Methoxyl poly (ethylene glycol) (mPEG-OH) was successfully grafted onto branched polyethyleneimine (hy-PEI) to yield a water soluble graft copolymer mPEG-g-PEI. This copolymer may package super- paramagnetic iron oxide (SPIO) by ligand exchange. The SPIO weight percentage in the polymer coated nanoparticles was determined to be 55%, the size and zeta potential of nanoparticles was 50 nm and 12 mV respectively. Antibody fixation onto the complex (mPEI-g-PEG-SPIO) surface layer was achieved by activated single chain monoclonal antibody against prostate stem cell antigen (PSCA). Our study showed that the single chain antibody functionalized nanoprobe (scAbPSCA-PEI-g-PEG-SPIO) with a small size can specifically enter the prostate cancer cells, decreasing MRI T2-weighted signal intensity of prostate cancer cells to 44.76%. Our results revealed that the potential of this magnetic nanoparticulate system promised as a novel MRI nanoprobe for early diagnosis of prostate cancer (PCa).
