Automatic Detoxification Medicine Delivery by Thermo-Sensitive Poly(ethylene glycol)-Based Nanogels

During the medication-assisted treatment of drug abuse, side effects and addiction liabilities are commonly observed. Thus, control of the medication dose is very important. According to body temperature abnormalities in drug abusers, a thermo-sensitive nanogel was synthesized as a drug carrier to automatically deliver detoxification medicines. This nanogel was prepared through the synthesis of polystyrene (PS) core microspheres, followed by coverage with a nonlinear poly(ethylene glycol)-based copolymer shell. The PS core microspheres were found to be an ideal hydrophobic core for loading the detoxification medicines effectively. The nonlinear poly(ethylene glycol)-based copolymer shell layer consisted of 2-(2-methoxyethoxy)ethyl methacrylate (MEO₂MA) and oligo(ethylene glycol) methyl ether methacrylates (M_n = 300 g mol^-1, MEO₅MA). The monomer feeding molar ratio n(MEO₂MA)/n(MEO₅MA) of 1:3 enabled PS@P(MEO₂MA-co-MEO₅MA) nanogels to exhibit a distinguished colloidal stability and an adjustable volume phase transition temperature which is within the drug addicts' abnormally fluctuating temperature range. Importantly, it was found that the obtained PS@P(MEO₂MA-co-MEO₅MA) nanogels displayed good biocompatibility with rat aortic endothelial cells in the given concentration range. The nanogels also exhibited a satisfactory loading efficiency and thermo-sensitive/sustained release characteristics for three detoxification medicines: sinomenine, diltiazem and chlorpromazine.