Iron Oxide Nanoparticles

Iron oxide nanoparticles are composed of iron oxide particles of size 1—100 mm. The two primary biocompatible forms of iron oxide are magnetite (Fe3Og) and the oxide form maghemite (y-Fe3Og). Magnetic fluids, data storage, catalysis, and biomedical applications are some of the key applications. In biomedical research, magnetic nanoparticles are applied in magnetic bioseparation, biological detection, detoxification, immunoassays, hyperthermia, medical diagnosis, tissue repair, tumor therapy, and targeted drug delivery [3]. Advantages ofvarious polymers used in functionalization ofiron oxide nanoparticles is shown in Table 10.1. Iron oxide nanoparticles are known to improve imaging contrast in magnetic resonance imaging (MRI) [3,5].

Iron oxide nanoparticles tend to aggregate due to their large surface to volume ratio exhibiting strong supraparamagnetic properties. Physiochemical properties such as the particle size, distribution, and concentration are invaluable for adjusting the optical

Nanosystems for Diagnostic Imaging, Biodetectors, and Biosensors 219

Strategies used for drug loading and functionalization of nanosystems [3]

Figure 10.1 Strategies used for drug loading and functionalization of nanosystems [3].

and magnetic properties. Combinatorial therapies assisted by iron oxide nanoparticles are indicated in cancer therapy. FegOg nanoparticles can provide targeted drug delivery and enhance imaging and therapeutics through high localization at the target site under magnetic field. Synergistically these nanoparticles also cause tumor cell death via localized hyperthermia under alternating magnetic fields and/or photon application (with therapeutic agents) that generates heat [6].

Multiple techniques are applied for the synthesis of magnetic nanoparticles. Although coprecipitation of iron salts is the most common method, desired size range and nonuniform distribution of the particle are some of the drawbacks [6]. Sonolysis, electrospray synthesis, flow injection synthesis, polyol method, sol—gel reaction, hydrothermal synthesis, and microemulsions are just a few of these techniques [5]. Naked iron oxide nanoparticles are highly unstable. This material oxidizes in air due to strong chemical activity from the large surface to volume ratio that leads to loss of magnetism and dispersibility. To enhance the stability of the particles, the particles are often surface modified or coated to protect the

Table 10.1 Advantages of various polymers for functionalization of iron oxide nanoparticles [6]






Enables optimum polar interactions with iron oxide surfaces, improves the blood circulation time, stability, and biocompatibility


Improves the biocompatibility, good for

magnetic resonance imaging, and drug target delivery


Used as a gelling agent, hydrophilic emulsifier, biocompatible


Nontoxic, alkaline, hydrophilic, widely used as nonviral gene delivery system, biocompatible, and hydrophilic




Enhance the hydrophilicity and water solubility, improves the biocompatibility, blood circulation times

Poly(vinyl alcohol)

Prevents agglomeration, giving rise to monodispersibility

Poly(lactic acid)

Improves the biocompatibility, biodegradability, and low toxicity in human body


Improves the stability and biocompatibility


Generally used as thermosensitive drug delivery and cell separation

Polyacrylic acid

Improves stability and biocompatibility as well as bioconjugation

nanoparticle as well as to introduce advanced functionality. Both organic and inorganic compounds can be conjugated for surface functionalization [6].

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