Dongtao Ge

Nonenzymatic biosensor based on CuxO nanoparticles deposited on polypyrrole nanowires for improving detectionrange

Cu(x)O (CuO and Cu₂O composite) nanoparticles modified polypyrrole (PPy) nanowires were fabricated and used as a biosensor for detecting glucose (GLC). PPy nanowires were prepared through electrodeposition, while Cu(x)O nanoparticles were deposited on PPy nanowires by electrodeposition and electrochemical oxidation in situ. The scanning electron microscopy images showed the Cu(x)O nanoparticles aligned along the PPy nanowires uniformly and the average size of Cu(x)O nanoparticles is about 90 nm. The electrocatalytic activity of Cu(x)O/PPy/Au towards GLC was investigated under alkaline conditions using cyclic voltammetry and chronoamperometry. The sensor exhibited a linear range up to 8 mM of GLC, which is more than two times of most of the existing non-enzymatic GLC sensors based on CuO or Cu₂O. The sensitivity of the sensor is 232.22 μAmM⁻¹ cm⁻² and detection limit is 6.2 μM (at signal/noise=3). Moreover, the sensor showed excellent selectivity, reproducibility and stability properties. These excellent performances make Cu(x)O/PPy/Au a good nonenzymatic GLC sensor.

Electrochemical synthesis of polypyrrole nanowires on composite electrode

Abstract Polypyrrole nanowires growing with two-dimensional instantaneous nucleation and one-dimensional growth pattern were realized on graphite/paraffin composite electrode in phosphate buffer solution.

Starch-assisted synthesis of polypyrrole nanowires by a simple electrochemical approach

Starch, one of the most commonly used polysaccharides, has been adopted for the first time as morphology-directing agent to the electrochemical synthesis of polypyrrole (PPy) nanowires on various electrodes.

Nanowire-Based Polypyrrole Hierarchical Structures Synthesized by a Two-Step Electrochemical Method

A simple two-step electrochemical method is proposed for the synthesis of nanowire-based polypyrrole hierarchical structures. In the first step, microstructured polypyrrole films are prepared by electropolymerization. Then, polypyrrole nanowires are electrodeposited on the surface of the as-synthesized microstructured polypyrrole films. As a result, hierarchical structures of polypyrrole nanowires on polypyrrole microstructures are obtained. The surface wettabilities of the resulting nanowire-based polypyrrole hierarchical structures are examined. It is expected that this two-step method can be developed into a versatile route to produce nanowire-based polypyrrole hierarchical structures with different morphologies and surface properties.

Cellular Uptake Mechanism of Molecular Umbrella

Molecular umbrella provided a promising avenue for the design of the intracellular delivery of hydrophilic therapeutic agents. However, the limited understanding of its cellular uptake would be a roadblock to its effective application. Herein, we investigate the ability and mechanism of cellular entry of a fluorescently labeled diwalled molecular umbrella, which was synthesized from cholic acid, spermine, and 5-carboxyfluorescein, into Hela cells, with the extent of uptake analyzed by confocal fluorescence microscopy and flow cytometry. It is found that the as-synthesized diwalled molecular umbrella can greatly facilitate cellular uptake of hydrophilic agent, 5-carboxyfluorescein. In vitro experiments with diffuse marker, endocytic marker, and inhibitors suggested that several distinct uptake pathways (e.g., passive diffuse, clathrin-mediated endocytosis, and caveolae/lipid-raft-dependent endocytosis) are involved in the internalization of diwalled molecular umbrella. These results, together with its low toxicity and good biocompatibility, thus demonstrate the suitability of molecular umbrella for application as vectors in drug delivery systems.

Surface-modified anodic aluminum oxide membrane with hydroxyethyl celluloses as a matrix for bilirubin removal

Microporous anodic aluminum oxide (AAO) membranes were modified by 3-glycidoxypropyltrimethoxysilane to produce terminal epoxy groups. These were used to covalently link hydroxyethyl celluloses (HEC) to amplify reactive groups of AAO membrane. The hydroxyl groups of HEC-AAO composite membrane were further modified with 1,4-butanediol diglycidyl ether to link arginine as an affinity ligand. The contents of HEC and arginine of arginine-immobilized HEC-AAO membrane were 52.1 and 19.7mg/g membrane, respectively. As biomedical adsorbents, the arginine-immobilized HEC-AAO membranes were tested for bilirubin removal. The non-specific bilirubin adsorption on the unmodified HEC-AAO composite membranes was 0.8mg/g membrane. Higher bilirubin adsorption values, up to 52.6mg/g membrane, were obtained with the arginine-immobilized HEC-AAO membranes. Elution of bilirubin showed desorption ratio was up to 85% using 0.3M NaSCN solution as the desorption agent. Comparisons equilibrium and dynamic capacities showed that dynamic capacities were lower than the equilibrium capacities. In addition, the adsorption mechanism of bilirubin and the effects of temperature, initial concentration of bilirubin, albumin concentration and ionic strength on adsorption were also investigated.

