Multimodal Dispersion of Nanoparticles: A Comprehensive Evaluation of Size Distribution with 9 Size Measurement Methods

Purpose : Evaluation of particle size distribution (PSD) of multimodal dispersion of nanoparticles is a difficult task due to inherent limitations of size measurement methods. The present work reports the evaluation of PSD of a dispersion of poly(isobutylcyanoacrylate) nanoparticles decorated with dextran known as multimodal and developed as nanomedecine. Methods : The nine methods used were classified as batch particle i.e. Static Light Scattering (SLS) and Dynamic Light Scattering (DLS), single particle i.e. Electron Microscopy (EM), Atomic Force Microscopy (AFM), Tunable Resistive Pulse Sensing (TRPS) and Nanoparticle Tracking Analysis (NTA) and separative particle i.e. Asymmetrical Flow Field- Flow Fractionation coupled with DLS (AsFlFFF) size measurement methods. Results : The multimodal dispersion was identified using AFM, TRPS and NTA and results were consistent with those provided with the method based on a separation step prior to on-line size measurements. None of the light scattering batch methods could reveal the complexity of the PSD of the dispersion. Conclusions : Difference between PSD obtained from all size measurement methods tested suggested that study of the PSD of multimodal dispersion required to analyze samples by at least one of the single size particle measurement method or a method that uses a separation step prior PSD measurement

Gradual disaggregation of the casein micelle improves its emulsifying capacity and decreases the stability of dairy emulsions

The casein micelle is a highly aggregated colloid consisting of phosphoproteins and minerals, in particular calcium and phosphate. Its properties are affected by physico-chemical changes which provide possibilities for the development of new casein aggregates (CAs) with novel functionalities. The aim of this study was to investigate the emulsifying and emulsion-stabilizing capacity of gradually demineralized CAs in model dairy emulsions. Tri sodium citrate (TSC) was used to remove calcium and inorganic phosphate from pure casein micelles in order to produce four suspensions of differently demineralized CAs. Two types of milkfat-in-suspension (30:70 v/v) emulsions were then prepared to study the emulsifying and emulsion-stabilizing capacity of these CAs separately. Casein micelles were progressively demineralized (from 24 to 81% calcium reduction) and dissociated with the increase in TSC concentration. Three distinct populations of particles (micelle-like aggregates, sodium caseinate-like aggregates and casein monomers) were present in every suspension in different proportions. The smaller CAs had better emulsifying capacity and similar surface activity according to interfacial studies. The state of aggregation of the CAs was thus the main factor that controlled their emulsifying capacity. However, the emulsions formed with these smaller aggregates were less stable against creaming and flocculation, but still resisted coalescence under our storage conditions (21 days at 50 °C). The properties of the interfacial casein layers did not depend on the aggregation state of the CAs used to form the emulsions. The differences in instability were attributed to the nature of the non-adsorbed CAs and storage conditions

Asymmetrical flow field-flow fractionation with multi-angle light scattering and quasi-elastic light scattering for characterization of polymersomes: comparison with classical techniques

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