The invention relates to a lock-release method to be applied to biomolecules, such as antibodies, to improve the purification, production, stability and storage of biomolecules. A biomolecule is covalently bound to a polymer support comprising a diketone group so that the biomolecule can be purified, produced and/or stored before being released from the support. The diketone group of the polymer support is a 1,3-ketoester, 1,3-ketothioester or 1,3-ketoamide is a group of Formula (1): R1 is an optionally substituted hydrocarbyl, perhalogenated hydrocarbyl, or a heterocyclyl group; Y is hydrogen, an optionally substituted hydrocarbyl, or a heterocyclyl group; X is —O, —NR2 or —S, wherein the free valence of —O, —NR2 or —S is bonded to the support optionally via a linker; and R2 is hydrogen, an optionally substituted hydrocarbyl, or a heterocyclyl group. The invention also relates to a polymer support comprising the diketone group.