Biosensing for the environment and defence: aqueous uranyl detection using bacterial surface layer proteins

Area of Science:

• Biotechnology
• Environmental Science
• Analytical Chemistry

Background:

• Uranyl (UO(2)(2+)) ions pose environmental and health risks.
• Traditional methods for uranyl detection can be slow and lack sensitivity.
• Development of rapid, sensitive, and specific biosensors is crucial for environmental monitoring.

Purpose of the Study:

• To fabricate and characterize novel uranyl ion biosensors using a bacterial S-layer protein.
• To evaluate the performance of these biosensors in terms of sensitivity, specificity, and stability.
• To elucidate the uranyl binding mechanism involving the JG-A12 protein.

Main Methods:

• Fabrication of biosensors by tethering Lysinibacillus sphaericus JG-A12 S-layer protein to gold electrodes.
• Testing biosensor response to varying concentrations of uranyl ions.
• Assessing interference from other metal ions (Ni(2+), Cs(+), Cd(2+), Co(2+)).
• Chemical modification of protein functional groups (phosphate and carboxyl) to investigate binding sites.

Main Results:

• The biosensor demonstrated rapid response (minutes) to picomolar levels of uranyl ions.
• The S-layer protein-based sensor exhibited greater stability and a longer electrode lifespan than traditional sensors.
• High specificity for uranyl ions was observed, with minimal interference from other tested ions.
• Chemical modification confirmed the involvement of phosphate and carboxyl groups in uranyl binding.

Conclusions:

• Lysinibacillus sphaericus JG-A12 S-layer protein is a suitable bioreceptor for developing highly sensitive and specific uranyl biosensors.
• The fabricated biosensor offers advantages in stability and detection speed over existing methods.
• Understanding the protein-ligand interaction provides insights for further biosensor optimization.