Preparation Of Biomimetic SF/CM-PDA Nanofibrous Scaffolds And Study On Chemo-Photothermal Therapy Of Osteosarcoma

Osteosarcoma is the most common primary bone malignant tumor in children and adolescents.Although the prognosis has been greatly improved through adjuvant chemotherapy combined with surgical treatment,in recent 30 years,osteosarcoma still has a recurrence rate of 30%-40%after 3 years of surgical treatment,and bone defects will be caused after surgical treatment.At present,chemotherapeutic drugs commonly used in clinic,such as methotrexate and cisplatin,are prone to drug resistance and have many toxic and side effects,which makes the treatment of osteosarcoma encounter a bottleneck.Using new chemotherapeutic drugs,appropriate drug delivery system and multimodal therapy to improve the therapeutic effect of osteosarcoma have become the keys.Aiming at the problem of postoperative treatment of osteosarcoma,this paper designed a multifunctional silk fibroin（SF）nanofiber local delivery system,which effectively improved the bioavailability of curcumin（CM）,and combined photothermal therapy with chemotherapy to enhance the postoperative treatment effect of osteosarcoma.Curcumin loaded silk fibroin nanofiber porous scaffolds were prepared by using mild operating conditions and supercritical carbon dioxide（SC-CO₂）method with low solvent residue.The surface of scaffolds was modified with polydopamine（PDA）,and SF/CM-PDA composite scaffolds were successfully prepared.The physical and chemical properties of SF/CM-PDA scaffolds,such as the morphology and the effect of experimental parameters on the secondary structure of silk fibroin,were discussed.At the same time,the photothermal properties and responsive drug release behavior of the scaffolds were investigated.Finally,the synergistic effect of photothermal chemotherapy of SF/CM-PDA scaffolds in the treatment of osteosarcoma was studied by cell experiment in vitro.The experimental results show that the functionalized SF/CM-PDA composite scaffolds with macroporous interconnection and nanofiber structure were successfully prepared by SC-CO₂ technology,and polydopamine surface treatment.The scaffold can well simulate the structure of natural ECM.With the increase of 75%ethanol steam post-treatment time,theβsheet content of silk fibroin in the scaffold increased.PDA coating reduced the water contact angle of SF/CM-PDA scaffolds and improves the hydrophilicity of the scaffold.The porosity of SF,SF/CM and SF/CM-PDA scaffolds were 66.7%,65.6%and 56.0%respectively,which basically meet the requirements of composite tissue engineering scaffolds.The introduction of PDA coating improved the compression performance of the support at the same time.The PDA coating on the outer layer of the scaffold could delay the degradation rate of the scaffold.The residual amounts of SF/CM scaffolds and SF/CM-PDA scaffolds soaked in 2 mg/ml PDA solution after 14 days of degradation in enzyme solution are 10.23%and 28.97%respectively.Under 808 nm laser irradiation,the laser power and PDA content were positively correlated with the final temperature of the scaffold.SF/CM-PDA scaffolds exhibited excellent photothermal stability,and the photothermal conversion efficiency was23.8%.Near infrared light irradiation and low p H conditions could promote the release of CM from SF/CM-PDA scaffolds.When the scaffold was implanted into mice,it could still rise to 50.5°C.The results of anti-osteosarcoma experiment in vitro showed that the inhibitory effect of SF/CM-PDA scaffolds on the proliferation of MG-63 osteosarcoma cells was dependent on the content of CM.When the content of CM exceeded 1%,SF/CM-PDA scaffolds had good anti osteosarcoma activity and showed stable and continuous anti-tumor effect.When the content of CM was 0.05-0.5%,SF/CM-PDA scaffolds could promote the proliferation of osteoblast MC3T3-E1 cells.The survival rate of MG-63cells was positively correlated with laser power and irradiation time.Under the irradiation of near-infrared laser,SF/CM-PDA scaffolds play the function of photothermal chemical combined treatment of osteosarcoma.The survival rate of MG-63 cells is only 20.4%,and the effect of combined treatment is better than that of chemotherapy and photothermal treatment alone.As biocompatible biomaterials,the SF/CM-PDA bifunctional scaffolds have great potential for the treatment of osteosarcoma and tumor-related bone defect repair.