Synthesis of Cationized Magnetoferritin for Ultra-fast Magnetization of Cells.

Sara Correia Carreira,Walther Schwarzacher,Mitsuhiro Okuda,Annela M Seddon,Adam W Perriman,James P K Armstrong

doi:10.3791/54785

Abstract

Many important biomedical applications, such as cell imaging and remote manipulation, can be achieved by labeling cells with superparamagnetic iron oxide nanoparticles (SPIONs). Achieving sufficient cellular uptake of SPIONs is a challenge that has traditionally been met by exposing cells to elevated concentrations of SPIONs or by prolonging exposure times (up to 72 hr). However, these strategies are likely to mediate toxicity. Here, we present the synthesis of the protein-based SPION magnetoferritin as well as a facile surface functionalization protocol that enables rapid cell magnetization using low exposure concentrations. The SPION core of magnetoferritin consists of cobalt-doped iron oxide with an average particle diameter of 8.2 nm mineralized inside the cavity of horse spleen apo-ferritin. Chemical cationization of magnetoferritin produced a novel, highly membrane-active SPION that magnetized human mesenchymal stem cells (hMSCs) using incubation times as short as one minute and iron concentrations as lows as 0.2 mM.

Highlights

Surface binding or internalization of superparamagnetic iron oxide nanoparticles (SPIONs) has enabled magnetization of a variety of cell types for applications such as imaging and remote manipulation.[1]
We recently reported the synthesis of chemically cationized magnetoferritin, a novel SPION which was highly effective in magnetizing human mesenchymal stem cells using incubation times as short as one minute.[15]
Commercial apoferritin solutions can vary in quality and affect synthesis outcome

Summary

Introduction

Surface binding or internalization of superparamagnetic iron oxide nanoparticles (SPIONs) has enabled magnetization of a variety of cell types for applications such as imaging and remote manipulation.[1]. Surface functionalization is achieved due to addressable amino acids that can be chemically[20,21,22] or genetically modified.[23,24,25] We have shown that chemical cationization of the acidic amino acid residues of the protein shell generates a stable nanoparticle that readily interacted with anionic domains on the cell surface leading to rapid and persistent cell magnetization This procedure eliminates the need for laborious functionalization and lengthy incubation protocols, and due the non-specific labelling mechanism this rapid magnetization strategy should find wide-spread application in other cell types. Human mesenchymal stem cells (hMSC) were harvested from the proximal femur bone marrow of osteoarthritic patients undergoing total hip replacement surgery, in full accordance with Bristol Southmead Hospital Research Ethics Committee guidelines (reference #078/01) and after patient consent was obtained

Magnetoferritin Synthesis and Purification

Determining protein concentration

General remarks NOTE

Human Mesenchymal Stem Cell Labeling with Cationized Magnetoferritin

Representative Results

Discussion