Creating a plastic bag as a bio-container using electrically-charged plasma The humble Petri dish may soon be a thing of the past. A team of researchers in Germany have developed a new technique for treating plastic bags with plasmas to turn them into sealed, sterile containers suitable for microbiology work with much less chance of contamination than traditional containers. This holds the promise of not only decreasing the possibility of contamination in stem cell and live-cell therapy techniques, but also the potential for cultivating whole human organs for transplant surgery.
The Petri dish is one of those simple, elegant inventions that quietly changed the science world. Consisting of a shallow, straight-sided glass or plastic dish with a matching lipped cover to seal it, the Petri dish has been a staple of biology laboratories since its invention by the German bacteriologist Julius Petri in 1877.
A possible solution comes from a team of scientists in led by Dr. Michael Thomas at the Fraunhofer Institute for Surface Engineering and Thin Films IST in Braunschwieig, Germany. They have developed a technique for turning plastic bags into sterile, relatively inexpensive bio-containers. This is done by filling the bags with a special gas mixture at atmospheric pressure, then hermetically sealing them. The gas is then subjected to a high-frequency RF electric field, which turns the gas into an electrically-charged plasma. This chemically alters the inner surface of the bag, so that human cells can adhere to it and reproduce. Since the bag remains sealed at all times, it remains sterile. Cells are introduced into the bag using a hypodermic needle and samples are removed the same way, greatly reducing the chances of contamination. Also, like traditional Petri dishes, the bags can be filled with suitable growth media beforehand. However, unlike Petri dishes, experimental gases can be introduced as well before sealing the bag. And, being simply plastic bags, they are disposable, which removes the cost of cleaning and re-sterilization.