Compact Zwitterion-Coated Iron Oxide Nanoparticles for Biological Applications

Abstract

The potential of superparamagnetic iron oxide nanoparticles (SPIONs) in various biomedical applications, including magnetic resonance imaging (MRI), sensing, and drug delivery, requires that their surface be derivatized to be hydrophilic and biocompatible. We report here the design and synthesis of a compact and water-soluble zwitterionic dopamine sulfonate (ZDS) ligand with strong binding affinity to SPIONs. After ligand exchange, the ZDS coated SPIONs exhibit small hydrodynamic diameters (HD), and stability with respect to time, pH, and salinity. Furthermore, small ZDS coated SPIONs were found to have a reduced non-specific affinity (compared to negatively charged SPIONs) towards serum proteins; streptavidin/dye functionalized SPIONs were bioactive and thus specifically targeted biotin receptors.

Zwitterionic ceramics for biomedical applications

“…This has been exploited to develop 10 nm-sized zwitterionic SPIONPs sing a compact DOPA sulfonate ligand (structure 3, Figure 2) [28][29][30].…”

“…Zwitterionization of SPIONPs has arisen as a powerful tool to improve their potential in nanomedicine. Among zwitterionic ligands, SB derivatives have been widely exploited to enhance the stability of SPIONPs [28][29][30]75]. Thus, Stephan et al…”

“…Bawendi and coworkers developed zwitterionic DOPA sulfonate (ZDS) ligand coated SPIONPs (structure 3, Figure 2) for use in various medical applications [28,29] ZDS-coated SPIONPs were characterized by small hydrodynamic diameters, low nonspecific protein adsorption, the possibility of specific labeling, and stability with respect to time, pH, and salinity. Importantly, ZDS coatings did not reduce superparamagnetism or saturation magnetization of as-synthesized hydrophobic SPIONPs.…”

Exceedingly small iron oxide nanoparticles as positive MRI contrast agents

“…After synthesizing the above inorganic core SPIONs, the native hydrophobic oleic acid coating was exchanged with a zwitterionic dopamine sulfonate (ZDS) that we have previously developed and described (35,37). Our prior studies have demonstrated that ZDScoated SPIONs show small HDs, low nonspecific interactions in vitro with cells and in vivo in mice, offering the opportunity for specific labeling, and stability with respect to time, pH, and salinity.…”

Current Approaches to Designing Nanomaterials Inspired by Mussel Adhesive Proteins

“…Similarly, nanoparticles grafted with dendritic or hyperbranched PEG provide higher colloidal stability despite a smaller hydrodynamic radius as compared to linear PEG of similar MW [88]. The terminal end of PEG can be further functionalized with various bioligands to further decorate the surface of the PEG-coated nanoparticles for specific cell targeting, therapeutic treatment, and controlled drug delivery [83,89,90]. …”