A method of attaching a coupling molecule to a substrate, comprising: obtaining a substrate comprising a plurality of carboxylic acid groups for linking to a coupling molecule; contacting said substrate with a carboxylic acid activating compound formulation comprising a solvent and a carbodiimide precursor of formula (I): wherein R is selected from a group comprising substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, and substituted or unsubstituted heterocyclyl, and R further comprises a water-solubilizing group; and R' is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted cycloalkyl, and substituted or unsubstituted heterocyclyl, and wherein said carbodiimide precursor converts to a carbodiimide upon exposure to electromagnetic radiation at a defined wavelength; selectively exposing said carboxylic acid activating compound formulation to the electromagnetic radiation, thereby generating said carbodiimide and activating the carboxylic acid groups to form carbonyl groups on said substrate at a selectively exposed area; contacting said substrate with a coupling formulation comprising a coupling molecule and a solvent; coupling the coupling molecule to at least one of said plurality of carbonyl groups at said selectively exposed area. obtaining a substrate comprising a plurality of carboxylic acid groups for linking to a coupling molecule; contacting said substrate with a carboxylic acid activating compound formulation comprising a solvent and a carbodiimide precursor of formula (I): wherein R is selected from a group comprising substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, and substituted or unsubstituted heterocyclyl, and R further comprises a water-solubilizing group; and R' is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted cycloalkyl, and substituted or unsubstituted heterocyclyl, and wherein said carbodiimide precursor converts to a carbodiimide upon exposure to electromagnetic radiation at a defined wavelength; selectively exposing said carboxylic acid activating compound formulation to the electromagnetic radiation, thereby generating said carbodiimide and activating the carboxylic acid groups to form carbonyl groups on said substrate at a selectively exposed area; contacting said substrate with a coupling formulation comprising a coupling molecule and a solvent; coupling the coupling molecule to at least one of said plurality of carbonyl groups at said selectively exposed area. R is selected from a group comprising substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, and substituted or unsubstituted heterocyclyl, and R further comprises a water-solubilizing group; and R' is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted cycloalkyl, and substituted or unsubstituted heterocyclyl, and wherein said carbodiimide precursor converts to a carbodiimide upon exposure to electromagnetic radiation at a defined wavelength; selectively exposing said carboxylic acid activating compound formulation to the electromagnetic radiation, thereby generating said carbodiimide and activating the carboxylic acid groups to form carbonyl groups on said substrate at a selectively exposed area; contacting said substrate with a coupling formulation comprising a coupling molecule and a solvent; coupling the coupling molecule to at least one of said plurality of carbonyl groups at said selectively exposed area. <EOS>