A method for producing Metal Organic Framework (MOF) having a framework that encapsulates a bio-molecule, the method comprising combining in a solution the bio-molecule and MOF precursors, wherein the bio-molecule promotes formation of the encapsulating framework. The method stems from a surprising effect that a bio-molecule can promote or trigger the formation of MOF when combined together in a solution with MOF precursors. That is, it has now been found that a bio-molecule can effectively act as a seed around which the framework forms, with the resulting framework encapsulating the bio-molecule.