Multifunctional theranostic nanomedicine for photoacoustic imaging-guided combination tumor treatment

The use of small interfering RNA (siRNA) with chemotherapeutic drugs has a synergistic effect of inhibiting target genes. Furthermore, theranostics, which enables therapeutic drug delivery and provides immediate diagnosis, is also emerging as a promising technique. In line with this novel concept, we have developed an albumin-based nanomedicine capable of combination therapy (chemo- and gene therapy) and photoacoustic imaging. The multifunctional (combination therapy and photoacoustic imaging) theranostic nanomedicine contains paclitaxel (PTX), siRNA, and indocyanine green (ICG). Sulfhydryl-modified siRNA and sulfhydryl-modified human serum albumin form more stable nanoparticles mainly through the disulfide bond, unlike prevalent nanomedicines (e.g., lipid-based nanomedicine or siRNA bioconjugates). The albumin-based multifunctional nanomedicine shows double gene inhibition ability and a synergistic effect of chemo- and gene therapy. Inhibition of the expression of target genes (Bcl-2, VEGF, etc.) and simultaneous treatment with PTX exhibit a synergistic effect compared to single treatment in vitro and in vivo. Furthermore, using ICG, photoacoustic imaging was very efficient. Our study demonstrates that this multifunctional theranostic nanomedicine could perform co-delivery of PTX and siRNA and yield a synergistic effect for target cells. By virtue of combination gene therapy, this the ranostic nanomedicine has great potential to cure various diseases, including cancer, and aid the prognosis of target tumor cells or tissues by photoacoustic imaging. To the best of our knowledge, this is the first report of the development of a multifunctional theranostic nanomedicine for combination therapy and non-invasive photoacoustic imaging.