E. coli bacteria binding to cell bilayer (liposome)

A picture of E.coli bacteria (blue) sticking to liposome (red)

This picture appeared on this week's cover of ACS journal "Langmuir". The cover is basically about E.coli bacteria (blue) that is chemically bonded to cell bilayer (liposome) (red). 

Background: Polydiacetylene (PDA) molecules might be the next big thing in the field of sensing. These molecules have an interesting property that they change colors (Blue to red) after chemical binding. Authors have used these molecules to prepare liposomes which can bind selectively to E. coli bacteria. 

Result and discussion: The authors synthesized glucose tagged liposomes, why glucose? because E.coli binds to glucose. The resulting liposomes can selectively bind to desired molecule i.e E. coli here. They observed that as the bacteria binds to PDA it changes color from blue to red and the more e. coli binds to cell bilayer it changes more and more reddish. Author also used a technique called "Fluorescence Resonance Energy Transfer" for checking the proximity of two molecules.

Liposome (red), E.coli bacteria (blue)

Conclusion:   Polydiacetylene molecules can be successfully used for biological sensing (famously called Biosensing).

Reference: "Investigating Ligand–Receptor Interactions at Bilayer Surface Using Electronic Absorption Spectroscopy and Fluorescence Resonance Energy Transfer" Langmuir, 2012, 28 (36), pp 12989–12998