Hebai Shen

Chitosan-coated magnetic nanoparticles as carriers of 5-Fluorouracil: Preparation, characterization and cytotoxicity studies

The chitosan-coated magnetic nanoparticles (CS MNPs) were prepared as carriers of 5-Fluorouracil (CS-5-Fu MNPs) through a reverse microemulsion method. The characteristics of CS-5-Fu MNPs were determined by using transmission electron microscopy (TEM), FTIR spectroscopy and vibrating-sampling magnetometry (VSM). It was found that the synthesized CS-5-Fu MNPs were spherical in shape with an average size of 100+/-20 nm, low aggregation and good magnetic responsivity. Meanwhile, the drug content and encapsulation rate of the nanoparticles was 16-23% and 60-92%, respectively. These CS-5-Fu MNPs also demonstrated sustained release of 5-Fu at 37 degrees C in different buffer solutions. The cytotoxicity of CS-5-Fu MNPs towards K562 cancer cells was investigated. The result showed that CS-5-Fu MNPs retained significant antitumor activities. Additionally, it was observed that the FITC-labeled CS-5-Fu MNPs could effectively enter into the SPCA-1 cancer cells and induced cell apoptosis.

Functionalized halloysite nanotube-based carrier for intracellular delivery of antisense oligonucleotides

Halloysites are cheap, abundantly available, and natural with high mechanical strength and biocompatibility. In this paper, a novel halloysite nanotube [HNT]-based gene delivery system was explored for loading and intracellular delivery of antisense oligodeoxynucleotides [ASODNs], in which functionalized HNTs [f-HNTs] were used as carriers and ASODNs as a therapeutic gene for targeting survivin. HNTs were firstly surface-modified with γ-aminopropyltriethoxysilane in order to facilitate further biofunctionalization. The f-HNTs and the assembled f-HNT-ASODN complexes were characterized by transmission electron microscopy [TEM], dynamic light scattering, UV-visible spectroscopy, and fluorescence spectrophotometry. The intracellular uptake and delivery efficiency of the complexes were effectively investigated by TEM, confocal microscopy, and flow cytometry. In vitro cytotoxicity studies of the complexes using MTT assay exhibited a significant enhancement in the cytotoxic capability. The results exhibited that f-HNT complexes could efficiently improve intracellular delivery and enhance antitumor activity of ASODNs by the nanotube carrier and could be used as novel promising vectors for gene therapy applications, which is attributed to their advantages over structures and features including a unique tubular structure, large aspect ratio, natural availability, rich functionality, good biocompatibility, and high mechanical strength.

Sensitive ECL immunosensor for detection of retinol-binding protein based on double-assisted signal amplification strategy of multiwalled carbon nanotubes and Ru(bpy)32+ doped mesoporous silica nanospheres

A novel electrochemiluminescence (ECL) strategy based on the sandwich-type immunosensor for sensitive detection of retinol-binding protein (RBP) was developed. The primary antibody anti-RBP was immobilized onto multiwalled carbon nanotubes (MWCNTs), which have large surface area and high electrical conductivity. The RBP antigen and Ru-Nafion@SiO2-labeled secondary antibody were then successively conjugated to form sandwich-type immunocomplexes through the specific interaction between antigen and antibody. The ECL signal amplification was significantly improved due to the synergistic effect of MWCNTs and mesoporous silica nanospheres (mSiO2). The developed ECL immunosensor exhibited high sensitivity and specificity for the detection of RBP and responded linearly to the clinically-relevant concentration of RBP from 78 to 5000 ng mL(-1). Moreover, the MWCNT-based ECL immunosensor displayed excellent stability and reproducibility, as well as successfully achieved the detection of RBP in patient urine samples with desirable results. The present work provided a promising technique for the clinical screening of RBP and point-of-care diagnostics.

Synthesis of magnetic and fluorescent bifunctional nanocomposites and their applications in detection of lung cancer cells in humans.

We developed a novel strategy to detect lung cancer cells by utilizing magnetic and fluorescent bifunctional nanocomposites (BNPs) in combination with monoclonal anti-carcinoembryonic antigen (CEA) antibodies. The BNPs, consisting of silica-coated superparamagnetic nanoparticles and quantum dots (QDs), exhibited high luminescence and were easily separated in an external magnetic field. The binding specificity of the antibody-conjugated BNPs (immunonanoparticles) were confirmed via incubating with human lung adenocarcinoma SPCA-1 cells, human leukemic K562 cells and human embryonic lung fibroblasts MRC-5 cells. Further experiments demonstrated that the as-prepared immunonanoparticles can efficiently capture and detect cancer cells in pleural effusion from lung cancer patients. These results suggest that this method, of which the detection procedures are completed within 1h, could be applied to the rapid and cost-effective monitoring of cancer cells in clinical samples.

