A simple yet highly versatile process for assembling polymeric materials used as advanced delivery systems are multilayered films formed via layer-by-layer (LbL) assembly. This methodology was first described by Iler in 1966, and adapted 25 years later by Decher and colleagues in order to obtain thin films using polymers oppositely charged. LbL assembly present a wide number of advantages such as the possibility of being performed in entirely aqueous solutions, size and shape of the multilayers can be engineered by simply altering the template employed for polymer adsorption, allow the use of a large range of polymers, and mainly is a cheap procedure that only require simple laboratory equipment. For all this reasons LbL is considered a promising method to obtain efficient biomedical devices.
Nowadays the development of materials is fundamentally based in the aim of construct smart devices that may respond to external stimuli. The responsiveness in LbL materials to achieve spatial and/or temporal control over the release of incorporated therapeutics, can be effective by controlling specific template architectures (e.g. macroscopic films, capsules) or release triggers (e.g. pH, ionic strength, magnetic fields, temperature, redox, light) but also on mechanisms inside the LbL film to achieve film swelling, disassembly, degradation or destruction to facilitate the release.
Among other external stimuli, light-induced responses offers the ability to accomplish spatial control of cell detachment and drug release with less harmful effects than conventional enzyme treatment techniques that may cause severe damage to the cell membrane and protein adhesion. So in our knowledge, light-induced surface properties changes could potentially provide a more convenient and effective approach for cell harvesting, and drug release.