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Drug resistance and inability to distinguish between cancerous and non-cancerous cells are important obstacles in the treatment of cancer. Zinc oxide nanoparticles (ZnO NPs) is now emerging as a crucial material to challenge this global issue due to its tunable properties. Developing an effective, inexpensive, and eco-friendly method in order to tailor the properties of ZnO NPs with enhanced anticancer efficacy is still challenging. For the first time, we reported a facile, inexpensive, and eco-friendly approach for green synthesis of ZnO-reduced graphene oxide nanocomposites (ZnO-RGO NCs) using garlic clove extract. Garlic has been playing one of the most important dietary and medicinal roles for humans since centuries. We aimed to minimize the use of toxic chemicals and enhance the anticancer potential of ZnO-RGO NCs with minimum side effects to normal cells. Aqueous extract of garlic clove was used as reducing and stabilizing agent for green synthesis of ZnO-RGO NCs from the zinc nitrate and graphene oxide (GO) precursors. A potential mechanism of ZnO-RGO NCs synthesis with garlic clove extract was also proposed. Preparation of pure ZnO NPs and ZnO-RGO NCs was confirmed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and dynamic light scattering (DLS). The in vitro study showed that ZnO-RGO NCs induce two-fold higher cytotoxicity in human breast cancer (MCF7) and human colorectal cancer (HCT116) cells as compared to pure ZnO NPs. Besides, biocompatibility of ZnO-RGO NCs in non-cancerous human normal breast (MCF10A) and normal colon epithelial (NCM460) cells was higher than those of pure ZnO NPs. This work highlighted a facile and inexpensive green approach for the preparation of ZnO-RGO NCs with enhanced anticancer activity and improved biocompatibility.

Bismuth (III) oxide nanoparticles (Bi2O3 NPs) have shown great potential for biomedical applications because of their tunable physicochemical properties. In this work, pure and Zn-doped (1 and 3 mol %) Bi2O3 NPs were synthesized by a facile chemical route and their cytotoxicity was examined in cancer cells and normal cells. The X-ray diffraction results show that the tetragonal phase of β-Bi2O3 remains unchanged after Zn-doping. Transmission electron microscopy and scanning electron microscopy images depicted that prepared particles were spherical with smooth surfaces and the homogeneous distribution of Zn in Bi2O3 with high-quality lattice fringes without distortion. Photoluminescence spectra revealed that intensity of Bi2O3 NPs decreases with increasing level of Zn-doping. Biological data showed that Zn-doped Bi2O3 NPs induce higher cytotoxicity to human lung (A549) and liver (HepG2) cancer cells as compared to pure Bi2O3 NPs, and cytotoxic intensity increases with increasing concentration of Zn-doping. Mechanistic data indicated that Zn-doped Bi2O3 NPs induce cytotoxicity in both types of cancer cells through the generation of reactive oxygen species and caspase-3 activation. On the other hand, biocompatibility of Zn-doped Bi2O3 NPs in normal cells (primary rat hepatocytes) was greater than that of pure Bi2O3 NPs and biocompatibility improves with increasing level of Zn-doping. Altogether, this is the first report highlighting the role of Zn-doping in the anticancer activity of Bi2O3 NPs. This study warrants further research on the antitumor activity of Zn-doped Bi2O3 NPs in suitable in vivo models.

The fabrication of unique taper-ended GaN-Nanotowers structure based highly efficient ultraviolet photodetector is demonstrated. Hexagonally stacked, single crystalline GaN nanocolumnar structure (nanotowers) grown on AlN buffer layer exhibits higher photocurrent generation due to high quality nanotowers morphology and increased surface/volume ratio which significantly enhances its responsivity upon ultraviolet exposure leading to outstanding performance from the developed detection device. The fabricated detector display low dark current (~ 12 nA), high ILight/IDark ratio (> 104), fast time-correlated transient response (~ 433 µs) upon ultraviolet (325 nm) illumination. A high photoresponsivity of 2.47 A/W is achieved in self-powered mode of operation. The reason behind such high performance could be attributed to built-in electric field developed from a difference in Schottky barrier heights will be discussed in detail. While in photoconductive mode, the responsivity is observed to be 35.4 A/W @ − 3 V along with very high external quantum efficiency (~ 104%), lower noise equivalent power (~ 10–13 WHz−1/2) and excellent UV–Vis selectivity. Nanotower structure with lower strain and dislocations as well as reduced trap states cumulatively contributed to augmented performance from the device. The utilization of these GaN-Nanotower structures can potentially be useful towards the fabrication of energy-efficient ultraviolet photodetectors.

Numerous structures have been reported in search of affordable self-powered broadband photodetectors, however with limited success. The hybrid perovskite heterostructures have been attracted great attention due to their advance optical and electrical properties. The stability and facile synthesis are critical issues in achieving the potential success of realizing perovskite-based photodetectors. Herein, we report a facile one-step spray-coated method to synthesize MAPbI3 perovskite polycrystalline thin-film on the glass as photodetector followed by their morphological (Atomic force microscopy), structural (X-ray diffraction/Fourier transform infrared spectroscopy, optical (UV–Vis), and electrical characterization. The device shows a very good response for visible and NIR region with the responsivity, detectivity, and external quantum efficiency of 1.682 mA/W, 1.5065 × 1012 Jones, and 0.3799, respectively. Further, the device exhibits photoresponse under visible to IR (400–900 nm) light illuminations, which holds great futuristic promises for affordable, broadband, stable, and efficient energy-conserving electronics.

