Lysozyme-induced Degradation of Chitosan: the Characterisation of Degraded Chitosan Scaffolds - Lysozyme-induced Degradation of Chitosan: the Characterisation of Degraded Chitosan Scaffolds - Open Access Pub

Up till now, chitosan has confirmed its versatile application in skin, cartilage and bone tissue engineering, as well as in drug delivery applications. This study is focused on enzymatic degradation of porous chitosan structures usually designed for mentioned purposes. In vitro degradation was monitored during four weeks of incubation at physiological temperature and in two different media, phosphate buffer saline solution and water. The scaffolds were characterised before and after enzymatic degradation using scanning electron microscopy and infrared spectroscopy with Fourier transformations (FTIR). According to the gravimetric analysis, higher weight loss of chitosan scaffolds was observed in buffered medium with respect to the water. The results implied that the total weight loss obtained in buffer involves physical dissolution of chitosan and lysozyme cleavage of glycoside bond. Importantly, FTIR identification of chitosan scaffolds after enzymatic degradation indicated the absence of lysozyme activity in water, indicating that weight loss is a result of the chitosan dissolution. This finding greatly impacts design of degradation experiments and characterisation of degradation behaviour of chitosan-based materials utilised as implants or drug delivery systems. DOI 10.14302/issn.2640-6403.jtrr-17-1840 One of the most important derivatives of chitin is chitosan, poly (D-glucosamine), a product of chitin deacetylation process. Chitosan is a linear polysaccharide, crystalline polymer insoluble at pH greater than 71. Chitosan has proven to be biodegradable, with antibacterial activity and hydrophilic, possessing functional groups (–OH and –NH2) for secondary bonds formation2. Moreover, chitosan possesses high biocompatibility, good miscibility with other polymers and good coating properties for bulk implants. Even during degradation, chitosan-oligomers are found to be bioactive. Besides, chitosan-oligomers can act as probiotics that positively change intestinal microflora balance, inhibit growth of harmful bacteria, promote good digestion and boost immune function3, 4. Chitosan is nontoxic and has been approved by FDA for would dressing application5. In the pharmaceutical field, chitosan is used as a drug delivery system for oral, nasal, parenteral and transdermal applications, as well as implant for gene delivery. High chemical reactivity has also led to several chitosan-drug systems for treating tumours6, 7, 8. Moreover, it is used for encapsulation of living cells as an inner core of composite spheres9. In many cases, cross-linked chitosan membranes