Novel Acryloylated and Methacryloylated Nanocellulose Derivatives with Improved Mucoadhesive Properties.

In this work, three nanocellulose derivatives are synthesized with the aim of preparing new mucoadhesive materials. Nanocellulose is reacted with glycidyl methacrylate in dimethylsulphoxide, and with acryloyl and methacryloyl chloride in dimethylacetamide in the presence of 4-(N,N-dimethylamino)pyridine as a catalyst. These reactions are carried out under heterogeneous conditions, and the reaction products are characterized using various spectroscopic techniques, X-ray diffraction, atomic force microscopy, and thermogravimetric analysis. The Fourier-transform infrared spectra showed all the characteristic absorption bands typical for cellulose and also new peaks at 1720 cm-1 for the carbonyl group (C═O) and 1639, 812 cm-1 for the double bond (C═C). It is established that the crystal structure of the nanocellulose is slightly changed with derivatisation and the thermal stability of these derivatives increased. Mucoadhesive properties of nanocellulose and its derivatives is evaluated using the tensile test, rotating basket method, and fluorescence flow-through method. The retention of these polymers is evaluated on sheep oral mucosal tissue ex vivo using artificial saliva. Test results demonstrated that the new derivatives of nanocellulose have improved mucoadhesive properties compared to the parent nanocellulose.

Enhanced catalytic activity of new acryloyl crosslinked cellulose dialdehyde-nitrilase Schiff base and its reduced form for nitrile hydrolysis.

Immobilization of enzymes to improve their catalytic properties is an attractive protocol which makes them suitable candidates to meet various industrial demands. Present study describes the synthesis of new acryloyl crosslinked cellulose dialdehyde (ACCD) for nitrilase immobilization. Nitrilase was immobilized onto ACCD via Schiff base formation i.e. imine linkages (-CH=N-). Effect of different operational parameters viz. temperature, pH and substrate concentration on the free and the immobilized nitrilases were evaluated by hydrolysis of mandelonitrile. Immobilization resulted into enhanced catalytic activity of nitrilase under different operating conditions of temperature and pH. The optimum temperature and pH for immobilized forms of nitrilase was obtained to be 55 °C and 8.0 which was higher than its free form (40 °C, 6.0). Immobilized nitrilase also exhibited good thermal and storage stability over the free form and is reusable up to sixteen repeat cycles with an appreciable retention activity.

New glucose oxidase-immobilized stimuli-responsive dextran nanoparticles for insulin delivery.

Designing strategies for the use of biopolymer-based nanoparticles as drug delivery carriers is a considerable challenge in pharmaceutical science. Present study reports synthesis of a novel glucose responsive and in-vitro pH triggered insulin delivery system comprised of glucose oxidase immobilized on acryloyl crosslinked dextran dialdehyde (ACDD) nanoparticles. Scanning electron microscopy, transmission electron microscopy and particle size analysis data revealed that these carriers possess nanosize which is an important parameter for drug delivery applications. In-vitro insulin release studies were performed under artificial gastric fluid (AGF, pH 1.2) and artificial intestinal fluid conditions (AIF, pH 7.4) at physiological temperature (37 °C). Insulin release profile showed controlled release of about 70% under AIF conditions for 24 h. Insulin release mechanism studied using different kinetic models revealed that Korsmeyer-Peppas model appropriately explained the mechanism as 'non-Fickian' diffusion release of insulin. These glucose responsive stimuli sensitive nanocarriers exhibited controlled release of about 90% under AIF conditions in the presence of glucose. These findings revealed that these nanoparticles are promising and reliable delivery systems to overcome problems related with subcutaneous insulin therapy.