Graphical The best of both worlds : Indocyanine green (ICG), a near-infrared (NIR) imaging agent and perfect NIR light absorber for laser-mediated photothermal therapy, was successfully incorporated into superparamagnetic Fe 3 O 4 @mSiO 2 core–shell nanoparticles to combine the merit of NIR/MR bimodal imaging properties with NIR photothermal therapy. Multimodal imaging and simultaneous therapy is highly desirable because it can provide complementary information from each imaging modality for accurate diagnosis and, at the same time, afford an imaging-guided focused tumor therapy. In this study, indocyanine green (ICG), a near-infrared (NIR) imaging agent and perfect NIR light absorber for laser-mediated photothermal therapy, was successfully incorporated into superparamagnetic Fe 3 O 4 @mSiO 2 core–shell nanoparticles to combine the merit of NIR/magnetic resonance (MR) bimodal imaging properties with NIR photothermal therapy. The resultant nanoparticles were homogenously coated with poly(allylamine hydrochloride) (PAH) to make the surface of the composite nanoparticles positively charged, which would enhance cellular uptake driven by electrostatic interactions between the positive surface of the nanoparticles and the negative surface of the cancer cell. A high biocompatibility of the achieved nanoparticles was demonstrated by using a cell cytotoxicity assay. Moreover, confocal laser scanning microscopy (CLSM) observations indicated excellent NIR fluorescent imaging properties of the ICG-loaded nanoparticles. The relatively high r 2 value (171.6 m M −1 s −1 ) of the nanoparticles implies its excellent capability as a contrast agent for MRI. More importantly, the ICG-loaded nanoparticles showed perfect NIR photothermal therapy properties, thus indicating their potential for simultaneous cancer diagnosis as highly effective NIR/MR bimodal imaging probes and for NIR photothermal therapy of cancerous cells.
Fe3O4@mSiO2 (magnetic Fe3O4 core coated by a mesoporous silica shell) nanoparticles were successfully synthesized as a carrier. The anti-cancer drug doxorubicin (DOX) and chlorambucil (Chl) were used as the model cargo. After the drug-loading, a sodium hyaluronic acid (HA) cross-linked gel was adopted to coat the outside of the Fe3O4@mSiO2 nanoparticles as a layer (named as drug–Fe3O4@mSiO2–HA) to prevent drug pervasion. The detailed release kinetics were investigated, revealing the sensitive release triggered by hyaluronidase (HAase), a major enzyme which is rich in the tumor microenvironment, which can degrade the HA shell to induce the enzyme sensitive drug release. Moreover, there are some HA receptors in many tumor areas, associating with magnetic targets to further ensure the specific targeted drug delivery. With these improved performances, these smart multifunctional nanocomposites are expected to possess potential applications in the biopharmaceutical for cancer therapy.
Magnetic mesoporous nanoparticles of Fe3O4@mSiO2 were prepared through co-precipitation and tetraethoxysilane hydrolysis at 60 °C and pH 10 with hexadecyl trimethyl ammonium bromide as the template. Hydroxypropyl β-cyclodextrin was modified onto Fe3O4@mSiO2 under sodium citrate and N2 protection via an ultrasound process to increase the catalytic efficiency. The prepared nanoparticles were characterized by Fourier transform infrared spectrometry, X-ray diffraction, scanning electron microscopy and a peroxidase-like activity assay. The results showed that the prepared nanoparticles have magnetic properties, peroxidase-like activity and a loose spherical cluster structure. Compared with Fe3O4@mSiO2 nanoparticles, Fe3O4@mSiO2@HP-β-CD nanoparticles exhibit higher catalytic ability toward both H2O2 and 3,3′,5,5′-tetramethylbenzidine. Fe3O4@mSiO2@HP-β-CD nanoparticles can catalyse β-estradiol (β-E2) oxidation in the presence of H2O2 and be used as a colourimetric sensor for indirect detection of β-E2. A good linear relationship was obtained from 0.8 μM to 16 μM. The limit of detection of the proposed method was 0.2 μM. The visual method was successfully used in the analysis of β-E2 in commercial tablets and animal feeds, with recovery ranging from 92.6% to 110%.
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