In Situ Synthesis of Silver Nanoparticles for Ag‐NP/Cotton Nanocomposite and Its Bactericidal Effect

For years, nanotechnology has been considered as an important field that has opened new opportunities for extensive research. In biomedical applications, of all the metal nanoparticles, silver nanoparticles (Ag‐NPs) have played an important role because of their antibacterial properties. Ag‐NPs have been demonstrated to possess antibacterial properties in many applications. However, the minimum number of NPs required on the surface to prevent bacterial growth is yet to be determined. It is worthwhile studying the decrease of bacterial growth rate or the level of inhibition as a function of the size or density of NPs. Therefore, in this paper we discuss the size of the NPs that can stimulate the bactericidal property. It should also be noted that NPs larger than 100 nm might not be effective against bacteria. Moreover, this study employs polyvinyl pyrrolidone (PVP) and cellulose as reductants to form strong covalent bonds under UV light, which can help synthesize Ag‐NP/cotton nanocomposites. This type of nanocomposite displays high cell viability and improved antimicrobial activity. A fairly simple application involves the use of UV light to increase particle distribution and impart bactericidal property.     

A simple and highly repeatable colorimetric toxicity assay method using 2,6-dichlorophenolindophenol as the redox color indicator and whole eukaryote cells

A simple and highly reproducible toxicity assay method was studied by employing 2,6-dichlorophenolindophenol (DCIP) as a redox color indicator, baker’s yeast Saccharomyces cerevisiae, and a thermostable three-consecutive-stir unit. The absorbance of DCIP was decreased by increasing the metabolism activity of S. cerevisiae to intake glucose as an organic substance. By optimizing the measurement conditions, we obtained highly sensitive responses to glucose between 0.75 and 30 mg/L (eight points, n = 3) with an incubation time of the reaction mixture of 10 min at 30 °C. An excellent value of 1.15% was obtained as the average of the repeatability from eight points. Next, for the characterization of this method, we investigated the influence on the colorimetric response of dissolved substances, such as inorganic ions and surfactants, in natural water. Furthermore, the colorimetric responses to several toxicants were examined using Cu²⁺, Mn²⁺, Zn²⁺, Cr³⁺, and Fe³⁺ as heavy-metal ions and simazine as an agricultural chemical. As a result, notable colorimetric responses were obtained for Cu²⁺ and Mn²⁺ at several concentrations, and the results were compared with those obtained using river water as a real sample. In the stability test, responses to 30 mg/L glucose were obtained for 28 days when the yeast cell suspension was stored at 4 °C (response reduction, 43.9%; average of the relative standard deviation for nine testing days, 22.7%; average of repeatability, 1.01%). Figure Graphical image of the colorimetric toxicity assay     

Synthesis,structure and antimicrobial study of two new copper(II) complexes derived from N-(3-aminopropyl) benzylamine ligand (apba) and N-salicylidene-apba

Two new copper(II) complexes were synthesized by reaction of N-(3-aminopropyl)benzylamine (L1: apba, for complex 1) and N-salicylidene-apba (L2: for complex 2) with Cu²⁺. Crystals of complex 1 were orthorhombic, space group pccn, with a?=?15.2149(10), b?=?25.0071(16), c?=?7.6280(5)?Å and α?=?β?=?γ?=?90°. Complex 2 crystals were monoclinic, space group P2₁/c, with a?=?8.688(6), b?=?12.812(9), c?=?16.022(11)?Å and β?=?99.241(10)°. Structures of the two complexes were centro-symmetric and both Cu(II) atoms were four coordinate with a distorted square-planar geometry. The toxicity of the complexes was evaluated by testing antimicrobial activity against bacterial strands.     

