A water-soluble photo-activatable polymer including: a photo-activatable group adapted to be activated by an irradiation source and to form a covalent bond between the water-soluble photo-activatable polymer and a matrix having at least one carbon; a reactive group adapted to covalently react with a biomaterial for subsequent delivery of the biomaterial to a cell; a hydrophilic group; and a polymer precursor. A composition including a monomolecular layer of the water-soluble photo-activatable polymer and a matrix having at least one carbon, wherein the monomolecular layer is covalently attached to the matrix by a covalent bond between the photo-activatable group and the at least one carbon. The composition further includes a biomaterial having a plurality of active groups, wherein the biomaterial is covalently attached to the monomolecular layer by covalent bonding between the active groups and reactive groups. Also provided is a method for delivery of a biomaterial to a cell.