Affiliations: [a] Department of Immunology, College of Basic Medical Sciences, and Institute of Immuno- and Biotherapy, Nanchang University, Nanchang, Jiangxi, China | [b] Institute of nanomedicine, Jiangxi Academy of Medical Sciences, Nanchang, Jiangxi, China
Correspondence:
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Corresponding author: Yujuan Zhang, Department of Immunology, College of Basic Medical Sciences, and Institute of Immuno- and Biotherapy, Nanchang University, Nanchang 330006, Jiangxi, China. E-mail:zyj900203@sina.com
Abstract: RNA interference (RNAi) employs double-stranded RNA or
siRNA (small interfering RNA) to silence gene expression in cells. The
widespread use of RNAi therapeutics requires the development of clinically
suitable, safe and effective delivery vehicles. PEI (Poly(ethylene imine))
carrying the positive charges has attracted considerable attention for siRNA
delivery. Gold nanorods (GNRs) exhibit specially localized surface plasmon
resonance when excited by the visible and near-infrared laser, which is
useful for photothermal therapy. However, the toxicity derived from a large
amount of the surfactant cetyltrimethylammonium bromide (CTAB) during GNR
synthesis severely limits their medical applications. Here, we report the
synthesis of GNRs-PEI/GNRs-PEI-folate to improve biocompatibility, siRNA
delivery and photothermal therapy of GNRs. Firstly, GNRs were synthesized
according to the seed-mediated template-assisted protocol. The
characterization results of GNRs showed: the size was length about 218 nm
and width about 26.8 nm; the Zeta potential was +38.1 mV derived from CTAB
on their surface; the dipole resonance extinction spectrum peak was 752 nm
which is effective for photothermal therapy in vivo. Secondly, we
synthesized PEI-MUA (Mercaptoundecanoic acid) and PEI-MUA-folate based on
the chemical reaction between amino group of PEI and carboxyl group of MUA
or Folate. PEI-MUA or PEI-MUA-folate to replace CTAB on GNRs obtained the
GNRs-MUA-PEI system or the GNRs-MUA-PEI-folate system due to the solid
conjugation between the thiol group of MUA and GNRs. The products were
measured using the FTIR Spectrometer, and the spectra suggest MUA-PEI or
PEI-MUA-folate has successfully replaced CTAB on the surface of GNRs.
Finally, GNRs-MUA-PEI was incubated with siRNA-Cy3. The unbound siRNA-Cy3
was measured the intensity of fluorescence for calculating the uploaded
amount of siRNA by GNRs-MUA-PEI, and the results indicate that the uploaded
percentage of siRNA is about 70%. We conclude that the GNRs-MUA-PEI
system is an effective siRNA loading vehicle.
