Separation of virus-like particles and nano-emulsions for vaccine development by Capillary Zone Electrophoresis

Nano-emulsions with immunogenic properties can be incorporated into vaccines to act as an adjuvant where they can enhance the immune response of a given vaccine. Analytically, studying vaccine antigens, such as Virus-Like Particles (VLPs), in the presence of adjuvants, like nano-emulsions, is very challenging as they are both heterogenous nano species of similar sizes but very different physiochemical properties. Therefore, typical analysis of nanoparticles using separation approaches such as Size Exclusion Chromatography (SEC) and Field-Flow Fractionation (FFF) is difficult due to the size similarities among these nano-species which complicates their separation.

In this study, a Capillary Zone Electrophoresis (CZE) method was developed, which utilizes a separation mechanism based on the charge-to-size ratio of the analytes. The method was used to quantify VLPs of the Human Papilloma Virus (HPV) and Squalene Nano-Emulsion (SNE) adjuvant mixtures while also measuring buffer excipients, chloride and histidine. The method was assessed according to International Conference on Harmonization (ICH Q2) guidelines with respect to linearity, ranges, accuracy (87-109 %), precision (≤20 %), quantitation and detection limits.

This study was conducted to prove the feasibility of utilizing CZE to characterize VLPs and SNE mixtures with dilution as the only sample preparation. The CZE conditions are simpler than other CZE conditions suggested for VLPs and easily transferred between users. Similar CZE methods could also be developed for other vaccine and adjuvant mixtures as well as other emulsion and nanoparticle-based systems.