Conformational properties of block-polyampholytes adsorbed on charged cylindrical surfaces

Abstract

Polyampholytes are polymers that have positive and negative monomers along their chain. The adsorption of polyampholytes on charged surfaces has been the subject of a large number of theoretical, computational and experimental studies due to its importance in a variety of bio and nanothechnological systems. However, computational studies focusing on interaction between polyampholytes and cylindrical charged surfaces are rather scarce. This study, therefore, aims to investigate the conformational properties of block-polyampholytes in the presence of a negatively charged cylinder by means of Metropolis Monte Carlo simulations. Adopting a simplified model in which the electrolyte solution is treated at the Debye-Hückel level, the effects of the ionic strength, the linear charge density of the cylinder and the block length on monomers distributions have been investigated. It was found that increasing the salt concentration promotes a transition from a conformation characterized by large loops to a necklace-like conformation parallel to the surface. It was also shown that, at low cylinder charge density, the increase in salt concentration and the length of the blocks lead to a change in the orientation of the adsorbed chain.

Adsorption of Block-Polyelectrolytes on an Oppositely Charged Surface

“…1−9 The adsorption of PEs on the DNA cylindrical surface can prevent DNA from binding to undesired proteins, thus achieving the purpose of disease treatment. 1,10 The colloid system can be stable or coagulated by the adsorption of PEs on the spherical surface, 11−15 which is related to the competition between the electric double layer repulsion and the van der Waals attraction in the system. This principle has been used in the removal process of solid particles in industrial wastewater treatment.…”

“…Relevant researches have been investigated extensively by theory and simulation. 1,2,5,38,39 The adsorption−desorption transition and adsorption conformations of PEs near attractive interfaces are two of the recent research hotspots. 8,40−45 Carvalho et al investigated the chain length effect on two different critical surface charge densities (σ c l ) and (σ c nl ) which are obtained, respectively, using linear and nonlinear Poisson−Boltzmann equations.…”

“…Polyelectrolyte (PE, which is polymer whose repeating units can be partially or fully charged in a polar solvent) adsorption onto an oppositely charged surface has gained widespread attention in the past few decades. − Usually, the subject of PE adsorption can be divided into three categories in terms of surface curvature, namely, cylindrical, spherical, and planar. − The adsorption of PEs on the DNA cylindrical surface can prevent DNA from binding to undesired proteins, thus achieving the purpose of disease treatment. , The colloid system can be stable or coagulated by the adsorption of PEs on the spherical surface, − which is related to the competition between the electric double layer repulsion and the van der Waals attraction in the system. This principle has been used in the removal process of solid particles in industrial wastewater treatment.…”

Critical adsorption of multiple polyelectrolytes onto a nanosphere: splitting the adsorption–desorption transition boundary

“…The SNP has the surface-charge density σ and radius a = 100 Å. Attractive ES Debye–Hückel potentials of the SNP with the i th PE monomer at distance r i = | r i | from the sphere centre (the monomer–particle (m-p) potential) are given by [6,15,17,20,21]Unormalm−normalpfalse(rifalse)={normal∞,ri<a+b,14πϵsϵ04πa2σqi1+κae−κ(ri−a)ri,otherwise.Similar to [24,25,33–36,78,79], Metropolis Monte Carlo simulations in the NVT ensemble are employed below.…”

“…The adsorption onto heterogeneous/patchy [4,19,45,70–73], multicomponent responsive [68] and low-dielectric [21,74,75] interfaces was also considered. The conditions of critical adsorption under confinement [21,22,25], for pH-sensitive or titratable PEs [35] (see also [37,62,63,65,76,77]), block copolymers [78] and polyampholyte chains [35,63,79] were examined by theory and simulations as well. Recently, we quantified the conditions of critical PE adsorption onto dipolar Janus-type net-neutral spherical nanoparticles (SNPs) [24].…”