Journal of Pharmaceutical and Biomedical Analysis 71 (2012) 79–88 Contents lists available at SciVerse ScienceDirect Journal of Pharmaceutical and Biomedical Analysis jou rn al h om epage: www.elsevier.com/locate/jpba The effect of anionic surfactant on poliovirus particles during capillary electrophoresis Iuliana Oita a , Hadewych Halewyck b,c , Bert Thys b,c , Bart Rombaut b,c , Yvan Vander Heyden a,∗ a Vrije Universiteit Brussel-VUB, Center for Pharmaceutical Research-CePhaR, Department of Analytical Chemistry and Pharmaceutical Technology, Laarbeeklaan 103, B-1090, Brussels, Belgium b Vrije Universiteit Brussel-VUB, Center for Pharmaceutical Research-CePhaR, Department of Pharmaceutical Biotechnology & Molecular Biology, Laarbeeklaan 103, B-1090, Brussels, Belgium c Vrije Universiteit Brussel-VUB, Center for Pharmaceutical Research-CePhaR, Center for Neurosciences, Laarbeeklaan 103, B-1090, Brussels, Belgium a r t i c l e i n f o Article history: Received 10 May 2012 Received in revised form 26 July 2012 Accepted 30 July 2012 Available online 4 August 2012 Keywords: Capillary electrophoresis Poliovirus SDS Capsid dissociation Stability a b s t r a c t Because of its essential role in SDS-PAGE, sodium dodecylsulphate (SDS) is generally associated with protein denaturation. However, for SDS-PAGE, proteins are linearized in the presence of SDS, following the exposure to high temperatures and reducing agents. In comparison, the conditions employed during a capillary electrophoretic (CE) separation involve only a limited exposure to SDS, at much lower tem- peratures. As the outer surface of the non-enveloped viruses consists of proteins, virus interaction with SDS can be judged from the perspective of SDS–protein interaction. Several studies have indicated that proteins have a different susceptibility to SDS, depending on their secondary structure and number of sub- units. Therefore it is not straightforward to estimate what should be expected when intact polioviruses and subviral particles obtained by thermal conversion of the poliovirions, are exposed to SDS during CE separation. In this study it is shown that, during CE separations, SDS has no effect on the integrity of the poliovirion, but the presence of SDS in the separation system influences the poliovirus peak height and shape. The implication of SDS in the CE separation of poliovirus is discussed in detail. On the contrary, the proteinaceous subviral particles, such as the empty capsids, are less stable in the presence of SDS during the CE separation, and aggregates between the individual poliovirus capsid proteins and SDS are formed. Finally, we have proposed an alternative separation approach, involving an SDS gradient, for an improved separation of the subviral particles. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Sodium dodecylsulphate is a common chemical in most bio- chemistry, forensics and molecular biology labs. It is an essential reagent for SDS-PAGE, an electrophoretic technique used for pro- tein separation according to size. The role in SDS-PAGE established a fame of protein denaturant for SDS. Besides this, SDS is also known to inactivate enzymes, to disrupt biological systems, such as cells, viruses or membranes, as it has powerful dissociation and solubi- lization properties arising from its amphiphilic structure [1]. The amphiphilic properties of SDS were successfully exploited in analytical sciences for selectivity manipulation in modern sep- aration techniques, such as liquid chromatography or capillary electrophoresis [2]. When included above its critical micellar concentration in the composition of the CE buffers, the formed SDS micelles create a pseudostationary phase and the separation ∗ Corresponding author. E-mail address: yvanvdh@vub.ac.be (Y.V. Heyden). principles of both electrophoresis and chromatography are com- bined in a method called micellar electrokinetic chromatography [3]. In bioanalytical CE applications, SDS is a valuable additive to prevent or minimize protein adsorption to the capillary wall [4]. In well defined conditions, the inclusion of SDS in the CE sep- aration system offers the prerequisites for intra-column signal enhancement. For instance, the involvement in an isotachophoretic process has been described for high SDS concentrations in the injection plug [5,6]. Sweeping, i.e. a signal enhancing mechanism involving the presence of a pseudostationary phase, consists in picking and accumulating analyte molecules by the SDS micelles that enter the sample zone [7]. A feature of the signal enhancing mechanisms, involving SDS, refers to the importance of the rela- tive conductivities of sample and separation buffer, as described in detail elsewhere [6–10]. SDS was also found indispensable to obtain reproducible CE separation of human rhinovirus [11–14], poliovirus [15–17], bacte- riophage T5 [18], or rotavirus-like particles [19]. The concentration of SDS in the separation buffer appears to be a compromise between the separation needs and the virus stability. However, 0731-7085/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jpba.2012.07.033