Bacterial sunscreen: layer-by-layer deposition of UV-absorbing polymers on whole-cell biosensors.
UV-protective coatings on live bacterial cells were created from the assembly of cationic and UV-absorbing anionic polyelectrolytes using layer-by-layer (LbL) methodology. A cationic polymer (polyallylamine) and three different anionic polymers with varying absorbance in the UV range (poly(vinyl sulfate), poly(4-styrenesulfonic acid), and humic acid) were used to encapsulate  Escherichia coli  cells with two different green fluorescent protein (GFP) expression systems: constitutive expression of a UV-excitable GFP (GFPuv) and regulated expression of the intensely fluorescent GFP from amphioxus (GFPa1) through a theophylline-inducible riboswitch. Riboswitches activate protein expression after specific ligand-RNA binding events. Hence, they operate as a cellular biosensor that will activate reporter protein synthesis after exposure to a ligand target.  E. coli  cells coated with UV-absorbing polymers demonstrated enhanced protection of GFP stability, metabolic activity, and viability after prolonged exposure to radiation from a germicidal lamp. The results show the effectiveness of LbL coatings to provide UV protection to living cells for biotechnological applications.
Universal Technology Corporation and Air Force Research Laboratory, Materials and Manufacturing Directorate, Tyndall Air Force Base, 139 Barnes Drive, Building 1117, Tyndall AFB, Florida 32403, United States. donald.eby.ctr@us.af.mil
D Matthew
DM
Eby
Svetlana
S
Harbaugh
Randi N
RN
Tatum
Karen E
KE
Farrington
Nancy
N
Kelley-Loughnane
Glenn R
GR
Johnson
D015374:Biosensing Techniques; D004926:Escherichia coli / Q000166:cytology*; D049452:Green Fluorescent Proteins / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013473:Sunscreening Agents / Q000737:chemistry*; D013499:Surface Properties; D014466:Ultraviolet Rays
D011108:Polymers; D013473:Sunscreening Agents; D049452:Green Fluorescent Proteins