Hydrogel, preparation method thereof, and ph sensor comprising the same

Abstract

A method for preparing a hydrogel that reversibly changes color depending on pH includes: (S) dissolving a carboxyl group-containing polysaccharide in buffer to obtain a polysaccharide solution; (S) adding a cross-linker solution composed of a mixture of an organic solvent and a cross-linker to the polysaccharide solution; (S) adding, to the cross-linker-containing polysaccharide solution resulting from step (S), an organic solution composed of a mixture of an organic solvent and a first organic compound containing an aromatic functional group having at least one hydroxyl group bonded thereto, to form a mixture solution, and allowing the mixture solution to react; (S) obtaining a polymer complex from the reaction mixture resulting from step (S); and (S) mixing the polymer complex from step (S) with an organic dye comprising a second organic compound containing an aromatic functional group having at least one hydroxyl group bonded thereto.