| Resumo: |
Medical devices designed to be used in contact with blood can induce several biological effects in the patient, such as the thrombus formation and complement system activation. An strategy to avoid these adverse effects is the coating of the surfaces with hemocompatible and not immunogenic polymers. This study aimed to develop sulfated chitosan films with hemocompatible characteristics for biomedical applications. Natural (NC) and sulfated chitosan (SC) films were characterized by Elemental Analysis, Infrared spectroscopy (FTIR-ATR), Proton and Carbon Nuclear Magnetic Resonance (1H e 13C-NMR), Viscometry, Gel Permeation Chromatography (GPC), Scanning Electron Microscopy with EDX (SEM/EDX), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). The films hemocompatibility was analyzed studying the globular protein adsorption (BSA and fibrinogen), platelet adhesion, anticoagulant activity and cytotoxicity by LDH (lactate dehydrogenase). The elemental analysis demonstrated the sulfur presence in the sulfated films. The FTIR-ATR results confirmed the sulfation reaction, with the appearance of two new bands at 1206cm -1 (S = O) and 794cm -1 (C-S-O), assigned at sulfur group. The film QS6 with the highest sulfation degree (GS =1.37) was selected to perform the following analyzes. The 1HNMR analysis showed deacetylation degree (DD) of 77% and 58% for the natural and sulfated chitosan, respectively. 13CNMR analysis showed that chitosan was partially sulfated, obtaining 2, N-3,6,O-sulfated chitosan. The mass molecular (MM) of QN and QS were 78.093 Da and 5.050 Da, respectively, determined by viscometry. Homogeneous and smooth surfaces were observed by SEM/EDX images. The XRD showed semi-crystalline peaks for natural chitosan, while an amorphous structure was observed for sulfated chitosan. The TGA analyses revealed a reduction in the thermal stability to sulfated chitosan compared to natural chitosan. The hemocompatibility results showed that chemical modification on chitosan chain was able to decrease the BSA (36.8%) and fibrinogen (20%) adsorption and mainly the platelet adhesion (93.7%) in relation to QN, either by SEM and optical microscopy images. Only the QS presented anticoagulant activity in the intrinsic pathway (72.15s, 200µg/mL) compared with the QN (26.57s, 200µg/mL). It was also observed atoxicity of the studied polymers. These results indicate that sulfated chitosan films have hemocompatibility properties promising to blood-materials devices. |
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