Tariq Jan

Sn doping induced enhancement in the activity of ZnO nanostructures against antibiotic resistant S. aureus bacteria

Highly ionic metal oxide nanostructures are attractive, not only for their physiochemical properties but also for antibacterial activity. Zinc oxide (ZnO) nanostructures are known to have inhibitory activity against many pathogens but very little is known about doping effects on it. The antibacterial activity of undoped ZnO and tin (Sn) doped ZnO nanostructures synthesized by a simple, versatile, and wet chemical technique have been investigated against Escherichia coli, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa bacterial strains. It has been interestingly observed that Sn doping enhanced the inhibitory activity of ZnO against S. aureus more efficiently than the other two bacterial strains. From cytotoxicity and reactive oxygen species (ROS) production studies it is found that Sn doping concentration in ZnO does not alter the cytotoxicity and ROS production very much. It has also been observed that undoped and Sn doped ZnO nanostructures are biosafe and biocompatible materials towards SH-SY5Y Cells. The observed behavior of ZnO nanostructures with Sn doping is a new way to prevent bacterial infections of S. aureus, especially on skin, when using these nanostructures in creams or lotions in addition to their sunscreen property as an ultraviolet filter. Structural investigations have confirmed the formation of a single phase wurtzite structure of ZnO. The morphology of ZnO nanostructures is found to vary from spherical to rod shaped as a function of Sn doping. The excitation absorption peak of ZnO is observed to have a blue shift, with Sn doping leading toward a significant tuning in band gap.

Antimicrobial potential of green synthesized CeO2 nanoparticles from Olea europaea leaf extract.

This article reports the green fabrication of cerium oxide nanoparticles (CeO2 NPs) using Olea europaea leaf extract and their applications as effective antimicrobial agents. O. europaea leaf extract functions as a chelating agent for reduction of cerium nitrate. The resulting CeO2 NPs exhibit pure single-face cubic structure, which is examined by X-ray diffraction, with a uniform spherical shape and a mean size 24 nm observed through scanning electron microscopy and transmission electron microscopy. Ultraviolet-visible spectroscopy confirms the characteristic absorption peak of CeO2 NPs at 315 nm. Fourier transform infrared spectroscopy reflects stretching frequencies at 459 cm−1, showing utilization of natural components for the production of NPs. Thermal gravimetric analysis predicts the successful capping of CeO2 NPs by bioactive molecules present in the plant extract. The antimicrobial studies show significant zone of inhibition against bacterial and fungal strains. The higher activities shown by the green synthesized NPs than the plant extract lead to the conclusion that they can be effectively used in biomedical application. Furthermore, reduction of cerium salt by plant extract will reduce environmental impact over chemical synthesis.

Doping Induced Tailoring in the Morphology, Band-Gap and Ferromagnetic Properties of Biocompatible ZnO Nanowires, Nanorods and Nanoparticles

The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped ZnO nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of ZnO nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved. The prepared nanostructures have been found to be nontoxic to SH-SY5Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of ZnO nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.

Synthesis of highly efficient antibacterial agent Ag doped ZnO nanorods: Structural, Raman and optical properties

Here, synthesis, structural, morphological, Raman, optical properties and antibacterial activity of undoped and Ag doped ZnO nanorods by chemical co-precipitation technique have been reported. Structural analysis has revealed that Ag doping cannot deteriorate the structure of ZnO and wurtzite phase is maintained. Lattice constants are found to be decreased with the Ag doping. Fourier transform infrared and Raman spectroscopy also confirm the X-ray diffraction results. Scanning electron microscopy results have demonstrated the formation of ZnO nanorods with average diameter and length of 96 nm and 700 nm, respectively. Raman spectroscopy results suggest that the Ag doping enhances the number of defects in ZnO crystal. It has been found from optical study that Ag doping results in positional shift of band edge absorption peak. This is attributed to the successful incorporation of Ag dopant into ZnO host matrix. The antibacterial activity of prepared nanorods has been determined by two different methods and ...

