a) A glucose responsive MAM, comprised of a self-helical hydrogel fiber modified with phenylboronic acid groups that are repelled from each other in the presence of glucose. Readapted with permission [83a]. Copyright 2020, American Chemical Society. b) An enzymatically actuated MAM, in which enzyme cleavage removes charge shielding groups and causes electrostatic repulsion within the polymer network, causing gel swelling. Readapted with permission[84a]. Copyright 2009, Royal Society of Chemistry. c) A structurally programed MAM with large amplitude of enzymatic response that induces curvature to the material in the presence of an enzyme, due to the multilayered structure of the MAM. Readapted with permission[84c]. Copyright 2016, American Chemical Society. d) A sequence-specific DNA-responsive MAM, in which the presence of a specific target strand triggers a hybridization chain reaction resulting in large volume changes in the gel. Readapted with permission[23]. Copyright 2017, American Association for the Advancement of Science.