Complexation of a Weak Polyelectrolyte with a Charged Nanoparticle. Solution Properties and Polyelectrolyte Stiffness Influences

Abstract

The complex formation between a weak polyelectrolyte chain and an oppositely charged nanoparticle is investigated using Monte Carlo simulations. Global structural parameters such as the polyelectrolyte length, nanoparticle size, solution pH, and ionic concentration as well as local features, such as the nanoparticle surface charge density and polyelectrolyte intrinsic stiffness influences, are systematically investigated. Phase states of the polyelectrolyte/nanoparticle complexes are presented, and to bridge the gap with experiments, titration curves are calculated. It is shown that the presence of one oppositely charged nanoparticle significantly modifies the acid/base properties of the weak polyelectrolyte as well as the charge distribution along the polymer backbone and that the solution pH and ionic concentration largely control the polyelectrolyte conformation at the nanoparticle surface. Chain stiffness promotes the polyelectrolyte expansion as well as ionization but penalizes the polyelectrolyte adsorption at the nanoparticle surface, hence affecting its acid/base behavior.

Rodlike Complexes of a Polyelectrolyte (Hyaluronan) and a Protein (Lysozyme) Observed by SANS

“…These main trends have been checked experimentally by Kayitmazer et al who compare the binding of chitosan and PDADMAC, two polyelectrolytes with equal charge density but different persistence lengths, to oppositely charges micelles, dendrimers and proteins 32 . However the authors point out that the relevant parameter for binding is not necessarily the intrinsic persistence length of the chain L p , but the flexibility of the chain on the colloid length scale 6 6 In parallel, computer simulations also studied the role of electrostatic interactions in mixtures of charged strings with charged spheres and their interplay with parameters such as chain stiffness, at first in simulations involving only one protein and one polyelectrolyte chain 30,31 , and more recently on systems dealing with several proteins in the presence of an oppositely charged polyelectrolyte 33, 34 . In ref [34], the heterogeneous charge density of proteins in the presence of weak polyelectrolyte has also been taken into account, whereby different chain lengths and ionic strengths were employed:…”

Influence of Explicit Ions on Titration Curves and Conformations of Flexible Polyelectrolytes: A Monte Carlo Study

“…[1][2][3][4][5][6] The range of parameters influencing polyelectrolyte conformation, chemical reactivity, and complexation processes is not completely understood and continues to stimulate intensive research in this field because they control directly many industrial [7][8][9][10] and biological processes. [11][12][13][14] The particular physicochemical properties of polyelectrolyte chains arise from the long-range nature of the Coulomb interactions.…”

The many facets of polyelectrolytes and oppositely charged macroions complex formation

“…There is nowadays a considerable amount of available contributions investigating the PE/macroion complexation by [24][25][26][33][34][35][36]. The effect of chain stiffness of a strong PE were first studied by Wallin and Linse [22] and then further investigated by Stoll and Chodanowski [26] and Akinchina and Linse [27].…”

“…They also investigated the effect of added salt on the formation of complexes between a flexible, semiflexible, and rigid PE and an oppositely charged spherical macroion and the adsorption/desorption transition. According to these studies [22,26,27,36], a range of macromolecular structures such as tennis ball, solenoid, and multiloop or rosette were obtained (see Table 1). Using numerical simulations, Kunze and Netz [42,43] also investigated the case of complexation of a semi flexible PE and an oppositely charged sphere.…”

“…The effects of chain length were systematically investigated by Wallin and Linse [23]. For a high ratio of chain length upon macroion diameter, Stoll and coworkers [24,25,34,36] found that only a few number of monomers is adsorbed to the macroion, forming an extended tails in solution (Fig. 1).…”