Copper-doped cobalt sulfide (CuxCo1−xS2: x = 0–0.1) nanocrystalline thin films were deposited on glass substrates using successive ionic layer adsorption and reaction (SILAR) technique. The influence Cu element concentration on nanostructural, morphological, photoluminescence and impedance properties of CuxCo1−xS2 thin films were examined by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), electron dispersive X-ray (EDX) photoluminescence (PL) and impedance spectroscopy. XRD results revealed that all prepared films consist of pure cubic phase of CoS2 pyrites structure and were well crystallized with the preferentially oriented along (200) plane. Cu doping resulted in a significant increase in the crystallinity of the films and a noticeably alteration in crystallite size. FESEM images revealed that the deposited thin film having spherical grain distribution and the grain sizes decreased from 56 to 34 nm with increasing Cu doping level. The EDX analysis confirmed the stoichiometry of prepared thin films. Photoluminescence (PL) spectra display the broad emission bands centered at 411 with a hump at 417 nm, due to the intrinsic defects. From the impedance spectroscopy analysis, we examined the equivalent circuit and frequency-dependent relaxation phenomenon in dielectric dipoles, loss of electrical energy and AC conductivity of the pure and Cu-doped thin films. Finally, all properties have been discussed, as an impartial of the research work, in terms of the Cu doping content.

Recent attention has been focused on reproductive toxicity of nanoscale materials in combination with pre-existing environmental pollutants. Due to its unique characteristics, bismuth (III) oxide (Bi2O3) nanoparticles (BONPs) are being used in diverse fields including cosmetics and biomedicine. Benzo[a]pyrene (BaP) is a known endocrine disruptor that most common sources of BaP exposure to humans are cigarette smoke and well-cooked barbecued meat. Hence, joint exposure of BONPs and BaP in humans is common. There is scarcity of information on toxicity of BONPs in combination with BaP in human reproductive system. In this work, combined effects of BONPs and BaP in mouse spermatogonia (GC-1 spg) cells were assessed. Results showed that combined exposure of BONPs and BaP synergistically induced cell viability reduction, lactate dehydrogenase leakage, induction of caspases (-3 and -9) and mitochondrial membrane potential loss in GC-1 spg cells. Co-exposure of BONPs and BaP also synergistically induced production of pro-oxidants (reactive oxygen species and hydrogen peroxide) and reduction of antioxidants (glutathione and several antioxidant enzymes). Experiments with N-acetyl-cysteine (NAC, a reactive oxygen species scavenger) indicated that oxidative stress was a plausible mechanism of synergistic toxicity of BONPs and BaP in GC-1 spg cells. Present data could be helpful for future in vivo research and risk assessment of human reproductive system co-exposed to BONPs and BaP.

Maqusood Ahamed,1 Mohd Javed Akhtar,1 MA Majeed Khan,1 Hisham A Alhadlaq1,2 1King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia; 2Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi ArabiaCorrespondence: Maqusood AhamedKing Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi ArabiaEmail mahamed@ksu.edu.saBackground: Therapeutic selectivity and drug resistance are critical issues in cancer therapy. Currently, zinc oxide nanoparticles (ZnO NPs) hold considerable promise to tackle this problem due to their tunable physicochemical properties. This work was designed to prepare SnO2-doped ZnO NPs/reduced graphene oxide nanocomposites (SnO2-ZnO/rGO NCs) with enhanced anticancer activity and better biocompatibility than those of pure ZnO NPs.Materials and Methods: Pure ZnO NPs, SnO2-doped ZnO (SnO2-ZnO) NPs, and SnO2-ZnO/rGO NCs were prepared via a facile hydrothermal method. Prepared samples were characterized by field emission transmission electron microscopy (FETEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible (UV-VIS) spectrometer, and dynamic light scattering (DLS) techniques. Selectivity and anticancer activity of prepared samples were assessed in human breast cancer (MCF-7) and human normal breast epithelial (MCF10A) cells. Possible mechanisms of anticancer activity of prepared samples were explored through oxidative stress pathway.Results: XRD spectra of SnO2-ZnO/rGO NCs confirmed the formation of single-phase of hexagonal wurtzite ZnO. High resolution TEM and SEM mapping showed homogenous distribution of SnO2 and rGO in ZnO NPs with high quality lattice fringes without any distortion. Band gap energy of SnO2-ZnO/rGO NCs was lower compared to SnO2-ZnO NPs and pure ZnO NPs. The SnO2-ZnO/rGO NCs exhibited significantly higher anticancer activity against MCF-7 cancer cells than those of SnO2-ZnO NPs and ZnO NPs. The SnO2-ZnO/rGO NCs induced apoptotic response through the upregulation of caspase-3 gene and depletion of mitochondrial membrane potential. Mechanistic study indicated that SnO2-ZnO/rGO NCs kill cancer cells through oxidative stress pathway. Moreover, biocompatibility of SnO2-ZnO/rGO NCs was also higher against normal breast epithelial (MCF10A cells) in comparison to SnO2-ZnO NPs and ZnO NPs.Conclusion: SnO2-ZnO/rGO NCs showed enhanced anticancer activity and better biocompatibility than SnO2-ZnO NPs and pure ZnO NPs. This work suggested a new approach to improve the selectivity and anticancer activity of ZnO NPs. Studies on antitumor activity of SnO2-ZnO/rGO NCs in animal models are further warranted.Keywords: ZnO nanocomposites, improved anticancer activity, better selectivity, reactive oxygen species, caspase-3, breast cancer

