Physico-chemical and sensory evaluation of potato (Solanum tuberosum L.) after irradiation.

This work evaluated the effects of ionizing radiation on the physico-chemical and sensory characteristics of the potato cultivar Ágata (Solanum tuberosum L.), including budding and deterioration, with the end goal of increasing shelf life. For this, four groups of samples were harvested at the maturation stage. Three of them were separately exposed to a Co-60 source, receiving respective doses of 0.10, 0.15 and 2.00 kGy, while the non-irradiated group was kept as a control. All samples were stored for 35 days at 24 °C (± 2) and at 39% relative humidity. The following aspects were evaluated: budding, rot, loss of weight, texture, flesh color, moisture, external and internal appearance, aroma, soluble solids, titratable acidity, vitamin C, protein, starch and glucose. The results indicated that 0.15 kGy was the most effective dose to reduce sprouting and post-harvest losses, under the conditions studied.

Non-specific interactions of CdTe/Cds Quantum Dots with human blood mononuclear cells.

In order to study biological events, researchers commonly use methods based on fluorescence. These techniques generally use fluorescent probes, commonly small organic molecules or fluorescent proteins. However, these probes still present some drawbacks, limiting the detection. Semiconductor nanocrystals - Quantum Dots (QDs) - have emerged as an alternative tool to conventional fluorescent dyes in biological detection due to its topping properties - wide absorption cross section, brightness and high photostability. Some questions have emerged about the use of QDs for biological applications. Here, we use optical tools to study non-specific interactions between aqueous synthesized QDs and peripheral blood mononuclear cells. By fluorescence microscopy we observed that bare QDs can label cell membrane in live cells and also label intracellular compartments in artificially permeabilized cells, indicating that non-specific labeling of sub-structures inside the cells must be considered when investigating an internal target by specific conjugation. Since fluorescence microscopy and flow cytometry are complementary techniques (fluorescence microscopy provides a morphological image of a few samples and flow cytometry is a powerful technique to quantify biological events in a large number of cells), in this work we also used flow cytometry to investigate non-specific labeling. Moreover, by using optical tweezers, we observed that, after QDs incubation, zeta potentials in live cells changed to a less negative value, which may indicate that oxidative adverse effects were caused by QDs to the cells.