Synthesis, functionalization and biological identity of layered double hydroxide nanoparticles for biomedical applications

RICARDO ROJAS; CECILIA VASTI; DARIANA ARISTIZABAL BEDOYA; YADIRA ESTEFANÍA SALGUERO SALAS; CARLA E. GIACOMELLI

Granada

Conferencia; 16th International Clay Conference; 2017

Spanish Clay Society

Layered double hydroxides nanoparticles (LDH-NPs) present excellent properties to grant the complex functionality needed for biomedical applications. They can be easily prepared with a size between 50 and 200 nm and their anion exchange capacity provides a high loading capacity for acid drugs and biomolecules. Besides, they present release mechanisms based on the anion exchange with the anions in the biological media and the dissolution of their layers at slightly acid media [1]. Nevertheless, there are many aspects regarding the physicochemical properties of LDH-NPs and their interaction with the biological media that are still unclear to rationally design LDH-NPs with genuine potential to be applied in biomedical applications. A precise control of the LDH-NPs size is necessary to ensure their capacity to evade clearing by the mononuclear phagocyte system (MPS) and to optimize the transfection capacity of the cellular membrane [2]. Likewise, new strategies to surface functionalize LDH-NPs are required to increase their colloidal stability in biological media, and to provide site specificity. Another aspect to be addressed is the interaction between serum proteins and the surface of LDH-NPs that produces a biological coating known as protein corona. The protein corona determines the physicochemical properties of LDH-NPs and their interactions with the cellular membrane, which leads to a so-called ?biological identity? that can be quite different to that of the as-prepared LDH-NPs. Controlling the biological identity of LDH-NPs is a key aspect to reduce elimination by the MPS and to optimize the interaction with the target cells.Here we present diverse strategies to control the physicochemical properties and biological interactions of LDH-NPs. In first place, different synthesis routes were explored to intercalate anions such as methotrexate, fluorescein or nalixidate, the best results being obtained with a coprecipitation method at variable pH involving separate nucleation and aging steps [3]. Secondly, different compounds were used to functionalize the synthesized LDH-NPs: risedronate, a bone antiresorptive drug with high affinity for hydroxyapatite, was used to provide bone targeting capabilities, while polylelectrolytes were explored to enhance their colloidal stability. Finally, the interaction between albumin and LDH-NPs was studied as a first insight to the protein corona formation mechanism and its effect on the physicochemical properties of LDH-NPs. Afterwards, the biological identity of LDH-NPs and its modulation by the surface coating with serum proteins was explored in cell culture conditions. The cytotoxicity and transfection capacity of the prepared LDH-NPs were tested in adequate model cell lines.The use of different synthetic strategies and a careful selection of the operational parameters allowed the synthesis of LDH-NPs with different interlayer anions. In all cases, the drug was selectively located in the interlayer of the LDH-NPs, which allowed their surface functionalization with a minor drug loss. The functionalization with either risedronate and polyacrylate increased the colloidal stability of LDH-NPs even in high ionic strength due to electrostatic repulsion and/or steric impediments. Further, risedronate functionalized LDH-NPs attached to hydroxyapatite due to risedronate bridging. A protein corona was formed on the LDH-NPs surface in all cases upon interaction with serum proteins; albumin was its main component in all cases. The extent of the protein adsorption, as well as the components of the protein corona were affected by functionalization, which ultimately affected the unspecific cell transfection of LDH-NPs. These studies clearly show the potential of rationally and thoroughly designed LDH-NPs to produce drug delivery to specific tissues and cells.[1]R. Rojas, D. Aristizabal Bedoya, C. Vasti, C.E. Giacomelli, LDH nanoparticles: Synthesis, Size Control and Applications in Nanomedicine, in: I.T. Sherman (Ed.), Layer. Double Hydroxides, Nova Press, New York, 2015: pp. 101?120.[2]C. Vasti, D.A. Bedoya, R. Rojas, C.E. Giacomelli, Effect of the protein corona on the colloidal stability and reactivity of LDH-based nanocarriers, J. Mater. Chem. B. 4 (2016) 2008?2016. doi:10.1039/C5TB02698A.[3]C. Vasti, V. Pfaffen, E. Ambroggio, M.R. Galiano, R. Rojas, C.E. Giacomelli, A systematic approach to the synthesis of LDH nanoparticles by response surface methodology, Appl. Clay Sci. 137 (2017) 151?159. doi:10.1016/j.clay.2016.12.023.