We herein present the development of sensitive halogen sensors based on InN nanocolumns (NCs) directly grown onto p-Si(111). Their activation with InN QDs then followed this growth by using plasma-assisted molecular beam epitaxy (PA-MBE). The activated NCs were then probed for their morphological, structural, optical, and electrical properties. Atomic force microscopy divulges the presence of the InN QDs on top of the NCs, which further confirm by deconvoluted two peaks in PL measurements. The XPS valance band measurements confirm the pinning to the conduction band with ∼ 0.15 eV, which manifests the presence of positively charged surface donor states. We further have utilized these surface donor states and investigated these activated NCs toward halogen ions. The results demonstrated the sensitivity of 0.724 µF/cm2/M, 2.32 mF/m2/M, and 0.95 mF/cm2/M, for fluoride, chloride, and bromide ions, respectively. Moreover, we have not observed any effect due to hydroxide ions on the areal capacitance of the InN NCs.

The present work describes the synthesis of Ag-CoFe2O4/rGO nanocomposite as a photocatalyst through the hydrothermal process by the attachment of silver and cobalt ferrite (CoFe2O4) nanoparticles on the surface of reduced graphene oxide. The effect of Ag and reduced graphene oxide (rGO) on the structure, optical, magnetic, photocatalytic, and electrochemical performance of the CoFe2O4 is systematically explored through various analytical techniques. The analyses of the observed outcomes reveal that the graphene sheets are exfoliated and decorated with well-dispersed Ag and CoFe2O4 nanoparticles. UV-vis spectra indicate a gradual shift in the absorption edge toward the higher wavelength with the addition of Ag ions, which signifies variation in the energy gap of the samples. Photoluminescence results divulge that graphene can decline the electron-hole recombination rate and improve the photocatalytic activity of the Ag-CoFe2O4/rGO nanocomposite. In this context, the Ag-CoFe2O4/rGO sample presents good catalytic activity as compared to the CoFe2O4 and Ag-CoFe2O4 photocatalysts for the degradation of methylene blue (MB) dye and suggests that the rGO plays a vital role in the Ag-CoFe2O4/rGO nanocomposite. The deterioration rate of the samples is found to be in the order of CoFe2O4(78.03%) < Ag-CoFe2O4(83.04%) < Ag-CoFe2O4/rGO(93.25%) in 100 min for MB dye, respectively, under visible-light irradiation. The room-temperature ferromagnetic behavior of the samples is confirmed by the M-H hysteresis loop measurements. Overall, the Ag-CoFe2O4/rGO nanocomposite promises to be a strong magnetic photocatalyst for contaminated wastewater treatment. The electrochemical performance of all of the samples was examined by the cyclic voltammetry (CV) that exhibits a superior rate performance and cycle stability of the Ag-CoFe2O4/rGO nanocomposite as compared to the other samples.

Herein, we reported the preparation of BaTiO3 nanoparticles and BaTiO3@rGO nanocomposite by sol-gel route and microwave assisted co-precipitation method respectively. A series of analysis such as X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, UV-visible absorption, photocatalytic activity, photoluminescence and Brunauer-Emmett-Teller (BET) method were employed to determine the properties of prepared samples. The dielectric properties of BaTiO3 nanoparticles and BaTiO3@rGO nanocomposite were studied at different frequencies and different temperatures. Photocatalytic performance of obtained BaTiO3@rGO nanocomposite was evaluated via photocatalytic degradation process of methylene blue (MB) as a model dye under irradiation of visible light. The cumulative outcome of results indicated the superior performance of BaTiO3@rGO nanocomposite as photocatalyst when compared with pure BaTiO3 nanoparticles, which might be attributed to distensible surface area and effective separation of photo-excited electron-hole pairs. Our findings demonstrate that the prepared nanocomposite as reported here may be utilized as photocatalyst for degrading organic pollutants and as electrode in charge storage devices.

Highly crystalline and monophasic silver nanospheres with a high specific surface area of 57 m2/g have been synthesized by an environmentally benign rapid chemical reduction using l-alanine for catalytic transformation, photocatalytic degradation, and bacterial disinfection, which can provide an ample strategy for water remediation. Electron microscopic analysis confirms the spherical morphology of as-prepared silver nanoparticles with an average grain size of 20 nm. Silver nanospheres showed excellent catalytic activity for the catalytic hydrogenation and conversion (95.6%) of 4-nitrophenol to 4-aminophenol. Significant photocatalytic degradation proficiency was also shown for methylene blue (94.5%) and rhodamine B (96.3%) dyes under solar irradiation. The antibacterial behavior of Ala–Ag nanospheres was demonstrated through the disk diffusion antibacterial assay against Gram-positive (Escherichia coli) and Gram-negative (Staphylococcus aureus) bacteria. Multifunctional efficiency of as-prepared Ala–Ag nanospheres for water remediation has also been established.

A cost-effective bimetallic NiCo2O4@nitrogen-doped carbon (NC) nanocomposite was prepared through bimetallic nickel/cobalt metal organic frameworks (Ni/Co-MOF) by employing a smart approach to utilize the waste Polyethylene terephthalate (PET) plastics for energy storage applications. The NiCo2O4@NC nanocomposite was characterized successfully using analytical techniques. The nanocomposite comprises high surface area (813 m2 g− 1) and mesoporosity (~ 15 nm). NiCo2O4@NC nanocomposite demonstrates excellent electrochemical performance with high specific capacitance of ~ 890 F g− 1 at 5 mV s− 1 and ~ 913 F g− 1 at 1 A g− 1 in 6 m KOH electrolyte. The cyclic stability tests confirm excellent retention capacity (~ 99%) with fifty cyclic segments. Low-cost, environmental friendly approach, and rich redox activity of NiCo2O4@NC nanocomposite make it an alternate potential electrode material for energy storage devices.

