Search

Bacteria employ numerous resistance mechanisms against structurally distinct drugs by the process of multidrug resistance. A study was planned to discover the antibacterial potential of a graphene oxide nanosheet (GO), a graphene oxide–zinc oxide nanocomposite (GO/ZnO), a graphene oxide-chitosan nanocomposite (GO–CS), a zinc oxide decorated graphene oxide–chitosan nanocomposite (GO–CS/ZnO), and zinc oxide nanoparticles (ZnO) alone and in a blend with antibiotics against a PS-2 isolate of Pseudomonas aeruginosa. These nanocomposites reduced the MIC of tetracycline (TET) from 16 folds to 64 folds against a multidrug-resistant clinical isolate. Efflux pumps were interfered, as evident by an ethidium bromide synergy study with nanocomposites, as well as inhibiting biofilm synthesis. These nanoparticles/nanocomposites also decreased the mutant prevention concentration (MPC) of TET. To the best of our knowledge, this is the first report on nanomaterials as a synergistic agent via inhibition of efflux and biofilm synthesis.

The composite adsorbent graphene oxide-chitosan was prepared using graphite and chitosan as the initial materials. The structures and morphology of the products were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy. The products were used to remove uranium from aqueous solution by batch adsorption experiments. The effects of pH, adsorbent dosage, contact time, initial uranium concentration and temperature on the uranium removal were investigated, and the results were fitted by the adsorption isotherm models. The adsorption kinetic and thermodynamic were also studied in detail. [ABSTRACT FROM AUTHOR]

Magnetic architecture incorporating graphene-chitosan has demonstrated encouraging application in wastewater purification. Herein, a ternary hybrid based on Fe 3 O 4 -graphene oxide-chitosan (MGOCS) was fabricated and employed as adsorbent to remove aqueous Zn(II). The adsorption mechanism was intensively inspected based on the hard and soft acid base (HSAB) theory. Results present, MGOCS removes 96.73 % of Zn(II) in 38 min, with adsorption quantity 386.92 mg·g−1. Electron transfer and energy lowering determined by the HSAB theory illuminate the plausible adsorption sites in each component of MGOCS: O 2 − in Fe 3 O 4 , -C(=O)NH-, -NH 2 in chitosan and -OH in graphene oxide. The exploration was upheld by spectroscopic analyses. Thereby, following adsorption mechanism was proposed. (1) Zn O bond was formed featured by electron donation. (2) The -C(=O)NH- group formed via amidation between graphene oxide and chitosan contributes to Zn(Π) uptake. This work may inspire the development of efficient adsorbent based on magnetic graphene-chitosan for wastewater remediation. ▪ CS ▪ GO ▪ Fe 3 O 4 ▪ Zn(Π) → direction of electron flow. Plausible adsorption mechanism of Zn(Π) by MGOCS. [Display omitted] • Fe 3 O 4 -graphene oxide-chitosan (MGOCS) was facilely fabricated. • MGOCS removes 96.73 % of Zn(II) in 38 min, with adsorption quantity 386.92 mg·g−1. • HSAB theory illuminates the plausible adsorption sites in MGOCS. • -C(=O)NH- was formed via amidation reaction between graphene oxide and chitosan. • -C(=O)NH- and π electrons contributes to Zn(Π) uptake mainly featured by Zn O bond. [ABSTRACT FROM AUTHOR]

Three dimensional (3D) magnetic graphene oxide–chitosan (GO–CS) composites with orderly self-assembled magnetite (Fe 3 O 4 ) nanoparticles (GO–CS–Fe3O4) were successfully fabricated. First, the covalent functionalization of graphene oxide (GO) using chitosan (CS) was successfully accomplished via a facile amidation process, forming a 3D network. In the as-fabricated GO–CS composites, GO sheets remained less aggregated, exhibiting a large surface area, and the interconnected pores in the hydrogels allowed object molecules to diffuse easily into the composites. Subsequently, the GO–CS–Fe 3 O 4 composites were synthesized using FeCl 3 ·6H 2 O and GO–CS composite as the starting materials through a solvothermal reaction. The resulting composite combined the features of the high surface area of GO, abundant amino, and hydroxyl functional groups of CS, and the magnetic response of magnetic nanoparticles. For further application, these composites were utilized to immobilize Candida rugosa lipase via different routes, and they showed excellent immobilization capacities. [ABSTRACT FROM AUTHOR]

• Nanomaterial was used as the novel adjuvant to enhance the efficacy of CSBV vaccines. • An high-efficient immunization program for production of high-titer EYA was established. • Different adjuvants, immunization protocols and CSBV vaccine types were compared. • EYA offer a significant protection rate (98.9 to 100%) against the CSBV infection. • EYA have been applied more than two years against CSBV in Chinese actual bee breeding. Chinese sacbrood virus (CSBV) poses a serious threat to the apiculture of China. Although several approaches have been attempted to control CSBV infection, their applications have been greatly limited in practical breeding of honeybees due to poor effectiveness. Egg yolk antibodies (EYA) have shown a promising protection for bees against CSBV infection. This study was conducted to produce high titer EYA and then further improve their antiviral effect. Among three vaccination groups, the EYA titer in graphene oxide-chitosan group was highest (1.591 ± 0.145), in Freund's group was modest (1.195 ± 0.040), and in white oil group was lowest (1.058 ± 0.056). After three injections of each vaccine in hens, EYA were produced at the highest level with a 14-day period. After application of EYA for more than two years in actual bee breeding, prevention and treatment assays showed that EYA confered 98.9 to 100% protection from CSBV infection. The mortality of the control group reached to a range of 91.2 to 100%. This study demonstrated that the high titer EYA have been successfully prepared with significant anti-CSBV activity and that these antibodies may feasibly be used for CSBV treatment to meet the practical needs of apiculture. [ABSTRACT FROM AUTHOR]

Bacteria employ numerous resistance mechanisms against structurally distinct drugs by the process of multidrug resistance. A study was planned to discover the antibacterial potential of a graphene oxide nanosheet (GO), a graphene oxide–zinc oxide nanocomposite (GO/ZnO), a graphene oxide-chitosan nanocomposite (GO–CS), a zinc oxide decorated graphene oxide–chitosan nanocomposite (GO–CS/ZnO), and zinc oxide nanoparticles (ZnO) alone and in a blend with antibiotics against a PS-2 isolate of Pseudomonas aeruginosa. These nanocomposites reduced the MIC of tetracycline (TET) from 16 folds to 64 folds against a multidrug-resistant clinical isolate. Efflux pumps were interfered, as evident by an ethidium bromide synergy study with nanocomposites, as well as inhibiting biofilm synthesis. These nanoparticles/nanocomposites also decreased the mutant prevention concentration (MPC) of TET. To the best of our knowledge, this is the first report on nanomaterials as a synergistic agent via inhibition of efflux and biofilm synthesis. [ABSTRACT FROM AUTHOR]