodo tubular apresentava um intervalo de linearidade de 5×10-4 mol L-1 a 8×10-3 mol L-1, declive de -64,5 ± 1,6 mV/dec e melhores coeficientes de selectividade potenciométrica (log Kpot) do que os obtidos com eléctrodos convencionais. Na análise de amostras comercializadas em Portugal obtiveram-se desvios padrão de 0,01 e 0,4 (n= 4) e um ritmo de amostragem de 30 amostras/hora.

This work describes the determination of gibberellic acid in growth promoters formulations used in agriculture by sequential injection analysis and potentiometric detection. The potentiometric detectors with improved characteristics used a PVC membrane prepared with Mn(III)tetraphenylporphyrin-Cl as electroactive specie. Different membranes formulated with several ionic additives were compared in order to select the most suitable one concerning slope, response time, reproducibility and selectivity. A membrane containing 6 wt% of manganese tetraphenylporphyrin-Cl [(Mn(TPP)Cl], 27 wt% of PVC, 66 wt% of dibutylphthalate (DBP), as mediator solvent, and 1 wt% of sodium tetraphenylborate, as anionic additive, was chosen for analytical applications. When coupled to a SIA system the tubular electrode presented a linear range between 5×10-4 mol L-1 and 8×10-3 mol L-1, a slope of -64.5 ± 1.6 mV/dec and lower potentiometric selectivity coefficients (log Kpot) than those obtained with the conventional electrodes. Standard deviation of 0.01 and 0.4 (n= 4) and a sampling rate of 30 samples/hour were obtained in the analysis of real samples.