An algorithm for the calculation of the electrostatic repulsion between surface coated with a charge membrane

We propose a numerical procedure for the calculation of the electrostatic repulsion force between two identical, parallel surfaces immersed in anab electrolyte solution. These surfaces are coated with an ion-penetrable membrane carrying fixed charges. The amount of fixed charges is governed by the dissociation of the functional groups in the membrane phase. The effect of pH on the degree of dissociation of these functional groups is taken into account. The difficulty of extensive use of Jacobi elliptic function in the numerical treatment of Poisson-Boltzmann equation can be circumvented by resorting to the present algorithm.     

Electrical Potential Distribution around a Charged Colloidal Particle: Nonlinear Integral Equation

多电解质溶液中带电胶体粒子的电势分布由球形Ｐｏｉｓｓｏｎ－Ｂｏｌｔｚｍａｎｎ方程（ＰＢＥ）描述．ＰＢＥ是一个非线性的微分方程，且难以求得其解析解．本文采用非线性Ｐ－Ｂ积分方程，计算电势分布的数值解．首先，根据静电场和热力学系统中的物理定理，导出描述电势分布的Ｐ－Ｂ积分方程（ＰＢＩＥ）；其次，用迭代方法求ＰＢＩＥ的数值解．最后，计算了在３－１型电解液中无量纲半径κａ分别为０．１２和０．２２，无量纲表面电势ξ分别为１，２，４，６时球形胶体粒子外部的电势值．为了检验数值解的精度，计算了表面电荷密度，并与Ｌｏｅｂ（１９６１）和Ｏｓｈｉｍａ（１９９５）等人的结果比较，本文结果的相对误差小于１％，优于Ｏｓｈｉｍａ的结果．     

Principles of electrostatic interactions and self-assembly in lipid/peptide/DNA systems: Applications to gene delivery

Recently, great progress has been achieved in development of a wide variety of formulations for gene delivery in vitro and in vivo, which include lipids, peptides and DNA (LPD). Additionally, application of natural histone–DNA complexes (chromatin) in combination with transfection lipids has been suggested as a potential route for gene delivery (chromofection). However, the thermodynamic mechanisms responsible for formation of the ternary lipid–peptide–DNA supramolecular structures have rarely been analyzed. Using recent experimental studies on LPD complexes (including mixtures of chromatin with cationic lipids) and general polyelectrolyte theory, we review and analyze the major determinants defining the internal structure, particle composition and size, surface charge and ultimately, transfection properties of the LPD formulations.     

pePC-SAFT: Modeling of polyelectrolyte systems: 1. Vapor–liquid equilibria

A molecular thermodynamic model for polyelectrolyte systems—called pePC-SAFT—is proposed. The effect of charged monomers within the polyelectrolyte chain is explicitly taken into account in the reference term by replacing the hard-chain contribution of the PC-SAFT model by a charged-hard-chain contribution. Moreover, counterion condensation is accounted for to determine the effective number of charges along the polyion as well as of free counterions. The electrostatic contribution of the free counterions is described by a Debye–Hückel term.     

Electrowetting — From statics to dynamics

More than one century ago, Lippmann found that capillary forces can be effectively controlled by external electrostatic forces. As a simple example, by applying a voltage between a conducting liquid droplet and the surface it is sitting on we are able to adjust the wetting angle of the drop. Since Lippmann's findings, electrocapillary phenomena – or electrowetting – have developed into a series of tools for manipulating microdroplets on solid surfaces, or small amounts of liquids in capillaries for microfluidic applications. In this article, we briefly review some recent progress of fundamental understanding of electrowetting and address some still unsolved issues. Specifically, we focus on static and dynamic electrowetting. In static electrowetting, we discuss some basic phenomena found in DC and AC electrowetting, and some theories about the origin of contact angle saturation. In dynamic electrowetting, we introduce some studies about this rather recent area. At last, we address some other capillary phenomena governed by electrostatics and we give an outlook that might stimulate further investigations on electrowetting.