Superparamagnetic Iron Oxide Nanoparticles and Essential Oils: A New Tool for Biological Applications

Abstract

Essential oils are complex mixtures of volatile compounds with diverse biological properties. Antimicrobial activity has been attributed to the essential oils as well as their capacity to prevent pathogenic microorganisms from forming biofilms. The search of compounds or methodologies with this capacity is of great importance due to the fact that the adherence of these pathogenic microorganisms to surfaces largely contributes to antibiotic resistance. Superparamagnetic iron oxide nanoparticles have been assayed for diverse biomedical applications due to their biocompatibility and low toxicity. Several methods have been developed in order to obtain functionalized magnetite nanoparticles with adequate size, shape, size distribution, surface, and magnetic properties for medical applications. Essential oils have been evaluated as modifiers of the surface magnetite nanoparticles for improving their stabilization but particularly to prevent the growth of microorganisms. This review aims to provide an overview on the current knowledge about the use of superparamagnetic iron oxide nanoparticles and essential oils on the prevention of microbial adherence and consequent biofilm formation with the goal of being applied on the surface of medical devices. Some limitations found in the studies are discussed.

Keywords: antibiofilm; antimicrobial; stabilization; superparamagnetic iron oxide nanoparticles; synthesis.

Figure 1

Schematic representation of the different strategies available to obtain water-soluble and chemically active nanoparticles. The final ligands on the nanoparticles can be either small molecules or polymers. (MNP—magnetic nanoparticles). Adapted from Wallyn et al. [86].

Figure 2

Inhibition of biofilm formation by nanostructured bioactive coating surfaces. (A) The uncoated surface allows the adherence of planktonic cells (cells in suspension) with the subsequent production of exopolysaccharides (or glycocalyx) (I) that enclose the sessile cells (adherent cells), forming a mature biofilm (II) and at a later stage can detach from the aggregate and initiate a new cycle of colonization of the same or new surfaces (III). (B) A bioactive coating allows the inhibition of the first stage of the biofilm formation: the bacterial adherence and the production of glycocalyx (I). Sessile cells are not able to multiplicate inside the aggregate and the layer of glycocalyx is thinner (II), resulting in a deficient mature biofilm that will collapses (III).