MSCs-engineered biomimetic PMAA nanomedicines for multiple bioimaging-guided and photothermal-enhanced radiotherapy of NSCLC.

BACKGROUND: The recently developed biomimetic strategy is one of the mostly effective strategies for improving the theranostic efficacy of diverse nanomedicines, because nanoparticles coated with cell membranes can disguise as "self", evade the surveillance of the immune system, and accumulate to the tumor sites actively. RESULTS: Herein, we utilized mesenchymal stem cell memabranes (MSCs) to coat polymethacrylic acid (PMAA) nanoparticles loaded with Fe(III) and cypate-an derivative of indocyanine green to fabricate Cyp-PMAA-Fe@MSCs, which featured high stability, desirable tumor-accumulation and intriguing photothermal conversion efficiency both in vitro and in vivo for the treatment of lung cancer. After intravenous administration of Cyp-PMAA-Fe@MSCs and Cyp-PMAA-Fe@RBCs (RBCs, red blood cell membranes) separately into tumor-bearing mice, the fluorescence signal in the MSCs group was 21% stronger than that in the RBCs group at the tumor sites in an in vivo fluorescence imaging system. Correspondingly, the T1-weighted magnetic resonance imaging (MRI) signal at the tumor site decreased 30% after intravenous injection of Cyp-PMAA-Fe@MSCs. Importantly, the constructed Cyp-PMAA-Fe@MSCs exhibited strong photothermal hyperthermia effect both in vitro and in vivo when exposed to 808 nm laser irradiation, thus it could be used for photothermal therapy. Furthermore, tumors on mice treated with phototermal therapy and radiotherapy shrank 32% more than those treated with only radiotherapy. CONCLUSIONS: These results proved that Cyp-PMAA-Fe@MSCs could realize fluorescence/MRI bimodal imaging, while be used in phototermal-therapy-enhanced radiotherapy, providing desirable nanoplatforms for tumor diagnosis and precise treatment of non-small cell lung cancer.

Role of Protecting Groups in Synthesis and Self-Assembly of Glycopolymers.

Protection and deprotection are basic procedures in oligosaccharide synthesis. By taking advantage of the processes of attaching and removing the protecting groups, preparation of oligosaccharides with complex structures can be achieved with relatively high yields. However, the role of protecting groups in solution properties and self-assembly of synthetic glycopolymers has been overlooked in the literature. In this paper, we focused on such effects for well-designed copolymers in which different numbers of benzyl (Bn) groups are installed regioselectively in saccharide rings. Thus, three block copolymers P1, P2, and P3 composed of a common block of PNIPAm and a glycopolymer block with trisaccharide triMan side chains differing in the respective number of Bn (0, 2, and 6) were prepared. The solutions of these block copolymers in water were investigated by dynamic and static light scatting and VT-1H NMR. We found that all of the three copolymers P1, P2, and P3 formed association at room temperature. Particularly, P1 associated loosely due to carbohydrate-carbohydrate interaction (CCI) while P3 formed tight aggregates due to hydrophobic interactions between Bn, and P2 behaved between those of P1 and P3. Moreover, upon heating, phase transition of PNIPAm block took place leading to micelle formation. Hydrodynamic radius of P1 and P2 increased significantly as expected, while P3 did not follow this trend, because during heating, collapse and accumulation of the PNIPAm chains would occur within the tight aggregates mainly, so it leads to a little change of the size.

Enzymatic Activities of Polycatalytic Complexes with Nonprocessive Cellulases Immobilized on the Surface of Magnetic Nanoparticles.

