Cells are multifunctional structures which, due to a unique hierarchical and compartmentalized organization, allow numerous compounds to be transported, proteins to be synthesized and enzymatic reactions to be regulated within their cytoplasm.

Inspired by the cells’ structure, we present compartmentalized gel beads with temperature and magnetic-based responsiveness, and hierarchical organization ranging from the nano to the visible scales. Liquefied alginate macroscopic beads coated with a layer-by-layer chitosan/alginate shell served as containers both for model fluorophores and microcapsules, which in their turn encapsulated either another fluorophore or magnetic nanoparticles (MNPs). The microcapsules were coated with a chitosan/elastin-like recombinamer shell, the latter being a genetically engineered polypeptide exhibiting temperature responsiveness. By varying the temperature from 25 ºC to 37 ºC, the 2-hour release of rhodamine encapsulated within the microcapsules and its diffusion through the external compartment decreased from 84% and 71%. The devices could withstand handling and centrifugal stress, with 50% remaining intact at a rotation speed of 2000g. MNPs attributed magnetic responsiveness towards external magnetic fields, as a biomimetic approach inspired by the unique properties of magnetotactic bacteria [1].

Such customizable system can be envisaged for targeted delivery and localized immobilization allied with sustained drug delivery at physiological temperature, protection from premature drug leakage, and transportation of bioactive agents and cells in tissue engineering applications.

[1] R.R. Costa, E. Castro-Otero, F.J. Arias, J.C. Rodríguez-Cabello, J.F. Mano, Biomacromolecules, in press (2013)