Production of bacterial nanocellulose was pursued as a matrix system for the stabilization of human insulin. The biomembranes produced by Gluconacetobacter hansenii were washed with 2% aqueous sodium dodecylsulfate solution, rinsed with ultrapure water and immersed in 1 mol L-1 NaOH aqueous solution at 60 °C for 90 min until neutralization. For the insulin adsorption assays, the biomembranes were soaked in a buffered solution of human insulin until no protein could be detected in the supernatant. The membranes with adsorbed insulin were characterized via mechanical resistance (resilience, relaxation, perforation), Differential Scanning Calorimetry (DSC), Thermal Gravimetrical Analysis (TGA), Fourier Transform Infrared Spectrophotometry (FTIR), X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) analyses. The FESEM photomicrographs of the surface of the biomembranes showed a rugged surface without cracks. The biomembranes exhibited adequate mechanical characteristics. The infrared spectra indicated that the chemical aspect of the protein moiety was preserved during adsorption onto the BNC biomembranes. According to the XRD analyses, the biomembranes showed a generalized amorphous behavior. Thermal analyses indicated an adequate thermal stability for a pharmaceuticals product. Hence, an elastic and malleable biomembrane was produced, suitable for incorporation of human insulin, aiming at transdermal delivery.
Over the last few years, researchers have started to explore a particular class of compounds defined as ionic liquids (ILs) in attempts to use their unique characteristics. Since ILs have a very low vapor pressure, these fascinating compounds hold great potential as high performance chemicals for several applications in the (bio)pharmaceutical industry. In general, and unlike common organic solvents with comparable polarities, ILs are quite compatible with enzymes (enhancing their structural and chemical stability) and other proteins, since they can promote higher selectivities, faster reaction rates and greater enzyme stabilities in biocatalytic reactions providing, at the same time, a path for the structural and functional stabilization of protein entities. ILs appear to enhance the delivery of macromolecules, particularly protein entities, and their interactions with ILs will be tackled in detail in this review paper.