(692d) Encapsulation of Laccase in Chitosan Micro-Carriers by Two-Fluid and Three-Fluid Nozzle

Encapsulation of laccase in chitosan micro-carriers by
two-fluid and three-fluid nozzle

Ondøej Ka?par, Franti?ek ?tìpánek^*

Department of Chemical Engineering, Institute of Chemical Technology Prague,

Technická 5, 166 28 Prague
6, Czech Republic

*Corresponding author. E-mail:
Frantisek.Stepanek@vscht.cz; Tel.: +420 220 443 236

Chitosan is a biocompatible and
biodegradable polymer suitable for the encapsulation of both small molecules
and biomolecules. The simultaneous encapsulation of a precursor (substrate) and
immobilization of catalyst (enzyme) in a core-shell chitosan particle makes it
possible to deliver active molecules with a short half-life by forming them
in-situ from stable precursors. This is desirable e.g. in the case of biocidal
molecules or sensorially active substances.

The first objective of our
study is to investigate the effect of composition (in particular, the TPP/chitosan
ratio) and cross-linking method (ex-situ vs. in-situ) on the properties of chitosan
microspheres formed by spray drying. The particle size distribution, particle
morphology, zeta potential and swelling behaviour have been systematically
investigated. A novel cross-linking method, based on in-situ contact of TPP and
chitosan solutions directly at the nozzle orifice (3-fluid nozzle), has been
developed and compared with a more conventional approach of spray-drying a
pre-mixed TPP/chitosan colloid solution using a 2-fluid nozzle. The second
objective is encapsulation of active substance (enzyme - laccase) and study of
the influence of experiment set-up (inlet temperature, TPP/chitosan ratio, type
of nozzle and cross-linking method) on enzymatic activity.

It will be shown that by a
suitable combination of process and formulation parameters, cross-linked chitosan
particles with a narrow size distribution and defined swelling properties and
stability in aqueous media can be formed. Moreover, the immobilized enzyme (laccase)
is shown to keep its activity even within the chitosan matrix after spray
drying and rehydration, which makes it a suitable system for in-situ delivery
of actives.