## 2 Preparation of Magnetic-Fluorescent Nanocomposites
### Fluorescent Polymer Coated Magnetic Nanoparticles
#### 2.2.2 Polymer and Organic Dye Magnetic-Fluorescent Nanocomposites  
A different approach in the development of fluorescent and magnetic nanocomposites is the incorporation of polymer to the nanostructure. A magnetic core can be encapsulated or embedded into a polymer matrix which can be functionalized with different luminescent entities. For example, [PERSON] et al. synthesized amphiphilic pyrenyl polyethylene glycol (PEG) by the conjugation of hydrophilic PEG with hydrophobic and fluorescent 1-pyrenebutyric acid through an esterification process resulting in a high UV fluorescent intensity in aqueous phase. The polymer was incorporated into MnFe\({}_{2}\)O\({}_{4}\) magnetic nanoparticles (NPs) [18]. In another study, iron-platinum nanoparticles were embedded in a poly(methacrylic acid) (PMA) polymer shell and fluorescently labelled with the dye ATTO 590 [43]. Hydrophobic up-conversion nanoparticles (UCNPs) together with iron oxide nanoparticles (IONPs) were encapsulated by using an amphiphilic block copolymer, poly (styrene-block-allyl alcohol) (PS16-b-PAA10), via a microemulsion method, obtaining an UC-IO@Polymer multi-functional nanocomposite system. Fluorescent dye and anti-cancer drug molecules can be further loaded inside the UC-IO@Polymernanocomposite for additional modalities [44]. Magnetic-fluorescent semiconductor polymer nanospheres (MF-SPNs) have been synthesized by encapsulation of hydrophobic conjugated polymers and iron oxide nanoparticles in phospholipid micelles. Following the same synthesis, four different fluorescent conjugated polymers were used, yielding aqueous dispersions of nanoparticles which emit across the visible spectrum [45]. Novel water-soluble dendritic-linear-brush-like triblock copolymer polyamidoamine-b-poly(2-dimethylamino)ethyl methacrylate-b-poly(poly(ethylene glycol) methyl ether methacrylate) (PAMAM-b-PDMAEMA-b-PPEGMA)-grafted superparamagnetic iron oxide nanoparticles (SPIONs) were successfully prepared via a two-step copper-mediated atom transfer radical polymerization (ATRP) method by [PERSON] et al. (Figure 5) [46]. Polymer-coated magnetic particles (MPs) were also prepared to study the binding of fluorescent dye (3-(dansylamino)phenylboronic acid) on the surface and its H\({}_{2}\)O\({}_{2}\)-induced release. For this goal, multilayer films were produced by LBL deposition of shikimic acid-appended poly(allylamine hydrochloride) (SA-PAH) and poly(styrenesulfonate) (PSS) on the surface of MPs [47]. Dual-modal fluorescent-magnetic nanoparticles with surface folic acid have also been produced by co-encapsulation of a far-red/near-infrared (FR/NIR)-emissive conjugated polymer (Poly[9,9-bis(6\({}^{\prime}\)-(N,N-dimethylamino)hexyl)fluoreryldivinylene-alt-4,7-(2,1,3-benzothadiazol)]) (PFVBT) and lipid-coated iron oxides (IOs) into a mixture of poly(lactic-co-glycolic-acid)-poly(ethylene glycol)-folate (PLGA-PEG-FOL) and PLGA [48]. Similarly, Fe\({}_{3}\)O\({}_{4}\) nanoparticles coated with biodegradable poly (dl-lactic acid-co-\(\alpha\),\(\beta\)-malic acid) copolymer were covalently bound to FITC [49]. Figure 4: Schematic illustration of the formation of Fe\({}_{3}\)O\({}_{4}\)/NaYF\({}_{4}\)nanocomposites through EDC/NHS coupling chemistry. Adapted from ref. [41]. [PERSON] et al. reported the preparation of (PEG)ylated polymeric lipid vesicles containing iron oxide nanoparticles and the anticancer drug doxorubicin (DOX) [50]. In another study, Fe\({}_{3}\)O\({}_{4}\)/poly(St-_co_-GMA) nanoparticles were first synthesized as seed particles. Eu(AA)3 Phen was then copolymerized with the remaining styrene and GMA (glycidyl methacrylate) to form the fluorescent polymer shell in the second step. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2-photon confocal scanning laser microscopy [51].