Team:Groningen/Template/MODULE/project/bandage

Most people would think it is a bad thing to have a bacteria inside a bandage. And in many ways this makes a lot of sense, since most will damage wounds more then heal them. But this one won't! One of the biggest problems in hospitals right now, are drug resistant bacteria. However, despite the hesitation of a large group of people we think we can change a lot in bandages by having a inducible secreting system. In order to achieve a safe and easy solution a lot had to be discussed. This is our idea: Bacteria inside a hydrogel.

Lactococcus lactis would be the perfect candidate as a chassis for our engineered construct mainly because the unlikeliness of infecting humans and its ability to produce lactic acid. Of course there is a lot of expertise of L. lactis in our building which enables us to get acces to a lot of information. Before we started it was already proven that L. lactis cells can survive the harsh conditions of freeze drying¹. What also counted is that this bacteria is already used in production process in the dairy industry². These caracteristics make ourproduct more approachable to the public.

Although it is a relatively save bacteria, it is still a risk to have bacteria this close to the wound. That is why we designed the bandage, a containment device to store and activate bacteria at the right time. This bandage consists of 3 layers. A top membrane that diffuses gases like oxygen and carbon dioxide, a middle layer (a hydrogel) containing freeze dried bacteria and a bottom membrane that makes sure our bacteria stay inside the bandage. This last membrane also allows diffusion of several molecules/peptides.

Although the needs for this bandage were pretty clear from the start, finding the specific materials was harder than expected. For our top membrane a polymer from the iGEM 2012 team could be used. This is called TPX or polymethylpentene. TPX is available as a thin, transparent sheet, while it still stays strong. For our middle membrane tests with polyacrylamide gels are carried out. Although acrylamide is toxic when unpolymerized, it will no longer be toxic when polymerized and properly washed. Polyacrylamide was chosen because it is a cheap and easy to handle material. For our final product we could use a different hydrogel named PMBVF/PVA. This material is harder to handle and more expansive, but it has been tested before with bacteia inside³. Our last part is the bottom membrane. A Cellulose Nitrate membrane with a pore size of 0.2µm could be used. This is small enough to keep the bacteria inside and large enough for the molecules to diffuse freely through the membrane.

More information about the bandage design and the experiments are stated below.