Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study.

A.A Tsukanov,S.G Psakhie

doi:10.1038/srep19986

Abstract

The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered.

Highlights

A single layer of anionic clay is a positively charged nanosheet of metal hydroxide that can be viewed as an independent object[25,26]
The aim of the present work is to investigate the interaction of organic anions – aspartic amino acid anion, glutamic amino acid anion and bicarbonate ion with a single nanosheet of Mg/Al-LDH
molecular dynamics (MD) methods are widely used to study the interaction of ions and water molecules with the surface of layered hydroxides and oxyhydroxides of metals[31,32,33,34,35,36]

Summary

Introduction

A single layer of anionic clay is a positively charged nanosheet of metal hydroxide that can be viewed as an independent object[25,26]. When LDH-based nanoparticles are used as carriers/capsules for the delivery of drugs and genes, fragments of LDH nanosheets remain in the cell medium after delivery of the agent These nanosheets of LDH generally have a significant surface charge density[29] (the charge is assumed to be positive, and its density is determined by the number of trivalent metal atoms MIII per unit area of LDH). This allows LDHs to act as effective adsorbents or even “traps” for anions of the cell medium. The aim of the present work is to investigate the interaction of organic anions – aspartic amino acid anion, glutamic amino acid anion and bicarbonate ion (which occur free or as part of larger molecules and together represent the main anions of the cell) with a single nanosheet of Mg/Al-LDH

Objectives

Methods

Results

Conclusion