Photoactivatable water soluble cross-linking agents containing an onium group

A photoactivatable cross-linking agent comprising a compound of the formula:

• X--Y--X
• wherein each X, independently, is a radical containing a photoreactive group and Y is a radical containing one or more charged groups, wherein the number and/or type of charged group(s) is sufficient to provide the molecule with sufficient aqueous solubility to allow the agent to be used in a solvent system having water as the major component, and wherein each charged group comprises, independently, an onium group, provided however, that Y itself contains no more than one photoreactive group for each charged group.

A photoactivatable cross-linking agent selected from the group consisting of:

• ##STR12##

A method of coating a surface with a target molecule, the method comprising the steps of:

• a) providing a photoactivatable chemical linking agent capable, upon activation, of covalent attachment to the surface and the target molecule, the agent comprising a charged, nonpolymeric di- or higher functional photoactivatable compound comprising two or more photoreactive groups, the compound comprising one or more charged groups, each charged group, independently, comprising an onium group;
• and forming a solvent system having water as the major component and comprising the linking agent and a target molecule;
• b) placing the solvent system in bonding proximity to the surface, and c) activating the photoreactive groups of the linking agent in order to cross-link the target molecule to the surface.

A surface bearing a coating comprising a target molecule cross-linked to the surface by the activation of a photoactivatable chemical linking agent, the agent comprising a charged, nonpolymeric di- or higher functional photoactivatable compound, the compound comprising two or more photoreactive groups activated to form covalent bonds with the surface and the target molecule and one or more charged groups sufficient to allow the agent to be used as a cross-linking agent in a solvent system having water as a major component, wherein the charged groups each comprise, independently, an onium group.