PEG-Lipid core micelles with pH responsiveness for tumor cell targeting

In the latest years, investigations have been performed to develop smart stimuli responsive drug delivery systems. These systems are intended to move through the body in a dormant state but can selectively respond to physiopathological environmental changes. These systems can be exploited for ameliorating cell targeting or for controlled drug release in specific body districts [1]. Typically, solid tumours present lower pH, higher temperature, peculiar enzymatic pool and higher redox potential as compared to normal tissues. Therefore, these physiopathological stimuli can promote surface or macroscopic alterations of nanocarriers chemically constructed to sense the stimulus. This may result in exposition of the targeting moieties, improved cellular association or activation of drug release. Here we report the synthesis and characterization of a new stimulus responsive supramolecular system based on the pH sensitive amphiphilic unimer stearoyl-PEG-poly-sulfadimethoxine (stearoyl-PEG-(SDM)7). Sulfadimethoxine (SDM) was chosen for its ionic character (pKa = 6.1) which allows for pH induced hydrophobic/hydrophilic switching [2].