Importance of Combining Advanced Particle Size Analysis Techniques To Characterize Cell-Penetrating Peptide–Ferrocifen Self-Assemblies

Abstract

The design of a simple platform to target the delivery of notably hydrophobic drugs into cancer cells is an ultimate goal. Here, three strategies were combined in the same nanovector, in limiting the use of excipients: cell-penetrating peptides, an amphiphilic prodrug, and self-assembly. Light scattering and cryogenic transmission electron microscopy revealed one size population of objects around 100 nm with a narrow size distribution. However, in-depth analysis of the suspension by nanoparticle tracking analysis, small-angle X-ray scattering, and nuclear magnetic resonance (NMR) diffusometry demonstrated the presence of another population of small objects (<2 nm). It has been shown that these small self-assemblies represented >99% of the matter! This presence was clearly and unambiguously demonstrated by NMR diffusometry experiments. The study highlights the importance and the complementary contribution of each characterization method to reflect the reality of the studied nanoassembly.

Relevant Physicochemical Methods to Functionalize, Purify, and Characterize Surface-Decorated Lipid-Based Nanocarriers

“…The study of Guyon et al highlighted the essential and complementary contribution of each characterization methods to reflect the reality of the studied nanostructure. 8 In fact, DLS and transmission electron microscopy (TEM) analysis revealed a 100 nm size population with a narrow size distribution. However, high resolution method (NTA, small-angle X-ray scattering and NMR diffusometry) showed the presence of another population of small objects (<2 nm) which represents more than 99% of the matter.…”

“…It was previously pointed out that complementary and more complex methods should be used to provide reliable information even for the determination of one parameter such as the size of nanoparticles. 8,9 Indeed, this characterization step may be much more difficult after surface functionalization, but the complete understanding of the entire structure is crucial before preclinical studies.…”

NMR diffusometry: A new perspective for nanomedicine exploration

“…Indeed, the NMR signal is proportional to the number of 1 H nuclei involved weighted by the relaxation effects (smaller species with longer relaxation times yielding to sharper NMR peaks than larger ones) which favor the visibility of a small object. Guyon et al [55] have shown that PFG-NMR was able to identify the main nanoassembly population that was masked in DLS by small traces of large aggregates. Whereas, small formulation residual components such as micelles which can be masked in DLS by the larger main nanomedicine population could be detected [56,57] using PFG-NMR.…”

Albumin-driven disassembly of lipidic nanoparticles: the specific case of the squalene-adenosine nanodrug

“…Effect of Fetal Bovine Serum on SQAd nanoparticles -Characterizing nanoparticles in media as complex as blood plasma is difficult because of the high concentration of blood components of nanometric size. Dynamic Light Scattering (DLS), which is usually used to estimate the size of squalene-based nanoparticles 31,34,46,47 remains a low-resolution method not adapted to study polydisperse assemblies of nanoparticles 48 within a concentrated complex media. By contrast, Small Angle Neutron Scattering is a powerful method for characterizing the squalenoyl conjugated nanoparticles dispersed in D 2 O 47 and is suitable to study multicomponent systems.…”