Figure . Design of polymer prodrugs by the "grafting from" or "drug-initiated" method and their use in drug delivery under the form of polymer prodrug nanoparticles, polymer prodrugs loaded into drug delivery systems or as water-soluble polymer prodrugs. Adapted from ref. . Similarly to polymer prodrugs obtained by the two previous strategies, pH-sensitivity has also been implemented into polymer prodrugs from the "grafting from" pathway via the easy insertion of pH-sensitive linkers between the drug-controlling agent and the growing polymer chain.