Biodegradable macroporous polyHIPEs with specific cavity sizes and selective interfacial functionalization of the inner surface with NHA are produced.

No abstract

The droplet phase of a reverse microemulsion formed by the surfactant cetyltrimethylammonium ferrocyanide was used as a matrix to synthesize nanoparticles of nickel hexacyanoferrate by adding just a solution of NiCl2 to the microemulsion media. Dynamic light scattering and small-angle neutron scattering measurements show that the reverse microemulsion droplets employed have a globular structure, with sizes that depend on water content. Transmission electron microscopy and electron diffraction are used to obtain information about the structure of the synthesized nanoparticles. The results show that the size and shape of the coordination compound nanoparticles correspond with the size and shape of the droplets, suggesting that the presented system constitutes an alternative method of the synthesis of metal hexacyanoferrate nanoparticles.

Unbleached cellulose obtained from corncobs was used to synthesize cellulose nanocrystals (CNCs). Corncobs are an agro-industrial residue that has a high cellulose content and can be used as a raw material to obtain CNCs. The cellulose was extracted from the corncobs by means of delignification in two stages. The first stage consisted of a pulping process with ethanol and acetic acid (organosolv method), and in the second stage, the corncob was treated with an organosolv method and potassium hydroxide, followed by sodium hydroxide and boric acid (extraction and purification) to eliminate hemicellulose. The obtained cellulose was not bleached, in order to maintain the groups corresponding to lignin and hemicellulose on their surface. Afterward, the obtained cellulose underwent acid hydrolysis to obtain CNCs, using sulfuric acid at 64%. These nanocrystals were characterized by X-ray diffraction, atomic force microscopy, thermogravimetric analysis and zeta potential. The CNCs obtained from the two types of unbleached cellulose showed lengths from 125.18 to 225.86 nm and diameters from 11.61 to 35.92 nm. The results indicate not only that CNCs can be obtained from unbleached cellulose corncobs but also that their characteristics are similar to those of CNCs obtained by means of bleached cellulose.

A cheap, reproducible, environmentally friendly, and biocompatible method for stabilizing and storing gold nanoparticles for prolonged time is presented. Adding a diluted pectin solution immediately after the synthesis of gold nanoparticles increases the stability of the aqueous nanoparticle dispersion, avoiding agglomeration and further precipitation, regardless of the initial size and shape of the nanoparticles. When the gold nanoparticles-pectin solution is freeze-dried, a sponge-like solid is obtained, improving significantly the pectin capacity to stabilize gold nanoparticles. Because the gold nanoparticles are immobilized into the freeze-dried pectin matrix, the size, size distribution, and shape remain unchanged, regardless of how long the solid is stored. The solid can be redispersed in water to obtain a solution that is able to maintain the stability of the gold nanoparticles, even for more than 20 weeks. This solution can be freeze-dried again, with no changes in the gold nanoparticles size. The proposed method is an alternative for stabilizing nanoparticles with no toxic agents, increasing significantly the storage time.