Polycatalytic enzyme complexes made by immobilization of industrial enzymes on polymer- or nanoparticle-based scaffolds are technologically attractive due to their recyclability and their improved substrate binding and catalytic activities. Herein, we report the synthesis of polycatalytic complexes by the immobilization of nonprocessive cellulases on the surface of colloidal polymers with a magnetic nanoparticle core and the study of their binding and catalytic activities. These polycatalytic cellulase complexes have increased binding affinity for the substrate. But due to their larger size, these complexes were unable to access to the internal surfaces of cellulose and have significantly lower binding capacity when compared to those of the corresponding free enzymes. Analysis of released soluble sugars indicated that the formation of complexes may promote the prospect of having consistent, multiple attacks on cellulose substrate. Once bound to the substrate, polycatalytic complexes tend to remain on the surface with very limited mobility due to their strong, multivalent binding to cellulose. Hence, the overall performance of polycatalytic complexes is limited by its substrate accessibility as well as mobility on the substrate surface.

Adjusting Local Molecular Environment for Giant Ambient Thermal Contraction.

A low-energy triggered switch that can generate mechanoresponse has great technological potential. A submolecular moiety, S-dibenzocyclooctadiene (DBCOD) that is composed of a flexible eight-membered ring connecting to a phenyl ring at each end, undergoes a conformational change from twist-boat to chair under a low-energy stimulus such as near infrared irradiation, resulting in thermal contraction of DBCOD-based polymer. Experimental evidence corroborated by theoretical calculations indicates that introducing molecular asymmetry can reduce crystallinity significantly and consequently facilitate the kinetics of the conformational change. It has been demonstrated that the negative thermal expansion (NTE) coefficient of a DBCOD-based polymer system can be adjusted in a range from -1140 to -2350 ppm K-1 . -2350 ppm K-1 is ≈10 times better than the value reported by the second best NTE system.

Immobilization of ALA-Zn(II) Coordination Polymer Pro-photosensitizers on Magnetite Colloidal Supraparticles for Target Photodynamic Therapy of Bladder Cancer.

5-Aminolevulinic acid (ALA) is a widely used photodynamic therapy (PDT) prodrug in the clinic. It can be metalized to the photosensitizer PpIX, which produces toxic singlet oxygen to kill cancer cells upon visible light irradiation. Herein, a core/shell-structured vehicle is designed to comprise magnetite colloidal supraparticles (MCSPs) as cores and ALA-Zn(II) coordination polymers as shells (Fe3O4@ALA-Zn(II) ) for target pro-photosensitizer delivery. The coordination polymers with 2D layered structures are locally deposited on the MCSPs by the complexation of the ALA and Zn(II) ions, and are readily controlled by varying the feed precursors and reaction temperatures. The maximum conjugated ALA amount is up to 17%. The Fe3O4@ALA-Zn(II) microspheres exhibit pH-sensitive release of ALA in acidic environment and rapid magnetic responsiveness. Cytotoxicity results demonstrate that Fe3O4@ALA-Zn(II) shows a significant inhibitory effect to T24 cells and is nontoxic to 293T normal cells as exposed to the 630 nm visible light for a very short time, which may due to the selective accumulation of ALA-induced PpIX in T24 cancer cells. Compared to the ALA used alone, the coordination polymer form is more efficient because of the bioactivity of incorporated Zn ions despite underlying the same apoptosis mechanism as ALA agent.

Selective Capture and Quick Detection of Targeting Cells with SERS-Coding Microsphere Suspension Chip.

Circulating tumor cells (CTCs) captured from blood fluid represent recurrent cancers and metastatic lesions to monitor the situation of cancers. We develop surface-enhanced Raman scattering (SERS)-coding microsphere suspension chip as a new strategy for fast and efficient capture, recovery, and detection of targeting cancer cells. Using HeLa cells as model CTCs, we first utilize folate as a recognition molecule to be immobilized in magnetic composite microspheres for capturing HeLa cells and attaining high capturing efficacy (up to 95%). After capturing cells, the composite microsphere, which utilizes a disulfide bond as crosslinker in the polymer shell and as a spacer for linking folate, can recycle 90% cells within 20 min eluted by glutathion solution. Taking advantage of the SERS with fingerprint features, we characterize captured/recovered cells with the unique signal of report-molecule 4-aminothiophenol through introducing the SERS-coding microsphere suspension chip to CTCs. Finally, the exploratory experiment of sieving cells shows that the magnetic composite microspheres can selectively capture the HeLa cells from samples of mixed cells, indicating that these magnetic composite microspheres have potential in real blood samples for capturing CTCs.

