Chengyong Li

Mussel-inspired synthesis of polydopamine-functionalized calcium carbonate as reusable adsorbents for heavy metal ions

A new high-efficiency adsorbent (PDA-CaCO3) is fabricated via simple thermal calcination of ostracean shells and chemical modification with dopamine. The adsorption capacity for Pb(II) and Cd(II) was 336.32 and 175.48 mg g−1, respectively. Importantly, it can be easily regenerated by low-cost reagents, and exhibited a high adsorption capacity after multiple adsorption–desorption cycles.

Novel low temperature (<37 °C) chitosan hydrogel fabrication under the synergistic effect of graphene oxide

A novel low temperature chitosan hydrogel (<37 °C) was fabricated via a simple mixing method under the synergistic effect of graphene oxide. The effect of the concentration of chitosan, β-glycerophosphate and graphene oxide on the gelation temperature and time of the chitosan hydrogel was studied. It can begin to form a gel at under 33 °C after adding 0.3 wt% graphene oxide, which is 6 °C lower than the temperature required for a chitosan hydrogel without graphene oxide. In addition, the gelation time is shortened to 9 min under the synergistic effect of graphene oxide. The controlled release of drugs from this hydrogel is also improved compared with that from traditional chitosan hydrogels. This novel low temperature hydrogel is expected to be applied in the field of hydrogel medical coatings.

A GRAPHENE/ENZYME-BASED ELECTROCHEMICAL SENSOR FOR SENSITIVE DETECTION OF ORGANOPHOSPHORUS PESTICIDES

A sensitive and fast sensor for quantitative detection of organophosphorus pesticides (OPs) is obtained using acetylcholinesterase (AChE) biosensor based on graphene oxide (GO)–chitosan (CS) composite film. This new biosensor is prepared via depositing GO–CS composite film on glassy carbon electrode (GCE) and then assembling AChE on the composite film. The GO–CS composite film shows an excellent biocompatibility with AChE and enhances immobilization efficiency of AChE. GO homogeneously disperses in the GO–CS composite films and exhibits excellent electrocatalytic activity to thiocholine oxidation, which is from acetylthiocholine catalyzed by AChE. The results show that the inhibition of carbaryl/trichlorfon on AChE activity is proportional to the concentration of carbaryl/trichlorfon. The detection of linear range for carbaryl is from 10nM to 100nM and the correlation coefficients of 0.993. The detection limit for carbaryl is calculated to be about 2.5nM. In addition, the detection of linear range for trichlorfon is from 10nM to 60nM and the correlation coefficients of 0.994. The detection limit for trichlorfon is calculated to be about 1.2nM. This biosensor provides a new promising tool for trace organophosphorus pesticide detection.

Changes in the myosin secondary structure and shrimp surimi gel strength induced by dense phase carbon dioxide

Dense phase carbon dioxide (DPCD) could induce protein conformation changes. Myosin and shrimp surimi from Litopenaeus vannamei were treated with DPCD at 5-25MPa and 40-60°C for 20min. Myosin secondary structure was investigated by circular dichroism and shrimp surimi gel strength was determined using textural analysis to develop correlations between them. DPCD had a greater effect on secondary structure and gel strength than heating. With increasing pressure and temperature, the α-helix content of DPCD-treated myosin decreased, while the β-sheet, β-turn and random coil contents increased, and the shrimp surimi gel strength increased. The α-helix content was negatively correlated with gel strength, while the β-sheet, β-turn and random coil contents were positively correlated with gel strength. Therefore, when DPCD induced myosin to form a gel, the α-helix of myosin was unfolded and gradually converted to a β-sheet. Such transformations led to protein-protein interactions and cross-linking, which formed a three-dimensional network to enhance the gel strength.

Zein-paclitaxel prodrug nanoparticles for redox-triggered drug delivery and enhanced therapeutic efficiency

Prodrug, in which the inactive parent drug with good bioavailability is metabolized into an active drug in the body, is one of the main strategies to target the disease site to improve the drug efficiency and reduce the adverse effects of chemotherapy. Because of the good capability of chemical modification, zein, a plant derived protein, and drugs can be conjugated through environmentally sensitive links to form prodrugs capable of triggered drug release. In this study, a novel prodrug was synthesized using paclitaxel (PTX), zein, and a disulfide linker, and nanoparticles were formed by self-assembly of the prodrug. An effective in vitro triggered release, 80-90% in 5 min, of the prodrug based nanoparticles (zein-S-S-PTX_NP) was successfully approached. The cytotoxicity of zein-S-S-PTX_NP as well as the zein encapsulation of PTX (zein_PTX_NP) and pure PTX on HeLa cells and NIH/3T3 fibroblast cells was tested using MTS assay. It showed that, after the treatment of zein-S-S-PTX_NP at the equivalent PTX concentrations of 0.1, 0.5, 1, and 5 μg/mL, respectively, zein-S-S-PTX_NP had zero damage to normal cells but a similar cytotoxicity to cancer cells as pure PTX. In the animal study, the tumor was 50% of the original size after the treatment of zein-S-S-PTX_NP for 9 days with 3 doses. This study suggested that the novel prodrug based nanoparticle zein-S-S-PTX_NP could be a promising approach in chemotherapy with targeted delivery, improved efficacy, and reduced side effects.

Fabrication of CNx/C nanotube arrays via chemical modification in situ and application in an electronic nano-device

CNx/C nanotube arrays were fabricated via a simple chemical modification porous alumina membrane in situ method. The nanotubes consist of two sections featuring straight and hollow cylinder structure, one section made of N-doped carbon and the other one made of pure carbon. The metal–semiconductor junction was formed in the middle as a result of being doped or undoped with nitrogen. The on–off current ratio at ±5 V is 25. The applicability of chemical modification in situ technique provides us with a good opportunity for practical use of the multiwall nanotube for future nano-devices.