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Description: TITLE: BIOLOGICAL EXTRACTION OF CHITIN + PROCESSING OF THE BIOMATERIAL FOR POTENTIAL BIOMEDICAL APPLICATIONS

Abstract: The seafood processing industries generate tons of waste crab, shrimp and lobster shells globally every year. Shellfish waste management is a huge problem faced by these industries. Approximately 50-60% of the total weight of the shells in lobster, shrimp, crab, is the non-edible exoskeleton, which is very rich in chitin, along with other components like calcium, proteins, and pigments.

In this study, lobster shell wastes were used as the source of chitin raw material. Effectiveness and impact of chemical and biological treatments of lobster shell waste for chitin recovery were performed and compared. It was shown that treatment using successive cocultures with a combination of Serratia marcescens and Lactobacillus plantarum resulted in effective removal of proteins and minerals from lobster shells.

The biological chitin extraction method is preferable to the chemical method, which requires strong acids and bases like HCl and NaOH. For fabrication of chitin membranes, ioni c liquid s (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was used as a solvent media for the chitin. The resulting materials were thoroughly characterized, revealing that freeze-drying produced membranes that were highly porous. The drying methods and the concentration of chitin used defined the membrane properties. The use of ionic liquids (ILs) is a promising alternative strategy to enhance their solubility and processability, without the use of harsh chemicals and solvent systems. An empirical model was generated to correlate the different membrane properties. This allowed for prediction of the properties (e.g., tensile strength) of the chitin membrane made with different wt% of chitin-IL solutions and gives the ability to tune the properties of the biomaterial.

These chitin membranes were shown to be suitable as a substrate for growth of mammalian cells. Chitin membranes were also used as a matrix for loading and prolonged in vitro release of bioactive compounds. Blendi ng of ot her polymers like poly-lactide (PLA) and hydroxyapatite with chitin altered the material properties. The polymers were mixed at different concentrations and the effect of variation of the polymer concentrations on the behavior of the resulting composite was investigated.

These composite materials also supported the growth of osteocytes, which makes them promising candidates for scaffolds for use in bone regeneration that are not exposed to excessive forces. The utilization of shellfish wastes can potentially solve environmental problems, as well as providing economic benefits. The direct processing of chitin out of nonhazardous, nontoxic solvents could give us access to a sustainable material that has the potential to be used in many biomedical applications.

Committee members: Dr. Tracie Ferreira, Bioengineering; Dr. Mark Silby, Biology; Dr. Chen-Lu Yang, Research Engineer at CIE: and Dr. Christopher Brigham from WIT.