Cytochrome c biosensor for determination of trace levels of cyanide and arsenic compounds

An electrochemical method based on a cytochrome c biosensor was developed, for the detection of selected arsenic and cyanide compounds. Boron doped diamond (BDD) electrode was used as a transducer, onto which cytochrome c was immobilised and used for direct determination of Prussian blue, potassium cyanide and arsenic trioxide. The sensitivity as calculated from cyclic voltammetry (CV) and square wave voltammetry (SWV), for each analyte in phosphate buffer (pH = 7) was found to be in the range of (1.1–4.5) × 10⁻⁸ A μM⁻¹ and the detection limits ranged from 4.3 to 9.1 μM. The biosensor is therefore able to measure significantly lower than current Environmental Protection Agency (EPA) and World Health Organisation (WHO) guidelines, for these types of analytes. The protein binding was monitored as a decrease in biosensor peak currents by SWV and as an increase in biosensor charge transfer resistance by electrochemical impedance spectroscopy (EIS). EIS provided evidence that the electrocatalytic advantage of BDD electrode was not lost upon immobilisation of cytochrome c. The interfacial kinetics of the biosensor was modelled as equivalent electrical circuit based on electrochemical impedance spectroscopy data. UV–vis spectroscopy was used to confirm the binding of the protein in solution by monitoring the intensity of the soret bands and the Q bands. FTIR was used to characterise the protein in the immobilised state and to confirm that the protein was not denatured upon binding to the pre-treated bare BDD electrode. SNFTIR of cyt c immobilised at platinum electrode, was used to study the effect of oxidation state on the surface bond vibrations. The spherical morphology of the immobilised protein, which is typical of native cytochrome c, was observed using scanning electron microscopy (SEM) and confirmed the immobilisation of the cytochrome c without denaturisation.     

Synthesis and Anti-leukemia Evaluation of Tetrahydro-4H-pyrano[3,2-c]pyridines and Corresponding Anti-CD14 Monoclonal Antibody Conjugates

A series of novel tetrahydro-4H-pyrano[3,2-c]pyridines（3a-3p） were synthesized and found to possess potent antiproliferative activity against leukemia K562 cells in vitro. Preliminary bioassay indicates that compounds 3a and 3e afford the best activity, the IC50 values of them were 6.93 and 7.51μg/mL, respectively, which were lower than that of the anticancer drug 5-FU（1C50=8.56μg/mL）. To reduce the toxicity of compounds 3a-3p to the prolife- ration of normal bematopoietic cells, a tumor targeted CD14 monoclonal antibody（McAb） was used in conjugation with compounds 3a--3p to get conjugates 4a--4p, respectively. The inhibitory activities of conjugates 4a--4p toward K562 cells were discovered to approach those of compounds 3a--3p. In the presence of CD14 McAb, tumor cells were found to be much more susceptible to conjugates 3a--3p than normal hematopoietic cells. Therefore, the toxicity of conjugates 4a--4p to normal hematopoietic cells declined obviously. For example, as for the toxicity of compound 3a compared with that of compound 4a, the value of ICs0 increased from 35.90 μmol/L to 39.52 μmol/L.     

Evaluation of ferricyanide effects on microorganisms with multi-methods

In this study, we report the effects of ferricyanide on organisms based on the changes in physiological state and morphology of Escherichia coli (E. coli) DH 5 α after being pretreated by ferricyanide. The impact on bacterial cell growth and viable rate of exposure to different concentrations of ferricyanide was determined, and the morphology change of E. coli was studied by atomic force microscopy (AFM). Finally, recovery test was used to evaluate the recovery ability of injured cells. The results showed that the effects on growth and morphology of E. coli were negligible when the concentration of ferricyanide was below 25.0 mM. While the results showed 50.8% inhibition of growth in the presence of 50.0 mM ferricyanide for 3 h, 89.6% viability was detected by flow cytometry (FCM) assay. AFM images proved that compact patches appeared on the bacterial surface and protected the bacterial viability. Furthermore, the results revealed that deterioration of bacterial surface closely related to the incubation time from 0.5 to 3 h at 100.0 mM ferricyanide. In the recovery test, microbial cell population and dissolved oxygen individually decreased 36.7% and 28.3% with 25.0 mM ferricyanide. These results clearly demonstrated that ferricyanide indeed affected viability of cells than morphology damaged, and the effects of toxin on bacteria were not reversible.     

