Bacterial bioprinting on a flexible substrate for fabrication of a colorimetric temperature indicator by using a commercial inkjet printer.

Background: Bacterial sensors are recommended for medical sciences, pharmaceutical industries, food industries, and environmental monitoring due to low cost, high sensitivity, and appropriate response time. There are some advantages of using bacterial spores instead of bacteria in vegetative forms as spores remain alive without any nutrient for a long time and change to vegetative form when a suitable environment is provided for them. Methods: For biosensor fabrication, it is important to define how the bacterial spores are delivered to the substrate media. The main purpose of this paper is an investigation of transferring bacterial spores on a flexible substrate media using a commercial inkjet printer (HP Deskjet 1510). It should be noted that in the previous researches, the special printers were used to transfer bacteria on rigid films. Results: These printed bacterial spores are used as a colorimetric temperature indicator. The custom-made bio-inks are prepared by bacterial spores along with a gelling agent and pH indicator. Conclusions: Finally, transformation of bacterial spores into vegetative bacteria is occurred by changing of temperature. A color change in the bio-prints is demonstrated because the bacterial transformation and growth change the environmental pH to an acidic level. [ABSTRACT FROM AUTHOR]