Discipline: Technology and Engineering
Subcategory: Biomedical Engineering
Nettie Brown - University of Georgia
Co-Author(s): Guillaume Chantereau, University of Bordeaux, Bordeaux, France ; Christian Gardrat, University of Bordeaux, Bordeaux, France ; Veronique Coma, University of Bordeaux, Bordeaux, France ; Hitesh Handa, University of Georgia, Athens, Georgia
One of the major limiting factors to the clinical application of blood contacting materials is that they can lead to infection. The Centers for Disease Control and Prevention (CDC) estimates that roughly 1.7 million hospital-associated infections, from all types of bacteria combined cause up to 99,000 deaths per year; 60% related to blood contacting materials. The goals of our study is to develop materials that maintain the nano-sized network of bacterial cellulose (BC) and exhibit antimicrobial properties for potential use in wound healing.
BC is a polysaccharide produced by Gluconacetobacter sacchari bacteria and it is already used in the medical field and food industry for its unique physiochemical properties. There are a plethora of uses for BC like artificial skin, artificial blood vessels and vascular grafts, but it lacks properties like antioxidant and antimicrobial ability to help it advance in the medical field. To overcome this issue, we are studying applicability of BC by synthesizing composites. Composites consists of two types of individual materials, the matrix and the reinforcement material. The matrix, in our case BC, acts as a scaffold and supports the reinforcement material (chitosan), while the reinforcements impart physic-chemical and biological properties to the matrix. Chitosan is amino-polysaccharide produced by the partial de-acetylation of chitin but can also be produced naturally by plant synthesis or via microbial synthesis.
In this study, we developed non-covalent bacterial cellulose-chitosan composites with acetic acid (AA), citric acid (CA) and lactic acid (LA). Fourier transformed infrared spectroscopy (FTIR) spectroscopy was used to study the molecular structure of BC impregnated materials. Thermogravimetric Analysis (TGA) was conducted to examine the effect of sample composition on the thermal degradation of the BC impregnated films. Elementary Analysis was used to determine amounts of Carbon, Oxygen, Hydrogen, and Nitrogen present in samples. The morphology of the prepared films was observed using SEM on fractured surfaces. Antimicrobial activity was assessed against a non-pathogen strain Escherichia coli (E. Coli). Experiments were performed on air-dried films and neutralized freeze-dried foams. After freeze drying, chitosan was more present in BC-CS-CA as determined from elementary analysis, FTIR, and TGA. Improvement of the neutralization method is needed to maintain chitosan in free-dried foams. Morphology analysis showed the maintenance of the nano-sized network with BC+CS-AA and BC+CS-CA but destroyed with BC-CS-LA. This suggests CS-LA film-forming solution is not a viable option to impregnate BC. Further experiments to characterize our materials include cytotoxicity, water contact angle, and porosity.
References: Siro I, Plackett D (2010) Microfibrillated cellulose and new nanocomposite materials: a review. Cellulose 17:459-494
Funder Acknowledgement(s): I would like to thank Louisiana State University and the LSAMP iREU NSF Grant NO. CHE 1560390 for the opportunity to complete research in France and my peach state LSAMP for financial support through NSF Grant NO. 0503278. I would also like to thank my home lab 'Handa Biomaterials' for the constant teaching and support through the NIH-RO1-134899 and CDC-200-2016-91933.
Faculty Advisor: Hitesh Handa, firstname.lastname@example.org
Role: I was trained on NMR, GPC/SEC and SEM. Since this was my labs first time combining the two materials, I was responsible for developing protocols for dissolution, impregnation, and neutralization. After finalizing protocols to prepare the materials, I performed characterization tests using FTIR, TGA, NMR, SEM, GPC/SEC, and DDA.