One-pot synthesis of functional peptide-modified gold nanoparticles for gene delivery

A facile and mild method for construction of peptide-modified gold nanoparticles (AuNPs) for gene delivery has been developed. A peptide with sequence of (CRGDKGPDC)GPLGLAGIIIGRRRRRRRR-NH 2 (CPIR28) has been de novo designed to have four functional segments, that is, the cyclic iRGD segment of c(CRGDKGPDC) with Au binding cystine group, the enzyme responsive segment of PLGLA, the hydrophobic segment of III and the positive transmembrane segment of R 8 . By a simple one-pot reaction between CPIR28, HAuCl 4 and NaBH 4 in aqueous solution, the AuNPs with sizes < 10 nm are successfully produced, which have CPIR28 molecules grafted on their surface. The AuNPs have a high density of surface positive charges attributing to R 8 segment. They can interact with negatively charged DNA electrostatically to form condensed complexes, which show low level of cytotoxicity. In this system, CPIR28 not only serves as a modifier to regulate the nucleation and growth of AuNPs for controlling their morphology and size but also acts as an excellent stabilizer by grafting on the AuNPs surface to prevent their aggregation and precipitation. Moreover, the surface grafted peptide molecules provide positive charges to facilitate interactions with cells, which benefit the efficient gene delivery. The study paves a new way for synthesizing peptide-functionalized AuNPs for gene delivery applications.