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Starch is a biopolymer which demand has increased because of its multiple industrial applications. The present work was performed to characterize, both flour and starch obtained from Cucurbita foetidissima root as a non-conventional source. According to its physicochemical, rheological (flow curves), thermal and morphological properties. The flour was composed of a 77% total of carbohydrates, and the isolated starch showed 88% purity. Granules found in both samples exhibited birefringence and mixed morphology. Particle size distribution varied from 1 to 35 µm for flour and from 1 to 29 µm for starch. The k and n indices from their evaluated suspensions at 25, 50 and 70 °C indicated a non-Newtonian behavior of pseudoplastic type for both materials. Gelatinization temperature was 63.58 ± 3.08 °C with ΔH = 5.64 ± 3.81 J/g for flour, and of 66.50 ± 0.06 °C with ΔH = 12.27 ± 0.17 J/g for starch. XRD patterns were mixed A and B, characteristic of cereal starches and rubbers, with changes in the crystallinity percentage with each other. These materials characteristics are similar to those of other sources such as cassava (Manihot esculenta), but different from cereals as corn (Zea mays), and other tubers, as potato (Solanum tuberosum). [ABSTRACT FROM AUTHOR]

Silver sulfide nanoparticles, smaller than 5 nm, are of great interest in the biomedical field due to their improved optical properties from the quantum confinement of charge carriers. The effect of silver sulfide nanoparticles (6.4 ± 2.2, 13 ± 4.9, and 33 ± 12.5 nm) coated with BSA (bovine serum albumin) on cytotoxicity, cell proliferation (MTT assay), and cell morphology was determined in vitro using 3T3 fibroblast cell line as assay model. The synthesized Ag2S-BSA nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. Transmission electron microscopy and dynamic light scattering were used for particle size measurement. The MTT results showed a tendency to decrease cell viability with time exposure rather than concentration, in all particle's groups. A greater affectation was observed in cells incubated with smaller nanoparticles, and this is associated with a higher speed of cell uptake due to a higher content of adsorbed BSA. It was found that the largest nanoparticles (33 ± 12.5 nm) at 72 h and at higher concentration presents the same cell viability as observed with the smallest attributing it to the agglomeration of particles formed by the low stability of the sample. Regarding cell morphology, fluorescence microscopy showed good cell growth in all the nanoparticle groups, observing a slighter increase in the cell population of the sample of intermediate particle size (13 ± 4.9 nm). [ABSTRACT FROM AUTHOR]