H. Francis Webster

Current research projects

Electrostatic Layer-By-Layer Self-assembly of Antimicrobial Films


Layer-by-layer (LbL) self-assembly is a method for developing multilayer films by alternating the adsorption of positive and negatively charged materials via alternating immersion in a solution of each substance. LbL assembly is unique in that the created film retains properties of both of the substances used to develop it.


In this work, a positively charged protein from the moringa bean and negatively charged carbon nano-particles will be used to construct LbL films with antimicrobial properties.The Moringa tree (moringa oleifera) is found in equatorial climates and produces a seed that contains a natural cationic protein that has demonstrated anti-microbial properties as the result of positively charged, glutamine rich areas found in the protein.

This image shows the results for a slide with 10 bilayers that had been exposed to E Coli bacteria for 3 hours. All bacteria shown as green are living and all those shown as red are dead using the LIVE/DEAD stain from Life Technologies and fluorescence microscopy.

Typical results for these slides show a limited number of attached bacteria and that most have been killed. Control slides show many more attached bacteria and no death under the same conditions. The upper magnified image shows a cluster of bacteria with what seems to be living bacteria on top of dead or dying bacteria. The lower magnified image shows a typical region of dead bacteria.