Multifunctional Magnetic Gd(3+) -Based Coordination Polymer Nanoparticles: Combination of Magnetic Resonance and Multispectral Optoacoustic Detections for Tumor-Targeted Imaging in vivo.

To overcome traditional barriers in optical imaging and microscopy, optoacoustic-imaging has been changed to combine the accuracy of spectroscopy with the depth resolution of ultrasound, achieving a novel modality with powerful in vivo imaging. However, magnetic resonance imaging provides better spatial and anatomical resolution. Thus, a single hybrid nanoprobe that allows for simultaneous multimodal imaging is significant not only for cutting edge research in imaging science, but also for accurate clinical diagnosis. A core-shell-structured coordination polymer composite microsphere has been designed for in vivo multimodality imaging. It consists of a Fe3 O4 nanocluster core, a carbon sandwiched layer, and a carbocyanine-Gd(III) (Cy-Gd(III) ) coordination polymer outer shell (Fe3 O4 @C@Cy-Gd(III) ). Folic acid-conjugated poly(ethylene glycol) chains are embedded within the coordination polymer shell to achieve extended circulation and targeted delivery of probe particles in vivo. Control of Fe3 O4 core grain sizes results in optimal r2 relaxivity (224.5 × 10(-3) m(-1) s(-1) ) for T2 -weighted magnetic resonance imaging. Cy-Gd(III) coordination polymers are also regulated to obtain a maximum 25.1% of Cy ligands and 5.2% of Gd(III) ions for near-infrared fluorescence and T1 -weighted magnetic resonance imaging, respectively. The results demonstrate their impressive abilities for targeted, multimodal, and reliable imaging.

Benzoboroxole-functionalized magnetic core/shell microspheres for highly specific enrichment of glycoproteins under physiological conditions.

Efficient enrichment of specific glycoproteins from complex biological samples is of great importance towards the discovery of disease biomarkers in biological systems. Recently, phenylboronic acid-based functional materials have been widely used for enrichment of glycoproteins. However, such enrichment was mainly carried out under alkaline conditions, which is different to the status of glycoproteins in neutral physiological conditions and may cause some unpredictable degradation. In this study, on-demand neutral enrichment of glycoproteins from crude biological samples is accomplished by utilizing the reversible interaction between the cis-diols of glycoproteins and benzoboroxole-functionalized magnetic composite microspheres (Fe3O4/PAA-AOPB). The Fe3O4/PAA-AOPB composite microspheres are deliberately designed and constructed with a high-magnetic-response magnetic supraparticle (MSP) core and a crosslinked poly(acrylic acid) (PAA) shell anchoring abundant benzoboroxole functional groups on the surface. These nanocomposites possessed many merits, such as large enrichment capacity (93.9 mg/g, protein/beads), low non-specific adsorption, quick enrichment process (10 min) and magnetic separation speed (20 s), and high recovery efficiency. Furthermore, the as-prepared Fe3O4/PAA-AOPB microspheres display high selectivity to glycoproteins even in the E. coli lysate or fetal bovine serum, showing great potential in the identify of low-abundance glycoproteins as biomarkers in real complex biological systems for clinical diagnoses.

Design of Unconventional Polymers with Thermal Contraction Units for High-Performance Dental Adhesives.

