Antimicrobial Coatings By Nikki Buck and David Brink-Roby Mentors: Danielle Leiske and Alia Mulder

Background Information Background To compare the effectiveness of antimicrobial proteins and other inhibiting bacterial growth on biomedical devices. What is bioengineering? Applies engineering approaches to problems dealing with biological systems. How does this apply to life? Bacteria grows on tracheal tubes. Antimicrobial coatings are needed to prevent infection.

Equipment and Materials Agar A gelatin compound used to stimulate the growth of bacteria. Pediococcus A gram positive bacteria grown in MRS agar. E. Coli A gram negative bacteria found naturally in the human body that causes stomach sickness. Caliper A tool used to measure the thickness of a solid. Sterilization Process of disinfecting a surface. Stir Plates/ Stir Bars A machine that uses magnets to stir a solution. Tracheal Tube A medical tube used in hospitals to clean out the air passageways of the trachea. Autoclave A machine used for sterilization. Gram Positive Bacterial with thicker cell walls. Gram Negative Bacteria with thinner cell walls.

Procedure Experiment #1 Make plates of MRS and McConkey Agar Cut equal sized pieces of sterile tracheal tubing Soak pieces of tubing in antimicrobial solutions Rinse tubing in phosphate buffer Place tubing in agar plates Incubate the plates overnight Measure and record the diameter of kill zones around each piece of tubing Experiment #2 Repeat previous steps but air-dry tracheal tubing after rinsing in phosphate buffer

Antimicrobial Coatings SDS- has a negatively charged head, hydrophobic tail. It is a surfactant. DTAB- Has a hydrophobic tail and a hydrophilic head Nisin- a natural antimicrobial agent used as a lantibacterial Lysozyme- causes hydrolysis of bacterial cell walls, fights against bacterial infections Albumin- Protein manufactured by liver, helps fluid remain in the blood stream Phosphate Buffer- a salt or ester of phosphoric acid (a colorless liquid used in pharmaceuticals) that minimizes change in the acidity of a solution when an acid or base is added

Analysis DTAB and Nisin worked best when killing pediococcus, a gram positive bacteria Only high concentration DTAB, and low concentration lysozyme, killed E. Coli For Nisin: Low concentration was more effective The wet tubing killed more bacteria than the dry The SDS high and DTAB low concentrations showed a larger kill zone for the dry tubing than the wet Albumen did not bond with gram positive bacteria Works well when it does Our second trial had better results Tubing was fully sterilized Phosphate buffer was used as a control so it did not kill bacteria.

Thank You To our mentors, Alia Mulder, Danielle Leiske, and David Pulitzer for teaching us the concepts used in our experiments. To Dr. Skip Rochefort for leading us in this great learning adventure that will change us forever, we will never forget you!