Double perovskite La2MnNiO6 nanoparticles (approximately 30 nm in diameter) were synthesized using a modified sol-gel method followed by a firing process and used as promising electrode materials for oxygen evolution reactions (OERs). The phase purity of the nanoparticles was verified using X-ray diffraction and Raman spectroscopy measurements. La2MnNiO6 nanoparticles crystallize in a monoclinic structure (P21/n space group) with refined lattice parameters of a = 5.461(5) A, b = 5.512(3) A, c = 7.760(5) A, and β = 90.10(2)°. The elemental composition, particle size, size distribution, and surface area of the La2MnNiO6 nanoparticles were also investigated. La2MnNiO6 nanoparticles are ferromagnetic in nature and exhibit hysteresis with a saturation magnetization value of approximately 9 emu/g. La2MnNiO6 nanoparticles exhibit highly efficient electro-catalytic activity for OERs with a low onset over-potential (approximately 65 mV) and low Tafel slope values (120 mV/dec) in alkaline media. The over-potential of La2MnNiO6 nanoparticles at a current density of 10 mA/cm2 is in good agreement with the reported over-potential (ƞ10) of double perovskites, commercial Pt/C and IrO2 electro-catalysts for promoting OERs.

Pure and palladium (Pd)-doped cadmium sulfide (CdS) thin films were deposited on glass substrate by successive ionic layer adsorption and reaction (SILAR) process with different doping concentrations. X-ray diffraction results confirmed the crystalline and hexagonal phase structure of prepared samples. The increase in the main diffraction peak (002) intensity with increasing Pd concentration revealed the substitution of Pd+2 with Cd+2 in the lattice. The crystallite size increased from 58.32 to 89.71 nm with Pd concentration. Morphology of the thin films shown that the average grain size increases by the agglomeration of nano-grains which become cluster of particles after Pd+2 incorporation. The energy bandgap of the CdS thin films is decreased from 2.44 to 2.37 eV with increasing Pd percentage. Photoluminescence (PL) spectra described that the pure and Pd-doped thin films show a broad PL emission peak associated to the transition of sulfur ion vacancy transfers to the valence band. Moreover, the Pd doping improved the film photostability as well as the photocatalytic degradation of methylene blue (MB).

In this research, an effective usage of quantum size effect is a foregrounded strategy to produce and employ excellent visible light-driven photocatalytic materials. Zn100−xCoxO (x = 0, 2.5, 7.5) particles at nanoscale were synthesized successfully by chemical co-precipitation method and then investigated by some complimentary analytical techniques. Physical structure and chemical states were analysed by X-ray diffraction and X-ray photoelectron spectroscopy. XRD and HRTEM analysis confirmed the formation of wurtzite-type structure without any traces of secondary phase. XPS spectra exhibited the incorporation of Co2+ ions into ZnO lattice. Optical spectra of Zn100−xCoxO nanoparticles (NPs) indicated that bandgap is significantly narrowed with increasing Co concentration. Ferromagnetic behaviour was observed at room temperature in pure and Co-doped ZnO, due to the effect of quantum confinement and of Co2+ ions incorporation. The frequency and composition dependence of dielectric constant and dielectric loss have been analysed in detail using Maxwell–Wagner model and Cole–Cole plots. The activity of synthesized photocatalysts under simulated sunlight irradiation was characterized through decomposition of methylene blue (MB) dye in aqueous suspension, which revealed that Co2+ ions incorporation in ZnO greatly enhanced the photocatalytic degradation efficiency and hence employable in environmental cleaning.

Delafossite AgFeO2 nanoparticles were synthesized by the modified hydrothermal procedure for excellent photochemical performances for the removal of organic dye from neutral and alkaline aqueous medium. The structure, morphology, and elemental studies of the delafossite AgFeO2 nanoparticles were done by analytical methods. AgFeO2 nanoparticles show the refined lattice parameters of “a” = 3.033(2) A and “c” = 18.591(3) A of R3m phase. The excellent photocatalytic performance of delafossite AgFeO2 nanoparticles was observed under the full sunlight irradiations, which resulted ~92% degradation of methylene blue (MB) dye in 40 min using alkaline medium. The kinetic studies confirm the pseudo-first-order reactions of MB dye degradation in presence of photocatalysts. The fragmentations of organic dye molecules in presence of delafossite AgFeO2 photocatalysts under sunlight irradiations were also studied using the GC–MS technique. The delafossite AgFeO2 nanoparticles show excellent photocatalytic regeneration efficiency.

In this work, undoped and iron doped titania nanoparticles (Fe:TiO2 NPs) were successfully prepared by sol-gel route with two different Fe concentration (5 and 10 mol.%). The effects of Fe doping into TiO2 were thoroughly investigated by XRD, TEM, HRTEM, XPS, FTIR, Raman, UV–Visible spectroscopy and VSM. The obtained nanoparticles have narrow size distribution 41–49 nm and were recognized as anatase TiO2 structure with no signature of Fe cluster or iron oxides as analyzed by X-ray diffraction and Raman. The optical band gap of undoped and iron doped TiO2 NPs is red shifted with respect to the incorporation of iron content. Room temperature M-H loops revealed that all the samples showed a significant paramagnetic behaviour. The enhanced photocatalytic performance was observed for iron doped titania nanoparticles compared with pure TiO2 NPs in respect of methylene blue dye degradation in aqueous suspension under visible light illumination.

