A zwitterionic polymer-based nanoparticle with response to tumor
acidity is developed for enhanced drug delivery to tumors. The
nanoparticles are neutrally charged at physiological conditions and show
prolonged circulation time; after leaking into tumor sites, in the
acidic extracellular tumor environment, nanoparticles are activated and become positively charged and are
therefore efficiently taken up by tumor cells, leading to enhanced
therapeutic effects in cancer treatment.