Biological Sample Printing

摘要: Microarray spotters equipped with solenoid valves are capable of printing a wide range biological samples, including reagents, growth media, compounds, hydrogels, genes, proteins, viruses, and cells, for biochemical cell-based assays. Solenoid valve-driven bioprinting has clear advantages over other technologies in terms controlling sample volume dispensed flexibility the type samples printed. Unlike robotic liquid dispensers that more robust due to relatively large orifice sizes dispensing volumes, microarray must take precautions prevent clogging ceramic tips extremely small Therefore, it is essential avoid dust precipitates (e.g., compound filamentous microbes), test viscosity material printed, understand mechanism gelation hydrogels used cell encapsulation. In general, temperature-sensitive such as Matrigel have high risk forming gel spontaneously inside tubes, tips, slight change temperature. lower temperature be maintained constantly across chip-loading deck head. The may result replacement valves, which can an expensive affair. Gelation 3D culture occurred two steps clogging. Typically, crosslinkers/initiators printed first on micropillar/microwell chip platform then containing cells top form gel. ionic crosslinking alginate CaCl2, PuraMatrix salts), affinity/covalent bonding functionalized polymers streptavidin biotin), photopolymerization methacrylated photoinitiators), biocatalysis fibrinogen thrombin) favorable mechanisms gelation. Developing proper surface chemistry attach spots robustly also critical. Covalent poly(maleic anhydride-alt-1-octadecene) poly-l-lysine), affinity interaction (poly-l-lysine negatively charged alginate) commonly introduced enhance spot attachment chip. Viscosity another important factor affects performance printing, valve/tip rinsing. low 10–30 centipoise (equivalent 1 % or distilled water) preferred. Samples cannot difficult remove from by rinsing water. diluted properly either solvents media ensure reproducible printing. case encapsulation culture, maintaining suspension while crowded (typically seeding density higher than 10 million cells/mL) issues. addition, tend settle down quicker solution. Finally, mechanical strength time needs considered support long-term culture. Peptide-based fibrinogen, Matrigel, PuraMatrix) lose their degradation matrix metalloproteinases (MMPs) secreted many mammalian cells. These MMPs responsible hydrogel eventual detachment. To sustain longer minimize detachment degradation, peptide-based mixed stable alginate. When mixed, resulting transparent minimal background fluorescence should not interfere high-content imaging (HCI) protocols provided this chapter will give researchers guidance towards multiplex, 3D-cell based assays platform.