Smart glass slide for microarrays

A method of modulating the pH or ionic concentration in a biosensor, the method comprising:

• a) providing a biosensor, the biosensor comprising a multisite array of test sites, wherein a test site of the multisite array of test sites comprises:
• (i) a transparent support substrate supporting one or more electrodes;
• (ii) a biomolecular interface layer that includes:
• a layer of immobilized polymer that covers the transparent support substrate by attachment directly to the transparent support substrate;
• a plurality of pH sensitive fluorescent proteins that are immobilized by covalent bond attachment directly to the layer of immobilized polymer at a first point of attachment or immobilized by covalent bond attachment through a covalently bonded linker that is covalently bonded to the layer of immobilized polymer at a first point of attachment, wherein the plurality of pH sensitive fluorescent proteins fluoresce in the visible light spectrum;
• and
• one or more probes immobilized by covalent bond attachment directly to the layer of immobilized polymer at one or more second points of attachment or immobilized by covalent bond attachment through a covalently bonded linker that is covalently bonded to the layer of immobilized polymer at one or more second points of attachment;
• and
• (iii) an aqueous solution comprising water and an electrochemically active agent dissolved in the water, wherein:
• the electrochemically active agent is a compound capable of undergoing an electrochemical reaction;
• the first point of attachment is spatially separated from the one or more second points of attachment;
• the transparent support substrate is in contact with the aqueous solution;
• and
• at each test site of the multisite array of test sites, conditions for interacting with a biomolecule analyte can be varied independently;
• b) reacting at the one or more electrodes the electrochemically active agent dissolved in the water to produce H+ ions and/or OH− ions through an electrochemical reaction to modulate the pH;
• and
• c) measuring pH of the aqueous solution using fluorescence intensity of the plurality of pH sensitive fluorescent proteins relative to fluorescence intensity of a same amount of the plurality of pH sensitive fluorescent proteins in the aqueous solution having a different pH.