Bioactive gelatin-siloxane hybrids as tissue engineering scaffold

Ca2+-containing porous gelatin-siloxane hybrids were prepared using sol-gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A bone-like apatite layer was able to form in the Ca2+-containing porous gelatin-siloxane hybrids upon soaking in a stimulated body fluid. The porous gelatin-siloxane hybrids could release gentamicin sulfate which is an antibiotic drug in bone chemotherapy. Thus, those hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.

Polydopamine-functionalized nanographene oxide: a versatile nanocarrier for chemotherapy and photothermal therapy

For releasing both drug and heat to selected sites, a combination of chemotherapy and photothermal therapy in one system is a more effective way to destroy cancer cells than monotherapy. Graphene oxide (GO) with high drug-loading efficiency and near-infrared (NIR) absorbance has great potential in drug delivery and photothermal therapy, but it is difficult to load drugs with high solubility. Herein, we develop a versatile drug delivery nanoplatform based on GO for integrated chemotherapy and photothermal therapy by a facile method of simultaneous reduction and surface functionalization of GO with poly(dopamine) (PDA). Due to the excellent adhesion of PDA, both low and high solubility drugs can be encapsulated in the PDA-functionalized GO nanocomposite (rGO-PDA). The fabricated nanocomposite exhibits good biocompatibility, excellent photothermal performance, high drug loading capacity, an outstanding sustained release property, and efficient endocytosis. Moreover, NIR laser irradiation facilitates the release of loaded drugs from rGO-PDA. These features make the rGO-PDA nanocomposite achieve excellent in vivo synergistic antitumor therapeutic efficacy.

Synthesis of polypyrrole nanowires with positive effect on MC3T3-E1 cell functions through electrical stimulation

Conducting polymer polypyrrole (PPy) possesses good biocompatibility and conductivity and has been used as functional coatings in bone tissue regeneration. In this study, a cholic acid doped PPy nanowires (PPy NWs) coating was electrochemically polymerized on the surface of titanium (Ti). The porous intertwined PPy NWs coating exhibited excellent electrical conductivity and electrochemical activity, better hydrophilicity and higher surface energy. In vitro cell experiments demonstrated that the PPy NWs coating together with a 10μA substrate-mediate electrical stimulation (ES) was capable to positive regulate the functions of MC3T3-E1 such as cell adhesion, proliferation and differentiation. Further long-term functions of cell tests including alkaline phosphatase (ALP) activity, bone-carboxyglutamic acid-containing protein (BGP) and calcium deposition were all thoroughly increased. These confirmed that the combination of PPy NWs and ES could accelerate MC3T3-E1 cells mature and osteogenesis. Hence, the PPy NWs coating was an electro bioactive coating and may have potential applications in the treatment of bone damage repairing and regeneration with ES.

One-step deposition of a melanin-like polymer on individual Escherichia coli cells exhibiting a special UV resistance effect

Melanin has an excellent ability to absorb UV radiation and to convert harmful radiant energy into heat or antioxidants. Therefore, melanin has a significant potential to endow fragile organisms such as recombinant or bioengineered microbes with a photoprotective ability. Inspired by mussel adhesive foot protein, a dopamine monomer (DA) was reported to self-polymerize into a melanin-like polymer, named polydopamine (PDA). Herein, combining the similarity to natural melanin and chemical adhesivity of the melanin-like PDA polymer, we prepared PDA encapsulated Escherichia coli cells (E. coli@PDA) with a simple method. The PDA encapsulation could retain E. coli cells viability and inhibited cell division. More importantly, the aromatic PDA shells could absorb the UV light and protect the cells against damage from UV radiation. After a prolonged exposure time to UV radiation, the protein stability, cellular metabolically active and cell viability of the E. coli cells were preserved. We believe that our work provides new insights for both fundamental research and applications of cell encapsulation for UV resistance.