13 / 2021-05-18 16:09:35

3D PRINTING CONSTRUCTION OF BIOACTIVE NANOCELLULOSE-ULVA POLYSACCHARIDES SCAFFOLD TOWARDS BIOMEDICAL APPLICATION

Ulva polysaccharides; nanocellulose; Bioprinting; 3D cell culture

Nanocellulose is a kind of biological nanomaterial that comes from a variety of renewable biomass with a huge potential market, especially in the field of biomedicine owing to its unique biocompatibility and low toxicity. 3D printing technology has been adapted to fabricate a variety of nanocellulose-based scaffolds for tissue engineering application. However, native nanocellulose shows no biological activity, which limits the potential application in the field of biomedicine. Therefore, it is of significance to functionalize nanocellulose with desired bioactivity so as to extent its high value-added application in biomedicine. In addition, the outbreak of Ulva prolifera algae caused by the eutrophication is a serious environmental problem that has plagued people for a long time. Extracting bioactive polysaccharides from Ulva prolifera has been proved as a novel method for high value-added utilization of this biomass waste. Meanwhile, various biological activities of Ulva polysaccharides may make up for the shortcomings of nanocellulose in the field of biomedicine. In the current work, nanocellulose-based bioink was formulated, then a series of bioprinting parameters (including printability, rheology, porosity, swelling rate, crosslinking stability and mechanical properties) of nanocellulose hydrogels was evaluated to construct a nanocellulose scaffold. Extraction of bioactive Ulva polysaccharides from the Ulva prolifera algae was optimized with the response surface methodology. An in-situ adsorption of the bioactive Ulva polysaccharides was applied to fabricate the 3D printed nanocellulose- Ulva polysaccharides composite scaffolds for 3D cell culture application. Results show that the optimized printing conditions were found at the air pressure of 27 KPa, printing speed of 10 mm/s, bioink concentration of 2.6 %, and with a print nozzle of G25. The Ulva polysaccharides with high molar mass and decent bioactivties was extracted using a short autoclave process at the extraction time of 26 minutes, the solid-liquid ratio of 1:10, and the sodium carbonate concentration of 1.3%. The extracted Ulva polysaccharide was found to have comparable antioxidant capacity with commercial vitamin C (including reducing power, hydroxyl radical scavenging ability, superoxide radical scavenging ability and DPPH free radical scavenging ability). The adsorption capacity of the nanocellulose scaffold for Ulva polysaccharide was 99.8 mg/g. The results of immunostaining and confocal imaging showed that the composite scaffold had no obvious toxicity to the NIH 3T3 fibroblasts. After 3 days of 3D cell culture, the cells were evenly dispersed in it. The current work demonstrated the feasibility of nanocellulose-based bioactive scaffolds construction by 3D printing and in situ adsorption of Ulva polysaccharides for 3D cell culture, which extends the possibility of applying nanocellulose in the field of biomedicine.