For example, because the concentration of matrix metalloproteinase-2(MMP-2) enzyme at the tumor site is higher than that at normal physiologicalconditions, hydrogel-based helical microswimmers demonstrate a quickerresponse to the evaluated concentration of MMP-2 enzyme, resultingin a boost-release of embedded cargo (i.e., antibody-tagged Fe3O4 nanoparticles) through the swell behavior ofthe hydrogel.128 The released antibody-taggedpayloads from the micromotors can be further used for active labelingof targeted tumor cells (Figure 14E). Here, MMP2 is linked to neoplasm.