Morphological and Physicochemical Characterization of Agglomerates of Titanium Dioxide Nanoparticles in Cell Culture Media

Titanium dioxide nanoparticles (TiO2 NP) are possible carcinogenic materials (2B-IARC) and their toxicity depends on shape, size, and electrical charge of primary NP and on the system formed by NP media. The aim of this work was to characterize agglomerates of three TiO2 NP by evaluating their morphometry, stability, and zeta potential (ζ) in liquid media and their changes with time. Sizes of agglomerates by dynamic light scattering (DLS) resulted to be 10–50 times larger than those obtained by digital image analysis (DIA) given the charged zone around particles. Fractal dimension (FD) was highest for agglomerates of spheres and belts in F12K, and in E171 in FBS media. E171 and belts increased FD with time. At time zero, using water as dispersant FD was larger for agglomerates of spheres than for of E171. Belts suspended in water had the smallest values of circularity (Ci) which was approximately unchanged with time. All dispersions had ζ values around −30 mV at physiological pH (7.4) and dispersions of NP in water and FBS showed maximum stability (Turbiscan Lab analysis). Results help in understanding the complex NP geometry-size-stability relationships when performing in vivo and in vitro environmental-toxicity works and help in supporting decisions on the usage of TiO2 NP

Effect of traditional dehydration processing of pepper jalapeno rayado (Capsicum annuum) on secondary metabolites with antioxidant activity

Jalapeno rayado peppers (Capsicum annuum) are usually subjected to a traditional smoke-dehydration process using Quercus sp. This treatment provides peppers with their characteristic functional attributes. To differentiate the production of antioxidant metabolites during the dehydration-smoking process, this process was compared with convective dehydration, both at 60°C. A higher antioxidant activity in smoke-dried pepper was observed due to the increase in concentration of phenolic compounds, flavonoids and Maillard products in the last hours of the process and was related to the presence of radicals with m/z (-) values: 585.32, 292.2, 326.18, 653.28, 240.11 and 210.14, generated during both dehydration processes. The change in colour was mainly due to the increase of Maillard compounds. Convective dehydration favoured the extraction of capsaicinoids, whereas no significant change was observed in smoke-dehydration, and carotenoid degradation was 40% with either process. A similar final moisture content was achieved in both processes