Elements of the process remain mysterious, but researchers are now using something called hydrogel stamping, a medical 3D printing process wherein liquid hydrogel is deposited in dots of a lipid and protein mixture on the surface of a substrate, to further their understanding of life at the cellular level.
These simply manufactured, cheap, artificial cells made via microprinting are the next wave in drug and genomic delivery tools. A team of Penn State engineers in bio-medicine say the technique will have a wide-ranging impact on the development of biosensing, biomaterials and biotechnology applications.
Using the technique, the researchers create an array of artificial cells, apply an alternating current to the substrate, and as the lipid and protein mixture is electrified, tiny bubbles appear which then organize themselves into an artificial cell.
One of the team leaders, Sheereen Majd, an Assistant Professor of Biomedical Engineering, says that in naturally occurring cells, the extreme complexity of what's going on makes them difficult to study. Majd says that using artificial cells – in this case liposomes – researchers can use only the shell of the structures, and that gives them the ability to dissect events at the membrane as they happen.
The way in which drugs and pathogens migrate across cell membranes is a key factor in understanding diseases and delivering drugs through those membranes.
"These giant proteoliposomes closely mimic cellular membranes," Majd said. "They're excellent model systems for studying processes that happen at the surface of cells such as the molecular events that occur when pathogens and drugs enter cells."
"The physical phenomenon of exactly how the AC field creates the bubbles is not yet understood," says Majd. "The AC electric field produces agitation that creates the tiny bubbles that merge to form the cells. This process is called electroformation. The beauty of this method is that a lot of labs already use liposomes and electroformation. Traditionally, they do not have proteins attached."
Majd says the pharmaceutical industry might use large numbers of the artificial cells – all of them the same size and existing under similar environmental conditions – in an array to allow them to monitor many cells at once.
The previous methods of creating artificial cells failed when it came to using them with proteins. The cells became useless as proteins dried out. They also suffered a lack of consistent size and location, but the hydrogel stamping method allows scientists to easily control the size of artificial cells and it lets them generate efficiently and in large numbers to speed the process.