Disulfide linkage: a potent strategy in tumor-targeting drug discovery.

Targeted drug delivery has attracted much attention in improving the curative effect of existing chemotherapy drugs, and many published studies have suggested the disulfide linkage for key unit in constructing a targeting conjugate. An appropriate disulfide bond,through which cytotoxic agents and drug carriers were linked together, would guarantee the conjugate stable during circulation in vivo and, readily cleavable to release the drug. The aim of this article is to review various design strategies based on disulfide linkage which have been used to assemble a tumor-targeting conjugate, with the goal of presenting a promising avenue in the field of targeted drug delivery.