Characterization of a Nanoparticulate Drug Delivery System Using Scanning Ion Occlusion Sensing



To explore the application of scanning ion occlusion sensing (SIOS) as a novel technology for characterization of nanoparticles.


Liposomes were employed as model nanoparticles. The size distribution of the liposomes was measured by both SIOS and dynamic light scattering (DLS). Particle number concentration was determined based on particle translocation rate. The ability of SIOS and DLS to resolve bimodal samples was evaluated by measuring a mixture of 217 and 355 nm standard nanoparticles. Opsonization of liposomes by plasma was also studied using SIOS.


SIOS was shown to measure the size of different liposomes with higher sensitivity than DLS and it requires a smaller sample volume than DLS. With appropriate calibration, SIOS could be used to determine particle number concentrations. In comparison, SIOS analysis of the mixture showed accurate resolution of the population as a bimodal distribution over a wide range of number ratios of the particles. SIOS could detect plasma opsonization of liposomes by demonstrating a increase in particle size and also changes in the particle translocation rate.


SIOS is a useful technology for nanoparticle characterization. It shows some advantages over DLS and is clearly a useful tool for the study of nanoparticle drug delivery systems.

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The research was conducted during the tenure of a Health Sciences Career Development Award from the University of Otago to Lin Yang. The authors report no conflicts of interest.

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Correspondence to Lin Yang.

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Yang, L., Broom, M.F. & Tucker, I.G. Characterization of a Nanoparticulate Drug Delivery System Using Scanning Ion Occlusion Sensing. Pharm Res 29, 2578–2586 (2012).

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  • DLS
  • liposomes
  • nanoparticles
  • opsonization
  • SIOS