Bacteria Removal Using Dense Phase Carbon Dioxide

What is Sterilization?

Sterilization is any process which removes an acceptable amount of bacteria from the a material.  The acceptable level is determined by the situation in which the material is being used.  Tools used in a medical scenario require a higher level sterilization, meaning that more bacteria be removed than perhaps someone sterilizing their kitchen after working with raw meat.  Classic methods include using high pressure of high temperature processes in order to kill bacteria, or the use of harsh chemical.

However, such harsh conditions are not acceptable for usage on certain equipment.  Since certain materials such as titanium implants can be pressure and temperature sensitive, meaning that high pressure conditions have an adverse affect on the material causing it to become less strong, and chemicals that are used to sterilize can also affect the material's properties in addition to leaving harmful residues on the material surface which could have harmful affects on the person in which the implant is being placed alternate methods must be developed in order to accommodate the ever growing needs of the medical field. 

My Research:

The purpose of my research is to develop a new method to sterilize equipment.  The method chosen to accomplish this goal is usage of dense phase carbon dioxide.  The first step in this process is to adhere bacteria to titanium and titanium alloy disks.  S. aureus bacteria has been chosen to use in this process because it is considered a standard for most sterilization processes.  Once the bacteria have been adhered to the surface and allowed to grow for a limited period of time so that concentration of bacteria on the surface is large enough to analyze the disks are placed within the carbon dioxide reactor.  Within the reactor the disks are engulfed by a bath of dense carbon dioxide.  Each experiment can be run at different conditions, allowing us to change the pressure, temperature length of time for processing and even chemical additive used to sterilize the disks.  Once the process has been completed the disks are removed from reactor and analyzed using Florescence microscopy.  The florescence microscope is used to view the number of cells remaining on the disk and compare that number to control disks prepared at the same time as the processed disks.

Moving Forward:

Currently no experiments have been performed using the carbon dioxide reactor however once experimentation begins the hope is that the number of bacteria viewed on the titanium surface will be significantly reduced, and that by modifying the process the sterilization technique will reach industry standards and be able to process sensitive materials.