A notable example of aptamer plasticity was reported by Smith and colleagues (17), who used a modified SELEX process to blend high-affinity binding with covalent inhibition of an enzyme. To achieve enzyme inactivation, Smith and colleagues linked a weakly reactive valyl phosphonate moiety to a random aptamer pool, and selected for aptamers capable of rapid covalent linkage to human neutrophil elastase. The result is a combination of high-affinity binding with specific active-site inhibition. This pairing inactivates elastase nearly 100-fold more rapidly than do peptide-based phosphonate inhibitors. This aptamer has been further modified to incorporate a radio-metal chelation moiety and has been used to target neutrophil-bound elastase in an in vivo inflammation model (17). Many aptamer adaptations use simple succinimidyl ester chemistry, which is accessible even to the most faint-of-heart among us. Importantly, modification can be directed to a single site away from the aptamer’s active surface, preventing loss of function. Radiolabeling and conjugations can be performed using high temperatures (95 C), organic solvents, and pH ranging from 4 to 8.5. Thus, escort aptamers can attend a variety of functions through their chemical adaptability.