Highly efficient multifunctional graphene/chitosan/magnetite nanocomposites for photocatalytic degradation of important dye molecules.

Multifunctional chitosan/magnetite (CS/Fe3O4) and graphene/chitosan/magnetite (Gr/CS/Fe3O4) nanocomposites (NCs) were synthesized using a simple hydrothermal method. The NCs were subsequently evaluated as magnetic photocatalysts towards the photodegradation of dye molecules that are detrimental to the environment. In the present study, sphere shaped Fe3O4 nanoparticles (NPs) were found to uniformly decorate CS and Gr surfaces. The synthesized Fe3O4 NPs, CS/Fe3O4 and Gr/CS/Fe3O4 NCs were characterized by powder X-ray diffraction, Fourier-transform infrared and Raman spectroscopy, thermogravimetric analysis, UV-visible diffuse reflectance and photoluminescence spectroscopy, and field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The Gr/CS/Fe3O4 NCs showed 100% photocatalytic efficiency against rhodamine B (40 min), bromothymol blue (60 min), methylene blue (80 min) and methyl orange (100 min) compared to Fe3O4 NPs (100 min for Rh-B, 120 min for BTB, 160 min for MB and 180 min for MO) and CS/Fe3O4 NCs (90 min for Rh-B, 100 min for BTB, 140 min for MB and 150 min for MO). The photocatalytic irradiation efficiency of Fe3O4 NPs, CS/Fe3O4 and Gr/CS/Fe3O4 NCs, evaluated against visible light, was found to be significantly higher for Rh-B (100% within 40 min) compared to the other tested dyes.

Maruthupandy M ，Muneeswaran T ，Anand M ，Quero F ... -  《-》

Highly efficient antibacterial activity of graphene/chitosan/magnetite nanocomposites against ESBL-producing Pseudomonas aeruginosa and Klebsiella pneumoniae.

In the present study, chitosan-containing nanocomposites were investigated as new antibacterial agents. Magnetite (Fe3O4) nanoparticles (NPs) as well as chitosan (CS)/Fe3O4 nanocomposites (NCs) and graphene(Gr)/CS/Fe3O4 NCs were synthesized by simple hydrothermal method. Their composition, structure and morphology were studied, followed by the evaluation of their antibacterial activity against ESBL-producing and gram-negative P. aeruginosa and K. pneumoniae bacterial strains. The Gr/CS/Fe3O4 NCs showed significantly higher antibacterial activity compared to Fe3O4 NPs and CS/Fe3O4 NCs (105 and 69 % higher against P. aeruginosa as well as 91 and 77 % higher against K. pneumoniae, respectively). The minimum inhibitory concentration (MIC) of Gr/CS/Fe3O4 NCs against P. aeruginosa and K. pneumoniae were 60 and 70 μg/mL, respectively. The synergistic antibacterial activity and facile synthesis of Gr/CS/Fe3O4 NCs suggests their applicability as novel highly efficient antibacterial agents with potential for a wide range of biomedical applications, where antibacterial properties are needed.

Maruthupandy M ，Rajivgandhi G ，Muneeswaran T ，Anand M ，Quero F ... -  《-》

Chitosan, magnetite, silicon dioxide, and graphene oxide nanocomposites: Synthesis, characterization, efficiency as cisplatin drug delivery, and DFT calculations.

Drug delivery systems with controlled release have been considered important tools for the treatment of various diseases. The efficacy of the drug can be enhanced by increasing its solubility, stability, bioavailability, and specific site delivery. Herein, we investigated cisplatin (cisP) loading efficacy and release potentiality on chitosan (CS) functionalized with magnetite (M), silicon dioxide (S), and graphene oxide (GO) nanoparticles. Different nanocomposites [chitosan-coated magnetite, silicon dioxide, and graphene oxide (CS/M/S/GO); chitosan-coated magnetite and silicon dioxide (CS/M/S); chitosan-coated silicon dioxide (CS/S); and chitosan-coated magnetite (CS/M)] were prepared. The prepared nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). DFT calculations were employed to explore the interaction mechanism of cisP with a selected chitosan-functionalized nanocomposite in the gas phase and water media. The UV-Vis spectroscopy was used to study cisP loading and release from the prepared nanocomposites. The results showed that the highest loading efficacy was achieved by CS/M and CS/M/S/GO nanocomposites (87% and 84% respectively). While the releasing potentiality for CS/M composite was the highest compared with the other ones (91%).

Abdel-Bary AS ，Tolan DA ，Nassar MY ，Taketsugu T ，El-Nahas AM ... -  《-》

Magnetic Fe(3)O(4)@V(2)O(5)/rGO nanocomposite as a recyclable photocatalyst for dye molecules degradation under direct sunlight irradiation.

Reduced graphene oxide nanosheets decorated with Fe3O4 and V2O5 nanoparticles as a magnetically recoverable nanocomposite (Fe3O4@V2O5/rGO) was synthesized by a simple solution chemistry approach. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR), fluorescence, and zeta potential measurements. The narrow band gap and different band gap energies of Fe3O4 and V2O5 proved to be suitable for the absorption of visible light in the solar spectrum. The Fe3O4@V2O5/rGO displayed indeed excellent photocatalytic activity towards the degradation of harmful cationic Bismarck Brown (BB) as well as anionic Acid Orange 7 (AO) dyes under direct sunlight irradiation. The photocatalytic activity of the Fe3O4@V2O5/rGO is influenced by solution pH, catalyst loading, initial dye concentration and the presence of different inorganic ions (NH4+, Na+, Mg2+, Ca2+, SO42-, Br-, NO3-, Cl-, HCO3-). This study provides a new scientific knowledge on the sunlight driven photocatalytic degradation of dye molecules using novel mixed metal oxide/rGO nanocomposite photocatalyst.

Boruah PK ，Szunerits S ，Boukherroub R ，Das MR ... -  《-》

Synthesis and characterization of methyl pyrazolone functionalized magnetic chitosan composite for visible light photocatalytic degradation of methylene blue.

TiO2/Fe3O4, TiO2/Fe3O4/chitosan and Methylpyrazolone functionalized TiO2/Fe3O4/chitosan (MPyTMChi) were successfully prepared. The chemical structure of the prepared materials was confirmed by FT-IR spectra, XRD, SEM and TEM. BET surface area increased from 2.4 to 3.1m2/g, Eg decreased from 2.58 to 2.25eV and more quenching of PL emission spectra was observed upon functionalization of TMChi by MPy. Moreover, high Ti and oxygen percentages were detected by EDX. Magnetization value (Ms) reached 21 emu.g-1 for MPyTMChi. MPyTMChi showed enhanced photocatalytic degradation rate of methylene blue (MB) dye under visibe light irradiation (99.8% after 40min) as compared with that for TiO2/Fe3O4 (96.7% after 100min) and TMChi (98.9% after 60min), respectively. It was regarded that the photocatalytic degradation of MB dye on MPyTMChi follows apparent pseudo-first-order according to the Langmuir-Hinshelwood (L-H) model and kapp value was 0.089min-1. Active species trapping experiment revealed that h+ and O2- played the main role in the photodegradation of MB dye while OH quenching did not greatly affect photodegradation rate. Additionally, MPyTMChi can be efficiently reused for six repetitive cycles. MPyTMChi showed higher antimicrobial activity against gram-positive, gram- negative bacterial and fungal strains while large inhibition zone was observed for gram-positive bacteria.

Abdelwahab NA ，Morsy EMH 《-》