Synthesis of Fluorescent Silica Nanoparticles and Their Applications as Fluorescence Probes

This paper presents the synthesis of organic dye molecules embedded silica nanoparticles by Stöber method and their applications as fluorescence probes in cell imaging. By modifying the surface of fluorescent silica nanoparticles (FSNs) with amino, biologically functionalized and monodisperse FSNs can be obtained. In this work, FSNs were conjugated with monoclonal anti-Carcinoembryonic Antigen (anti-CEA) antibody via covalent binding. The antibody-conjugated FSNs can be used to label the SPCA-1 cells successfully, demonstrating that the application of FSNs as fluorescence probes in fluorescence imaging and bioassay would be feasible.

Multifunctional nanocarrier based on clay nanotubes for efficient intracellular siRNA delivery and gene silencing

RNA interference-mediated gene silencing relating to disease has recently emerged as a powerful method in gene therapy. Despite the promises, effective transport of siRNA with minimal side effects remains a challenge. Halloysites are cheap and naturally available aluminosilicate clay nanotubes with high mechanical strength and biocompatibility. In this study, a novel multifunctional nanocarrier based on functionalized halloysite nanotubes (f-HNTs) has been developed via electrostatic layer-by-layer assembling approach for loading and intracellular delivery of therapeutic antisurvivin siRNA and simultaneously tracking their intracellular transport, in which PEI-modified HNTs are used as gene vector, antisurvivin siRNA as gene therapeutic agent, and mercaptoacetic acid-capped CdSe quantum dots as fluorescent labeling probes. The successful assembly of the f-HNTs-siRNA complexes was systematically characterized by transmission electron microscopy (TEM), UV–visible spectrophotometry, Zeta potential measurement, fluorescence spectrophotometry, and electrochemical impedance spectroscopy. Confocal microscopy, biological TEM, and flow cytometry studies revealed that the complexes enabled the efficient intracellular delivery of siRNA for cell-specific gene silencing. MTT assays exhibited that the complexes can enhance antitumor activity. Furthermore, Western blot analysis showed that f-HNTs-mediated siRNA delivery effectively knocked down gene expression of survivin and thereby decreased the levels of target proteins of PANC-1 cells. Therefore, this study suggested that the synthesized f-HNTs were a new effective drug delivery system for potential application in cancer gene therapy.

Regulation of multifunctional mesoporous core–shell nanoparticles with luminescence and magnetic properties for biomedical applications

Gd3+-based/mesoporous silica-coated multifunctional core-shell (Y,Gd)2O3:Eu3+@nSiO2@mSiO2 nanoparticles (YGO-Bmnc NPs) with red luminescence, paramagnetic and mesoporous properties are developed as a novel nanomedical platform for combined multimodal diagnosis and therapy. 40 nm sized (Y,Gd)2O3:Eu3+ (YGO-Ac) nanocore is synthesized by a labor-saving solvothermal method, 20 nm sized perpendicularly aligned mesoporous silica shell is then successfully coated onto the nanocore through two-step sol-gel process and a highly efficient surfactant removal method (NH4NO3-EtOH). The surface area of nanocore can be increased from 24 m2 g-1 to 562 m2 g-1 after coating mesoporous silica shell without any core-free silica NPs. Light-emitting Eu3+ ion is chosen as a model to study the solvothermal mechanism and downconversion/upconversion luminescence properties of nanocore; Y3+ is doped into matrix to enhance energy transfer from Gd3+ to the doped Eu3+. Further investigation of luminescence property of YGO-Bmnc NPs shows that they are good red phosphors with millisecond-lever fluorescence lifetime (τ = 2.54 ms, 612 nm, 5D0-7F2). MTT assay reveals low cytotoxicity of the system with IC50 ([Gd]) > 1000 µg mL-1 (6.36 mM). The possibility of using YGO-Bmnc NPs for optical imaging in vitro has been demonstrated. Magnetic resonance imaging (MRI) in vitro exhibits a high r1 relaxivity of 5.05 mM-1 s-1 and low r2/r1 ratio of 1.216 (3.0 T) which is much lower than other existing Gd3+-based nanoscale contrast agents, manifesting that YGO-Bmnc NPs can be efficient T1 contrast agents. In light of their good performance in optical-MR imaging and highly ordered mesoporous structure, it is anticipated that they are suitable for combined multimodal diagnosis and therapy, they can load other imaging agents or drugs to provide complementary information from each imaging modality and guide individual treatment. Whats more, the mesoporous silica shell can provide a large venue for the effective modification of various functional groups and biotargets with selectivity and specificity.