چكيده لاتين
In recent decades, bone injuries have become a major medical challenge. In this regard, tissue engineering is used as a novel approach in the treatment of bone injuries. In this study, 3D printed scaffolds of hydroxyapatite nanoparticles and polycaprolactone were fabricated, with surface modification by maleimide and conjugation of a targeted aptamer. In this study, hydroxyapatite nanoparticles were synthesized by the hydrothermal method, and the characterization of the nanoparticles was performed through XRD, SEM, and BET tests. The results obtained showed the successful synthesis of single-phase hydroxyapatite, spherical morphology in the nanoscale with a pore size of about 11 nanometers. According to previous studies, the scaffold containing 25% hydroxyapatite and 75% polycaprolactone was selected as the optimal composition and showed a compressive strength of 29.4 MPa, a compressive modulus of 0.78 GPa, and a yield strength of 8.7 MPa, which was a significant increase compared to pure PCL. The biodegradability and bioactivity of the scaffolds were investigated by immersing them in PBS and SBF solutions. In the results, the formation of an apatite layer on the scaffolds was observed by changing the concentration of calcium and phosphorus ions. Also, during 28 days, 16% weight loss and degradation were observed in the scaffolds. By performing surface modification, maleimide was attached to the surface of the scaffolds. FTIR analysis was used to confirm the successful surface modification process of the scaffold. Then, the designed aptamer with the ability to specifically bind to target molecules was attached to the maleimide groups on the scaffold surface. Confirmation of the successful attachment of the aptamer to the scaffold was done through labeling with carbon quantum dots (C-QDs) synthesized in this study. The results of the MTT cytotoxicity test showed that the viability of cells on the surface-modified scaffold containing aptamer has increased significantly. Also, SEM results showed increased cell adhesion on the modified scaffold. Qualitative and quantitative data of Alizarin Red staining confirmed the increased presence of dense and regular calcium deposits on the surface of the modified scaffold, which means increased calcium absorption in the scaffold containing aptamer. DAPI/Phalloidin staining also showed that the scaffold containing aptamer provides a suitable environment for cell growth and proliferation. These results indicate that aptamers, by establishing specific interactions with cell surface receptors, have provided a suitable environment for cell adhesion and proliferation, accurate guidance of cells, and improved biocompatibility, and as a result, accelerated the formation of engineered tissue.
