Magnetic nanoparticles coated with carbohydrates for 3D culture of bacteria

Magnetic nanoparticles (MNPs) are a specific type of nanomaterial whose applications are widespread into several fields including biomedicine as a smart drug targeter and environmental engineering due to their interactions with contaminants. Lately, the use of MNPs has also been demonstrated in structuring three-dimensional (3D) cultures of mammalian cells. However, MNPs application to other cell types is still limited. In this sense, some planktonic microorganisms when adhered to surfaces perform the swarming phenomenon to guarantee the expansion of the colony and to guarantee more niches. Therefore, the aim of this study was to produce MNPs coated with four carbohydrates (galactose - gal, glucose - glu, sucrose - suc, and maltose - mal) aiming microorganism culture applications and also for possible 3D arrays. The results showed that carbohydrate-coated MNPs showed hydrodynamic diameters ranging from 100 to 200 nm and that their coatings influenced the chemical behavior in different ways. Indeed, when subjected to biological tests to determine their potential level of cytotoxicity, it was found that in concentrations of 1 mM, 800, 600, and 400 μM (iron equivalent), there was not any alteration on growth of model microorganisms when visually evaluated. Besides, magnetization of bacteria was promoted in different ways as well as the modulation of swarming formation in Escherichia coli when exposed to MNP-Glu. In sum, MNPs coated with carbohydrates and even uncoated were atoxic to bacteria and one of them was able to modulate E. coli swarming formation showing the potential for applications in 3D cultures of bacteria.