Introduction

What is Microencapsulation ?

Application of Microencapsulation

Hot melt coating

Cyclodextrins

Extrusion

Emulsion Stabilisation

Jet break-up Processes

Super Critical Fluid technology

Complex Coacervation

Introduction

Molecular encapsulation changes the properties of the included molecules in many different ways, with regard to their thermodynamic properties, their solubilities, their spectroscopic and transport properties and some more. Moreover, inclusion complexation can be used for isolation of compounds from natural products.

Technology

Cyclodextrins are cyclic macromolecules obtained by degradation of starch by glycosyltransferases. Depending on the specific character of the respective transferases, different cyclodextrins results, consisting of 6 (alpha-cyclodextrin), 7 (beta-cyclodextrin) of 8 (gamma-cyclodextrin) glucose units. The molecular shape of cyclodextrins resembles that of cones. They build up a hydrophobic cavity, where small or mediumsized molecules can be included.

Beta cyclodextrin with molecule in its hole

Stabilities and properties of these host-guest complexes are dependent on the size of the cyclodextrins rim, but also on the molecular properties of the guest molecules. Generally, cyclodextrins are introduced since many years in pharmacy, chemistry and environmental research.

Application

Cyclodextrins are widely used in pharmaceutical technology as excipients.

A broad range of application concerns the enhancement of the bioavailability of drugs and the increase of the stability of drug formulations.

A broad variety of host compounds exists from very apolar, rather rigid compounds like calixarenes to more flexible not so apolar compounds, like specific carriers like serum albumines.