"An Unfulfilled Dream" (叶わぬ夢, Kanawanu Yume, Viz: Impossible Dream) is chapter 274 of the original Naruto manga.
Despite having been struck by a poisonous blade, Sakura manages to hold on to the sword to prevent Sasori from escaping. She tells Chiyo to take the last antidote, Chiyo having been struck earlier, but Chiyo ignores her and injects her with the antidote. Chiyo collapses and Sasori, disconnecting from the sword, moves to finish her. Chiyo uses the Mother and Fatherpuppets to stab him through his core, the only part of his humanity he kept when turning himself into a puppet so that he could still use chakra. Chiyo begins healing Sakura but Sasori observes that the wound is too severe. Chiyo responds that she is not healing Sakura but transferring her life to Sakura with a technique she created to give life to Sasori's Mother and Father puppets, something he will no longer need.