In the present work, we have investigated the structural, optical, photocatalytic activity, electrical transport and magnetic properties of Fe3O4 nanoparticles and its composite with reduced graphene oxide (Fe3O4/RGO) by varying the ratio of reduced graphene oxide (RGO: 2% and 4%). Fe3O4 nanoparticles and RGO were synthesized by the modified sol-gel and Hummers methods respectively. The as-prepared samples were examined by various analytical techniques to investigate their functional properties and possible applications. Rietveld refinement analysis of the XRD data reveals face-centered cubic (fcc) structure of the Fe3O4 nanoparticles and confirms the characteristic planes of magnetite phase. The average crystallite size of the Fe3O4, Fe3O4/RGO (2%) and Fe3O4/RGO (4%) samples was estimated using Scherrer's equation and found to be ∼10, 15 and 19 nm respectively. TEM/HRTEM micrographs establish spherical shapes of the magnetite nanoparticles with an average diameter of ∼12 nm for Fe3O4, while 17 and 20 nm in the nanocomposites respectively. The low temperature resistivity measurements exhibit semiconducting nature of all the samples and follow variable range hopping (VRH) mechanism. The magnetic measurements demonstrate typical superparamagnetic behavior of the samples at room temperature. The photocatalytic performance of the samples has been investigated for the decolorization of methylene blue (MB) organic dye under visible light irradiation. The Fe3O4/RGO nanocomposites display better adsorption behaviour and excellent photocatalytic activity than RGO and Fe3O4 nanoparticles. This may be due to strong interactions between Fe3O4 nanoparticles and graphene sheets.

In this study, pristine and Zr-doped CeO2 nanoparticles with chemical formula Ce1−xZrxO2 (x = 0, 0.05, 0.075 and 0.1) have been prepared through facile hydrothermal process. The influence of Zr doping on the microstructure, thermal, optical and photocatalytic properties of CeO2 was systematically explored through various analytical techniques. Analysis of the XRD data reveals cubic fluorite structure of the samples with average crystallite size of 12, 15, 21 and 30 nm respectively for different Zr doping. The optical properties of the nanoparticles were studied through UV–visible absorption and photoluminescence (PL) spectroscopy. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy measurements were performed to examine the chemical state and microstructure of the synthesized materials. The functional groups and mode of vibrations have been identified by the Fourier transform infrared (FTIR) spectroscopy. A reduction in the optical band gap of CeO2 (from 3.25 to 3.10 eV) is observed on systematic Zr doping. In addition, significant enhancement in the photocatalytic performance is also noticed for the doped samples (92.2%) as compared to the pristine one (68.7%) for the degradation of methylene blue (MB) dye under visible light irradiation.

Bismuth oxide nanoparticles (Bi2O3 NPs) have shown great potential for several applications including cosmetics and biomedicine. However, there is paucity of research on toxicity of Bi2O3 NPs. In this study, we first examined dose-dependent cytotoxicity and apoptosis response of Bi2O3 NPs in human breast cancer (MCF-7) cells. We further explored the potential mechanisms of cytotoxicity of Bi2O3 NPs through oxidative stress. Physicochemical study demonstrated that Bi2O3 NPs have crystalline structure and spherical shape with mean size of 97 nm. Toxicity studies have shown that Bi2O3 NPs reduce cell viability and induce membrane damage dose-dependently in the concentration range of 50–300 μg/ml. Bi2O3 NPs also disturbed cell cycle of MCF-7 cells. Oxidative stress response of Bi2O3 NPs was evident by generation of reactive oxygen species (ROS), higher lipid peroxidation, reduction of glutathione (GSH) and low superoxide dismutase (SOD) enzyme activity. Interestingly, supplementation of external antioxidant N-acetyl-cysteine almost negated the effect of Bi2O3 NPs induced oxidative stress and cell death. We also found that exposure of Bi2O3 NPs induced apoptotic response in MCF-7 cells suggested by impaired regulation of Bcl-2, Bax and caspase-3 genes. Altogether, we found that Bi2O3 NPs induced cytotoxicity in MCF-7 cells through modulating the redox homeostasis via Bax/Bcl-2 pathway. This study warranted further research to delineate the underlying mechanism of Bi2O3 NPs induced toxicity at in vivo level.

The PdS/p-Si heterojunction was fabricated by preparation of PdS thin films on the p-type Si (10 0) substrates using versatile SILAR method. The alteration of nanostructural, morphological, optical and I–V characterization of CuxPd1−xS/p-Si (x = 0–0.1) heterojunction was examined at the different Cu-doping level to inspect the doping effects on the properties of heterojunction. The X-ray diffraction investigated that the crystallinity of prepared thin films enhanced as a function of Cu concentration. The morphological analysis presented that the PdS thin films was smooth, homogeneous and closed packed spherical grains. Electron dispersive X-ray (EDX) analysis confirmed the stoichiometric composition of PdS thin films. The diffuse reflectance spectroscopy in the prepared PbS/p-Si heterojunction was reduced and the band edge showed the blue shift in the visible range. Photoluminescence (PL) spectra revealed that the PbS/p-Si heterojunction recombination rate is decreased with Cu-doping. The effects of Cu-doping level on the electrical parameters of heterojunction such as ideality factor (n), saturation current (IS), barrier height (Φb) and series resistance (Rs) were computed by the execution of current–voltage (I–V) properties. Electrical properties indicated that behavior of the PdS/p-Si heterojunction were precisely controlled by doping level.

