Prostate cancer-targeted imaging using magnetofluorescent polymeric nanoparticles functionalized with bombesin

Purpose. In this work, the aim was to prepare and characterize a magnetofluorescent polymeric nanoparticle for prostate cancer imaging in vivo. Methods. Glycol chitosan (GC) was chemically modified with N-acetyl histidine (NAHis) as a hydrophobic moiety, and bombesin. (BBN) was conjugated to the hydrophobically modified GC for use in targeting gastric-releasing peptide receptors (GRPR) overexpressed in prostate cancer cells. NAHis-GC conjugates were labeled, with the near-infrared (NIR) fluorophore Cy5.5 (C-NAHis-GC conjugate). Results. BBN-conjugated C-NAHis-GC nanoparticles (BC-NAHis-GC nanoparticles) showed significantly higher binding to the PC3 cell surface than nanoparticles without BBN, and the cellular binding was clearly inhibited, by BBN. The tumor-to-muscle ratios of C- and BC-NAHis-GC nanoparticles were 2.26±0.66 and 5.37±0.43, respectively. The tumor accumulation of BC-NAHis-GC nanoparticles was clearly reduced by co-injection of BBN. Further, iron oxide nanoparticles (10) were loaded into BC-NAHis-GC nanoparticles to investigate the possibility of use as a probe for MRI. IO-BC-NAHis-GC nanoparticles were well observed in the PC3 cells, and the blocking with BBN significantly reduced the cellular binding of the nanoparticles. Conclusion. These results demonstrate that the BBN conjugation to NAHis-GC nanoparticles improves their tumor accumulation in PC3-bearing mice in comparison to nanoparticles without BBN, suggesting that BC-NAHis-GC nanoparticles may be useful for prostate cancer imaging.