Friction Of Hydrogel Scaffold Fabricated By 3D Printing

Due to the high lubrication, high water content, well biocompatibility and other excellent performance, hydrogel is considered to be a potential raw material of tissue engineering scaffolds. Meanwhile, as rapid prototyping technology developed, hydrogel scaffold fabricated by rapid prototyping technology has been widespread. Based on rapid prototyping technology, a 3D printing system with a nozzle was developed to form silica/polyvinyl alcohol(SiO2/PVA) hydrogel scaffold and sodium alginate(SA) hydrogel scaffold. The morphology, mechanical properties and the biocompatibility of the two kinds of hydrogel scaffolds were studied, also the process of 3D printing system with a nozzle was discussed.SiO2/PVA hydrogel scaffold and SA hydrogel scaffold were fabricated by 3D printing system with a nozzle. The scaffold can have a high resolution 200 μm and also it can have a 3D structure with a high porosity of 64.7%. The resolution of the scaffold can be controlled by adjusting the parameters of the 3D printing device. The resolution of scaffold is increased with the decrease of VS:VN. Scaffolds with different structure can be manufactured by the model designed through computer. The 3D printing sytem with a nozzle is limited by the viscosity of the sol. The sol should have a zero shear viscosity of higher than 10000 Pa·s and the viscosity of which is lower than 100 Pa·s at a shear rate of 10 s-1. Also it is demand for that G’>G” at low frequency and G’<G” at high frequency.Due to the dense of network, the compressive modulus of hydrogel scaffolds decrease with the increase of porosity and it is lower than that of fabricated as the same formula to the scaffolds. The scaffold exhibits a better compressive resilience than the bulk hydrogel as the woodpile structure of scaffolds dissipate part of the external force.At low sliding velocity(10-6~10-3 m/s), the frictional force of scaffolds is slightly higher than the bulk hydrogel and it decreases with the increase of porosity. At high sliding velocity(10-2~1 m/s), the frictional force of scaffold is equal to the bulk hydrogel and it is not sensitive to the porosity. Hydrogel scaffold shows a higher frictional force at low sliding velocity(10-6~10-3 m/s)compared with bulk hydrogel and they are equal at high sliding velocity(10-2~1 m/s). At small pressure(0.3 KPa), the hydrogel scaffold shows a well reproducibility in friction. In contrast, the bulk hydrogel shows poor reproducible friction behaviors. The differences of friction behaviors between hydrogel scaffold and bulk hydrogel are related to the structure of the scaffold which can keep a stable hydrated lubrication layer.Both of SiO2/PVA and SA hydrogel scaffolds are able to support the growth and adhesion of cell. The scaffolds contribute to the proliferation of cells as the 3D structure through wich culture medium and cell metabolism waste can pass. The SA hydrogel scaffold shows a well adhesion than the SiO2/PVA hydrogel scaffold and the proliferation rate of cells on the SA hydrogel is higher than that on the SiO2/PVA hydrogel. SA hydrogel has a more excellent biological properties than SiO2/PVA hydrogel scaffold.