Smart microgels for controlled uptake and release

Y. Li

Research output: Thesisinternal PhD, WU


This dissertation describes a systematic study on oxidized starch microgel particles. It begins with the preparation and characterization of oxidized starch gels in terms of some important physical-chemical properties, with the aim to select an optimum gel for further investigation of protein uptake. The gel with the highest degree of oxidation DO100% is chosen for lysozyme uptake because of its high protein uptake capacity and low swelling capacity. In addition, DO30% gels have been used in many experiments, since DO30% starch allows for preparation of well-defined spherical microgel particles and because it is enzymatically degradable. The two main aspects of interest are the protein binding affinity and protein saturation. Neutral pH and low salt concentration are found to be the optimum protein uptake conditions for high protein saturation. For more detailed studies, spherical microgels with a narrow size distribution have been made by optimizing the preparation process. The mobility of lysozyme molecules inside those microgel particles has been investigated. The main conclusion is that high salt and high pH increase the mobility of lysozyme in the gel particles. It implies that high pH and high salt concentration are potential triggers for lysozyme release from the gel. Subsequently, the kinetics of protein release by high pH and high salt concentration is presented. For the aim of application, the antimicrobial activity of lysozyme containing starch gel particles against some bacterial strains is determined. Finally, the deposition of poly-lysine/poly-glutamic acid  complex layer around microgel surface is used to stabilize the microgel particle and optimize our system. 

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
  • Cohen Stuart, Martien, Promotor
  • Norde, Willem, Promotor
  • Kleijn, Mieke, Co-promotor
Award date21 Oct 2011
Place of Publication[S.l.]
Print ISBNs9789085859994
Publication statusPublished - 2011


  • gels
  • starch
  • colloids
  • lysozyme
  • controlled release

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