Multifunctional Cargo Systems based on Multicomponent Polymeric Vesicles

摘要

Recently introduced as multifunctional nano-engineered composite polymer layer-by-layer assembled capsules have a strong impact on research community. The method is based on the layer- bylayer adsorption of oppositely charged macromolecules, mainly polyelectrolytes (PE) on colloidal particles. These multilayers can be made from a variety of layer constituents, such as synthetic and natural PEs, nanoparticles, lipids, multivalent dyes and hence the build-up is extremely modular with regards to tailoring the composition of the capsule wall. Shell thickness is determined by the layer number and defined in the range of a few nanometers. Each of the involved components brings functionality to the multilayer capsules. The core of the particles can be dissolved leaving hollow capsules, which can be refilled with substances of interest. The variable size of the capsules can be fully controlled from 50nm to tens of microns. Tuneable permeability for a wide class of substances can be reached by designed layer thickness. The capsule wall can be subjected to densification. Temperature leads to shrinking of capsules with compensated charges, which result in increasing wall thickness and drastically reduced permeability. The possibility of tailoring different functionalities by charge-driven adsorption within multilayers, impregnating inorganic and organic substances, both inside the capsule volume and in the polyelectrolyte shell, control release of encapsulated material provided continuous scientific and industrial interest in employing capsules as microcontainers and microreactors. Composite capsules composed of inorganic and organic components could combine the advantages of both: storage, susceptibility to external forces for inorganic and responsiveness for polymeric constituents. Smart polymers involved in capsule build-up exhibit reversible sensitivity to environmental conditions, such as temperature, pH, ions, etc.