Designing novel starch/cellulose acetate structures for biomedical applications

Abstract

Starch-based blends present an enormous potential to be widely used in the biomedical area, because they are totally biodegradable, inexpensive, available in large quantities. However, natural-based polymers have great limitations in processability particularly due to their usually high crystallinity which limits their solubility. This can be overcome by the use of ionic liquids which are recognized as ‘green’ replacements for conventional organic solvents. Earlier reports emphasized the use of certain ionic liquids to solubilize some natural macromolecules such as cellulose, starch, chitin, chitosan and silk fibroin. Furthermore, they present unique physicochemical properties, namely lower vapour pressure, excellent chemical and thermal stabilities, high ionic conductivity and easy recyclability. Starch based materials have been proceed in a variety of different morphologies and shapes by a number of different processes. In this work, starch/cellulose acetate (SCA) was dissolved in 1-butyl-3-imidazolium acetate, followed by regeneration of the polymer in different non-solvents (water, ethanol and isopropanol) in order to obtain membranes. Different concentrations of SCA (5 and 10%) in ionic liquid and drying techniques (vacuum oven and freeze drying) were studied. The starch/cellulose acetate structures were evaluated by their swelling capability, degradation behaviour and morphological features. Moreover, the influence of thickness on physical chemical properties of the membranes was assessed. The results revealed that membranes with lower thickness showed high water absorption, which by its turn accelerated their degradation rate. Furthermore, the membranes dried by vacuum oven present a more compact structure as compared those prepared by freeze drying. Some previous works reported SCA as a suitable material for tissue engineering purposes, supporting the cell adhesion. Then, in vitro cell culturing assays will be performed using osteoblast like cells (SaOs-2) and mouse fibroblast-like cell line (L929).The cell viability and proliferation on membranes will be evaluated through the MTS test and the DNA quantification. The development of innovative technology such as novel natural polymers materials is of grater interest in medical field. All findings suggested that the obtained structures (membranes) present adequate properties for several biomedical applications for instance drug delivery, skin substitutes, guided bone regeneration or as coatings for medical devices.