Recent advances in food-packing, pharmaceutical and biomedical applications of zein and zein-based materials.

Zein is a biodegradable and biocompatible material extracted from renewable resources; it comprises almost 80% of the whole protein content in corn. This review highlights and describes some zein and zein-based materials, focusing on biomedical applications. It was demonstrated in this review that the biodegradation and biocompatibility of zein are key parameters for its uses in the food-packing, biomedical and pharmaceutical fields. Furthermore, it was pointed out that the presence of hydrophilic-hydrophobic groups in zein chains is a very important aspect for obtaining material with different hydrophobicities by mixing with other moieties (polymeric or not), but also for obtaining derivatives with different properties. The physical and chemical characteristics and special structure (at the molecular, nano and micro scales) make zein molecules inherently superior to many other polymers from natural sources and synthetic ones. The film-forming property of zein and zein-based materials is important for several applications. The good electrospinnability of zein is important for producing zein and zein-based nanofibers for applications in tissue engineering and drug delivery. The use of zein's hydrolysate peptides for reducing blood pressure is another important issue related to the application of derivatives of zein in the biomedical field. It is pointed out that the biodegradability and biocompatibility of zein and other inherent properties associated with zein's structure allow a myriad of applications of such materials with great potential in the near future.

Study of the reaction of grafting acrylamide onto xanthan gum.

The present study aimed to study the reaction conditions of grafting of acrylamide on xanthan gum. It was analyzed the influence of reaction conditions, mainly type of initiator activation, initiator concentration and initiator/acrylamide ratio, on graft parameters and copolymer properties. Potassium persulfate was employed as an initiator and heating or N,N,N',N'-tetramethylethylenediamine was used to activate the initiator. Reaction time and initiator concentration were varied and final values for grafting percentage and grafting efficiency were the same for both methods, whereas speed in reaching these values differs from one technique to another. We found that reaction time was inversely proportional to intrinsic viscosity, likely due to main chain degradation promoted by potassium persulfate (KPS); furthermore, the increasing in the KPS concentration lowers grafting percentage, acrylamide conversion and chain degradation, possibly as a result of O(2) formation at high KPS concentrations.