Single‐atom catalysts (SACs) are highly enviable to exploit the utmost utilization of metallic catalysts; their efficiency by utilizing nearly all atoms to often exhibit high catalytic performances. To architect the isolated single atom on an ideal solid support with strong coordination has remained a crucial trial. Herein, graphene functionalized with nitrile groups (cyanographene) as an ideal support to immobilize isolated copper atoms G(CN)‐Cu with strong coordination is reported. The precisely designed mixed‐valence single atom copper (G(CN)‐Cu) catalysts deliver exceptional conversions for electrochemical methanol oxidation (MOR) and CO2reduction (CO2RR) targeting a “closed carbon cycle.” An onset of MOR and CO2RR are obtained to be ≈0.4V and ≈−0.7 versus Ag/AgCl, respectively, with single active sites located in an unsaturated coordination environment, it being the most active Cu sites for both studied reactions. Moreover, G(CN)‐Cu exhibited significantly lower resistivity and higher current density toward MOR and CO2RR than observed for reference catalysts.

Based on 1-phenylpyrrolidine (PT) dye, six new metal-free organic molecules S1–S6, containing PT as donor (D) connected through different linkages (π) and cyanoacrylic acid as acceptor (A), were designed and studied for dye sensitised solar cells (DSSCs). In this paper, D-π-A system of S1–S6 dye molecules was investigated by quantum chemical calculations to inspect the optical absorption properties and photovoltaic (PV) parameters. In particular, there are applied three long-range corrected (LC) functionals, such as B3PW91, CAM-B3LYP and ωB97XD with the time-dependent DFT (TD-DFT) calculation to systematically investigate the absorption peak in PT dye. From the calculated results, CAM-B3LYP functional was a good match with the PT dye. Therefore, the S1–S6 molecules’ optical absorption spectra have been computed by using the CAM-B3LYP/6-31+G(d) theory. The conductor-like polarisable continuum model (C-PCM) results show that the precise absorption spectra have attained solvent effect included in the excited state geometries. The frontier molecular orbitals (FMOs) of the HOMOs and LUMOs energies of S1–S6 derivatives confirm positive results on the dye regeneration and electron injection processes. The outcomes display that the benzo[c][1,2,5]thiadizole (S4) and benzo[c][1,2,5]oxadizole (S5) molecules are the most suitable spacers for D to A, owing to longer absorption peaks and revealing red-shifted optical absorption.

Barium titanate (BaTiO3) nanoparticles (BT NPs) have shown exceptional characteristics such as high dielectric constant and suitable ferro-, piezo-, and pyro-electric properties. Thus, BT NPs have shown potential to be applied in various fields including electro-optical devices and biomedicine. However, very limited knowledge is available on the interaction of BT NPs with human cells. This work was planned to study the interaction of BT NPs with human lung carcinoma (A549) cells. Results showed that BT NPs decreased cell viability in a dose- and time-dependent manner. Depletion of mitochondrial membrane potential and induction of caspase-3 and -9 enzyme activity were also observed following BT NP exposure. BT NPs further induced oxidative stress indicated by induction of pro-oxidants (reactive oxygen species and hydrogen peroxide) and reduction of antioxidants (glutathione and several antioxidant enzymes). Moreover, BT NP-induced cytotoxicity and oxidative stress were effectively abrogated by N-acetyl-cysteine (an ROS scavenger), suggesting that BT NP-induced cytotoxicity was mediated through oxidative stress. Intriguingly, the underlying mechanism of cytotoxicity of BT NPs was similar to the mode of action of ZnO NPs. At the end, we found that BT NPs did not affect the non-cancerous human lung fibroblasts (IMR-90). Altogether, BT NPs selectively induced cytotoxicity in A549 cells via oxidative stress. This work warrants further research on selective cytotoxicity mechanisms of BT NPs in different types of cancer cells and their normal counterparts.

Combined exposure of single-walled carbon nanotubes (SWCNTs) and trace metal lead (Pb) in ambient air is unavoidable. Most of the previous studies on the toxicity of SWCNTs and Pb have been conducted individually. There is a scarcity of information on the combined toxicity of SWCNTs and Pb in human cells. This work was designed to explore the combined effects of SWCNTs and Pb in human lung epithelial (A549) cells. SWCNTs were prepared through the plasma-enhanced vapor deposition technique. Prepared SWCNTs were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and dynamic light scattering. We observed that SWCNTs up to a concentration of 100 &micro, g/mL was safe, while Pb induced dose-dependent (5&ndash, 100 &micro, g/mL) cytotoxicity in A549 cells. Importantly, cytotoxicity, cell cycle arrest, mitochondrial membrane potential depletion, lipid peroxidation, and induction of caspase-3 and -9 enzymes following Pb exposure (50 &micro, g/mL for 24 h) were efficiently attenuated by the co-exposure of SWCNTs (10 &micro, g/mL for 24 h). Furthermore, generation of Pb-induced pro-oxidants (reactive oxygen species and hydrogen peroxide) and the reduction of antioxidants (antioxidant enzymes and glutathione) were also mitigated by the co-exposure of SWCNTs. Inductively coupled plasma-mass spectrometry results suggest that the adsorption of Pb on the surface of SWCNTs could attenuate the bioavailability and toxicity of Pb in A549 cells. Our data warrant further research on the combined effects of SWCNTs and Pb in animal models.

