Immobilization of Protein A on Monodisperse Magnetic Nanoparticles for Biomedical Applications

Abstract

We presented synthesis and physical characterization of iron oxide magnetic nanoparticles (Fe3O4) for biomedical applications in the size range of 10-30 nm. Magnetic nanoparticles were synthesized by the coprecipitation method, and the particles’ size was controlled by two different injection methods of sodium hydroxide (NaOH). The synthesized magnetic nanoparticles were then modified by using series of linkers including tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and glutaraldehyde (GA) to generate the structure of Fe3O4/SiO2/NH2/CHO, which can be used for immobilization of protein A. Additionally, we used transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating-sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR), for characterization of properties and structure of the nanoparticles. An immobilization of protein A on magnetic nanoparticles was studied with a UV-Vis spectrum (UV-Vis) and fluorescence electron microscopy and Bradford method. Results showed that an XRD spectrum with a peak at (311) corresponded to the standard peak of magnetic nanoparticles. In addition, the magnetic nanoparticles with d≥30 nm have higher saturation magnetizations in comparison with the smaller ones with d≤10 nm. However, the smaller magnetic nanoparticles offered higher efficiency for binding of protein A, due to the high surface/volume ratio. These particles with functional groups on their surface are promising candidates for biomedical applications, e.g., drug delivery, controlled drug release, or disease diagnosis in point-of-care test.

Sortase-Mediated Quantifiable Enzyme Immobilization on Magnetic Nanoparticles

“…In order to couple enzymes to solid supports, we chose Sortase A (SrtA) to enable both oriented immobilization and physiological coupling conditions, thus retaining functionality of coupled enzymes. In recent years, magnetic nanoparticles (MNPs) emerged as a new standard for protein immobilization mainly because of their versatility and easy handling. , Therefore, we decided to combine the advantages of SrtA-mediated protein immobilization and MNPs. In order to equip MNPs with a polypeptide which serves as a SrtA substrate, we chose a peptide (peptide 1) based on repeating sequences of commonly used polyGly/Ser motifs providing flexibility and solubility .…”

Magnetic Separation of Antibodies with High Binding Capacity by Site-Directed Immobilization of Protein A-Domains to Bare Iron Oxide Nanoparticles

“… A previous study could show the competitiveness of Protein G immobilized on such nanoparticles in direct comparison with chromatographic beads . Several studies focus on the use of magnetic nanoparticles as carrier material for Protein A and suggest their applicationfor antibody purification and sensorics. − Typically, these particles are modified with functional silanes or saccharide-based polymers to subsequently cross-link Protein A to the activated particles. Even if thin and homogeneous coatings are possible, the processing of the particles increases their size compared to bare iron oxide nanoparticles (BION) and decreases their magnetization .…”

Magnetite-Based Biosensors and Molecular Logic Gates: From Magnetite Synthesis to Application

“…The main pathways involved in the interactions of proteins with MNP surfaces are electrostatic attraction/repulsion, hydrophobic attraction/repulsion, Van der Waals interactions, and coordinative bonding [ 84 ], and it has been shown that proteins bind with MNPs via carboxyl groups [ 85 ]. Despite the fact that the overall mechanism and driving forces of such interactions remain unclear [ 86 ], this has not hindered scientists from using proteins for MNP functionalization for the creation of new facilities for biomedical applications [ 87 , 88 , 89 ].…”