Responsive layer-by-layer materials for drug delivery

Due to its versatility and ease of use the layer-by-layer (LbL) assembly technique has been under intensive investigation for drug and gene delivery applications. Especially the development of responsive LbL materials has advanced significantly in recent years. Responsiveness plays an important role in many delivery applications, either for loading of therapeutics or controlled and triggered release. In general four basic mechanisms within responsive LbL films have been identified: disruption of layer interactions, degradation of the LbL film, multilayer destruction via physical stimuli, and phase transitions or polymer rearrangements within the LbL film. This review will outline these different mechanisms and highlight recent advances in these fields.