Glass surfaces patterned with enzymes

SECM was used for the fabrication of diaphorase-pattemed surfaces (134). Diaphorase, a flavin enzyme, was immobilized on glass surfaces. The oxidation of Br or Cl at the tip generated a reactive species, which deactivated the enzyme molecules on glass forming unreactive patterns. The circular and Unear patterns were then imaged by SECM based on the detection of catalytic current of feirocenylmethanol coupled with oxidation of DADH. 

A related technique was demonstrated by Shiku et al. (91), who formed alkylsilane monolayers at glass substrates and used electrochemical generation of OH radicals at the tip via the Fenton reaction to locally destroy the SAM. Diaphorase could then be patterned on the surface by physical adsorption to the undamaged hydrophobic areas or via covalent linkages to the radical-attacked areas. The former process was imaged in feedback mode with a ferrocenyl mediator and showed a decreased current over the disk of destroyed SAM and a constant background of enzyme activity over the rest... 

Another class of immunosensors utilizes enzyme conjugates with antigens at the surface of antibody coated capillaries or thick film patterned glass plates (15). This report describes a PMT and CCD camera based immunosensor for the herbicide (2,4-D) and fertihzers (Atrazine and Simazine). The detection principle improves the sensitivity of the sensor by atleast three orders of magnitude compared to a microtitre plate assay. 

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