Characterization of positively charged polyplexes by tunable resistive pulse sensing

Area of Science:

• Nanotechnology
• Biotechnology
• Materials Science

Background:

• Non-viral small interfering RNA (siRNA) delivery is gaining traction with recent drug approvals.
• Positively charged lipid and polymer formulations are key in non-viral delivery research.
• Characterizing polydisperse nanoparticles, especially positively charged ones, poses significant challenges for current methods.

Purpose of the Study:

• To develop and validate a novel coating solution for tunable resistive pulse sensing (TRPS) of positively charged nanoparticles.
• To enable accurate particle-by-particle characterization of size, polydispersity index (PDI), and concentration for these challenging formulations.
• To lay the groundwork for enhanced characterization of polyplexes and other positively charged nanoparticles.

Main Methods:

• Development of a choline-chloride-based coating solution.
• Verification of the coating's efficacy using current-voltage (I-V) recordings.
• Application and testing of the coating on positively charged siRNA/PEG-PCL-PEI polyplex formulations using TRPS.

Main Results:

• The choline-chloride coating successfully enabled TRPS measurements of positively charged nanoparticles.
• Accurate determination of size, PDI, and concentration was achieved for siRNA-loaded PEI-based polyplexes.
• The new coating overcomes limitations of existing methods for positively charged sample analysis.

Conclusions:

• A choline-chloride coating provides a viable solution for TRPS characterization of positively charged nanoparticles.
• This advancement facilitates more reliable assessment of nanoparticle formulations for non-viral gene delivery.
• The findings support further particle-by-particle analysis of polyplexes and similar positively charged nanomaterials.