Novel microbial cellulose/alginate composite for biomedical applications: synthesis and characterization

CACICEDO M.; LEON IE; GONZALES J; PORTO LM; CASTRO GR

Lille

Simposio; 10th European Symposium on Biochemical Engineering Sciences and 6th Internation Forum on Industrial Biopreocesses; 2014

IFIB - ACS (USA), University of Liege, Institute Pascal

The objective of the present work is the development of Microbial cellulose/alginate composite films as a drug delivery device for localized therapy. Films were produced in static culture of Gluconoactobacter hansenii by the in situ modification method. While the bacteria produce cellulose fibers, sodium alginate solution in the range between 1 to 2 % was added to the culture and kept under incubation. As a result, more closed structure hybrids films than only microbial cellulose films were obtain. This allows a better entrapment of biomolecules. Characterization of films was carried out by Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). TGA results show a shift in the degradation temperature of films, from 350 to 300 ºC for microbial cellulose and microbial cellulose/alginate composite, respectively. Essentially, this can be explained considering the intermolecular interactions between both biopolymers. Moreover, the appearance of a new peak at 650ºC in the derivative of weight graph for hybrid matrix suggests the presence of alginate. The microbial cellulose/alginate spectra show a peak at 1597 cm -1, showing the existance of a shift from 1591 cm-1 for the carboxyl group of pure alginate. This could be attributed to intermolecular interactions between cellulose and alginate as previously reported. In addition, SEM images were obtained to describe the morphology of the composite and images revealed the synthesis of a nanostructured hybrid biomaterial between microbial cellulose and alginate. Once films were characterized, encapsulation assays with the anti-cancer drug doxorubicin were performed. Results showed the capability of the system to incorporate 4, 13 and 25 µmols of doxorubicin per gram of hybrid matrix, after incubation in doxorubicin solutions of 0.5, 1.0 and 2.0 mg/ml respectively. This confirmed a dependence of doxorubicin encapsulation rate with external drug concentration, the higher the concentration the higher the encapsulation rate. Subsequently, kinetics release of films were studied at 37 ºC showing a doxorubicin release of 45, 55 and 115 µM at 24 h for the three encapsulated concentrations. Finally, systems were evaluated in colon adenocarcinoma cells (HT-29) in order to test their citotoxicity at 24 h. Films with doxorubicin encapsulation of 4 and 13 umols/gram showed 70% of viability and no significant differences were found between both concentrations. Films with 25 µmols/gr showed 55% of cell viability, whereas direct exposition to free doxorubicin at 100uM and 200uM expressed 75% and 55% of live cells respectively. As far as we concern microbial cellulose/alginate films that released around 50 µM to 115 µM of doxorubicin, with a sustained kinetic, showed the same citotoxicity that those observed for 100 to 200 µM of direct drug exposition. Finally, citotoxicity of doxorubicin encapsulated films in HT-29 adenocarcinoma cells, showed an enhanced antitumor capabilty for cancer therapy in comparison with free drug administration