Frit inlet field-flow fractionation techniques for the characterization of polyion complex self-assemblies

Abstract

Polymer self-assemblies joining oppositely charged chains, known as polyion complexes (PICs), have been formed using poly(ethyleneoxide - b - acrylic acid)/poly(l-lysine), poly(ethyleneoxide-b-acrylic acid)/dendrigraft poly(l-lysine) and poly[(3-acrylamidopropyl) trimethylammonium chloride - b - N - isopropyl acrylamide]/poly(acrylic acid). The self-assemblies have been first characterized in batch by Dynamic Light Scattering. In a second step, their analysis by Flow Field-Flow Fractionation techniques (FlFFF) was examined. They were shown to be very sensitive to shearing, especially during the focus step of the fractionation, and this led to an incompatibility with asymmetrical FlFFF. On the other hand, Frit Inlet FlFFF proved to be very efficient to observe them, either in its symmetrical (FI-FlFFF) or asymmetrical version (FI-AsFlFFF). Conditions of elution were found to optimize the sample recovery in pure water. Spherical self-assemblies were detected, with a size range between 70-400nm depending on the polymers. Compared to batch DLS, FI-AsFlFFF clearly showed the presence of several populations in some cases. The influence of salt on poly(ethyleneoxide-b-acrylic acid) (PEO-PAA) 6000-3000/dendrigraft poly(l-lysine) (DGL 3) was also assessed in parallel in batch DLS and FI-AsFlFFF. Batch DLS revealed a first process of swelling of the self-assembly for low concentrations up to 0.8M followed by the dissociation. FI-AsFlFFF furthermore indicated a possible ejection of DGL3 from the PIC assembly for concentrations as low as 0.2M, which could not be observed in batch DLS.

Asymmetric flow field-flow fractionation as a multifunctional technique for the characterization of polymeric nanocarriers

“…It can be demonstrated that homogeneous hard spheres have a shape factor close to 0.778, while values > 1 are indicator of particles with high aspect ratio. Values of the shape factor < 0.7 suggest particles with a dense core surrounded by a lighter shell [90]. Sometimes determining the shape of a particle only on the basis of the shape factor may lead to results of difficult physical interpretation [91,92].…”

Mechanistic Insights into Polyion Complex Associations

“…Chemicals. Poly(ethylene oxide)-b-poly(acrylic acid) (PEO−PAA) was purchased from Polymer Source Inc. (Dorval Montreál, Canada) and was characterized by 1 H NMR and size exclusion chromatography; the obtained number-average molecular weights of the polymers are reported in Table 1 37 using the general-purpose nonnegative least-squares (NNLS) method. This treatment provided residuals lower than 5 × 10 −3 .…”

Encapsulation of a cationic antimicrobial peptide into self-assembled polyion complex nano-objects enhances its antitumor properties

“…In the literature PICs sizes ranging from some tenths of nanometers to few hundred of nanometers have been reported [30]. We have previously demonstrated that the size and the internal structure of such self-assemblies depends on the molecular weight of the charged block in the copolymer used [31,32]. In order to confirm the presence of peptide P6 in the interior of the self-assemblies, both absorption and fluorescence measurements were performed.…”