Single stranded siRNA complexation through non-electrostatic interactions

Abstract

As double stranded, single stranded siRNA (ss-siRNA) has demonstrated gene silencing activity but still requires efficient carriers to reach its cytoplasmic target. To better understand the fundamental aspect driving the complexation of ss-siRNA with nanocarriers, the interactions between surfaces of various compositions across a ss-siRNA solution were investigated using the Surface Forces Apparatus. The results show that ss-siRNA can adsorb onto hydrophilic (positively and negatively charged) as well as on hydrophobic substrates suggesting that the complexation can occur through hydrophobic interactions and hydrogen bonding in addition to electrostatic interactions. Moreover, the binding strength and the conformation of ss-siRNA depend on the nature of the interactions between the ss-siRNA and the surfaces. The binding of ss-siRNA with nanocarriers, such as micelles or liposomes through non-electrostatic interactions was also evidenced by a SYBR Gold cyanine dye. We evidenced the presence of interactions between the dye and oligonucleotides already complexed to non-cationic nanovectors biasing the quantification of the encapsulation. These results suggest that non-electrostatic interactions could be exploited to complement electrostatic interactions in the design of nanocarriers. In particular, the different highlighted interactions can be used to complex ss-siRNA with uncharged or anionic carriers which are related to lower toxicity compared to cationic carriers.

Tribological Behavior of Surface-Immobilized Novel Biomimicking Multihierarchical Polymers: The Role of Structure and Surface Attachment

“…The amino-silane AUTES was covalently attached to the OH-activated mica via silanization, providing reactive primary amines to the surfaces as also previously done. 31,34 The increase in the static water contact angle (Table 1) compared to the initial substrate, the surface roughness, and morphology (Figure S1) are similar to those previously reported for similar surfaces, 31,34 confirming the formation of a relatively smooth, homogeneous, and hydrolytically stable monolayer of AUTES. The polymers were then immobilized onto the amino-functionalized surfaces via chemisorption and physisorption.…”

pH/Redox Dual-Responsive Polyplex with Effective Endosomal Escape for Codelivery of siRNA and Doxorubicin against Drug-Resistant Cancer Cells

“…The protonation of PHis would compromise the structural integrity of the polyplex by hydrophobic–hydrophilic transition and translocation of PHis blocks, as well as the inducement of water molecules in the polyplex. This change would diminish the stabilization effect of nonelectrostatic interactions provided from PHis-PLA blocks. , Moreover, PHis blocks showed no electrostatic binding with siRNA under a pH of 5.5, despite the increased protonation because of the low cationic charge density (Figure S2). OEI protonation was increased by about 10% as pH declined from 7.4 to 5.5, demonstrating a slight increase of electrostatic interactions with siRNA.…”

“…This change would diminish the stabilization effect of nonelectrostatic interactions provided from PHis-PLA blocks. 25,55 Moreover, PHis blocks showed no electrostatic binding with siRNA under a pH of 5.5, despite the increased protonation because of the low cationic charge density (Figure S2). OEI protonation was increased by about 10% as pH declined from 7.4 to 5.5, 56 demonstrating a slight increase of electrostatic interactions with siRNA.…”

Engineering the Aromaticity of Cationic Helical Polypeptides toward “Self-Activated” DNA/siRNA Delivery

“…42 Motivated by these understandings, in the current study we incorporated various aromatic groups, including benzyl (Bn), naphthyl (Naph), biphenyl (Biph), anthryl (Anth), and pyrenyl (Py), into the side chains of guanidinated, α-helical polypeptides, attempting to potentiate their nonendocytic as well as "non-pore formation" membrane activities to allow effective gene transfection with reduced cytotoxicity (Scheme 1). Considering the additional hydrophobic interactions between aromatic polypeptides and siRNA molecules, 43 we further hypothesized that the siRNA binding affinity of helical polypeptides could be enhanced to allow effective intracellular siRNA delivery. To demonstrate such design strategies, the membrane binding affinity, membrane penetration capacity, intracellular DNA/siRNA delivery efficiency, "pore formation" capability, internalization kinetics, cytotoxicity, in vitro DNA transfection efficiency, in vitro tumor necrosis factor (TNF-α) siRNA transfection efficiency, and in vivo anti-inflammation TNF-α silencing efficiency of the aromatically modified, helical polypeptides were comprehensively explored and compared to their unmodified as well as aliphatically modified analogues.…”