Chitosan-BaTiO3 nanostructured piezopolymer for tissue engineering.

Herein we report the synthesis of a piezopolymer composed of chitosan (CS)/hydroxylated BaTiO3 (OH-BTO) nanoparticles with enhanced biocompatibility, non-toxicity, and piezoelectric behavior that can be advantageously used in biomedical applications. Our CS/OH-BTO nanocomposites exhibit piezoelectric coefficient (d33 = 11.29 pC/N) between those of dry skin (0.05-0.19 pC/N) and bone (4-11 pC/N), demonstrating biocompatibility in contact with human fibroblasts (HF) cells after 24 h. SEM, XRD, FTIR and Raman measurements were performed to assess the mechanism of interaction between CS matrix and OH-BTO NPs and their correlation with the biological responses. Cytotoxicity assays with HF cells reveal that hydroxylation of BTO NPs does not affect the cell viability of CS/OH-BTO films with NPs concentration from 1 to 30 wt.%. In contrast, non-hydroxylated BTO NPs showed significant cell damage, which could be traced to uncontrollable NPs agglomeration. This behavior suggests that CS/OH-BTO nanocomposites can act as active material that promotes cell growth and can be used for biomedical purposes.

Efecto del tiempo de cocimiento y reposo del grano de maíz (Zea mayz L. ) nixtamalizado, sobre las características fisicoquímicas, reológicas, estructurales y texturales del grano, masa y tortillas de maíz / Effects of cooking and steep time of nixtamalized corn grain (sea mayz L. ) on the physicochemical, rheological, structural and textural characteristics of grain, mass and tortillas

The corn tortilla is elaborated using corn grain masa processed by the traditional nixtamalization method, which consists of two steps: cooking and steeping. In these steps the physicochemical and structural properties are strongly affected, resulting in changes in the textural characteristics of the tortilla produced. In this work the effects of cooking and steeping time on the moisture content, amylographic profiles, crystallinity, weigh loss from masa to tortilla, starch damage, rollability, elasticity and cutting force for grain, masa and corn tortillas, were evaluated. The milling of the nixtamalized grain and the cooking of tortilla conditions were the same in all treatments. All tortillas samples showed a good rollability. The results show that the moisture content of corn grain was increased up to 42 g/100 g during the total cooking time (45 min), and it further increased to 52-53 g/100 g after when the cooked grain was steeped for 4 h. All evaluated parameters showed high correlation coefficients with the texture properties of tortillas. The starch damage was the variable with the best correlation among all evaluated parameters. The correlation coefficients between starch damage and moisture content, weigh loss and maximum viscosity for corn grain, masa and tortillas were larger than 0.92 (p < 0.01). The best tortillas were produced using nixtamal with the follow characteristics: moisture content of nixtamal, 42-44 g/100 g and tortilla, 43-44 g/100 g; adhesiveness of masa, 30-50 g; maximum viscosity of nixtamal, 860-880 cp and tortilla 490-510 cp; starch damage of nixtamal, 14 g/100 g and tortilla, 35-37 g/100 g, and weigh loss of tortilla during cooking, 16 g/100 g.