What materials do you use for printing? What is the challenging part?
Ovsianikov: For a process using live cells one needs materials with high water content, usually such so-called bio-inks are over 80 percent cell culture medium. One has to also make sure that these materials are not toxic. Finally, the combination of the materials and the process has to stay cell friendly. Unfortunately, in case of MPL there is not really a catalogue of materials or components which one can select from, in accordance to such a "wish list". Therefore, we went forward and developed such materials, for example specialized gelatin-based bio-inks.
In case of MPL, since the resolution is so high, it is also important that the process is fast. Otherwise it might take very long to produce structures of relevant size. Processing speed relies on the material sensitivity. We have developed specialized bio-inks that can be processed with a laser scanning speed of up to one meter per second in the presence of cells. This is an absolute record.
Where is MPL used?
Ovsianikov: MPL itself is quite universal and is used wherever precise 3D structures are needed: in micro-optics and microfluidics, microneedles for transdermal drug delivery and biodegradable scaffolds for tissue engineering.
One of the important areas of application of bioprinting is realization of 3D tissue models. Among other things, these are highly relevant for drug development in the form of organs-on-a-chip. The idea is to create a mini version of different human organs in a microfluidic chip format, in order to for example test safety of different drugs in a high throughput manner. We have already used the MPL to produce a barrier membrane for a placenta-on-a-chip. A recent work demonstrated a possibility to produce branching vascular structures with diameters in the sub-50 micrometer range.