Magnetic Fe3O4 nanostructures for electrochemical water splitting and supercapacitor applications were synthesized by low temperature simple wet-chemical route. The crystal structure and morphology of as-acquired nanostructures were examined by powder X-ray diffraction and transmission electron microscopy. Magnetic measurements indicate that the as-synthesized Fe3O4 nanostructures are ferromagnetic at room temperature. The synthesized nanostructures have a high-specific surface area of 268 m2/g, which affects the electrocatalytic activity of the electrode materials. The purity of the as-synthesized nanostructures was affirmed by Raman and X-ray Photoelectron studies. The electrochemical activity of the magnetic iron oxide nanoparticles (MIONPs) for the hydrogen evolution reaction (HER) and supercapacitors were investigated in alkaline medium (0.5 M KOH) versus Ag/AgCl at room temperature. The electrocatalysts show low onset potential (~0.18 V) and Tafel slope (~440 mV/dec) for HER. Additionally, the specific capacitance of MIONPs was investigated, which is to be ~135 &plusmn, 5 F/g at 5 mV/s in 1 M KOH.

This study determined the heavy metals (HMs) accumulation in different vegetables in different seasons and attributed a serious health hazard to human adults due to the consumption of such vegetables in Jhansi. The total amounts of zinc (Zn), lead (Pb), nickel (Ni), manganese (Mn), copper (Cu), cobalt (Co), and cadmium (Cd) were analysed in 28 composite samples of soil and vegetables (Fenugreek, spinach, eggplant, and chilli) collected from seven agricultural fields. The transfer factor (TF) of HMs from soil to analysed vegetables was calculated, and significant non-carcinogenic health risks due to exposure to analysed heavy metals via consumption of these vegetables were computed. The statistical analysis involving Principal Component Analysis (PCA) and Pearson's correlation matrix suggested that anthropogenic activities were a major source of HMs in the study areas. The target hazard quotient of Cd, Mn, and Pb for fenugreek (2.156, 2.143, and 2.228, respectively) and spinach (3.697, 3.509, 5.539, respectively) exceeded the unity, indicating the high possibilities of non-carcinogenic health risks if regularly consumed by human beings. This study strongly suggests the continuous monitoring of soil, irrigation water, and vegetables to prohibit excessive accumulation in the food chain.

Nanostructure titanium dioxide (TiO2) thin films were grown by atomic layer deposition on florin-doped tin oxide (FTO) substrates at 200 °C of thickness 100 nm. The TiO2 films were annealed at 300–500 °C in air for a period of 1 h. The prepared thin films have been studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy, photoluminescence (PL) spectroscopy and current–voltage (I–V) properties. From X-ray diffraction patterns, as-deposited TiO2 thin films have a mixed anatase and rutile phases with FTO peaks. When the films were annealed the phase transformed to single anatase phase of the TiO2 films. The optical transmittance of as-deposited thin films is more than 58% and decreased with the increase in annealing temperatures. The energy band gap value was found to change with annealing temperature. The room-temperature PL spectra of TiO2 thin films show the band gap and defect peak at 409 nm and 420 nm with excitation at 325 nm. An enhancement of luminescence intensity is found due to change in the crystalline environment and reduction in oxygen amount with temperature. The value of ideality factor of prepared heterojunction is more than one, while the calculated values of saturation current, series resistance and barrier height altered with annealing because of defect-induced carrier capturing on interface between TiO2 and FTO.

Numerous applications of reduced graphene oxide (RGO) and pervasive cadmium (Cd) have led concern about their co-exposure to the environment and human. We studied the combined effects of RGO and Cd in human liver (HepG2) cells. Initially, we found that RGO (up to 50 μg/ml) did not harm to HepG2 cells while Cd induced dose-dependent (1–10 μg/ml) cytotoxicity. Exciting observations were that a non-cytotoxic concentration of RGO (25 μg/ml) effectively mitigates the toxic effects of Cd (2 μg/ml) such as cell viability reduction, lactate dehydrogenase release, and irregular cell morphology. Cd-induced cell cycle arrest, induction of caspases (3 and 9) enzymes activity, and loss of mitochondrial membrane potential were also significantly alleviated by RGO co-exposure. Moreover, generation of pro-oxidants (reactive oxygen species and hydrogen peroxide levels) and depletion of antioxidants (glutathione level and superoxide dismutase activity) due to Cd exposure was effectively attenuated by RGO co-exposure. Mitigating effect of RGO could be due to strong adsorption of Cd on the large surface area of RGO sheets, which decrease the cellular uptake and bioavailability of Cd for HepG2 cells. This study warrants future research on potential mechanisms of mitigating effects of RGO against Cd-induced toxicity in animal models.

