Abstract
We created an automated bioassay system based on inkjet printing. Compared to conventional manual bacterial culture systems our printing approach improves the quality as well as the processing speed. A hydrophobic/hydrophilic pattern as a container supporting a culture medium was built on filter paper using a toluene solution of polystyrene for hydrophobization, followed by toluene printing to create several hydrophilic areas. As culture media we used a novel poly(vinyl alcohol) based hydrogel and a standard calcium alginate hydrogel. The poly(vinyl alcohol) hydrogel was formed by physical crosslinking poly(vinyl alcohol) with adipic acid dihydrazide solutions. The conditions of poly(vinyl alcohol) gelation were optimized for inkjet printability and the optimum mixture ratio was determined. The calcium alginate hydrogel was formed by chemical reaction between sodium alginate and CaCl2solutions. Together with nutrients both hydrogel solutions were successfully printed on paper by means of the modified inkjet printer. The amount of each solution was demanded simply by outputting CMYK values. In the last step bacterial cells were printed on both hydrogel media. For both media we achieved a stable bacteria growth which was confirmed by microscopical imaging of the developed bacterial colonies.
Highlights
Inkjet-based bioprinting becomes increasingly important for scientific and industrial use related to bio- and biomedical applications
The results showed that Poly(vinyl alcohol) (PVA) and calcium alginate (CA) hydrogels could be printed by using single cartridge system (SCS) and multicartridge system (MCS) printers on paper
CA hydrogel formed by chemical reaction between sodium alginate (SA) solution and CaCl2 solution
Summary
Inkjet-based bioprinting becomes increasingly important for scientific and industrial use related to bio- and biomedical applications. Common agarose solution has very high viscosity and as agarose contains long chains of polysaccharides and solidifies after cooling, the temperature must be maintained higher than 37∘C to prevent gelling inside the printing system Both make it unsuitable for smooth ejection from the head nozzles of the inkjet printer. The hydrolysis processes took a long time, and the viscosity adjustment required precise control To overcome this shortcomings we introduce in this work two culture media, poly(vinyl alcohol) (PVA) hydrogel and calcium alginate (CA) hydrogel, as alternative to agarose. Hydrogels are formed by cross-linking polymer chains through physical, ionic, or covalent interactions and are well known for their ability to absorb water [17–19] They are widely used for various pharmaceutical and biomedical applications [20–23]. Properties of PVA and CA hydrogels were compared in terms of the operation performance and the applicability of those gels was evaluated as culture media on paper
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