Temperature and pH dually-responsive poly(β-amino ester) nanoparticles for drug delivery

Stimuli-responsive polymers have undoubtedly been of great interest in the past decades due to a variety of their potential applications in biomedical territory. However, their non-degradability limits their in vivo applications. Herein, we report a novel pH and temperature dual-stimuli responsive-poly(beta-amino ester). The pH/temperature sensitivities are interrelated and can be easily tuned by changing PEG-diacrylate chain length and the percentage of biamines in the feed ratio. These dual-responsive polymers are very useful in drug delivery. Reaction of methyl ether poly(ethylene glycol) (MPEG) and poly(beta-amino ester) resulted in an amphiphilic MPEG-PBAE block copolymer which could form nanoparticles by self-assembly. A hydrophobic drug (DOX) was loaded in the self-assembled nanoparticles at low temperature without using organic solvents. The loaded drug was released very slowly and steadily at 37 A degrees C under physiological conditions (pH 7.4), but rapidly released from the micelles in weakly acidic environments (pH 6.4 and 5.0) for intracellular drug release. Thus, these poly(beta-amino ester) polymers constitute ideal drug carriers since their thermal sensitivity allows the drug loadings without using organic solvent and their pH sensitivity permits fast intracellular drug release.