Process for the preparation of a composition comprising a biofunctional polymer substrate and biofunctional material substrate adapted for use in or in association with the human or animal body, cultivated or uncultivated living matter, wherein the biofunctional material substrate is substantially insoluble in the polymer substrate and/or a supercritical fluid, wherein the process comprises contacting a mixture of the substrates or their precursors with a supercritical fluid under supercritical conditions and conditions of reduced viscosity and physical blending to plasticise and swell the polymer and distribute the biofunctional material substrate throughout the polymer, and releasing the fluid under subcritical conditions, wherein the substrates are adapted to be isolated in form of a solid admixture comprising the biofunctional material substrate in substantially unchanged chemical form, and in substantially unchanged physical form, composition obtained thereby, polymer matrix embodiment thereof and the process for its preparation.