Carboxylated Polysaccharides Decorated with Ultrasmall Magnetic Nanoparticles with Antibacterial and MRI Properties

Two natural polymers, namely, cellulose and pullulan, are selectively oxidized employing the well-established (2,2,6,6-tetramethylpiperidine-1-yl)-oxyl radical protocol in order to introduce in their structural unit negatively charged carboxylic groups. These newly introduced moieties further serve as efficient matrix for the in situ iron oxide nanoparticles fabrication. The morphology, structure, stability, and magnetic properties of the as-prepared carboxylated polysaccharides embedded ultrasmall iron oxide nanoparticles are analyzed using various techniques, such as Fourier transform infrared spectroscopy, dynamic light scattering, zeta potential, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analyses, and vibrating sample magnetometer. The results show that the two used polysaccharides are excellent materials to produce highly uniform shaped nanoparticles with an average size of about 3 nm. Moreover, the nanoparticles have excellent water dispersibility and stability. The prepared magnetic samples show antibacterial effect against Gram-positive bacteria and also exhibit characteristics as contrasting agent for noninvasive cellular and molecular imaging.