طراحي، ساخت و مشخصه يابي پوشش نانوكامپوزيتي كراتين - شبكه آلي فلزي جهت رهايش كنترل شده عوامل ضدالتهاب بر زيرلايه منيزيمي جهت كاربرد كاشتني استخوان

Nowadays, the number of patients requiring biomedical implants for organ repair an‎d bone defects is increasing. In this regard, the use of biodegradable magnesium-based implants to treat these diseases is expan‎ding. However, the chemically active nature of magnesium alloy causes its rapid degradation in the physiological environment, which will lead to premature implant failure an‎d limitations in clinical applications. The aim of the present study is to fabricate an‎d characterize a nanocomposite coating of keratin/ bio-MOF on AZ91 magnesium-based alloy in order to improve its corrosion behavior, bioactivity, an‎d biocompatibility. In this regard, keratin was extracted from pigeon feathers, an‎d the results of Bradford, Biuret, Fourier transform infrared spectroscopy, an‎d X-ray diffraction showed that keratin extraction was successful. Subsequently, the synthesis of bio-MOF particles by the subcritical point sol-thermal method using curcumin an‎d copper was successfully performed. Next, after modifying the substrate surface by alkaline method, keratin/bio-MOF composite coating was performed on the alkalized substrate using electrospray method at three different times (2, 1 an‎d 3 hours). In order to eva‎luate an‎d optimize the coatings, X-ray diffraction, roughness, wettability, scanning electron microscopy, electrochemical tests, bioactivity an‎d cell culture were performed. The results showed that with increasing the coating time, the roughness significantly decreased from 12.26 ± 1.4 μm for the alkalized substrate (Mg (OH)₂) to 13.5 ± 1.9 μm for the 3-hour coated sample (M-(K/MOF)3). Also, with increasing the coating time, the contact angle changed from about 56 ± 1.2 degrees to 87 ± 1.1 degrees. Electrochemical studies also showed that the keratin/bio-MOF composite coating significantly reduced the rate of metal dissolution by affecting the kinetics of electrochemical reactions an‎d significantly increasing corrosion resistance. For example, by examining the corrosion behavior, the results showed that the corrosion current density decreased from 8.96 μA/cm2 in the uncoated sample to 0.25 μA/cm2 in the 2-hour coated sample (M-(K/MOF)2). According to the results, the antioxidant activity in the M-(K/MOF)2 an‎d M-(K/MOF)3 samples increased compared to M-(K/MOF)1 an‎d M-K2, an‎d the M-(K/MOF)2 sample was able to inhibit about 77±1.7% of free radicals within 24 hours. Also, the bioactivity results indicated the highest calcium an‎d phosphorus deposition in this sample after 14 days of immersion, resulting in its excellent bioactivity. Also, the Nyquist plots indicated that the keratin/metal organic network nanocomposite coating, due to the crosslinking of keratin under alkaline conditions an‎d the presence of the bioorganic framework, had the property of Self-healing. eva‎luation of the interaction of MG63 cells with composite coatings showed that not only did the composite coatings not have any toxic effects on the cells, but they also increased cell growth an‎d proliferation. So that the M-(K/MOF)2 sample had 236±6.3% cell viability control on the fifth day. Also, a significant increase in alkaline phosphatase activity an‎d calcium deposition confirmed the acceleration of osteogenic activity in the presence of this coating. Based on these findings, the keratin/bio-MOF composite coating has high potential for application in bone implants due to improved corrosion resistance, increased bioactivity, self-healing properties, an‎d cell growth.

مهشيد خرازيهاي اصفهاني , مسعود عطاپور

زهرا قاسمي

مهران نحوي , عليرضا علافچيان