The coefficient of thermal expansion (CTE) of adhesives is considered to be a vital parameter for dental restoration due to the oral temperature fluctuation induced by hot and cold drinks in daily life. Even more challenging, the adhesives need to bond various materials with different CTE values, and mismatched thermal expansion at the interface of two materials will produce thermal stress and cause cracking, leading to bond failure. In this study, we designed and synthesized a divinyl monomer containing a dibenzocyclooctadiene (DBCOD) unit, which was incorporated into a commercial adhesive, Single Bond Universal (SBU) to prepare low CTE adhesives. The CTE value of the adhesives can be adjusted low to 6.5 ppm/K, which is much lower than that of pure SBU. Mimicking the real applying conditions, the composite resin columns were bonded to the zirconia ceramics as a dental crown with our designed adhesives, and the shear bond strength test was carried out before and after 10 000 thermal cycles between 5 and 55 °C. The shear bond strength of pure SBU retains 44.7% of its original value after 10 000 thermal cycles, while those low CTE adhesives retain 74.6% and 61.9% of shear bond strength due to less deformation and interfacial stress during thermocycling. The newly designed adhesives provide a persistent way to enhance the shear bond strength and achieve a long lifetime in tooth restoration.

Highly sensitive detection of target ssDNA based on SERS liquid chip using suspended magnetic nanospheres as capturing substrates.

A new approach for sensitive detection of a specific ssDNA (single-stranded DNA) sequence based on the surface enhanced Raman spectroscopy (SERS) liquid chip is demonstrated. In this method, the probe DNA (targeting to one part of target ssDNA) was attached to the nano-SERS-tags (poly(styrene-co-acrylic acid)/(silver nanoparticles)/silica composite nanospheres), and the capture DNA (targeting to the other part of target ssDNA) was attached to the Fe3O4/poly(acrylic acid) core/shell nanospheres. The nano-SERS-tags with probe DNA were first allowed to undergo hybridization with the target ssDNA in solution to achieve the best efficiency. Subsequently, the magnetic composite nanospheres with capture DNA were added as the capturing substrates of the target ssDNA combined with the nano-SERS-tags. Upon attraction with an external magnet, the nanospheres (including the nano-SERS-tags) were deposited together due to the hybridization, and the deposit sediment was then analyzed by SERS. Quantitative detection of target ssDNA was achieved based on the well-defined linear correlation between the SERS signal intensity and the target ssDNA quantity in the range of 10 nM to 10 pM, and the limit of detection was approximately 10 pM. Multiplexed detection of up to three different ssDNA targets in one sample was demonstrated using three different types of nano-SERS-tags under a single excitation laser. The experimental results indicated that the liquid-phase DNA sequencing method, thus named the SERS liquid chip (SLC) method, holds significant promises for specific detection of trace targets of organisms.

Combined Doxorubicin Mesoporous Carbon Nanospheres for Effective Tumor Lymphatic Metastasis by Multi-Modal Chemo-Photothermal Treatment in vivo.

Introduction: Sentinel lymph node (SLN) is the first regional lymph node where tumor cells metastasize, and its identification and treatment are of great significance for the prevention of tumor metastasis. However, the current clinical modalities for identification and treatment of SLN are still far from satisfactory owing to their high cost, invasiveness and low accuracy. We aim to design a novel nanomedicine system for SLN imaging and treatment with high efficacy. Methods: We designed and prepared hollow mesoporous carbon spheres (HMCS) and loaded with the chemotherapeutic drug doxorubicin (DOX), which is then modified with polyvinyl pyrrolidone (PVP) to obtain nanomedicine: HMCS-PVP-DOX. Results: HMCS-PVP with a size of about 150 nm could retain in the lymph nodes for a long time and stain the lymph nodes, which could be easily observed by the naked eye. At the same time, HMCS-PVP exhibited excellent photoacoustic and photothermal imaging capabilities, realizing multimodal imaging to locate lymph nodes precisely. Due to its high specific surface area, HMCS could be largely loaded with the chemotherapeutic drug doxorubicin (DOX). HMCS-PVP-DOX displayed highly efficient synergistic chemotherapy-photothermal therapy for lymphatic metastases in both cellular and animal experiments due to its significant photothermal effect under 1064 nm laser irradiation. HMCS-PVP-DOX also displayed great stability and biosafety. Discussion: Multifunctional nanomedicine HMCS-PVP-DOX is expected to provide a novel paradigm for designing nanomedicine to the diagnosis and treatment of lymphatic metastases because of its good stability and safety.

