3D Printing an Elephant — Inside a Living Cell
A novel way to complete the entire printing process of active and passive resin structures within cell membranes.
Researchers at the J. Stefan Institute in Slovenia have created a resin 3D print of an elephant 10 microns (0.01mm) long inside a living cell. This isn’t the first time micron-scale objects have been put inside cells, but this is pretty unique for reasons that have immense implications in biological research. The technique can produce more useful things than minuscule pachyderms.
First, the elephant in the room, how did they do it? The team led by Maruša Mur of the Department of Condensed Matter Physics used a fine, glass tube to inject a blob of resin into a cell. Then using an incredibly precise optical 3D printing technique called two-photon polymerization (TPP) the resin was scanned and solidified into the shape of a model elephant through the walls of the cell. The elephant, by the way, came straight out of the Tinkercad shape library.
They used the HeLa “immortal” cell line originally taken under dubious circumstances from the cancer patient Henrietta Lacks back in the 1950s. These are 20-40 microns in diameter, and the first hurdle was getting a relatively large blob of resin inside without killing the cell (very often, anyway). Also the resin had to be non-toxic and slowly absorbed by the cell so the finished structure could be released inside.
The printing system used was a commercial near-IR femtosecond laser, scanning in 100 nanometre layers, which can print a complete object in mere seconds. After the remaining liquid is absorbed the printed structure remains, which can be significantly larger than the fine tube used to insert the resin.
The practical applications are significant. Custom structures can now be built inside cells that do not naturally engulf objects. The researchers created microscopic tags like QR codes that could be used to track individual cells, even after they had divided.
Lattice-like lasing cavities were made that could be excited externally, and in the future might change might their frequency depending on chemical variations inside the cell. Further advancements could even include mechanical logic capable of releasing drugs under specific conditions.
Being able to change cells is one thing, but you need to find out what to change first. This novel technique can do both.
Images from "Two-photon 3D printing of functional microstructures inside living cells" Maruša Mur et al.,J. Stefan Institute, Slovenia