Team:Oxford/Test/Design
Design
Introduction
Following on from all of the safety research we conducted we put that knowledge into designing a catheter in order to get our proteins (DNase and DispB) into the urinary track where we want them.
Designing a novel method of getting our bacteria into the urinary tract was a big consideration during the beginning stages of our project. The approach of delivering our bacteria directly through the catheter into the bladder would probably be the most effective. However we found that the biofilm also forms on the outside of the catheter so in our design we attempted to tackle the biofilm from outside and in.
While our bacteria could potentially be used to a large range of different pipes to tackle a growing world problem with biofilms we decide to focus on a medical application for them. We focused on the problem of urinary tract infections as a member of our team, George Driscoll, had seen first hand the extreme impact it can have on people’s, especially women’s lives.
“Biofilms are shit and a big problem in the world”
Ria Dinsdale
Catheter Fanatic
Our catheter would have a three-pronged attack on the biofilm. First the biofilm forming in the lining of the bladder, then the biofilm beginning to form on the outside of the catheter itself, and finally attacking the biofilm trying to form on the inside walls of the catheter.
Our initial research into the current designs of catheter began online, where we started to get a better understanding of the size that we were working with. We looked into the problems with insertion, removal and general life with having a catheter in place. Through out the design process we attempted to keep these constantly in our mind in order to create something that would not only help with infection but was practical for the patient, doctor and manufacturer.
To get some more first hand experience of how small a catheter is we purchased a catheter. This made us realise how small our containment method would have to be. As UTIs mainly affect women we decided to buy a 14F female Foley catheter. This gave us a much better idea of the size we were working with i.e. very small. Knowing this leads us to adjust the chemical that we were hoping to use to make the beads that will contain our bacteria.
The idea of having a containment method as part of our project was first realised during the safety research as it would be dangerous to allow free bacteria into the human body. This could lead to possible fatal consequence as the bacteria could mutate and you don’t know what will happen in several generations.
However to reduce the risk of infect we would not be able to access the beads for the duration on the catheter being in place, as this could allow for foreign bacteria to get into the urinary tract and cause greater infection. Therefore any nutrients that the bacteria would need have to be present in the beads, or be available from the urine running through the catheter.
The bacteria would have to be able to survive for 3 months so in an ideal world we would have been able to test the bacteria in the beads, for 3 months, however the time scale of the project did not allow us to do that as the concept of the beds was not realised until the later stages of the project. We would have also liked to tested whether or not the bead would remain in tack out of the CaCl2 for 3 months, and potential storage methods for the beads. Freezing the beads was however tested and found to be unsuccessful.
The gel must not be toxic to humans that we would have to make sure of, relates to the safety of the catheter. If we use a silicone polymer either as a sheet or in fibres then many medical devices are made from silicone due to its inert characteristics and the fact that it doesn’t cause any unwanted side effects. Therefore this fits in with the safety side of the project. Catheters themselves are made from silicon so it shows that they are safe to put into the body.
Beads containing Bacteria
In order to stop the biofilm forming on the inside of the catheter it will contain beads that have our bacteria encapsulated inside of them however the protein is still able to diffuse out. This is needed as a way to contain the bacteria so they won’t be free in the urinary tract and therefore cause potential health problems for the patient.
These beads could also be contained outside the body inside a bag of sterile water; this bag would then be plugged into a 3-way Foley catheter. This solution would then be washed through the catheter and into the bladder, therefore tackling any infection that may be present in the lining of the bladder.
To see our process of designing and making the beads, look here.
One problem with using an alginate to encapsulate the bacteria is that they are only structurally sound over a short period of time and break down over longer periods. This poses a problem, as the beads could therefore not be used to treat urinary tract infections were the catheter is to remain in place for up to 3 months.