With the discovery of RNA interference technology, small-interfering RNA (siRNA) has emerged as
new powerful tool for gene therapy because of its high targeting specificity and selectivity. However, one of the
limitations to successful gene therapy is the inability to monitor delivery of genes and therapeutic responses at the
targeted site. Hence, a combinatorial approach of gene therapy with molecular imaging has been crucial in optimizing
gene therapy. Recent advances in nanotechnology have made tremendous efforts to develop multifunctional
nanoparticles that contain imaging and therapeutic agents together for image-guided therapy. The nanoparticles
serve as contrast agents in imaging for disease detection with simultaneous delivery of therapeutics to cure the diseases.
The therapy also helps to monitor the drug accumulation and assimilation in the body, thereby facilitating the evaluation of treatment
effects. Here, we present an overview of polymer and lipid-based carriers for siRNA delivery, along with imaging agents as imageguided
therapy, in the treatment of breast, lung, liver, ovarian, cervical, and prostate cancers.