Hongda Zhu

Malachite green adsorption onto Fe3O4@SiO2-NH2: isotherms, kinetic and process optimization

Higher environmental standards have made the removal of dye from water an important problem for many industrialized countries. Among the removal methods, magnetic adsorbents have received much attention for adsorption of dyes. In this paper, a novel magnetic adsorbent with an amino-modified SiO2-coated Fe3O4 magnetite was prepared. The analysis of Fe3O4@SiO2-NH2 proved that the nanoparticles were uniform with a diameter of 90 nm. The difference between Fe3O4@SiO2-NH2 and Fe3O4@SiO2 on the adsorption behaviour of malachite green was studied. Fe3O4@SiO2-NH2 showed a good capacity for the adsorption of malachite green compared with Fe3O4@SiO2, which was shown to be influenced by the initial concentration and pH. Under the optimal conditions, the removal efficiency of malachite green was over 90% by Fe3O4@SiO2-NH2, while using Fe3O4@SiO2 efficiency was below 60%. The experimental data fit well with the Freundlich isotherm and the pseudo-second-order kinetic model. In further applications, real samples were treated with Fe3O4@SiO2-NH2 nanoparticles. All the results demonstrated that the Fe3O4@SiO2-NH2 nanoparticles could be promising and effective adsorbents.

The properties of mesoporous silica nanoparticles functionalized with different PEG-chain length via the disulfide bond linker and drug release in glutathione medium

Abstract In this paper, a novel drug-loaded material (MSNs-SS-PEG) was obtained by grafting the thiol-linked methoxy polyethylene glycol (MeOPEG-SH) onto the thiol-functionalized mesoporous silica nanoparticles (MSNs-SH) via the disulfide bond linker. In our designed experiment, three different chain lengths of PEG (PEG1000, PEG5000, and PEG1000-PEG5000) were used. The silica materials were characterized by Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering, field emission scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption measurements, and X-ray diffraction. The morphology of the MSNs-SS-PEG was spherical with an average diameter of about 150 nm. Due to the covalent modification of hydrophilic MeOPEG, the MSNs-SS-PEG was coated by a thin polymer shell, showing stable and inerratic MCM-41 type mesoporous structure as well as high specific surface areas and large pore volumes. Moreover, the releases of doxorubicin hydrochloride (DOX) from these materials at 10 mM of glutathione were investigated. The PEG functionalization could effectively cap drugs in the mesoporous channels. The release of DOX from the MSNs-SS-PEGn revealed redox-responsive characteristic. The obtained results showed that the MSNs-SS-PEG might be promising drug delivery carrier materials, which could play an important role in the development of drug delivery.

Redox-sensitive mesoporous silica nanoparticles functionalized with PEG through a disulfide bond linker for potential anticancer drug delivery

In this paper, redox-sensitive mesoporous silica nanoparticles functionalized with polyethylene glycol (PEG) through a disulfide bond linker (MSNs–SS–PEG) were successfully synthesized using silica nanoparticles modified with a thiol group (MSNs–SH) and thiol-functionalized methoxy polyethylene glycol (MeOPEG–SH). Meanwhile, the particle size, pore size and structural properties of these materials were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and nitrogen adsorption–desorption measurements. Furthermore, the in vitro drug release behaviour of DOX-loaded MSNs–SS–PEG (DOX@MSNs–SS–PEG) was investigated. It was shown that DOX release was markedly accelerated with the increasing concentration of glutathione (GSH), while DOX was not released from the carrier materials in the absence of GSH. Cytotoxicity evaluation revealed the good biocompatibility of the blank nanoparticles and the DOX@MSNs–SS–PEG exhibited comparative anticancer activity to free DOX towards BEL-7402 cells. Therefore, the MSNs–SS–PEG might be a great potential carrier for anticancer drug delivery.

A highly dispersible silica pH nanosensor with expanded measurement ranges

For accurate determination of local intracellular pH which could further improve our understanding of cellular processes and knowledge of advanced drug delivery system architecture, a fluorescent-based ratiometric nanosensor has been designed over the past decade. As a promising matrix for nanosensors and nanomedicines, silica nanoparticles (SNPs) have been widely used due to their desirable properties, which include a high loading level of guest molecules, low toxicity and easy functionalization. Amination of SNPs was essential for binding functional groups, such as fluorescent molecules and targeting groups, whereas positively charged amine will cause the aggregation of SNPs which limits the further application of SNPs. To circumvent this problem, a simple and effective strategy has been presented in this paper. Firstly, an acid was used as a catalyst instead of a base to inhibit SNP aggregation in the amination process. Subsequently, polymers (poly(ethylene glycol) and hyaluronic acid) were coated on the surface of monodispersed aminated SNPs to obtain excellent colloidal stability. The well dispersed core–shell SNPs were further functionalized with two pH sensitive fluorophores (fluorescein isothiocyanate and Oregon Green isothiocyanate) and one reference fluorophore (rhodamine B isothiocyanate), which resulted in ratiometric pH nanosensors with a hydrodynamic diameter of 76–100 nm. The sensors exhibited a broad pH measurement range from 3.8 to 7.4, which covers almost all intracellular pH values, and remarkable colloidal stability in buffer solution.

