Simple ultrasound method to obtain starch micro- and nanoparticles from cassava, corn and yam starches.

Starch nanoparticles (SNP) were produced employing a simple ultrasound method without chemical additives from cassava, corn, and yam starches, which contain 18%, 25% and 30% amylose, respectively. Simultaneously, starch microparticles (SMP) were also obtained, which were significantly smaller than the native starch granules. The yield of the process for all starch sources was 12 ± 1% SNP and 88 ± 5% SMP, starting with aqueous starch suspensions at 10% and 30 min of sonication.

Preparation of succinylated cellulose membranes for functionalization purposes.

The anhydroglucose chains of cellulose possess hydroxyls that facilitate different chemical modification strategies to expand on, or provide new applications for membranes produced by the bacteria Gluconacetobacter xylinus. Conjugation with biomolecules such as proteins, especially by the amine groups, is of great value and interest for the production of biomaterial derivatives from bacterial cellulose. To assist in these modifications, cellulose was succinylated in order to prevent steric hindrance and to create an attachment point for conjugation.

Preparation of cellulose II and IIII films by allomorphic conversion of bacterial cellulose I pellicles.

The structural changes resulting from the conversion of native cellulose I (Cel I) into allomorphs II (Cel II) and IIII (Cel IIII) have usually been studied using powder samples from plant or algal cellulose. In this work, the conversion of Cel I into Cel II and Cel IIII was performed on bacterial cellulose films without any mechanical disruption. The surface texture of the films was observed by atomic force microscopy (AFM) and the morphology of the constituting cellulose ribbons, by transmission electron microscopy (TEM).

Nanostructural reorganization of bacterial cellulose by ultrasonic treatment.

In this work, bacterial cellulose was subjected to a high-power ultrasonic treatment for different time intervals. The morphological analysis, scanning electron microscopy, and atomic force microscopy revealed that this treatment changed the width and height of the microfibrillar ribbons and roughness of their surface, originating films with new nanostructures. Differential thermal analysis showed a higher thermal stability for ultrasonicated samples with a pyrolysis onset temperature of 208 degrees C for native bacterial cellulose and 250 and 268 degrees C for the modified samples.