Experimental and theoretical determination of the pH inside the confinement of a virus-like particle

Stan J. Maassen, Paul van der Schoot, Jeroen J.L.M. Cornelissen

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)


In biology, a variety of highly ordered nanometer-size protein cages is found. Such structures find increasing application in, for example, vaccination, drug delivery, and catalysis. Understanding the physiochemical properties, particularly inside the confinement of a protein cage, helps to predict the behavior and properties of new materials based on such particles. Here, the relation between the bulk solution pH and the local pH inside a model protein cage, based on virus-like particles (VLPs) built from the coat proteins of the cowpea chlorotic mottle virus, is investigated. The pH is a crucial parameter in a variety of processes and is potentially significantly influenced by the high concentration of charges residing on the interior of the VLPs. The data show a systematic more acidic pH of 0.5 unit inside the VLP compared to that of the bulk solution for pH values above pH 6, which is explained using a theoretical model based on a Donnan equilibrium. The model agrees with the experimental data over almost two orders of magnitude, while below pH 6 the experimental data point to a buffering capacity of the VLP. These results are a first step in a better understanding of the physiochemical conditions inside a protein cage.

Original languageEnglish
Article number1802081
Number of pages7
Issue number36
Publication statusPublished - 6 Sep 2018


  • confinement
  • nanotechnology
  • pH measurements
  • physical chemistry
  • virus capsids
  • Models, Theoretical
  • Polystyrenes/chemistry
  • Virion/chemistry
  • Methacrylates/chemistry
  • Spectrometry, Fluorescence
  • Fluorescein/chemistry
  • Hydrogen-Ion Concentration


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