Size and charge characterization of polymeric drug delivery systems by Taylor dispersion analysis and capillary electrophoresis

Abstract

In this work, Taylor dispersion analysis and capillary electrophoresis were used to characterize the size and charge of polymeric drug delivery nanogels based on polyglutamate chains grafted with hydrophobic groups of vitamin E. The hydrophobic vitamin E groups self-associate in water to form small hydrophobic nanodomains that can incorporate small drugs or therapeutic proteins. Taylor dispersion analysis is well suited to determine the weight average hydrodynamic radius of nanomaterials and to get information on the size polydispersity of polymeric samples. The effective charge was determined either from electrophoretic mobility and hydrodynamic radius using electrophoretic modeling (three different approaches were compared), or by indirect UV detection in capillary electrophoresis. The influence of vitamin E hydrophobicity on the polymer effective charge has been studied. The presence of vitamin E leads to a drastic decrease in polymer effective charge in comparison to non-modified polyglutamate. Finally, the electrophoretic behavior of polyglutamate backbone grafted with hydrophobic vitamin E (pGVE) nanogels according to the ionic strength was investigated using the recently proposed slope plot approach. It was deduced that the pGVE nanogels behave electrophoretically as polyelectrolytes which is in good agreement with the high water content of the nanogels.

Moment theory for the analytical determination of rate constants for solute permeation at the interface of spherical molecular aggregates

“…To improve their chemical stability and control their release speed, drug molecules are included in molecular aggregates. CE and EKC have been used to characterize the molecular aggregates and to determine the distribution coefficients of the drug molecules into the molecular aggregates . On the other hand, the permeation rate of drug molecules at the interfacial boundary is correlated with their release speed from the molecular aggregates.…”

On the ionic strength dependence of the electrophoretic mobility: From 2D to 3D slope‐plots

“…For experimentalists that want to get information on the solute characteristics (notably charge and nature-i.e. small ion, nanoparticle, or polyelectrolyte-) from S and 5mM ep experimental values, the overall 2D slope-plot giving S = S 0 + S 1 as a function of 5mM ep may be very useful, as discussed [28] and exemplified for drug delivery applications in previous works [27]. Figure 3 displays the slope-plot for NP (R h Ͼ 1 nm) and SI (R h Ͻ 1 nm).…”

Generalized polymer effective charge measurement by capillary isotachophoresis

“…Fig. 5 points out two important trends regarding the measurement of effective charge by ITP: (i) when the uncertainty on the mobilities is higher than 1 × 10 −9 m 2 V −1 s −1 unit, A/A becomes the most important source of uncertainty with [6,19]). b The theoretical effective charge per charged monomer z 1,theo is given by the Manning theory as follows: z 1,theo is equal to b/l b , where b is the average charge spacing (in nm), l b is the Bjerrum length (0.713 nm at 298 K), when b/l b is lower than 1. z 1,theo = 1 when b/l b is higher than 1.…”

“…This parameter has a primary role in the control of interactions between charged species in solution [2][3][4][5][6]. It sets the strength of the relatively long-range electrostatic force between charged compounds.…”