Functionalization of magnetic nanoparticles with organic molecules: Loading level determination and evaluation of linker length effect on immobilization

Abstract

A general method is introduced to immobilize organic molecules on magnetic nanoparticles through silanization reactions and determine the maximum loading level by UV-vis spectroscopy. Loading levels of 1.5 x 10(-3) mol per gram of nanoparticle were obtained with structurally diverse compounds such as rhodamine B and glucosamine. The length of the linker did not have a significant effect on loading as comparable maximum amounts of rhodamine B were immobilized on magnetic nanoparticles regardless of the linker length. Interestingly, rhodamine B derivatives lost conjugation during synthetic manipulations due to reversible spiroisobenzofuran formation. Full regeneration of conjugation was found to be slow with rhodamine B attached on magnetic nanoparticles. The results obtained from these studies will be useful for studying surface functionalization of MNPs in general.

Superparamagnetic Composites: Magnetism with No Memory

“…Immobilization of organic molecules on SPNPs through silanization reactions is a route to enhance colloidal stability and compatibility. [98] Polymers with enhanced functionalities will be regularly used as matrixes for the formation of SPCs. The control of morphology and size in these SPCs could be achieved by using nanocasting techniques.…”

Quantitative Determination of 3-Aminopropylsilane on the Surface of FE3O4 Nanoparticles by Attenuated Total Reflection Infrared Spectroscopy

“…Magnetic materials are used routinely, e.g., in biology for magnetic separation of biomolecules and cells [4] or in chemistry for development of magnetic separation of catalysts [5]. A promising method for modifying iron-oxide nanoparticles (NP) consists of depositing an organic layer on MNP using functionalized alkoxysilanes, in particular, 3-aminopropyltrialkoxysilanes [6][7][8][9][10][11][12][13][14][15][16][17][18] that form an organosilicon layer with functional groups on the surface. This enables the NP to be modifi ed further.…”

“…Fluorescence or UV/vis spectrometry can determine the number of free molecules remaining in solution [6][7][8][9][15][16][17]. For example, MNP with surface 3-aminopropylsilane (APS) groups were modifi ed covalently with rhodamine B [15], N-difl uorenylmethoxycarbonyl-L-lysine [6], or S-naproxene [7] (production of amide derivatives) or p-nitrobenzaldehyde (Schiff base formation) [16,17] in order to determine the concentration of surface amines. The degree of functionalization of the starting MNP was determined from the difference between the amounts of reagent added to the reaction mixture and unreacted reagent.…”

Droplet microfluidics with magnetic beads: a new tool to investigate drug–protein interactions

“…The increasing number of commercially available magnetic beads with different surface groups gives further opportunity to extend the applications in the fields of biochemistry and biotechnology [6][7][8]. However, conventional liquid handling devices suffer from the inability to study fast kinetics, which often restricts the applications of MB-based assays [9].…”