Facile one pot microbe-mediatedin situsynthesis and antibacterial activity of reduced graphene oxide-silver nanocomposite

The present research deals with the development of a novel bioinspiredin situfabrication of reduced graphene oxide (rGO)-silver nanoparticle (AgNPs) nanocomposite (rGO@AgNCs) using microbes namelyPseudomonas aeruginosa(PA) andStaphylococcus aureus(SA). The fabricated rGO@AgNCs were characterized using Ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), particle size analysis, polydispersity index (PDI), zeta potential analysis, energy dispersive x-ray analysis (EDAX), Raman spectroscopy, powder x-ray diffraction (PXRD), high-resolution transmission electron microscopy (HR-TEM) analysis, etc. Furthermore, the rGO@AgNCs-PA and rGO@AgNCs-SA interaction with serum protein, pH stability study, andin vitrodissolution of AgNPs were also performed. The research findings of the proposed study demonstrated the simultaneous reduction of graphene oxide (GO) and AgNPs and the formation of rGO@AgNCs in the presence of microbes. Thein vitrodissolution studies of rGO@AgNCs composites showed better AgNPs dissolution with controlled release and offered remarkable matrix integrity throughout the dissolution period. The size and stability of rGO@AgNCs-PA and rGO@AgNCs-SA had no significant changes at physiological pH 7.4. A minimal decrease in the zeta potential of rGO@AgNCs was observed, which may be due to the weak interaction of nanocomposites and albumin. The antibacterial application of the synthesized nanocomposite was evaluated against a pathogenic mastitis-forming bacterium. The obtained results suggested an admirable antibacterial activity of synthesized nanocomposites against the tested microbes. This knowledge will assist the scientific fraternity in designing novel antibacterial agents with enhanced antibacterial activity against various veterinary pathogens in near future.

CdO nanoparticles, c-MWCNT nanoparticles and CdO nanoparticles/c-MWCNT nanocomposite fibres: in vitro assessment of anti-proliferative and apoptotic studies in HeLa cancer cell line

A simple ultrasonic assisted chemical technique was used to synthesise cadmium oxide (CdO) nanoparticles (NPs) and CdO NPs/c-Multiwalled carbon nanotube (c-MWCNT) nanocomposite fibres.To confirm the physio-chemico properties and to analyse surface morphology of the obtained nanomaterials X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) were performed. To evaluate the anti-cancer property of CdO NPs, c-MWCNT NPs and CdO NPs/c-MWCNT nanocomposite fibres, an anti-proliferative assay test (Methylthiazolyl diphenyl- tetrazolium bromide - MTT assay) were performed on HeLa cells which further estimated IC50 value (Least concentration of sample in which nearly 50% of cells remain alive) under in-vitro conditions. On comparison, CdONPs/c-MWCNT based system was found to be superior by achieving 52.3% cell viability with its minimal IC50 value of 31.2 μg/ml. Lastly, the CdO NPs based system was taken up for an apoptotic study using DNA fragmentation assay for estimating its ability to cleave the DNA of the HeLa cells into internucleosomal fragments using the agarose gel electrophoresis method. In conclusion, based on our observations, CdO NPs/c-MWCNT hybrid based system can be further used for the development of efficient drug delivery and therapeutic systems.

The antibacterial and anticancer properties of zinc oxide coated iron oxide nanotextured composites

Core-shell α-Fe₂O₃-ZnO structures of different nanotextured morphology were synthesized through wet chemical routes using different solvents like ethanol, ethanolamine, water and acetaldehyde. Morphological tuning using different solvents resulted in the formation of different shapes, such as disc, spindle, rod and sphere (abbreviated as FZ-ND, FZ-NSP, FZ-NR and FZ-NS, respectively). Structural, morphological and compositional characterization of these nanoparticles (NPs) has been carried out. Antibacterial efficacy of the synthesized NPs was checked against Gram negative V. cholerae N16961 (VcN16961) and Gram positive S. aureus bacteria by recording optical density (OD) at different time points. Among the NPs tested, FZ-NSP was found to be the most effective against VcN16961, while FZ-NR showed maximum efficacy against S. aureus, implying the importance of nanotextured surface as well as the morphology in the manifestation of antibacterial activity. The kinetics of growth for both the bacteria has been modelled using logistic approach. Cytotoxicity was evaluated through MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide) assay against human breast adenocarcinoma cell line (MCF-7), human hepatocarcinoma cell line (HepG2) and against normal human embryonic kidney cell line (HEK-293). The lesser toxicity of α-Fe₂O₃-ZnO towards HEK-293 and the potent anticancer activity against MCF-7 and HepG2 cells underline its applicability as anticancer agent. With continued improvement of nanotechnology, this study may pave the way for designing and construction of various morphologically diverse, nanotextured materials with desired functional attributes.

Anti-biofilm activity and food packaging application of room temperature solution process based polyethylene glycol capped Ag-ZnO-graphene nanocomposite

Present work reports on synthesis and anti-biofilm activity as well as food packaging application of Ag-ZnO-reduce graphene oxide (rGO)-polyethylene glycol (PEG) (AZGP) nanocomposites via adopting room temperature solution process by varying silver nitrate content (up to 0.1 M) with fixed content of graphene oxide and PEG used in the precursors. Presence of Ag and ZnO nanoparticles (NPs) distributed uniformly over rGO nanosheets has been confirmed by X-ray diffraction and transmission electron microscopic analyses whereas FTIR, Raman, UV-Visible and X-ray photoelectron spectral studies have been performed to confirm the existence of chemical interaction/complexation that happened between the available oxygen functionalities of rGO and PEG with the inorganic moieties (Ag-ZnO/Zn²⁺) of AZGP samples. A formation mechanism of AZGP nanocomposite is proposed based on the experimental results. Anti-biofilm activity has been studied on Staphylococcus aureus and Pseudomonas aeruginosa bacteria to confirm the efficiency of the nanocomposites for killing the bacterial cells. It is found that 0.05 M silver nitrate based AZGP nanocomposite at 31.25 μg/mL sample dosage shows about 95% inhibition activity towards the biofilm formation as well as eradication of preformed biofilm. Also, agar based AZGP film has been fabricated and characterized by X-ray diffraction study for the purpose of food packaging application. Textural analysis of agar based film shows an enhanced film tensile strength. The film also shows an excellent antimicrobial activity even after keeping it for a prolong period of about 90 days. This cost effective simple synthesis strategy can make an avenue for development of Ag incorporated other biocompatible metal oxide based rGO-PEG nanocomposites for potential food packaging application.