An immunomagnetic separation based fluorescence immunoassay for rapid myoglobin quantification in human blood

Magnetic nanoparticle (NPs) and fluorescent NP pairs were designed for myoglobin (Myo) detection in human blood. Magnetic NPs MNP@SiO2@BSA@Au with about 200 nm diameter (by TEM) were prepared through a layer by layer technique following by adsorption of anti-Myo antibody 4E2 on a Au surface. The MNPs were well dispersed in an aqueous solution. Fluorescent NPs were prepared by conjugating fluorescent Rhodamine Red-X (RhX) and another Myo antibody 7C3 on silica NPs with a final diameter of 80 nm. In the presence of Myo, magnetic NPs bearing 4E2 and fluorescent NPs bearing 7C3 form a sandwich structure, which can be separated from blood under a magnetic field. The concentration of Myo is quantified by the fluorescence intensity of SNP@RhX NPs in the sandwich structure. The calibration curve of the Myo showed a linear range between 0 and 250 ng mL−1 (R2 = 0.993). The minimum detectable concentration was 0.28 ng mL−1. The immunomagnetic separation based fluorescence immunoassay offered a simple and accurate way to determine Myo in human blood in 30 min.

Nanovesicles System for Rapid-Onset Sublingual Delivery Containing Sodium Tanshinone IIA Sulfonate: In vitro and In Vivo Evaluation

A novel formulation based on nanovesicles system for rapid-onset sublingual delivery of hydrophilic drug (sodium tanshinone IIA sulfonate, STS) was investigated. The nanovesicles system was composed of 1.5% soybean lecithin, 6% propylene glycol, and penetration enhancers (1% sodium dodecyl sulfate and 0.03% hyaluronan acid). The STS-loaded nanovesicles with an average diameter of 133 ± 9.04 nm and high entrapment efficiency of 85.65 ± 3.89% were characterized. The effects of permeation enhancers on the penetration of STS formulations were investigated using Franz diffusion cells in vitro, showing 86.1-235.8 times higher permeation rate than that of normal STS solution. The rapid symptom relief effect of the nanovesicles system on acute myocardial infarction rabbits was evaluated by in vivo study, ST-segment deviation(S and T wave abnormality in electrocardiogram) was attenuated markedly and rapidly within 5 min, infarct size of heart was significantly reduced and the biochemical indicators were substantially decreased, compared with the control groups (p < 0.05). This study provided a promising tool for the future sublingual delivery of hydrophilic compounds with the noninvasive and rapid onset clinical effect.

Synthesis of Gd-functionalized Fe3O4@polydopamine nanocomposites for T1/T2 dual-modal magnetic resonance imaging-guided photothermal therapy

A safe, efficient and inexpensive multifunctional nanoplatform is urgently needed for cancer diagnosis and treatment. Herein, we report the first example of fabrication of gadolinium-functionalized Fe3O4@polydopamine nanocomposites and evaluate their potential application in T1/T2 dual-modal magnetic resonance imaging-guided photothermal therapy in vitro. This was achieved by encapsulating iron oxide nanoparticles with polydopamine, and then grafting gadolinium chelates onto the surface of Fe3O4@polydopamine nanocomposites. The as-prepared nanocomposites, composed of low cost Fe3O4, polydopamine and gadolinium complexes, showed high stability and good biocompatibility. More importantly, these nanocomposites exhibited high photothermal conversion efficiency, with the temperature reaching 43.0 °C at a concentration of 0.35 mg mL−1 under near-infrared irradiation for a few minutes. Furthermore, according to the magnetic resonance imaging results, these nanocomposites could induce an efficient contrast enhancement for both T1 and T2 imaging at low concentrations of Gd and Fe. This provides a new platform for the development of new diagnosis and therapeutic agents.

cRGD-functionalized redox-sensitive micelles as potential doxorubicin delivery carriers for αvβ3 integrin over expressing tumors

Polymeric micelles as nanocarrier-based drug delivery systems provide an innovative platform for selectively delivering active molecules and offer better antitumour activity. However, circulation stability in vivo, controllable drug intracellular release and high targeting efficiency are several practical challenges for micelles. Therefore, we developed cRGD-modified and shell crosslinked micelles (RSCMs) based on amphiphilic poly(styrene-co-maleic anhydride) (SMA). RSCMs exhibited a spherical shape and were homogeneous with an average diameter of 106.1 nm and a low polydispersity of 0.087. In comparison, after crosslinking the micelles possessed better stability against dilution and stronger redox-response towards dithiothreitol (DTT). The SMA micelles displayed high drug loading capacity for hydrophobic DOX with a drug loading of approximately 14.1–19.2% (w/w) and an encapsulation efficiency of 72.1–82.7% (w/w). The in vitro release studies of shell crosslinked micelles showed that DOX release was minimal (<25%, 24 h) under physiological conditions. However, in the presence of 10 mM DTT, accelerated release of DOX was achieved (60%, 24 h). MTT assays in B16F10 cells indicated that RSCMs displayed low cytotoxicity up to a concentration of 500 μg ml−1. Moreover, the IC50 value showed that cRGD-DOX-ss-M could be more effective than other groups. In vitro, cellular uptake was further studied with confocal laser scanning microscopy and flow cytometry, both the qualitative and quantitative results demonstrated that cRGD-DOX-ss-M possessed much better specificity to cancer cells and superior stimulated release property in cytoplasm. Notably, cRGD-DOX-ss-M could more efficiently be delivered to and release into the nuclei of αvβ3 integrin over expressing tumor cell line (B16F10) than counterparts of integrin-deficient tumor cells (Hela). Thus, these cRGD-modified redox-sensitive micelles have appeared as a technology platform with great potential for targeted anticancer drug delivery and release for integrin over expressing tumor cells.