Introduction: Biomaterials used in medical devices in contact with blood can induce thrombus formation and inflammation. These two processes are interdependent and involve the coagulation cascade and complement system activation, with the consequent platelets and leukocytes adhesion and activation. The hemocompatibility of these devices can be improved by using natural polymers, since they have properties as biocompatibility, non-toxicity, biodegradability and antimicrobial potential. Chitosan is apromising biomaterial studied today, however, has thrombogenic characteristics in its natural form. This biopolymer is easy chemically modified due to its OH- and NH3+ groups, which are highly reactive. Thus, this study aims to analyze the anti-thrombogenic property of chitosan films chemically modified by sulfation reaction.
Materials and Methods: Natural chitosan (QN) and sulfated (QS) films were produced and characterized by elemental analysis, ATR-FTIR, H-NMR and SEM/EDS. Platelet adhesion assay was performed with whole blood in vitro to test the hemocompatibility and the results were quantified by fluorescence microscope.
Results and Discussion: The sulfur amount in the QS was 12% and its degree of substitution (DS) was 1.37, both obtained by elemental analysis. The introduction of sulfated group in the chitosan structure was confirmed by FTIR-ATR, with the appearance of a characteristic band of this group at 1215 cm-1 (S=O) and 806 cm-1 (C-S-O). The morphology of the films was observed using SEM/EDS, showing a smooth and homogeneous surface, with sulfur species homogeneously distributed on the modified surface. The degree of deacetylation (DD) of the films was measured H-NMR, which was found to natural chitosan DD of 77% and 58% formodified film. The DD reduction for modified chitosan is very important for applications involving blood contact, since the protonated amino groups from raw chitosan can interact with charged blood proteins and contributed to thrombus formation and inflammation. In the platelet adhesion assay was observed a reduction in the adherence of blood components on sulfated film compared with the QN film (Figure 1). From the image area (1,045393 x 10-4 mm2) was recorded a number of platelets in the QN of 1,15 x 10-8 mm2, as that for the QS was 0,3 x 10-9 mm2.
Conclusions: The chemical modification of chitosan by sulfonation reaction indicated an improvement in the hemocompatibility potential for biomedical applications.
CAPES; Embrapa; Central Analítica UFC
References:
[1] BALAN, V.; VERESTIUC, L. Strategies to improve chitosan hemocompatibility: A review. European Polymer Journal, v. 53, p. 171–188, 2014.
[2] AMIJI, M. Platelet adhesion and activation on an amphoteric chitosan derivative bearing sulfonate groups. Colloids and Surfaces B: Biointerfaces, v. 10, p. 263,1998.
[3] CARREÓN, J.; SAUCEDO, I.; NAVARRO,R.; MALDONADO, M.; GUERRA, R.; GUIBAL,E. Mercury recovery from aqueous solutions by polymer-enhanced ultrafiltration using a sulfate derivative of chitosan. Membrane Water Treatment, Vol. 1, No. 4 (2010) 231-251.