A team of researchers from the University of Crete have 3D printed bioreactors for DNA amplification purposes. By running through 25 different commercially available FFF filaments, the team was able to pick out the most suitable one, looking for transparency and compatibility with the enzymatic DNA amplification reagents used in the experiment. In the long term, the researchers hope to use the printed bioreactors for healthcare applications.
DNA amplification
DNA amplification, as the name might suggest, is the production of multiple copies of a sequence of DNA from a base sample. Many aspects of modern medicine rely on DNA amplification devices for things like medical diagnostics, microbial detection, and other DNA related bio-analysis. There is also the slightly more exciting, albeit grimmer, application in the field of forensic science whereby a DNA sample may not be large enough to analyse and profile. In situations such as that, DNA amplification will be employed to produce an adequately sized sample through a process called polymerase chain reaction.
3D printing bioreactors
The work was motivated by the need for genetic biomarker detection at the point of care. Systems for the process already exist, but they tend to be bound to laboratories due to their size and subsequent lack of portability. The team believes that 3D printing, with its design capabilities, has great potential in the development of open and closed micro-reactors in the form of vials and microwells.
The first stage of the study involved selecting the right filament. A Lulzbot TAZ 6 3D printer was used to extrude 25 different materials, creating a set of test vials which would go on to hold saliva samples during amplification. The filaments included ABS, HIPS, PETG, PLA, PP, and PMMA, with several variations of each type of material. With biological compatibility tests and SEM imaging to give insight into the porosity of each type of material, the team eventually settled on clear polypropylene (PP Centaur) as a suitable filament due to its relatively high density.
PP was then used to fabricate a cartridge with eight individual micro-well reactors. The cartridge was used to perform isothermal amplification on saliva samples in a purpose-built, 3D printed portable casing. Once the team had successfully detected CYP2C19*2, a mutation involved in the metabolism of a cardiovascular disease treatment, they concluded that their creation was suitable as a companion diagnostic tool at the point of care. The 3D printed bioreactors also proved their affordability, as a costing analysis at the end of the experiment revealed that each vial ended up costing less than a Euro to produce.
Further details of the study can be found in the paper titled ‘3D-printed bioreactors for DNA amplification: application to companion diagnostics’. It is co-authored by A.K. Pantazis, G. Papadakis, K. Parasyris, A. Stavrinidis, and E. Gizeli.
The DNA amplification process comes under microfluidics, a field of study that 3D printing has benefited greatly in recent years (and vice versa). Earlier in 2020, a team of researchers from UC Davis published a paper detailing the development of a new droplet-based 3D printing method using microfluidics. The technique allows the user to manipulate the extruded ink composition and properties in real time, enabling the fabrication of diverse structures. The team expects the technology to excel in soft robotics and tissue engineering.
Elsewhere, in Europe, researchers produced and published a review on 3D printing microfluidic applications. In the review the scientists state that the technology will allow for the creation of a new generation of increasingly smart, responsive, and autonomous devices, which are able to sense and act upon their environment with minimal human input.
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Featured image shows SEM imaging of the walls of the 3D printed vials. Image via University of Crete.
