Researchers have succeeded in printing genetically programmed living cells using a 3D printer. The cells are programmed to light up if they detect a certain chemical or molecular composition. The researchers see a variety of applications for their technique, ranging from wearable sensors to implants that release a particular substance in phases over a long period of time.
The technique was developed by a team of researchers at the Massachusetts Institute of Technology (MIT). The researchers have combined bacterial cells with a hydrogel and nutrients for the cells into a material that can be printed using a 3D printer. The material allows the creation of a three-dimensional object that responds to a particular chemical or molecular composition. The specific composition to which the cells respond can be determined by genetically programming the cells prior to the printing process.
Living tattoo
The team demonstrated its technique using what they call a 'living tattoo'. In this, the researchers printed a thin transparent patch of elastomer, using living cells to represent the shape of a tree. The tree consists of three different branches. Each branch is printed with living cells programmed to respond to a different chemical or molecular composition. The patch can be stuck on human skin and responds if the skin is exposed to the chemical or molecular for which the cells have been programmed. Based on the part of the cells that lights up, it can be deduced to which composition the cells have been exposed.
The material was printed using a custom-made 3D printer. This printer consists of standard components used in many Fused Deposit Modelling (FDM) based 3D printers in combination with some components custom developed by the team.
Wearable sensors and medical applications
The researchers foresee a variety of applications for their technique. For instance, the technique could be used to create wearable sensors or interactive screens that alert users to certain changes. For this, the living cells could be programmed to react to the presence of certain chemicals or pollution, as well as to changes in temperature or pH levels. The researchers are also thinking of medical applications, for example to create implants or drugs that can independently produce certain substances such as glucose and release them in phases over a long period of time.
In the distant future, the researchers expect that their technique could contribute to the creation of 'living computers'. These are computer systems made up of different types of living cells that can communicate with each other and transmit signals. This is similar to how multiple transistors on a contemporary microchip interact with each other.
Why bacterial cells?
This is not the first time that 3D printing of living cells has been experimented with. For instance, the researchers point out that this has previously been tried using cells from mammals. However, these cells proved less suitable; in particular, the fragility of mammalian cells proved to be a major limitation. This fragility is a problem as the material is printed using an FDM-based 3D printer, where the print material - also known as filament - is pushed through the nozzle with some force. Hyunwoo Yuk, an MIT student involved in the project, explains: "It turned out that these cells died during the printing process, since mammalian cells are basically double lipid balloons." According to Yuk, this makes the cells too weak and tearable to print using a 3D printer.
The MIT researchers deliberately chose bacterial cells for this reason, as they have a stronger cell wall and can withstand relatively harsh conditions better than mammalian cells. Another important reason for choosing bacterial cells was the possibility of combining these cells with a variety of hydrogels, something that is less the case with mammalian cells. Hydrogel is a gel-like material consisting of a combination of water and polymer. Research from MIT indicates that hydrogel can form an environment in which bacteria can live if nutrients are added to it.
In the video below, the MIT researchers explain their invention.
Author: Wouter Hoeffnagel
Source: MIT
Source photo: Pixabay / qimono
