Many biochemical processes in living cells are regulated by internal structuring of cells, i.e. compartmentalisation. Enzymes and reactants are separated by semi-permeable membranes. In order to mimic this feature we present internally structured alginate gel micro-particles containing thermo-responsive liposomes (filled with reactants) and colloidal iron oxide allowing remote heating of micro-particles by radiofrequency field.
Utilizing these particles we controlled the progress of the oxidation of ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) catalysed by the enzyme laccase. The substrate was encapsulated inside the immobilized liposomes and the enzyme was dispersed within the alginate hydrogel. We were able to dose the substrate by short RF pulses and the product of the reaction was stepwise released out of the gel micro-particles.
However, alginate gel particles are not very stable in isotonic buffers and are dissolved in few hours. Rigidity of such particles is necessary for further bio-adhesive study; therefore, a method of their stabilization in concentrated solutions was developed. The modification utilizes polycationic polysaccharide chitosan as a co-cross-linker of alginate gel. Such particles remain stable and rigid in an isotonic PBS buffer for more than a month.
ullrichm@vscht.cz
