Inexpensive DIY Bioprinting in a Secondary School Setting.

Bioprinting is a technique that allows custom printing of cell-laden tissue using the principle of three-dimensional (3D) printing. The technique has various applications, ranging from tissue engineering to materials science. Bioprinting is an attractive topic for science, technology, engineering, and math education due to its novelty and interdisciplinary nature. Nonetheless, a basic commercial bioprinter could cost several thousand U.S. dollars. There have been attempts to construct low-cost do-it-yourself bioprinters for research purpose. However, those methods required expertise, uncommon reagents, and professional equipment, making it difficult for teachers and students in secondary schools to replicate. Here, we demonstrate how teachers and students in a secondary school can convert a 3D printer into a bioprinter for conducting a hands-on bioprinting activity using secondary school-available resources. Briefly, an open-source Creality Ender 3 V2 3D printer in a school was converted into a bioprinter using 3D-printed parts and other readily available materials. Cell-laden bioink and support medium were made using school-available reagents. The bioprinter can be easily constructed and operated by teachers and students who do not have prior knowledge in coding and engineering. We used the bioprinter to print a coronary artery model and an algae-laden artificial leaf. The photosynthetic activity of the artificial leaf could be observed and investigated using a hydrogen carbonate indicator. The work described in this paper could make bioprinting available, comprehensible, and enjoyable to secondary school students, opening a door for inexpensive innovative teaching and learning activities using bioprinting in secondary schools.

A comprehensive web tool for toehold switch design.

Motivation: Toehold switches are a class of RNAs with a hairpin loop that can be unfolded upon binding a trigger RNA, thereby exposing a ribosome binding site (RBS) and permitting translation of the reporter protein. They have been shown very useful in detecting a variety of targets including RNAs from Zika and Ebola viruses. The base complementation between the toehold switch and the trigger RNA also makes it sensitive to sequence variations. Design of toehold switches involves a series of considerations related to their sequence properties, structures and specificities. Results: Here we present the first comprehensive web tool for designing toehold switches. We also propose a score for predicting the efficacy of designed toehold switches based on properties learned from ∼180 experimentally tested switches. Availability and implementation: The toehold switch web tool is available at https://yiplab.cse.cuhk.edu.hk/toehold/.