Research On 3D Printed Photothermal Materials For The Treatment And Repair Of Bone Tumor Defects

Bone tumor formation mainly includes the formation of tumor cells and bone tissue defects.Therefore,the process of removing tumor cells and repairing bone tissue must be included in the treatment of bone tumors.At present,the main methods for treating bone tumors in clinical practice are mainly surgical treatment,supplemented by chemical medicine treatment and radiation therapy.Clinical cases have proved that these methods can not completely remove tumor cells,and they are all affected by the side effects of chemotherapy and radiotherapy.These traditional treatments only partially remove the bone tumor tissue and do not further adopt clinical protocols to promote bone tissue repair.Therefore,the design and preparation of new biological materials to achieve the integration of bone tumor cells and promote bone repair has important clinical significance.Compared with traditional surgical treatment,chemotherapy and radiotherapy,photothermal therapy has attracted more and more researchers’ attention because of its non-invasive,non-toxic side effects and less damage to normal tissues.Using a combination of photothermal therapy and bone tissue engineering,the photothermal material and the bone repair ceramic are organically combined by 3D printing technology,so that the 3D printed bone tissue scaffold not only has the ability to repair bone tissue,but also has the effect of killing cancer cells.This will provide a new way of thinking for the treatment of bone tumors.Therefore,this paper focuses on the two processes of treating bone tumors,and designs artificial bone tissue scaffolds with induced bone tissue regeneration and photothermal properties.The main content and results of the article are as follows:(1)Combined with the macroscopic and microscopic structure of natural bone,the3 D printing method is used to design an artificial bone scaffold that conforms to the natural bone structure and mechanical properties.Bone scaffolds have similar physical properties to natural bones,such as three-dimensional channels that are interconnected,high porosity,large surface area,and high mechanical strength.(2)Using the 3D printing technology,the osteoinductive active factor P24 polypeptide was loaded in polylactic acid-glycolic acid copolymer(PLGA)and β-tricalcium phosphate(β-TCP)to prepare different percentages of PLGA/β-TCP/P24.The(PTP)polypeptide scaffold enables the P24 polypeptide to be efficiently and continuously released as the PLGA and β-TCP are degraded,thereby promoting cell growth and inducing osteogenic differentiation.The characterization of the material shows that the scaffold has interconnected pores with a porosity of 75%.The compressive strength of the scaffold is between 3.5 and 4.0MPa.The scaffold has good mechanical properties and the same compressive strength as the human cancellous bone.Has good mechanical properties.The in vitro degradation assay of the scaffold confirmed that the P24 polypeptide would continue to be released as the scaffold degraded.Cell proliferation and staining experiments revealed that PTP bone scaffolds containing 0.3% P24 polypeptide promoted proliferation of murine bone marrow mesenchymal stem cells(BMSCs).At the same time,in vitro osteogenic experiments showed that PTP bone scaffolds containing 0.3% P24 peptide could induce more alkaline phosphatase(ALP)activity and increase calcium ion deposition,and promote more OCN,OPN,RUNX-2,The expression of osteogenic related genes such as COL-1 indicated that PTP bone scaffold containing 0.3% P24 polypeptide could better promote the differentiation of BMSCs into osteoblasts and have better osteogenic ability.The results of this series of experiments confirmed that compared with the traditional bone repair scaffold,the scaffold containing the appropriate amount of P24 ceramic polypeptide can promote the proliferation and differentiation of the cells,and can induce the differentiation of BMSCs into osteoblasts,thereby inducing bone tissue regeneration.We have established a method of using 3D printing technology combined with tissue engineering to load osteoinductive active factors on bone repair materials to provide sustained release of osteoinductive factors,providing a new method for clinical treatment of bone defects.Ideas.(3)P24 polypeptide,doxorubicin hydrochloride(DOX)and ferric oxide(Fe3O4)were loaded on PLGA and β-TCP using drug-loading technology and 3D printing technology to obtain PLGA/β-TCP/P24(PTP),PLGA/ β-TCP/P24/DOX(PTPD),PLGA/β-TCP/P24/Fe3O4(PTPFe),PLGA/β-TCP/P24/DOX/Fe3O4(PTDFe)four-group scaffolds,which enable scaffold collection to promote bone tissue repair and Killing the dual function of bone tumor cells in order to achieve the purpose of "one-step" treatment of bone tumors.The characterization analysis of the scaffolds shows that the interconnected pores,porosity,surface area and mechanical properties of the bifunctional scaffolds are similar to those of natural bones,indicating that the bifunctional scaffolds meet the requirements of three-dimensional and mechanical properties of human bone.The results of photothermal performance experiments show that the surface temperature of the scaffold containing Fe3O4 will increase rapidly under the short-term illumination of 808 nm near-infrared light.By adjusting the content of Fe3O4 and the power of near-infrared light in the scaffold,the surface temperature of the scaffold can be 30.-120 ° C for regulation.In vitro photothermal anti-tumor experiments showed that the scaffold containing Fe3O4 could kill more than 90%of MG63 cells under 808 nm near-infrared light irradiation,and the scaffold containing Fe3O4 and DOX killed more bone tumor cells than the Fe3O4 scaffold alone,indicating light.Thermal therapy combined with chemotherapy can achieve better goals for the treatment of bone tumors.The results of in vitro osteogenic capacity test indicated that PTPDFe bifunctional scaffold can promote alkaline phosphatase activity and increase calcium ion deposition,and promote more osteogenic related genes of OCN,OPN,RUNX-2 and COL-1.The expression of PTPDFe also promoted the differentiation of BMSCs into osteoblasts.The results of this series of experiments indicate that the prepared PTPDFe dual-function scaffold can meet the requirements of human bone mechanical properties and meet the requirements of promoting the growth of BMSCs cells;the loading of Fe3O4 and DOX confers the ability of the stent to treat tumors.The combination of 3D printing technology and tissue engineering technology and the use of photothermal therapy in combination with chemotherapy can provide a new perspective for clinical bone tumor treatment and bone repair.