## 2 Preparation of Magnetic-Fluorescent Nanocomposites
### Fluorescent Polymer Coated Magnetic Nanoparticles
#### 2.2.3 Polymer and QDs-Magnetic-Fluorescent Nanocomposites
fabricated a multicomponent nanostructure system that involves the covalent attachment of 3 components; Fe\({}_{3}\)O\({}_{4}\) (Fe) NPs, PAMAM-G4-NH\({}_{2}\) (G4) dendrimer and Cy5 (Cy) on a graphene oxide (GO) surface to develop a biologically multifunctional system. The resultant GO-G4-Fe-Cy nanosystem exhibits high dispersion in aqueous media, and is magnetically responsive and fluorescent [74]. [PERSON] et al. reported the synthesis of an amphiphilic polymer, poly(isobutylene-alt-maleic anhydride)-functionalized near-infrared IR-820 dye and its conjugates with iron oxide (Fe\({}_{3}\)O\({}_{4}\)) magnetic NPs for optical and MRI imaging (Figure 10) [75]. After the absorption of dopamine, human serum albumin (HSA) was attached to the surface of the CoFe\({}_{2}\)O\({}_{4}\) magnetic NPs through a reversible non-covalent bond between HSA and -NH\({}_{2}\) in dopamine. With the same type of  
Figure 9: Preparation route of NH\({}_{2}\)-MNPs and FITC-MNPs from P(PEGMA)-MNPs by post-polymerization modification (MNPs—magnetic nanoparticles). Adapted from ref. [72]. interaction, the designed perylenediimide (PDI) based -NH\({}_{2}\) rich fluorescent molecule (PDI-4 NH\({}_{2}\)) was decorated onto the HSA-modified CoFe\({}_{2}\)O\({}_{4}\) nanoparticles (Figure 11) [76]. Figure 10: Top: **(a)** Schematic illustration of Dye-Pol-conjugated Fe\({}_{3}\)O\({}_{4}\) magnetic nanoparticles (MNPs) through hydrophobic interaction, yielding MNP@Dye-Pol. **(b)** HRTEM and **(c)** Size-distribution of MNP@Dye-Pol. **(d)** Labeling of HeLa cells incubated for 2 h with 50 \(\upmu\)L of MNP@Dye-Pol (1 mg/mL). Blue (DAPI), red (NIR), and DIC channels. (Lower panel) Images at high magnification. Scale bar: 20 \(\upmu\)m. **(e)** In vitro cell viability of HeLa cells incubated for 24 h (assay 1) and 6 h (assay 2) at 37 \({}^{\circ}\)C with different concentrations of MNP@Dye-Pol. Cell viability assays were carried out using CellTiter-Blue in triplicate. The error bars represent the standard deviations. Adapted from ref. [75]. A fluorescent ruthenium (Ru) complex was coupled to magnetic Fe\({}_{3}\)O\({}_{4}\) nanoparticles (NPs) via 3-(3,4-dihydroxyprophenyl) propanoic acid (DHPPA) and \(O\),\(O^{\prime}\)-_bis_(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polyppropylene glycol (PPG-PEG-PPG-diamine) [77]. Water soluble Fe\({}_{3}\)O\({}_{4}\)-DPA-PEG NPs were conjugated with the fluorescent Eu(III) complex of tris(dibenzoylmethane)-5-amino-1,10-phenanthroline (BMAP), giving an Fe\({}_{3}\)O\({}_{4}\)-DPA-PEG-BMAP-Eu NPs conjugate. The conjugate was both colloidally and chemically stable in phosphate buffered solutions and could be used as a probe for magnetic resonance and fluorescent imaging [78]. Novel Fe\({}_{3}\)O\({}_{4}\)@YPO\({}_{4}\): Re (Re = Tb, Eu) magnetic-fluorescent hybrid nanospheres are prepared and show a sustained release behaviour for the anticancer drug DOX and successful labelling of human cervical carcinoma Hela cells [79]. In the first step, St and NIPAM polymerize the NaUA on the surface of Fe\({}_{3}\)O\({}_{4}\) nanoparticles to form Fe\({}_{3}\)O\({}_{4}\)/poly(St-NIPAM) nanoparticles which act as seeds for the polymerization of Eu(AA)\({}_{3}\)Phen, with the remaining St and NIPAM in the second step, forming an outer fluorescent layer [80]. The Poly(MMA-HEMA-Eu(AA)\({}_{3}\)Phen)/Fe\({}_{3}\)O\({}_{4}\) nanospheres exhibit magnetic and fluorescent properties that are favorable for use in drug delivery, magnetic separation and MRI [81]. The microsphere formulations of Chit/TPP/Sm/Fe\({}_{3}\)O\({}_{4}\)/Rn were also prepared by an ionic gelation technique, where Chito = chitosan, TPP = tripolymbosphate, Sm = samarium and Rn = ranitidine. This microsphere formulation was found to exhibit excellent magnetic and fluorescent properties [82].