Protease-targeting peptide-functionalized porous silicon nanoparticles for cancer fluorescence imaging.

Abstract

Background: Porous silicon (pSi) nanoparticles (NPs) functionalized with suitable targeting ligands are now established cancer bioimaging agents and drug-delivery platforms. With growing interest in peptides as tumor-targeting ligands, much work has focused on the use of various peptides in combination with pSi NPs for cancer theranostics. Here, the authors investigated the targeting potential of pSi NPs functionalized with two types of peptide, a linear 10-mer peptide and its branched (Y-shaped) equivalent, that respond to legumain activity in tumor cells. Results: In vitro experiments established that the linear peptide-pSi NPconjugate had better aqueous stability under tumor conditions and higher binding efficiency (p<0.001) toward legumain-expressing cells such as RAW 264.7 cells compared with that of its branched equivalent. In vivo studies (analyzed using ex vivo fluorescence) with the linear peptide-pSi NPformulation using a syngeneic mouse model of breast cancer showed a higher accumulation (p>0.05) of linear peptide-conjugated pSi NPs in the tumor site within 4 hcompared with nonconjugated pSi NPs. Theseresults suggest that the linear peptide-pSi NPformulation is a nontoxic, stableand efficient fluorescence bioimaging agent and potential drug-delivery platform.