Antimicrobial Coatings

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

2. 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.

3. 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.

4. 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

5. 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

6. 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.

7. 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!