In this study, manganese ferrite-graphene oxide (MFO-GO) nanocomposites were prepared via a co-precipitation reaction of Fe3+ and Mn2+ ions in a GO suspension.

Recently, development of carbon nanocomposites composed of carbon nanostructures and metal nanoparticles has attracted much interests because of their large potential for technological applications such as catalyst, sensor, biomedicine, and disinfection. In this work, we established a simple chemistry method to synthesize multiwalled carbon nanotubes (MWCNTs) decorated with silver nanoparticles (Ag-NPs) using a modified photochemical reaction (Tollens process). The formation and interaction of Ag-NPs with functionalized groups on the surface of MWCNTs were analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the MWCNTs was approximately ∼7 nm with nearly uniform size distribution. Antibacterial effect of Ag-MWCNTs nanocomposites was evaluated against two pathogenic bacteria including Gram-negative Escherichia Coli and Gram-positive Staphylococcus aureus bacteria. Interaction and bactericidal mechanism of Ag-MWCNTs with tested bacteria was studied by adapting the electron microscopy. Analysis on ultrastructural changes of bacterial cells indicates that antibacterial action mechanism of Ag-MWCNTs is physical interaction with cell membrane, the large formation of cell-Ag-MWCNTs aggregates, and faster destructibility of cell membrane and disruption of membrane function, hence resulting in cells death.

Functional two-dimensional (2D) structured nanomaterials, e.g. graphene oxide (GO) and molybdenum disulfide (MoS2), exhibiting many advantages including large surface areas and excellent electronic/mechanical/catalytic properties, were shown to be strong candidates...

In this study, we have investigated the influence of crystallinity, phase ratio and heterojunction formation on the sensing performance of ZnO/ZnFe2O4 (ZnO/ZFO) nanocomposites-based electrochemical sensors for detection of furazolidone (FZD)...

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In this work, we clarify the roles of phase composition and copper loading amount on the CAP sensing performance of Cu–MoS2 nanocomposite-based electrochemical nanosensors.

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Great influences of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels of the analyte and their alignments compared to the Fermi level of the substrate on the charge transfer (CT) process, and consequently, on the surface-enhanced Raman scattering (SERS) phenomenon have been described via theoretical calculations. To provide experimental evidence, in this study, two antibiotics, chloramphenicol (CAP) and amoxicillin (AMX), were investigated as analytes in SERS sensors based on electrochemically synthesized colloidal silver nanoparticles (e-AgNPs) as the substrate. Despite the same experimental condition, similarities in analyte structure, and in the ability of absorbing onto e-AgNPs, the detection of the two antibiotics showed obvious distinction. While CAP was able to be detected using e-AgNP-based SERS sensors at concentrations down to 1.2 × 10 −9 M, there were no characteristic peaks observed in the SERS spectra of AMX even at a high concentration of 10 −3 M. The LUMO and HOMO energy levels of the two analytes were measured using electrochemical cyclic voltammetry. The obtained results showed that the LUMO levels of both analytes were higher than the Fermi level of Ag, and the LUMO level of AMX was higher than that of CAP. The larger gap between the LUMO level of AMX and the Fermi level of Ag might have prevented the metal-to-molecule CT process, which is related to the Raman signal enhancement in both chemical and electromagnetic mechanisms. In contrast, the smaller energy gap in the case of CAP might have allowed the transfer of hot electrons from the Fermi level of the e-AgNPs to the LUMO level of the analyte. Therefore, CAP could experience an SERS effect on the e-AgNPs under the excitation of a 785 nm laser source, while AMX could not. The hypothesis was then confirmed using three other organic compounds, including furazolidone, 4-nitrophenol, and tricyclazole. The results revealed a clear correlation between the LUMO level of the analytes and their SERS signals.