Effect of Co doping on morphology, optical and magnetic properties of ZnO 1-D nanostructures

One-dimensional Co doped ZnO nanostructures have been successfully synthesized by a wet chemical technique. X-rays diffraction results reveal that with Co doping ZnO retained its wurtzite structure, but lattice constants are slightly decreased. SEM results demonstrate that Co doping changes morphology of ZnO nanostructures from nanowires to nanorods. It has been confirmed through HRTEM results that Co dopant cannot change preferred growth orientation of ZnO, although it remarkably influenced the grain size and morphology. The Co dopant is found to be uniformly distributed over various parts of single nanorod and settles at 2+ chemical oxidation state without forming any secondary phases. In response to Co doping, near band edge peak in UV region is red shifted and VL band peak intensity is remarkably enhanced. It is also found that Co doping induces large amount of defects in ZnO band structure. Furthermore, the doped nanorods exhibit ferromagnetic behavior at room temperature, which is attributed to the presence of abundant amount of defects and oxygen vacancies. The tunned band gap and ferromagnetic behavior at room temperature with high Ms and Hc values make them potential for spintronics applications.

Structural, morphological, Raman, optical, magnetic, and antibacterial characteristics of CeO2 nanostructures

In this study, CeO2 nanostructures were synthesized by a soft chemical method. A hydrothermal treatment was observed to lead to an interesting morphological transformation of the nanoparticles into homogeneous microspheres composed of nanosheets with an average thickness of 40 nm. Structural analysis revealed the formation of a single-phase cubic fluorite structure of CeO2 for both samples. A Raman spectroscopic study confirmed the XRD results and furthermore indicated the presence of a large number of oxygen vacancies in the nanosheets. These oxygen vacancies led to room-temperature ferromagnetism (RTFM) of the CeO2 nanosheets with enhanced magnetic characteristics. Amazingly, the nanosheets exhibited substantially greater antibacterial activity than the nanoparticles. This greater antibacterial activity was attributed to greater exposure of high-surface-energy polar surfaces and to the presence of oxygen vacancies.

ROS mediated malignancy cure performance of morphological, optical, and electrically tuned Sn doped CeO2 nanostructures

To grapple with cancer, implementation of differentially cytotoxic nanomedicines have gained prime attention of the researchers across the globe. Now, ceria (CeO2) at nanoscale has emerged as a cut out therapeutic agent for malignancy treatment. Keeping this in view, we have fabricated SnxCe1-xO2 nanostructures by facile, eco-friendly, and biocompatible hydrothermal method. Structural examinations via XRD and FT-IR spectroscopy have revealed single phase cubic-fluorite morphology while SEM analysis has depicted particle size ranging 30-50nm for pristine and doped nanostructures. UV-Vis spectroscopy investigation explored that Sn doping significantly tuned the band gap (eV) energies of SnxCe1-xO2 nanostructures which set up the base for tremendous cellular reactive oxygen species (ROS) generations involved in cancer cells’ death. To observe cytotoxicity, synthesized nanostructures were found selectively more toxic to neuroblastoma cell lines as compared to HEK-293 healthy cells. This study anticipates that...

Structural, optical and magnetic properties of Co-doped ZnO nanoparticles prepared via a wet chemical route

In this paper, ZnO nanoparticles doped with varying amount of Co content (i.e., 0, 2, 4, 6, 8, and 10 at.%) have been prepared by wet chemical route. X-ray diffraction (XRD) results reveal the successful substitution of Co2+ ions on to sites of Zn2+ ions without forming any secondary phase. Furthermore, a linear increase in d-spacing of the ZnO lattice is found with the increase in Co content. SEM images demonstrate the formation of homogeneously distributed spherical nanoparticles with average size of 50–70 nm. It is observed from optical investigations that band gap energy of ZnO nanoparticles significantly decreased with the increase in Co doping level. Interestingly, it is found that the high Co dopant concentration can lead to room temperature ferromagnetism in ZnO nanoparticles.

Facile synthesis of Zn doped CuO hierarchical nanostructures: Structural, optical and antibacterial properties

ZnxCu1−xO (where x= 0, 0.01, 0.03, 0.05, 0.07 and 0.1 mol%) hierarchical nanostructures have been prepared via soft chemical route. X-ray diffraction(XRD) results of the synthesized samples reveal the monoclinic structure of CuO without any impurity related phases. The micro-structural parameters such as crystallite size and microstrain have been strongly influenced by Zndoping.Scanning electron microscope(SEM) analyses depict the formation of hierarchical nanostructures having average particle size in the range of 26-43 nm. The surface area of CuO nanostructures has been reduced systematically with the increase in Zn content which is linked with the variations in particle size. An obvious decrease in the optical band gap energy of the synthesized CuO hierarchical nanostructures has been observed with Zndoping which is assigned to the formation of shallow levels in the band gap of CuO and combined transition from oxygen 2p states to d sates of Cu and Zn ions. The bactericidal potency of the CuO hierarchical nanostructures have been found to be enhanced remarkably with Zndoping.