Widespread applications of conventional polymeric gene carriers are greatly hampered by their inefficient transfection performance under serum-containing environment. Aiming to overcome this limitation, we propose a bioreducible polyethylenimine-gold nanocomplex system (SSPEI-Au NC), which can be prepared by a simple layer-by-layer (LBL) assembly procedure. SSPEI-Au NC contains sequentially deposited layers of bioreducible polyethylenimine (SSPEI) and poly(ã-glutamic acid) (ã-PGA) for efficient binding and delivery of plasmid DNA (pDNA). SSPEI-Au NC was characterized for various physicochemical properties, including: UV-vis spectra, TEM imaging, hydrodynamic size, and pDNA binding ability. The SSPEI-Au NC were efficiently uptaken by mammalian cells as observed using dark-field microscopy. Comparing to nondegradable PEI25k, the bioreducible SSPEI-Au NC exhibited superior transfection capability under serum-containing condition while causing lower cytotoxicity on mammalian cell lines. The effect of serum on SSPEI-Au NC dispersity was studied using UV-vis spectrometry and the results suggest that serum-assisted colloidal stability of SSPEI-Au NC contributed to its serum-resistant transfection.
Absorbable Implants Cations