Passive and active targeting strategies in hybrid layered double hydroxides nanoparticles for tumor bioimaging and therapy

Layered double hydroxides (LDH) are recognized as a base to prepare a wide range of materials owing the versatility to modify the composition and structure of the particles, some of them with nanometric sizes. Within the biomedical science, there is a rising interest in preparing multifunctional materials to treat or identify cancer cells. This review presents three levels of molecular engineering techniques used to hybridize LDH nanoparticles aiming to produce multifunctional materials with a specific action in malignant tumors. The first level has been more developed and is related to modify the composition of the layered structure and interlayer spaces, whereas the other levels belong to more advanced strategies involving the assembly of different components. All the levels lead to produce hybrid materials, and the goal of this review is to correlate the molecular engineering techniques with the active and passive targeting mechanisms that promote the accumulation of the hybrid LDH nanoparticles in the desired cells and promote a more effective treatment or diagnosis. Finally, a discussion on the lack of information will be presented in order to identify the following the research questions that must be addressed to improve the state of the art before these particles were translated to clinical assays.