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Premature leakage of drugs into the bloodstream remains a problem in the process of drug delivery, resulting in higher toxic and side effects on normal tissue cells. Novel drug carriers enabling effective drug accumulation in the tumor site have got much attention of researchers. Poly (methyl acrylic acid diisopropyl amino ethyl ester) (PDPA) is a polymer with pH-sensitive response, the diisopropylamine in the side chains are protonated in an acidic environment, resulting in its changing from hydrophobic to hydrophilic. PDPA was grafted onto the surface of mesoporous silica nanoparticles (MSNs) by atom transfer radical polymerization (ATRP) reaction. Then folic acid (FA) was introduced onto PDPA as a targeting ligand for enabling the drug carrier to enter tumor cells effectively. Simultaneously poly [di (ethylene glycol) methyl ether methacrylate-co-oligo (ethylene glycol) methacrylate]-b-poly[methyl acrylic acid diisopropyl amino ethyl ester] (P(MEO2MA90-co-OEGMA10)-b-PDPA10) with dual sensitivity of temperature and pH was synthesized and the lower critical solution temperatures (LCST) of the polymer was adjusted to 44 ℃ by adjusting the proportion of three monomers. A drug carrier with a core-shell structure was self-assembled through hydrophobic force by covering the later polymer on the surface of MSNs-PDPA-FA. Finally, the drug release kinetics of the carrier was studied by using doxorubicin(DOX) as a model drug, and the result showed that the total leakage of the model drug DOX was less than 10% after 48 h in normal physiological environment (pH=7.4, 37 ℃). However, when the pH value was changed to 5.0 at 44 ℃, the shell was dissociated from the core and the drug was released. Then, the drug was released rapidly within 5 h and the cumulative drug release could reach to 65% in 48 h. Therefore, this research was expected to construct a shielding system based on the pH/temperature dualresponsive polymer, which could be used to avoid premature exposure of certain functional groups or molecules to the normal physiological environment, and it could also prevent the premature release of drugs in the normal tissues. [ABSTRACT FROM AUTHOR]