Hollow-core magnetic colloidal nanocrystal clusters with ligand-exchanged surface modification as delivery vehicles for targeted and stimuli-responsive drug release.

The fabrication of hierarchical magnetic nanomaterials with well-defined structure, high magnetic response, excellent colloidal stability, and biocompatibility is highly sought after for drug-delivery systems. Herein, a new kind of hollow-core magnetic colloidal nanocrystal cluster (HMCNC) with porous shell and tunable hollow chamber is synthesized by a one-pot solvothermal process. Its novelty lies in the "tunability" of the hollow chamber and of the pore structure within the shell through controlled feeding of sodium citrate and water, respectively. Furthermore, by using the ligand-exchange method, folate-modified poly(acrylic acid) was immobilized on the surface of HMCNCs to create folate-targeted HMCNCs (folate-HMCNCs), which endowed them with excellent colloidal stability, pH sensitivity, and, more importantly, folate receptor-targeting ability. These assemblages exhibited excellent colloidal stability in plasma solution. Doxorubicin (DOX), as a model anticancer agent, was loaded within the hollow core of these folate-HMCNCs (folate-HMCNCs-DOX), and drug-release experiments proved that the folate-HMCNCs-DOX demonstrated pH-dependent release behavior. The folate-HMCNCs-DOX assemblages also exhibited higher potent cytotoxicity to HeLa cells than free doxorubicin. Moreover, folate-HMCNCs-DOX showed rapid cell uptake apart from the enhanced cytotoxicity to HeLa cells. Experimental results confirmed that the synthesized folate-HMCNCs are smart nanovehicles as a result of their improved folate receptor-targeting abilities and also because of their combined pH- and magnetic-stimuli response for applications in drug delivery.

Toward designer magnetite/polystyrene colloidal composite microspheres with controllable nanostructures and desirable surface functionalities.

An effective method was developed for synthesizing magnetite/polymer colloidal composite microspheres with controllable variations in size and shape of the nanostructures and desirable interfacial chemical functionalities, using surfactant-free seeded emulsion polymerization with magnetite (Fe(3)O(4)) colloidal nanocrystal clusters (CNCs) as the seed, styrene (St) as the monomer, and potassium persulfate (KPS) as the initiator. The sub-micrometer-sized citrate-acid-stabilized Fe(3)O(4) CNCs were first obtained via ethylene glycol (EG)-mediated solvothermal synthesis, followed by 3-(trimethoxysilyl)propyl methacrylate (MPS) modification to immobilize the active vinyl groups onto the surfaces, and then the hydrophobic St monomers were polymerized at the interfaces to form the polymer shells by seeded emulsion radical polymerization. The morphology of the composite microspheres could be controlled from raspberry- and flower-like shapes, to eccentric structures by simply adjusting the feeding weight ratio of the seed to the monomer (Fe(3)O(4)/St) and varying the amount of cross-linker divinyl benzene (DVB). The morphological transition was rationalized by considering the viscosity of monomer-swollen polymer matrix and interfacial tension between the seeds and polymer matrix. Functional groups, such as carboxyl, hydroxyl, and epoxy, can be facilely introduced onto the composite microspheres through copolymerization of St with other functional monomers. The resultant microspheres displayed a high saturation magnetization (46 emu/g), well-defined core-shell nanostructures, and surface chemical functionalities, as well as a sustained colloidal stability, promising for further biomedical applications.

Short- and long-term toxicities of multi-walled carbon nanotubes in vivo and in vitro.

