Stabilization of protein-loaded starch microgel by polyelectrolytes

Area of Science:

• Materials Science
• Biotechnology
• Polymer Chemistry

Background:

• Biocompatible polyelectrolytes are crucial for controlled release systems.
• Starch microgels offer potential for encapsulating functional ingredients.
• Polyelectrolyte complexation is a promising strategy for modifying material properties.

Purpose of the Study:

• To create a polyelectrolyte complex layer around starch microgel particles.
• To control and slow down the release of encapsulated ingredients.
• To enhance the stability of microgel particles.

Main Methods:

• Investigated the distribution of poly(l-lysine) (PLL) with varying molecular weights within negatively charged starch microgel particles.
• Studied the exchange of lysozyme with PLL in loaded microgel particles.
• Formed a polyelectrolyte complex shell using PLL and poly(L-glutamic acid) (PGA).
• Assessed the effect of the PLL/PGA layer on lysozyme release rates and microgel stability.

Main Results:

• Large molecular weight PLL formed a shell structure within the microgel particles, while small PLL distributed homogeneously.
• Shell formation was dependent on salt concentration.
• PLL replaced lysozyme in the microgel particles, with exchange rates influenced by pH.
• The combined PLL/PGA layer significantly slowed lysozyme release at 0.05 M salt.
• The PLL/PGA layer provided protection against α-amylase degradation.

Conclusions:

• A stable polyelectrolyte complex layer (PLL/PGA) can be formed on starch microgel particles.
• This layer effectively controls the release kinetics of encapsulated substances like lysozyme.
• The developed system demonstrates enhanced stability and protection against enzymatic degradation.