Synthesis of pH-responsive polyzwitterions for activated cellular uptake and tumor accumulation of gold nanoparticles at tumorous acidity.

The response sensitivity of surface material plays an important role in adjustable nano-bio interaction in vivo. In this present, a zwitterionic polymer (polyzwitterion) containing quaternary ammonium cation and sulfonamide anion (PMPTSA) was synthesized by RAFT polymerization to explore the pH responsive behavior in tumors. The PMPTSA-coated gold nanoparticles (PMPTSA-@-Au NPs) showed zwitterionic nature such as antifouling ability, low cellular uptake and prolonged circulation time similar with common hydrophilic polymers, including polyethylene glycol (PEG), poly(carboxybetaine methacrylate) (PCBMA) and poly (sulfobetaine methacrylate) (PSBMA) functional gold nanoparticles in physiological environment (pH7.4). A high sensitivity and reversible positive charge conversion of P(MPTSA)-@-Au NPs at tumor slight acidic microenvironment(~pH6.8) leaded to an enhanced cellular internalization than that at pH7.4 and increased tumor accumulation compared with PEG, PCB and PSB functional gold nanoparticles. The highly pH responsive PMPTSA will provide the promising application in cancer nano-medicine.