Highly sensitive gold nanoparticles biosensor chips modified with a self-assembled bilayer for detection of Con A

In this paper, an improved method for detection of Concanavalin A (Con A) with label-free optical biosensors is reported. 1-Dodecanethiol (DDT) was self-assembled onto gold nanoparticles which were deposited on glass slides, and then glycolipid molecules were inserted into dodecanethiol by physical interactions only. The recognition between Con A and carbohydrate was observed by UV-vis spectrophotometry. The absorption spectrum shifted when Con A was bound to the sugar residues of glycolipids immobilized onto nanogold slides, while almost no spectrum change was observed when another nonspecific protein molecule met the nanogold slides. The self-assembled bilayer on nanogold substrates had very high sensitivity for Con A, the minimum detection concentration of Con A can be down to 0.1 nM. In addition to the ultra sensitivity for investigating carbohydrate-lectin interaction, the self-assembled bilayer structure, is expected to replace many receptors which require time-consuming organic syntheses for the fixation to the transducer. The simplicity and sensitivity of this biosensor architecture once again show the prospect of nanogold application in biosensor. (c) 2006 Elsevier B.V. All rights reserved.