Fruit as Template for Electrostatic Layer by Layer

1. Joy Walker Fruit as Template for Electrostatic Layer by Layer

2. Layer by Layer Process

3. Equipment/Instruments Quartz Crystal Microbalance - equations

4. Zeta Potential Analyzer

5. Confocal Microscope

6. Why Fruit? • The fruit is used as a template, because if the layer by layer assembly works it should impede the growth of microorganism becoming another form of preservation. • Theoretically the negative outer layer will work to repel the negative microorganism and/or the layers would make it harder for the microorganism to penetrate the surface of the fruit.

7. Set of E • Synthetic Polymers: PAH+ (Poly (allyamine hydrochloride) and PSS- ( Poly (sodium 4-styrene sulfate) • Biocompatible Polymers: CSS- (Carboxymethyl cellulose, sodium salt), PS+ (Protamine Sulfate) • Concentration: 3mg/ml • Templates: Cherries, Tomatoes, Grapes

8. Experiments Using the Grapes • Zeta Potential of grape skin= -39.86 std error = 2.35 • The zeta potential of each layer was unable to be determined • Coated grape vs. Non-layered grape • Synthetic Polymers, 3 bilayers • Coat grape vs. Non-layered grape • Biocompatible Polymers, 6 bilayers

9. Experiments Using the Cherries • Coated cherry skin and Non-layered cherry skin • Synthetic polymers, 6 bilayers • Dark and humid place • Coated cherry skin and Non-layered cherry skin • Biocompatible, 6 bilayers

10. Experiments Using the Tomatoes • Coated tomato skin vs. Non-layered tomato skin • Synthetic Polymers, 3 bilayers • Layered skin with PAH-RBITC (florescence) • Synthetic Polymers, 3 bilayers • Crossection of layered tomato skin with PAH-RBITC (florescence) • Synthetic Polymers, 3 bilayers • Coated tomato skin vs. Non-layered tomato skin • Synthetic Polymers, 6 bilayers • Dark and humid place • Coated tomato skin vs. Non-layered tomato skin • Biocompatible Polymers, 6 bilayers

11. Cherries and Bacteria • Coated cherries skin and Non-layered cherries skin • Sample 1- Synthetic Polymers, 3 bilayers Dipped in 50 mL of E. Coli • Sample 2- Synthetic Polymers, 7 layers ending with PAH 15 min adsorption time and 1 min wash Dipped into E. Coli • Sample 3- Synthetic Polymers, 6 layers 15 min adsorption time and 1 min wash Dipped into Lacto Biscillous Refrigerate • Sample 4- Biocompatible Polymers, 1 bilayer Cherry is dipped into bacteria and fungus that grew on the other cherries for 5 min.

12. Layer Thickness of Synthetic Polymers Thickness vs. Layers Thickness measured in nm

13. Thickness vs. Layers Thickness measured in nm 40 CMC P 35 30 CMC P 25 20 CMC P 15 CMC P 10 CMC P P 5 CMC 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Layer Thickness of Biocompatible Polymers

14. Tomato skin under Confocal Microscope

16. Conclusion The layer was shown not to have formed, instead absorbed into the cells. However the polymers did have an effect on the fruit. The polymers used seemed to probably cause some type of damage to the cell wall making it easier for the fruit to dry up and easier for the microorganism to grow on the fruit . It is still believed that layer by layer can work to block microorganisms.

17. Future Work • Treat the control fruit just like the layered except for the layering. • Look at why the polymers encouraged the growth of microorganisms instead of hindering this growth. • Add clay to the layer-by-layer procedure. • Using polymers that have already shown effective in preserving fruit

18. Acknowledgements • Dr. Lvov and Team • Dr. Steven A. Jones • REU Program/ National Science Foundation • Louisiana Tech University (IFM)