**1. Introduction**

Over the past few decades, magnetic nanoparticles (MNPs) have attracted tremendous attention due to their unique and tunable chemical and physical properties. Magnetic nanoparticles can selectively target specific biological surfaces of interest owing to the arrangement in dipoles in the absence and presence of an external magnetic field. Iron oxide nanoparticles (IONPs) are one of the mostly used MNPs since they are nontoxic and biodegradable, being promising candidates for use in biology and medicine for example imaging [1, 2], siRNA and drug delivery [3, 4], cell tracking [5], magnetic separation [6, 7] hyperthermia [8, 9], and bio- and chemo-sensoring and [10] biomedical applications. Moreover, IONPs are mostly used as magnetic resonance imaging (MRI) probes to differentiate between normal and cancerous cells for diagnosis [11, 12]. Moreover, magnetic imaging has no practical depth limitation for imaging, however spatial resolution is poor and

multiple imaging is problematic. To improve the versatility and efficiency in numerous technologies, the development of hybrid magnetic nanoparticles combining both fluorescent and magnetic properties magnetic are being developed [13–23]. The combination of MRI and fluorescent spectroscopy in one nanocomposite opens up unique multimodal properties to monitor complementary information in biological applications such as in multimodal biological imaging, drug delivery systems and medical diagnostics. Despite many problems related to the synthesis of hybrid magnetic-fluorescent nanoparticles, major advances in recent years have been made in this field. For the synthesis, both physical and chemical techniques have been used for the synthesis of IONPs; still, the chemical approach are easier to control the NPs, such as the co-precipitation, thermal decomposition, hydrothermal synthesis, microemulsion, and sol-gel and polyol methods. Of all these approaches, the chemical approach, particularly co-precipitation method is discussed in Section 2. As Fe3O4 NPs are the mostly used IONPs, in this section we focus on the chemical synthesis of Fe3O4 NPs. Also, covered in this section is the synthesis of fluorescentmagnetic nanocomposite material, using InP/ZnSe NPs as fluorophore. The syntheses of fluorescent-magnetic nanoparticles are challenging due to chemical stability and the aggregation of the nanoparticles in solution caused by electron transfer interactions between the particles. The main challenge associated is to overcome the quenching of the luminescence of the fluorophore when it is on the particle surface of the magnetic core. This can be due to the electron and energy transfer between the fluorophore and the magnetic nanoparticles [24–26]. The easiest and most commonly used method to overcome this hurdle is to isolate the magnetic core from the fluorescent molecule. This can be achieved by coating the magnetic nanoparticle with a shell before it is attached to the fluorescent structure or by placing a spacer between the two molecules. These solutions lead to most luminescent magnetic nanoparticles to have a core-shell structure [15]. The shell needs to have specific properties namely: non-toxic or harmful to human tissue, should not cause the body to emit an immune response, to avert or reduce agglomeration and reduce nonspecific interactions with proteins, cells and other components of biological media. Hence, Section 3 covers several procedures for the functionalization and formation of the fluorescent-magnetic nanocomposite material to overcome these challenges. In Section 4, the biomedical applications of IONPs including MRI, magnetic hyperthermia, magnetic targeting, and cell tracking, with focus on diagnosis for breast cancer treatment are reviewed.

## **1.1 Purpose of the study**

Nanocomposite material with dual or multiple properties have shown extensive potential to improve the performance of current cancer diagnostic tools and/or therapy, for biosensor applications, *in vivo* optical imaging or drug delivery. The aim of this project is to synthesize a nanohybrid material with luminescent and magnetic properties and having low or no toxicity, to be used for biological studies.

In this experiment the synthesis of the multifunctional material will be synthesized via the process seen in **Figure 1**. From the diagram the end product, the nanocomposite material, the QDs are expected to cluster around the MNPs.

In order to synthesize the Fe3O4-InP/ZnSe bifunctional nanocomposite material, the luminescent InP/ZnSe nanocrystals were prepared separately from the Fe3O4 magnetic nanoparticles. Once both the MNPs and QDs nanomaterials are synthesized they are both will be functionalized with a compound containing a thiol group. The MNPs and QDs were functionalized with dimercaptosuccinic acid (DMSA) and mercaptopropionic acid (MPA), respectively. Using thiol chemistry, the QDs will directly combine to the surface of the MNPs (as seen in **Figure 1**).

**137**

*Chemical Synthesis and Characterization of Luminescent Iron Oxide Nanoparticles…*

**2. Chemical synthesis of magnetic nanoparticles and magnetic-fluorescent** 

*Experimental schematic of the synthesis of the magnetic-luminescent nanomaterial.*

In this chapter, we discuss the general and recent progress of different chemical synthetic pathways for IONPs (Fe3O4). Their small and controllable sizes, easily functionalized, as well as the ability to be manipulated by external magnetic forces [15], are all attractive properties for various applications including biomedical pursuits. The properties of MNPs strongly depended on the synthesis route. Consequently, the controllable synthesis of monodispersed IONPs is critical for controlling their size distribution, structural defects, surface chemistry, and magnetic behavior for application in specific biomedical field. The synthesis of shapecontrolled, stable, biocompatible, and monodispersed IONPs have drawn much effort over recent years. IONPs have been produced by various chemical, physical and biological methods which have both advantages and disadvantages (**Table 1**). Chemical synthesis offers significant advantages over other methods, as it is a facile, cost-effective method with ease of control over the NPs characteristics. These methods include thermal decomposition, co-precipitation, microemulsion, hydrothermal synthesis, and sol-gel and polyol methods, also shown in **Table 1** [32]. Of these methods, co-precipitation is the mostly used as it tends to be green, simple and effective with low production cost, high reproducibility and high yields in one synthesis [27]. Hence, it is of interest, and discussed in detail in section below.

Co-precipitation method is the preferred choice among studied synthetic methods for the preparation of Fe3O4 NPs. It is a simple and classical approach to follow as it is simple, convenient, cheap with high reproducibility, solubility and scalability for large scale production. However, due to the high influence of kinetic factors on the growth of Fe3O4 NPs, such as low reaction temperatures, this resulted

*DOI: http://dx.doi.org/10.5772/intechopen.88165*

**nanoparticles**

**Figure 1.**

*2.1.1 Co-precipitation method*

**2.1 Magnetic nanoparticles: synthesis**

*Chemical Synthesis and Characterization of Luminescent Iron Oxide Nanoparticles… DOI: http://dx.doi.org/10.5772/intechopen.88165*

**Figure 1.** *Experimental schematic of the synthesis of the magnetic-luminescent nanomaterial.*