A novel non-invasive strategy for low-level laser-induced cancer therapy by using new Ag/ZnO and Nd/ZnO functionalized reduced graphene oxide nanocomposites

In the present research, an effective drug-free approach was developed to kill MCF7 breast cancer cells using low-level laser therapy (LLLT) combined with reduced graphene oxide (rGO)-based hybrid nanocomposites (NCs). Here, fruit extract of Rosa canina was used for the first time to obtain the rGO/ZnO, Ag-ZnO/rGO and Nd-ZnO/rGO NCs by green synthesis. Physico/photochemical properties of these NCs were evaluated using FTIR, XRD, Raman, XPS, SEM/EDX, UV-Vis, DLS and AFM. The potential of the as-synthesized NCs on ROS generating and antioxidant activity were assessed by DPPH. After optimizing the proper concentration of the NCs their anti-tumoral efficacy were evaluated by DAPI staining and MTT assay tests for laser therapy on MCF7 breast cancer cells. Interestingly, cell death was increased dramatically by increasing irradiation dose from 8-32 J/cm² and then decreased by enhancing laser dose. The maximum amount of cell death is 50% which was observed in the presence of ZnO/rGO 20% by irradiation dose of 32 J/cm². Furthermore, in comparison with 810 nm, 630 nm lasers were more effective in LLLT of MCF7 cells. The results show the potential of using rGO-based NCs in LLLT, which may be combined with other therapeutic approaches to assist our fight against cancer.

Studies on electrochemical glucose sensing, antimicrobial activity and cytotoxicity of fabricated copper nanoparticle immobilized chitin nanostructure

In this study, copper nanoparticle immobilized chitin nanocomposite (CNP/CuNP) was synthesized and used for the development of non-enzymatic electrochemical sensor. The CNP/CuNP was characterized by X-ray diffraction (XRD), fourier transform infra red (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM) analysis. The glucose sensing property of CNP/CuNP was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). As a result of the synergistic effect of CNP and CuNP, the modified electrode displayed effective electro-oxidation of glucose in 0.1M NaOH solution. At 0.45V potential the modified electrode showed response towards glucose in the linear range of 1-1000μM with a lowest detection limit of 0.776μM with better selectivity and stability. In addition, the antimicrobial activity of CNP/CuNP was evaluated against bacterial and fungal strains. CNP/CuNP displayed enhanced antimicrobial activity when compared to CNP and CuNP alone. Similarly, cytotoxicity of CNP/CuNP was tested against Artemia salina, which showed no toxic effect in the tested concentration.

Impact of rare-earth metal oxide (Eu2O3) on the electrochemical properties of a polypyrrole/CuO polymeric composite for supercapacitor applications

A ternary composite of polypyrrole/copper oxide/europium oxide (PPY/CuO/Eu₂O₃), synthesized via a facile in situ chemical oxidative polymerization method, exhibits the maximum specific capacitance of 320 F g⁻¹ at the current density of 1 A g⁻¹.

Synthesis, characterization and antibacterial activity of Ag incorporated ZnO–graphene nanocomposites

One pot low temperature synthesis of silver incorporated ZnO–chemically converted graphene nanocomposites is reported. An optimum of 10% Ag incorporated sample at 6.25 μg ml⁻¹ dose shows an excellent antibacterial activity on E. coli and S. aureus.

Low temperature synthesis of graphene hybridized surface defective hierarchical core–shell structured ZnO hollow microspheres with long-term stable and enhanced photoelectrochemical activity

Time dependent structural change (solid → core–shell → hollow) of in situ formed ZnO–graphene (ZG) microspheres by low temperature solution process and their photoelectrochemical stability.

Oxidative Stress and Mitochondrial Activation as the Main Mechanisms Underlying Graphene Toxicity against Human Cancer Cells

Due to the development of nanotechnology graphene and graphene-based nanomaterials have attracted the most attention owing to their unique physical, chemical, and mechanical properties. Graphene can be applied in many fields among which biomedical applications especially diagnostics, cancer therapy, and drug delivery have been arousing a lot of interest. Therefore it is essential to understand better the graphene-cell interactions, especially toxicity and underlying mechanisms for proper use and development. This review presents the recent knowledge concerning graphene cytotoxicity and influence on different cancer cell lines.

Pyridine-2,6-dicarboxylic acid for the sensitization of europium(iii) luminescence with very long lifetimes

Convenient and mild syntheses of two europium(iii) complexes, Na[Eu(dipic)₂·3H₂O]·4H₂O (dipic = dipicolinate anions) and Na[Eu(dipic)₂·phen]·H₂O (phen = 1,10-phenanthroline), were reported.

A multi-functional fluorescent scaffold as a multi-colour probe: design and application in targeted cell imaging

A new scaffold material based on a novel targeting strategy has been developed, benefiting from recent progress in the development of tailor-made fluorescent bioprobes for cellular imaging and opening a new viewpoint for further improvements in in vitro and in vivo imaging.