As nanomaterials are developed and applied, their potential for health hazards needs to be determined. In the present study, we used commercial nude multi-walled carbon nanotubes (MWCNTs) trimmed to a short length (50-200 nm; s-MWCNTs) and synthesized functionalized MWCNTs with polyethylene glycol (PEG) (s-MWCNTs-PEG). We then studied the toxic effects of s-MWCNTs and s-MWCNTs-PEG on cultured cells and in a mouse model. Peripheral haemograms and various biochemical markers of the heart, liver and kidney were measured. We found no toxicity of either type of nanotube on the viability of human SKBR-3 breast carcinoma cells or control cells. There were no differences in vivo on inflammatory responses, the coagulation system, haemograms or vital organ functions between the test and control groups. Additionally, we found no toxicity of these nanotubes on male mouse sperm production or mutagenesis in the long term. In conclusion, both s-MWCNTs and s-MWCNTs-PEG displayed good in vitro and in vivo biocompatibility, making future applications in biology and clinical therapy as a carrier for drug delivery feasible.

Sensitive and handy detection of pesticide residue on fruit surface based on single microsphere surface-enhanced Raman spectroscopy technique.

HYPOTHESIS: Surface-enhanced Raman spectroscopy (SERS) has become an emerging and reliable tool for detecting pesticide residues due to its high sensitivity, fast testing speed and easy sample handling. SERS active substrates are the key to achieve efficient and sensitive detection. However, for the most widely used noble metal nanoparticles, there are problems of high noble metal nanoparticle usage and random aggregation. The micron-scale Raman spot is focused on multiple randomly aggregated nanoparticles during the test, resulting in poor reproducibility. Therefore, the development of micron-scale cost-effective SERS substrates with good reproducibility and simple detecting method is of great significance in practical detection. EXPERIMENTS: Through deposition of silver nanoparticles (Ag-NPs) by chemical reduction on the surface of monodisperse sulfonated polystyrene (SPS) microspheres, micron-sized PS@Ag-NPs core-shell microspheres were prepared with excellent SERS activity. After that, two simple protocols (Method I and Method II) were explored for the determination of thiram on apple epidermis. FINDINGS: Based on our developed strategy of the single microsphere SERS technique, we successfully fabricated uniform PS@Ag-NPs substrate with high SERS activity and excellent detection sensitivity. The single microsphere SERS technique possesses the capability of anti-dilutability and the utilization of ultra-low PS@Ag-NPs microsphere dosage, realizing qualitative and quantitative detection of thiram on apple with detection limits far below the standard stipulated by China and the European Union.

Detecting trace melamine in solution by SERS using Ag nanoparticle coated poly(styrene-co-acrylic acid) nanospheres as novel active substrates.

A systematic study for the preparation of Ag nanoparticle (Ag-NP) coated poly(styrene-co-acrylic acid) (PSA) composite nanospheres by in situ chemical reduction is reported. The experimental results showed that the reaction temperature and the surface coverage of the -COOH determined the surface coverage and grain size of Ag nanoparticles on the PSA nanospheres. The surface enhanced Raman spectroscopy (SERS) sensitivity was investigated using 4-hydroxythiophenol (4-HBT) as the model probe in the solution of composite nanospheres stabilized by polyvinylpyrrolidone (PSA/Ag-NPs/PVP), with the detection limit of about 1 × 10(-6) M. Potential application of the new SERS substrate was demonstrated with the detection of melamine, and the detection limit was about 1 × 10(-3) M. Chemical noises from PVP and other impurities were observed and attributed mainly to the competitive adsorption of PVP on the surfaces of Ag-NPs. After tetrahydrofuran washing of the PSA/Ag-NPs/PVP substrates that removed the PVP and other residuals, the signal/noise levels of SERS were greatly improved and the detection limit of melamine was determined to be 1 × 10(-7) M. This result indicated that the new PSA/Ag-NPs system is highly effective and can be used as the SERS-active substrate for trace analysis of a variety of drugs and food additives.

Dual stimuli-responsive polymeric micelles exhibiting "AND" logic gate for controlled release of adriamycin.

