ir.ing. Frankje de Boer
Ornstein Laboratory, room 0.56A
Princetonplein 1, 3584 CC Utrecht
P.O. Box 80 000, 3508 TA Utrecht
phone: +31(0)30 253 2823
secretariat: +31(0)30 253 2952
Supervisors: Dr. A. Imhof and Dr. K.P. Velikov
Promotor: Prof.dr. A. van Blaaderen
Employed since June 2015
Funded by STW (St. Technische Wetenschappen)
Optically Functionalized Nanoparticles: Colloidal Colorants
DLS, Color determination and prediction
The primary aim of this project is to design optically functionalized nanoparticles from water insoluble proteins as a technology platform for the delivery of colorants.
The water insoluble protein that is chosen for this project is zein, which is a protein from corn. Zein has properties that may be beneficial for the possible future application of this project: it is renewable, food grade and soluble in mixtures of water and ethanol which are food safe solvents. Also zein has good barrier properties and therefore has the capability of encapsulating colorants.
The first part of this project is designing a colloidal dispersion with a white color from zein particles. The protein particles are synthesized by the use of the anti-solvent precipitation technique. The size of the colloids is measured with DLS. The color of this solution will be compared to a benchmark of TiO2, as shown in figure 1, and the size and the volume fraction of the protein particles will be optimized to obtain a similar whiteness as the TiO2 benchmark. The color will be calculated from reflectivity measurements, and measured directly by the use of the DigiEye.
Figure 1: model system from TiO2 benchmark to a similar white appearance from protein particles.
Apart from synthesizing the particles and measuring the color, also modeling of the color will be carried out by the use of Mie scattering theory and the Kubelka-Munk relationship .
 D.J. McClements et al., Food Hydrocolloids 15, 83-91 (2001)