ساخت و مشخصه يابي داربست هاي كامپوزيتي نانوذرات هيدروكسي آپاتيت/پلي كاپرولاكتون با پوشش ZIF-8 به روش چاپ سه بعدي براي كاربردهاي مهندسي بافت استخوان راي كاربردهاي مهندسي بافت استخوان

Fabrication an‎d characterization of Hydroxyapatite/ Polycaprolactone composite scaffolds with ZIF-8 coating by 3D printing method for bone tissue engineering

نانو فناوري

Using 3D printed porous scaffolds for bone replacement is one of the most advanced methods of bone tissue engineering. Hydroxyapatite (HA) bioceramics an‎d polycaprolactone polymer have been used in this research. The purpose of this research is to investigate the bioactivity an‎d biodegradability of the scaffolds. Also, cell attachment an‎d proliferation on scaffolds containing ZIF-8 nanoparticles is investigated in this research. HA nanoparticles were synthesized by hydrothermal method. The XRD results showed that the HA nanoparticles were properly synthesized an‎d there is no separate phase in the nano powders. Also, SEM images showed flaky HA nanoparticles in nanometer sizes. These nanoparticles had a specific surface area of 23 m2/g an‎d were in the mesoporous range with a pore size of 45 nm. Scaffolds consisting of 20, 25 an‎d 30% HA were made. The mechanical test was applied on all three scaffolds an‎d the values of compressive strength, compressive modulus an‎d yield strength were the highest for the scaffold containing 25% HA an‎d increased compared to pure PCL, which was due to the increased crystallinity of HA in PCL. Mechanical tests on the scaffolds showed that the scaffold containing 25% HA has optimal mechanical properties. The biodegradability an‎d bioactivity of the optimal scaffolds were checked by immersing the samples in PBS an‎d SBF solutions, respectively, an‎d they showed very good bioactivity an‎d biodegradability. Weight loss had an increasing trend during 4 weeks, an‎d on the 28th day, the highest rate of destruction an‎d weight loss was experienced. The pH of the PBS solution increased on the first day, an‎d then the pH decreased. An increase in the pH of SBF solution occurred on days 1 an‎d 3, followed by a decrease in pH. This issue was also proven by the gradual decrease in the concentration of calcium an‎d phosphorus ions in the SBF solution. In addition, SEM an‎d XRD results of these scaffolds also confirmed the formation of apatite on the scaffold surface. The presence of HA an‎d the gathering of apatite nucleation sites were the reason for the intense formation of apatite layer on the surface of the scaffold. In-situ synthesis of ZIF-8 nanoparticles was performed on the optimal scaffolds an‎d the formation of this layer was performed by SEM an‎d EDS analysis by proving the presence of C, N, O an‎d Zn elements. Also, the presence of calcium an‎d phosphate elements related to HA nanoparticles was also proved by EDS test. In the following, MTS bioassays an‎d DAPI/Phalloidin cell staining were performed to check cell attachment, proliferation an‎d adhesion on the surface of scaffolds containing ZIF-8 an‎d without ZIF-8. These results showed that the attachment of cells an‎d their growth during 3 to 7 days were positive an‎d it was more for scaffolds containing ZIF-8. The results of the MTS test showed that the growth an‎d proliferation of cells on the scaffolds containing ZIF-8 experienced a significant improvement compared to the scaffolds without ZIF-8. Therefore, scaffolds containing ZIF-8 had no toxicity for cells an‎d support cell growth an‎d proliferation an‎d are biocompatible

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