A new controlled release polymer micelle was designed and synthesized based on the concept of the "AND" logic with two orthogonal molecular triggers, namely pH and reduction, for intracellular drug delivery. Specifically, a hydrazine functionalized PEO-b-PMAA block copolymer was used to attach adriamycin (ADR) through the formation of hydrazone, then the as-prepared ADR-conjugated block copolymer micelles could be crosslinked by dithiodiethanoic acid. ADR was found to release most efficiently under both the low pH and the reductive conditions. This smart device is therefore equipped with two triggers with the "AND" logic for the releasing action, which is suitable for more complicated physiological conditions because the "ON" state is only realized under the simultaneous presence of the dual signal stimuli.

Entropy-Driven Quick Loading of Functional Proteins in Nanohydrogels for Highly Efficient Tumor Targeting Therapy.

With the gradual deep understanding of the tumorigenesis and development process, nanodrug are thought to have great prospects for individualized treatment of tumors. To deliver adequate concentration of active ingredients to targeted tissues, proteins are usually used as carriers to avoid clearance by the immune system. Herein, a new strategy is developed for preparation of the protein-functionalized targeting nanodrugs; different kinds of proteins (albumin, horseradish, transferrin, and ricin) can be quickly loaded in polyacrylic acid nanohydrogels (PAA-NGs) without discrimination within 1 min under the strong driving force of entropy; and the loading efficiency can reach 99% with about 50% loading content. Meanwhile, the activity of the released protein can be well retained. After oriented binding of the targeting agent on the surface of the nanocarriers by a unique and facile technique, the protein-loaded nanodrug exhibits excellent tumor cell uptake and targeting effect. The excellent targeting ability from the oriented binding is further proved by comparing with the non-oriented targeting system. With quick loading of the anti-tumor protein of ricin and oriented binding of transferrin protein (Tf), the targeting nanodrug (PAA-BB@Ricin/Tf) shows a remarkable anti-tumor effect. This study proves a new universal delivery and targeting strategy for improving the nanodelivery system, which has great potentials for clinical application.

Carbon nanotubes promote neuron differentiation from human embryonic stem cells.

Human embryonic stem cells (hESCs) hold great promise for regenerative medicine and transplantation therapy due to their self-renewal and pluripotent properties. We report that 2D thin film scaffolds composed of biocompatible polymer grafted carbon nanotubes (CNTs), can selectively differentiate human embryonic stem cells into neuron cells while maintaining excellent cell viability. According to fluorescence image analysis, neuron differentiation efficiency of poly(acrylic acid) grafted CNT thin films is significant greater than that on poly(acrylic acid) thin films. When compared with the conventional poly-L-ornithine surfaces, a standard substratum commonly used for neuron culture, this new type thin film scaffold shows enhanced neuron differentiation. No noticeable cytotoxic effect difference has been detected between these two surfaces. The surface analysis and cell adhesion study have suggested that CNT-based surfaces can enhance protein adsorption and cell attachment. This finding indicates that CNT-based materials are excellent candidates for hESCs' neuron differentiation.

Rational synthesis of magnetic thermosensitive microcontainers as targeting drug carriers.

A new approach to the fabrication of magnetic thermosensitive microcontainers of Fe(3)O(4) nanoparticles with poly(N-isopropylacrylamide) walls is presented. The microcontainers undergo a temperature-induced volume phase transition and present an impressive magnetic response. The microcontainers have a well-defined structure with a narrow size distribution. The wall thicknesses of the microcontainers can be controlled according to requirements. Compared to other preparation methods, the process is simple and reproducible. The magnetic saturation of these microcontainers is high enough to meet most requirements of bioapplications. To further investigate the potential application of these microcontainers, they are tested as drug carriers, with the drug loading and releasing processes carefully studied. The drug encapsulation efficiency and drug content in the carriers are pH-dependent, and the carriers have a maximal drug loading of about 50 wt% under alkaline conditions. The release of the drug from the microcontainers can be controlled by the environmental pH, temperature, and magnetic force.