Binjie Li

Synthesis of water-soluble Cu/PAA composite flowers and their antibacterial activities.

Water-soluble copper/polyacrylic acid (Cu/PAA) composites were synthesized by a facile solution-phase reduction route. The Cu/PAA composites presented flower-like architecture, consisting of several intercrossing sheets, and reaction conditions had an important effect on their morphologies. Their antibacterial activity towards the bacterial strains such as Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) were evaluated by the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC), cup diffusion method and optical density (OD600). Results indicated that Cu/PAA flower is selective in its antibacterial action. It displays more effective antibacterial activity against B. subtilis than other three stains, and better bactericidal activity against S. aureus, E. coli and P. aeruginosa than B. subtilis. There is no bactericidal ability against B. subtilis in the tested concentration range, which indicates that B. subtilis may be a copper-tolerant bacterium.

Synthesis of poly acrylic acid modified silver nanoparticles and their antimicrobial activities.

Poly acrylic acid modified silver (Ag/PAA) nanoparticles (NPs) have been successfully synthesized in the aqueous solution by using tannic acid as a reductant. The structure, morphology and composition of Ag/PAA NPs were characterized by various techniques such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis) and thermogravimetry analysis (TGA). The results show that PAA/Ag NPs have a quasi-ball shape with an average diameter of 10 nm and exhibit well crystalline, and the reaction conditions have some effect on products morphology and size distribution. In addition, the as-synthesized Ag/PAA NPs antimicrobial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were evaluated by the methods of broth dilution, cup diffusion, optical density (OD600) and electron microscopy observation. The as-synthesized Ag/PAA NPs exhibit excellent antibacterial activity. The antimicrobial mechanism may be attributed to the damaging of bacterial cell membrane and causing leakage of cytoplasm.

Biofunctionalization of silica microspheres for protein separation.

Mercapto-silica (SiO2-SH) microspheres were prepared via direct hydrolysis of 3-mercaptopropyltrimethoxysilane (MPS) in a basic aqueous solution. The content of surface thiol group (SH) of SiO2-SH microspheres was measured by Ellmans reagent method and X-ray photoelectron spectroscopy (XPS) and the content of surface thiol group of SiO2-SH microspheres is strongly dependent on the reaction conditions. The thermal stability of SiO2-SH microspheres was evaluated by thermogravimetric (TG) analysis, which tended to reduce with the increase of content of surface thiol groups. SiO2-SH microspheres can be easily modified with reduced glutathione (GSH) to generate SiO2-GSH microspheres for the affinity separation of Glutathione S-transferase (GST). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to examine the validity of the separation procedure. The results showed that SiO2-GSH microspheres were efficient in GST affinity separation from mixed proteins.

Preparation of AgBr@SiO2 core@shell hybrid nanoparticles and their bactericidal activity.

AgBr@SiO2 core@shell hybrid nanoparticles (NPs) were successfully prepared by sol-gel method. Their morphology and structure were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The hybrid NPs are predominantly spherical in shape, with an average diameter of 180-200 nm, and each NP contains one inorganic core. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the hybrid NPs were examined against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), respectively. Results indicated that the AgBr@SiO2 NPs had excellent antibacterial activity.

Multifunctional hydroxyapatite nanoparticle-based affinity adsorbent with sensing and fluorescence imaging capacity

Nickel hydroxide/hydroxyapatite (Ni(OH)2/HAP) nanoparticles (NPs) coated with rhodamine B hydrazide (RBH) were successfully synthesized in three steps. First, Ni(OH)2/HAP-COOH NPs were synthesized by a facile hydrothermal route in the presence of citric acid. Second, rhodamine B was reacted with hydrazine hydrate to obtain rhodamine B hydrazide (RBH). Finally, RBH was conjugated on the surface of Ni(OH)2/HAP-COOH NPs to form Ni(OH)2/HAP-RBH. As affinity adsorbents, these NPs can directly purify histidine-tagged (His-tagged) proteins from a mixture of lysed cells, and exhibit high protein adsorption capacity with a maximum value of 115 mg g-1. A prominent fluorescence enhancement at 578 nm was observed in the presence of Pt2+, accompanied by a change in absorption spectrum. These NPs display excellent selectivity and sensitive recognition of Pt2+ in comparison with other metal ions and anions with a detection limit of 0.03 μM. These NPs exhibit low cytotoxicity and can be used as a probe for Pt2+ and living cell imaging.

Synthesis of petal-like ferric oxide/cysteine architectures and their application in affinity separation of proteins

Petal-like ferric oxide/cysteine (FeOOH/Cys) architectures were prepared through a solvothermal route, which possessed high thiol group density. These thiol groups as binding sites can chelate Ni(2+) ions, which can be further used to enrich and separate his-tagged proteins directly from the mixture of lysed cells without sample pretreatment. These results show that the FeOOH/Cys architectures with immobilized Ni(2+) ions present negligible nonspecific protein adsorption and high protein adsorption capacity, with the saturation capacity being 88mg/g, which are especially suitable for purification of his-tagged proteins.

Synthesis and antibacterial activity of Ag/CeO2 hybrid architectures

AbstractFlower-like ceria (CeO2) architectures consisting of well aligned nanosheets were first synthesized by a glycol solvothermal method. The size of CeO2 architectures is about 5 μm in width and 10 μm in length, with the nanosheets thickness below 100 nm. Subsequently, the adsorbed Ag ions on the surface of CeO2 were in situ reduced to form Ag nanoparticles (NPs), leading to the fabrication of Ag/CeO2 hybrid architectures (HAs). The formed Ag NPs with sizes of 20–40 nm were uniformly loaded on the surface of the CeO2 sheets. The antibacterial properties of Ag/CeO2 HAs against Gram-negative E. coli and Gram-positive S. aureus were evaluated by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and a filter paper inhibition zone method. The results demonstrated that Ag/CeO2 HAs displayed excellent antibacterial activity toward S. aureus and E. coli, which were attributed to the synergistic antibacterial effect between Ag NPs and CeO2 in HAs. Here, CeO2 nanoflowers as a new substrate could restrict Ag NPs aggregations and improve their antibacterial activities. Therefore, the resulted Ag/CeO2 HAs would be considered as a promising antibacterial agent. HighlightsFlower-like Ag/CeO2 hybrid architectures (HAs) were successfully fabricated.Ag/CeO2 HAs displayed excellent antibacterial activity towards S. aureus and E. coli.The improved antibacterial performance of Ag/CeO2 HAs was attributed to the synergistic effect between Ag NPs and CeO2.