Design and evaluation of succinylated soy protein tablets as delayed drug delivery systems.

The impact of succinylation on soy proteins as excipients for delayed delivery of drugs in the gastrointestinal tract was studied. Succinylation decreased protein solubility and protein charge density at pH 1.2 and increased solubility and zeta potential at pH above 4.5. Tablet erosion and swelling were decreased at pH 1.2 and increased at pH 7.5. FTIR analysis indicated polypeptide chain unfolding as a result of succinylation. Tablets of protein succinylated 50% or 100% released less than 10% of loaded riboflavin or rifampicin in 2h at gastric pH in the presence of pepsin but released these compounds rapidly at intestinal pH. Succinylated soy protein tablets were thus gastroresistant, suggesting their use as excipients for controlled release of medicinal or nutraceutical agents.

Production of nanohole/nanodot patterns on Si(001) by ion beam sputtering with simultaneous metal incorporation.

We have established the conditions for which nanohole and nanodot patterns are produced on Si(001) surfaces by 1 keV Ar(+) ion beam sputtering (IBS) at normal incidence with an alternating cold cathode ion source (ACC-IS). Nanohole patterns are produced within a narrow IBS window for low ion fluxes (<100 µA cm(-2)) and relatively low ion fluences (<10(18) ions cm(-2)) whereas nanodot morphologies are produced above this window. The nanohole pattern is not stable after prolonged irradiation since it evolves to a nanodot morphology. Rutherford backscattering spectrometry (RBS) measurements show that nanohole patterns are produced when the metal content on the irradiated surfaces is higher (within (2.5-3.5 × 10(15)) atoms cm(-2)) than in the case of nanodots (<2.5 × 10(15) atoms cm(-2)). The different metal content is related to the ACC-IS operation, since the set-up provides simultaneous incorporation of Fe and Mo on the target surface from the erosion of the cathodes and sample holder, respectively. The role of metal incorporation on pattern selectivity has been corroborated qualitatively by extending the results obtained with the ACC-IS to a standard Kaufman-type source. In order to gain further information on the metal effects, chemical analysis of the surface has been performed to complement the compositional RBS results, showing for the first time the relevant participation of metal silicides. Further outlook and a discussion regarding the role of metal incorporation are also given.

Characterization of amino cross-linked soy protein hydrogels.

This study focused on amino cross-linking as means of forming soy protein hydrogels with modifiable properties. The efficiency of glyceraldehyde, a potential food-grade cross-linking agent, was compared to glutaraldehyde, a well-known dialdehyde. The influence of the concentration of these agents on the degree of cross-linking as well as macroscopic and supramolecular properties was studied. The effect of increasing the cross-linker concentration was mainly an increase in degree of cross-linking and gel storage modulus (G') and a decrease in gel swelling ratio and increase in gel deswelling ratio. However, the cross-linking influence was less pronounced in the case of glyceraldehyde. Glutaraldehyde displayed greater ability to form hydrogels with modifiable properties. Finally, electron micrographs suggested that cross-linking agent type had no impact on gel microstructure.