Monolayers of Natural and Recombinant Photosystem II on Gold Electrodes—Potentials for Use as Biosensors for Detection of Herbicides

Abstract

Two methods for monolayer immobilization of photosystem II (PSII) isolated from thermophilic cyanobacteria Synechococcus elongatus and prospects for its use as a biosensor for detection of herbicides are reported: (i) immobilization based on recombinant (His)₆‐tagged PSII coupled with nickel‐nitrilotriacetic acid (Ni‐NTA) chelator monolayer on Au electrode. (ii) immobilization based on the natural PSII coupled with the protein A‐anti‐D1 antibody modified Au electrode. Here, Cysteamine (CYS)‐self‐assembled monolayer (SAM)‐(NTA)‐PSII monolayers were compared with traditional bovine serum albumin (BSA)‐glutaraldehyde (GA)‐PSII crosslinked gel matrix and better performances of the derived electrochemical biosensors were pointed out. Better diffusion of inhibitors and mediators resulted in improved sensitivity, velocity of the response, and lower I ₅₀ for herbicides.

Keywords:

• Immobilization
• Protein A
• Inhibition curve
• Biosensors
• Photosystem

Acknowledgments

This work was supported partly by the ROSEPROMILK Project (QLK1‐CT2001‐01617, European Community, the 5th FW, Quality of Life Program), partly from COSMIC Project (ENEA Target Project on Biosensors and Bioelectronics) and by the project 522/03/0659 of Grant Agency of the Czech Republic.