2.1. Synthesis and Characterization of the Compact-Discrete
MANP.
The fabrication of MANP involved a
one-pot emulsification and
evaporation method, where superparamagnetic
Fe3O4 NPs@OA (Figure S1 ) and
red-emitting AIEgens (Figure S2 ) were co-assembled as
functional units, along with poly(maleicanhydride-alt-1-octadecene)
(PMAO) polymer as the supporting skeleton. In this process, 6 mg of
hydrophobic Fe3O4 NPs@OA, 6 mg of
AIEgens, and 5 mg of PMAO were dissolved in chloroform and underwent
micellar encapsulation in an aqueous phase using sodium dodecyl sulfate
(SDS) as a surfactant. During the evaporation of chloroform, the
components (Fe3O4 NPs@OA, AIEgens, and
PMAO) self-assembled and co-constructed a spherical nanocomposite called
MANP6:6. Scanning
electron microscopy (SEM) image (Figure 1 a) and transmission
electron microscopy (TEM) image (Figure 1 b)
demonstrate the homogeneous spherical morphology of
MANP6:6. The magnified TEM image (Figure1 c) clearly shows a core–shell nanostructure with a compact
AIE core and a discretely packed
Fe3O4NPs@OA shell, indicating a phase separation process within
MANP6:6 due to the different polarities of the building
blocks. By contrast, PMAO polymer nanoparticles
(PNP), AIE nanoparticles
(ANP6), and magnetic nanoparticles
(MNP6) were synthesized as single functional component
analogs. TEM image inFigure 1 d reveals the solid spherical structure of
PNP. However, ANP6 displays a distinct AIE core-PMAO
shell structure due to the polarity difference between AIEgens and the
polymer (Figure 1 e). Figure 1 f shows
that MNP6 exhibits a spherical geometry with
Fe3O4 NPs@OA homogeneously distributed
throughout the nanoparticle, owing to the high compatibility between OA
and PMAO. These results support the reasonable formation mechanism of
MANP: (i) the high mutual affinity between OA, PMAO, and SDS leads to
the uniform assembly of Fe3O4 NPs@OA on
the exterior PMAO shell, close to the SDS aqueous phase, with a discrete
distribution; (ii) the aromatic AIEgens tend to migrate to the particle
center and aggregate together due to their incompatible molecular
affinity with the shell components.
Furthermore, Figure 1 g shows that
MANP6:6 exhibits the characteristic UV–vis spectrum of
ANP6 and demonstrates an absorption lift in the 200–600
nm range due to the incorporation of the magnetic component. By
contrast, PNP exhibits negligible light absorption, indicating that the
polymer matrix does not contribute to optical interference in
MANP6:6. The energy dispersive X-ray (EDX) elemental
mapping images display the distribution of C, Fe, O, and S in
MANP6:6. Figure 1 h shows that the C
elements are primarily concentrated in the core position, Fe and O
elements are located on the exterior shell, and S elements are uniformly
distributed throughout MANP6:6. Further EDX line scan
(Figure 1 i) across the center of
MANP6:6 confirms the presence of a nuclear C core and an
out-layer Fe, verifying the distinct assembling spatiality of
Fe3O4 NPs@OA and AIEgens in the
core–shell magnetic-fluorescent
MANP6:6. X-ray
photoelectron spectroscopy (XPS) analysis (Figures 1 j, k,Figure S3 ) implies the co-existence of C, O, and Fe in
MANP6:6. In addition, the powder X-ray diffraction (XRD)
analysis (Figure 1 l) reveals characteristic
diffraction peaks corresponding to the (220), (311), (400), (511), and
(440) planes of superparamagnetic Fe3O4crystal, suggesting the successful loading of
Fe3O4 NPs@OA in MANP6:6.
Dynamic light scattering measurements show that MANP6:6is well-monodispersed with a uniform hydrodynamic size of
~320 nm (Figure 1 m). Moreover, the
surface of MANP6:6 becomes predominantly negatively
charged after the carboxylation process, which is beneficial for
subsequent biomodification (Figure 1 n). The fluorescent spectra
demonstrate that MANP6:6 exhibits maximum excitation
wavelengths at 365 and 465 nm, with a maximum emission peak at 600 nm
(Figure S4 ). This red-light emitter property enables
MANP6:6 to effectively resist biological interference.
Collectively, these results provide strong evidence for the successful
construction of MANP.