Dodecaborate cluster lipids with variable headgroups for boron neutron capture therapy: Synthesis, physical-chemical properties and toxicity

We have prepared two new boron-containing lipids with potential use in boron neutron capture therapy of tumors. These lipids consist of a diethanolamine frame with two myristoyl chains bonded as esters, and a butylene or ethyleneoxyethylene unit linking the doubly negatively charged dodecaborate cluster to the amino function of the frame, obtained by nucleophilic attack of the amino on the tetrahydrofurane and dioxane derivatives, respectively, of closo-dodecaborate. The latter cluster lipid can form liposomes at 25 °C whereas the former lipid at this temperature assembles into bilayer disks. Both lipids form stable liposomes when mixed with suitable helper lipids. The thermotropic behavior was found to be different for the two lipids, with the butylene lipid showing sharp melting transitions at surprisingly high temperatures. Toxicity in vitro and in vivo varies greatly, with the butylene derivative being more toxic than the ethyleneoxyethylene derivative.     

Degradation of chlortetracycline in wastewater sludge by ultrasonication,Fenton oxidation,and ferro-sonication

Residual emerging contaminants in wastewater sludge remain an obstacle for its wide and safe applications such as landfilling and bio-fertilizer. In this study, the feasibility of individual ultrasonication (UlS) and Fenton oxidation (FO) and combined, Ferro-sonication processes (FO) on the degradation of chlortetracycline (CTC) in wastewater sludge was investigated. UlS parameters such as amplitude and sonication time were optimized by response surface methodology (RSM) for further optimization of FS process. Generation of highly reactive hydroxyl radicals in FO and FS processes were compared to evaluate the degradation efficiency of CTC. Increasing in the ratio of hydrogen peroxide and iron concentration showed increased CTC degradation in FO process; whereas in FS, an increase in iron concentration did not show any significant effect (p > 0.05) on CTC degradation in sludge. The estimated iron concentration in sludge (115 mg/kg) was enough to degrade CTC without the addition of external iron. The only adjustment of sludge pH to 3 was enough to generate in-situ hydroxyl radicals by utilizing iron which is already present in the sludge. This observation was further supported by hydroxyl radical estimation with adjustment of water pH to 3 and with and without the addition of iron. The optimum operating UlS conditions were found to be 60% amplitude for 106 min by using RSM. Compared to standalone UlS and FO at 1:1 ratio, FS showed 15% and 8% increased CTC degradation respectively. In addition, UlS of sludge increased estrogenic activity 1.5 times higher compared to FO. FS treated samples did not show any estrogenic activity.     

Toxicity biomonitoring of degradation byproducts using freeze-dried recombinant bioluminescent bacteria

A toxicity biomonitoring system using freeze-dried recombinant bioluminescent bacteria was implemented to diagnose the biotreatment of 2,4,5-trichlorophenol and its degradation byproducts of using a cell-free culture broth of Phanerochaete chrysosporium. The cellular toxicity was measured by the bioluminescence of constitutive bioluminescent bacteria, such as Photobacterium phosphoreum and GC2, while information on the toxicity caused by unknown byproducts was obtained using the specific bioluminescent responses of stress-inducible bioluminescent bacteria, which included DPD2540 (membrane-damage sensitive), TV1061 (protein-damage sensitive), DPD2794 (DNA-damage sensitive), and DPD2511 (oxidative-damage sensitive) strains. An overall decrease in the cellular toxicity was observed as the treatment progressed, i.e. as 2,4,5-trichlorophenol disappeared. On the other hand, bioluminescent responses from DPD2511, DPD2540, and TV1061 increased as degradation progressed, most probably due to the formation of byproducts causing oxidative-, membrane-, and protein-damage. In conclusion, this toxicity biomonitoring method may be applied to evaluate the toxicities of degradation byproducts of the other environmental processes to provide more information about the mode of the byproducts’ toxicity.