Amphiphilic Gold Nanoparticles Displaying Flexible Bifurcated Ligands as a Carrier for siRNA Delivery into the Cell Cytosol

Abstract

The nanoparticle-based delivery of siRNA with a noncationic outermost surface at a low particle concentration is greatly desired. We newly synthesized a bifurcated ligand (BL) possessing hydrophobic and hydrophilic arms as a surface ligand for gold nanoparticles (AuNPs) to allow siRNA delivery. The concept underlying the design of this ligand is that amphiphilic property should allow AuNPs to permeate the cell cytosol thorough the endosomal membrane. BLs and quaternary cationic ligands were codisplayed on 40 nm AuNPs, which were subsequently coated with siRNA via electrostatic interaction. The number of siRNAs immobilized on a single nanoparticle was 26, and the conjugate showed a negative zeta potential due to siRNAs on the outermost surface of the AuNPs. Apparent gene silencing of luciferase expression in HeLa cells was achieved at an AuNP concentration as low as 60 pM. Almost no gene silencing was observed for AuNPs not displaying BLs. To reveal the effect of the BL, we compared the number of AuNPs internalized into HeLa cells and the localization in the cytosol between AuNPs displaying and those not displaying BLs. These analyses indicated that the role of BLs is not only the simple promotion of cellular uptake but also involves the enhancement of AuNPs permeation into the cytosol from the endosomes, leading to effective gene silencing.

Hydrophobic and Hydrophilic Au and Ag Nanoparticles. Breakthroughs and Perspectives

“…A specific example on this issue deals with the delivery of siRNA that was studied with a non-cationic bifurcated ligand (BL), possessing short hydrophobic (octyl ether) and hydrophilic (hexaethylene glycol) arms, as surface ligand for (AuNPs) [ 108 ]. Every single AuNPs (size 40 nm) stabilized by (16-mercapto-hexadecyl) trimethylammonium bromide (MTAB), immobilized 26 siRNA with electrostatic interaction and had negative zeta-potential due to siRNAs on the outermost surface.…”

Shape-dependent adjuvanticity of nanoparticle-conjugated RNA adjuvants for intranasal inactivated influenza vaccines

“…Nanoparticles are good candidates for use as uPIC(40:400) scaffolds to enhance adjuvanticity. Nanoparticles have already been widely used as vaccine carriers due to their ability to enhance cellular uptake of drugs [10][11][12] and activate immune systems. [13][14][15][16][17][18][19][20] The immobilization of antigens onto nanoparticles and resultant enhancement of immunogenicity were initially demonstrated in the 1980s.…”

Switching of Macromolecular Ligand Display by Thermoresponsive Polymers Mediates Endocytosis of Multiconjugate Nanoparticles

“…The range of ligands attached to AuNPs which have been used to influence cellular interactions includes small molecule agents, peptides, growth factor derivatives and proteins. 12,[19][20][21][22][23] High molecular weight ligands such as proteins offer high recognition selectivity with their cognate receptors under tightly-defined conditions and so are obvious candidates to target AuNPs to specific receptors on cells of interest. The iron binding protein transferrin (Tf), has been extensively studied as a delivery vector for specific therapeutics which otherwise show limited cellular uptake.…”