The invention discloses a pharmaceutical composition of multifunctional core-shell nanoparticles, each nanoparticle comprising: a core portion comprised of hydrophobic poly(D,L-lactic-co-glycolic acid) (PLGA) and a detection-enhancing substance, and a shell portion comprised of positively charged chitosan adapted to cause no aggregation of nanoparticles due to electrostatic repulsion between the positively charged nanoparticles. In one embodiment, the detection-enhancing substance includes SPIO, a quantum dot, a fluorescent quantum dot, a bubble, an air bubble, and the like.
