In Vitro Degradation Behavior of Absorbable Interface Screws / 中国医疗器械杂志

The composite material PLGA compounded with β-tricalcium phosphate (β-TCP) was prepared by melt blending method, and the absorbable interface screw was prepared by injection molding process. Prepare PBS buffer that simulates human body, conduct in vitro degradation experiments on interface screws according to relevant national and industry standards, then test and characterize interface screws at different time points for degradation of intrinsic viscosity, average molecular weight distribution, mass loss, mechanical properties and thermal properties. According to the degradation performance-time curve, determine the time node at which the interface screw loses the mechanical properties. In this paper, the in vitro degradation behavior of interfacial screws prepared from PLGA and β-TCP composites was studied in detail, providing a reference and basis for the degradation behavior of absorbable products prepared from PLGA and β-TCP composites.

Stress Relaxation Behavior of Collagen Type II- Silk Fibroin Composite Cartilage Scaffold under Different Degradation Cycles / 医用生物力学

Objective To study stress relaxation behaviors of cartilage scaffolds under different degradation cycles by using finite element analysis combined with theoretical models. Methods Based on the established degradation theoretical model, the elastic modulus of the scaffold was calculated under different degradation cycles. The finite element model of cartilage scaffolds was established and stress relaxation simulation was performed to analyze the variation of scaffold relaxation stress with time. The stress relaxation constitutive model was established to predict mechanical properties of the scaffold. Results The elastic modulus of cartilage scaffolds at 14 th, 28th, 42nd, 56th day after degradation was 32. 35, 31. 12, 29. 91, 28. 74 kPa, respectively. The upper layer for cartilage scaffolds was the largest. The overall relaxation stress of the scaffold decreased rapidly with time and then tended to be stable. At 8th week after degradation, the stress which the scaffold couldwithstand was still within the physiological load range of the cartilage. The predicted results of the stress relaxation constitutive model were in good agreement with the finite element simulation results. Conclusions The elastic modulus of the scaffold gradually decreases with the increase of degradation time. The longer the degradation period is, the less stress the scaffold can withstand. At the same degradation period, the larger the applied compressive strain, the larger the stress on the scaffold. Both the finite element simulation and stress relaxation constitutive model can effectively predict stress variations of cartilage scaffolds under degradation

Study on Degradation of Oxidized Regenerated Cellulose Absorbable Hemostatic Products / 中国医疗器械杂志

<p><b>OBJECTIVE</b>To study the degradation of oxidized regenerated cellulose absorbable hemostatic products.</p><p><b>METHODS</b>The morphology of the oxidized regenerated cellulose hemostatic products before and after degradation was observed by FTIR and SEM. The degradation products were determined by GPC and HILIC-ELSD.</p><p><b>RESULTS</b>In the initial stage of degradation, there was a great change in morphology. GPC determined its degradation end point was 10 d; it was determined that its degradation products contained glucose (0.13%) and cellobiose (0.17%) and other components.</p><p><b>CONCLUSIONS</b>A method was established for determining the end point of degradation of oxidized regenerated cellulose, which provided a new idea and reference for the study of the degradation end point.</p>

Physicochemical properties and in vitro degradation of a novel collagen scaffold material from basa fish (Pangasisus haniltoa) skin / 第二军医大学学报

Objective To prepare a novel collagen scaffold material using Basa fish (Pangasisus haniltoa) skin as the ingredient and to analyze the structural characteristics, physical properties and degradability of the prepared material, so as to explore whether Basa fish can replace terrestrial mammals for preparing a novel collagen scaffold material. Methods Basa fish skins were lyophilized to obtain the membrane material after repeated degreasing, decolorization and dedoping. Crude protein content was determined by the Kjeldahl method. Structure of the materials and its pore size and distribution were analyzed by scanning electron microscopy (SEM). Porosity was measured by the liquid displacement technique, and tensile strength was tested using universal testing machine. The changes of viscosity with temperatures were detected to determine the denaturation temperature of the material.The material was immersed in the phosphate-buffered solution (0.1 mol/L, pH 7.4), which was placed in a constant temperature shaker at 37°, and the water absorption and weight loss rates of the material were detected. Results The crude protein content of the collagen scaffold material was 95.2%, with visually uniform thickness. SEM photographs showed that one side of the material had a rough surface and porous structure, on which varying sizes of pores distributed uniformly; the other side was smooth with dense pores. The porosity of the material was (55.50±1.94)%, thickness was (0.66±0.10) mm and tensile strength was (18.82±0.94) MPa. The denaturation temperature of the material was 34° before thermo-crosslinking and 36° after thermo-crosslinking. The water absorption of the material was (379.77±77.81)% at 48 h. At 28 d after thermo-crosslinking, the degradation rate was (80.22±2.49)%, and the pH value of buffer was 6.67±0.05. Conclusion The collagen scaffold material from Basa fish skin can be made into the biological membrane with uniform thickness, and the membrane comprises double structures: dense layer and loose layer. This material exhibits excellent mechanical strength and appropriate denaturation temperature, but its degradation is fast, which needs further improvement.