Broad application of reduced graphene oxide (rGO) and ubiquitous lead (Pb) pollution may increase the possibility of combined exposure of humans. Information on the combined effects of rGO and Pb in human cells is scarce. This work was designed to explore the potential effects of rGO on Pb-induced toxicity in human alveolar epithelial (A549) cells. Prepared rGO was polycrystalline in nature. The formation of a few layers of visible creases and silky morphology due to high aspect ratio was confirmed. Low level (25 μg/mL) of rGO was not toxic to A549 cells. However, Pb exposure (25 μg/mL) induced cell viability reduction, lactate dehydrogenase enzyme leakage with rounded morphology in A549 cells. Remarkably, Pb-induced cytotoxicity was significantly mitigated by rGO co-exposure. Pb-induced mitochondrial membrane potential loss, cell cycle arrest and higher activity of caspase-3 and -9 enzymes were also alleviated by rGO co-exposure. Moreover, we observed that Pb exposure causes generation of pro-oxidants (e.g., reactive oxygen species, hydrogen peroxide and lipid peroxidation) and antioxidant depletion (e.g., glutathione and antioxidant enzymes). In addition, the effects of Pb on pro-oxidant and antioxidant markers were significantly reverted by GO co-exposure. Inductively coupled plasma-mass spectrometry suggested that due to the adsorption of Pb on rGO sheets, accessibility of Pb ions for A549 cells was limited. Hence, rGO reduced the toxicity of Pb in A549 cells. This research warrants further study to work on detailed underlying mechanisms of the mitigating effects of rGO against Pb-induced toxicity on a molecular level.

Iron oxide&ndash, reduced graphene oxide (Fe3O4-RGO) nanocomposites have attracted enormous interest in the biomedical field. However, studies on biological response of Fe3O4-RGO nanocomposites at the cellular and molecular level are scarce. This study was designed to synthesize, characterize, and explore the cytotoxicity of Fe3O4-RGO nanocomposites in human liver (HepG2) cells. Potential mechanisms of cytotoxicity of Fe3O4-RGO nanocomposites were further explored through oxidative stress. Prepared samples were characterized by UV-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The results demonstrated that RGO induce dose-dependent cytotoxicity in HepG2 cells. However, Fe3O4-RGO nanocomposites were not toxic. We further noted that RGO induce apoptosis in HepG2 cells, as evidenced by mitochondrial membrane potential loss, higher caspase-3 enzyme activity, and cell cycle arrest. On the other hand, Fe3O4-RGO nanocomposites did not alter these apoptotic parameters. Moreover, we observed that RGO increases intracellular reactive oxygen species and hydrogen peroxide while decrease antioxidant glutathione. Again, Fe3O4-RGO nanocomposites did not exert oxidative stress. Altogether, we found that RGO significantly induced cytotoxicity, apoptosis and oxidative stress. However, Fe3O4-RGO nanocomposites showed good biocompatibility to HepG2 cells. This study warrants further research to investigate the biological response of Fe3O4-RGO nanocomposites at the gene and molecular level.

Herein, an ultrafast, sensor has been developed for trace-level detection of Ammonia (NH3) gas using hexagonal-shaped ZnO nanoparticles (NPs). The ZnO NPs were grown by low-cost eco-friendly green synthesis process and characterized by various techniques. The electron microscopic images reveal the synthesis of uniform, highly dense and hexagonal-shaped ZnO NPs. The UV–Vis spectra illustrate a band gap of 3.89eV. XRD, XPS and Raman studies explain the high-quality hexagonal wurtzite-structure of ZnO NPs showing presence of electronic/chemical states of ions. The NH3 gas sensing properties of ZnO NPs were evaluated at different concentrations. The sensor exhibited an excellent response value of 2.5 at 5 ppm NH3 wherein quick response time was 5 s and fastest recovery time was 8 s. The sensing results could be attributed to the optimum number of oxygen species and active sites which are responsible for enhanced performance of the developed ZnO NPs based sensor.

Due to unique optical and electronic properties tin oxide nanoparticles (SnO2 NPs) have shown potential for various applications including solar cell, catalyst, and biomedicine. However, there is limited information concerning the interaction of SnO2 NPs with human cells. In this study, we explored the potential mechanisms of cytotoxicity of SnO2 NPs in human breast cancer (MCF-7) cells. Results demonstrated that SnO2 NPs induce cell viability reduction, lactate dehydrogenase leakage, rounded cell morphology, cell cycle arrest and low mitochondrial membrane potential in dose- and time-dependent manner. SnO2 NPs were also found to provoke oxidative stress evident by generation of reactive oxygen species (ROS), hydrogen peroxide (H2O2) and lipid peroxidation, while depletion of glutathione (GSH) level and lower activity of several antioxidant enzymes. Remarkably, we observed that ROS generation, GSH depletion, and cytotoxicity induced by SnO2 NPs were effectively abrogated by antioxidant N-acetylcycteine. Our data have shown that SnO2 NPs induce toxicity in MCF-7 cells via oxidative stress. This study warrants further research to explore the genotoxicity of SnO2 NPs in different types of cancer cells.

Present work focuses on the growth of single-walled carbon nanotubes (SWCNTs) using nickel as a catalyst onto the silicon substrate through plasma enhanced chemical vapour deposition (PECVD) method. As synthesised SWCNTs have been characterized by employing various analytical techniques like XRD, SEM, HR-TEM/EDS and UV-visible absorption spectroscopy. The HRTEM micrographs revealed that the SWCNTs were mostly entangled bundles with diameters of about 2 nm. The optical absorption data were used to estimate energy bandgap of the SWCNTs and found to be 2.67 eV. The photocatalytic performance of the nanotubes was examined by the deterioration of an organic dye methylene blue (MB) under visible light irradiation. The observed results exhibit excellent photocatalytic activity of the nanotubes that may be due to the large surface defects, surface area and small energy bandgap characteristics of the nanotubes.