Biotinylation of Silicon and Nickel Surfaces and Detection of Streptavidin as Biosensor

The availability of metal mesh device sensors has been investigated using surface-modified nickel mesh. Biotin was immobilized on the sensor surfaces consisting of silicon and nickel via a thiol–ene click reaction, known as the Michael addition reaction. Biotinylation on the maleimidated surface was confirmed by X-ray photoelectron spectroscopy. The binding of streptavidin to the biotinylated surfaces was evaluated using a quartz crystal microbalance and a metal mesh device sensor, with both techniques providing similar binding constant value. The recognition ability of the biotin immobilized using the thiol-maleimide method for streptavidin was comparable to that of biotin immobilized via several other methods. The adsorption of a biotin conjugate onto the streptavidin-immobilized surface via the biotin–streptavidin–biotin sandwich method was evaluated using a fluorescent microarray, with the results demonstrating that the biological activity of the streptavidin remained

Metal Mesh Device Sensor Immobilized with a Trimethoxysilane-Containing Glycopolymer for Label-Free Detection of Proteins and Bacteria

Biosensors for the detection of proteins and bacteria have been developed using glycopolymer-immobilized metal mesh devices. The trimethoxysilane-containing glycopolymer was immobilized onto a metal mesh device using the silane coupling reaction. The surface shape and transmittance properties of the original metal mesh device were maintained following the immobilization of the glycopolymer. The mannose-binding protein (concanavalin A) could be detected at concentrations in the range of 10^–9 to 10^–6 mol L^–1 using the glycopolymer-immobilized metal mesh device sensor, whereas another protein (bovine serum albumin) was not detected. A detection limit of 1 ng mm^–2 was achieved for the amount of adsorbed concanavalin A. The glycopolymer-immobilized metal mesh device sensor could also detect bacteria as well as protein. The mannose-binding strain of <i>Escherichia coli</i> was specifically detected by the glycopolymer-immobilized metal mesh device sensor. The glycopolymer-immobilized metal mesh device could therefore be used as a label-free biosensor showing high levels of selectivity and sensitivity toward proteins and bacteria