International Journal of Nanoscience

Surgical instruments and other bioimplant devices, owing to their importance in the biomedical industry require high biocompatibility to be used in the human body. Nevertheless, issues of compatibility, bacterial infections are quite common in such devices. Hence development of surface coatings on various substrates for implant applications is a promising technique to combat the issues arising in these implant materials. The present investigation aims at coating copper on stainless steel substrate using DC Magnetron sputtering which is used to achieve film of required thickness (0.5–8$\mu$m). The deposition pressure, substrate temperature, power supply, distance between the specimen and target are optimized and maintained constant, while the sputtering time (30–110min) is varied. The sputtered copper thin film’s morphology, composition are characterized by SEM and EDAX. X-ray diffraction analysis shows copper oriented on (111) and (002) and copper oxide on (111) planes. The contact angle of copper thin film is 92${}^{\circ }$ while AISI 316L shows 73${}^{\circ }$. The antimicrobial studies carried in Staphylococcus aureus, Escherichia Coli, Klebsiella pneumonia and Candida albicans show that the maximum reduction was seen upto 35, 26, 54, 39CFU/mL, respectively after 24h. The cell viability is studied by MTT assay test on Vero cell line for 24h, 48h and 72h and average cell viability is 43.85%. The copper release from the thin film to the culture medium is 6691$\mu$g/L (maximum) is estimated from AAS studies. The copper coated substrate does not show much reaction with living Vero cells whereas the bacteria and fungi are found to be destroyed.

Zinc oxide (ZnO) thin films have been deposited onto thoroughly cleaned stainless steel (AISI SS 304) substrates by reactive direct current (dc) magnetron sputtering and the films were doped with silver (Ag). The prepared thin films were analyzed using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) to investigate the structural and morphological properties. The thickness values of the films were in the range of 194 to 256nm. XRD results revealed that the films were crystalline with preferred (002) orientation. Grain size values of pure ZnO films were found to be 19.82–23.72nm. On introducing Ag into ZnO film, the micro-structural properties varied. Adhesion test was carried out with Staphylococcus aureus (S. aureus) in order to know the adherence property of the deposited films. Colony formation units (CFU) were counted manually and bacterial adhesion inhibition (BAI) was calculated. We observed a decrease in the CFU on doping Ag in the ZnO films. BAI of the film deposited at – 100 V substrate bias was found to be increased on Ag doping from 69 to 88%.

It has been recently investigated [A. Azizi and S. Ebrahimi, Nano 9, 1450088 (2004).] the Paclitaxel (PTX) anticancer drug molecule adsorption on nitrogen doped graphene (NG). However, the surface strain effect on adsorption is not considered in the literature. In this study, using molecular dynamics (MD) simulation, we show that the PTX molecule adsorption can be tuned by exploiting the rippling effect of the strained NG. The dependence of the nitrogen concentration in the presence of ripples on the surface, arising due to thermal fluctuations, is examined. We have also considered the connection between the average distance of PTX from NG surface and the maximum induced deformation on the surface structure. It is demonstrated that the average distance of PTX from NG is increased with increasing the strain until a critical value is reached, and then it has remained almost constant. To this end, the dependence of the degree of ripple-type distortion of the surface on the PTX adsorption is investigated.

TiO₂ powder was found to be polycrystalline with rutile system. TiO₂ films were deposited on quartz substrates by a sol–gel spin coating technique. X-ray diffraction and transmission electron microscope results have confirmed that the TiO₂ films have nanostructure nature. It is found the crystallite size increased with annealing temperature. The optical constants of nanostructured TiO₂ films were found to be independent of film thickness in the range from 100nm to 500nm. It is found that the optical constants and the dielectric constant of the thin films were all affected by annealing temperature. The existing allowed optical transitions in the as-deposited and annealed films were found to be direct and indirect transitions. Finally, the bandgaps of the as-deposited film were found to decrease with the annealing temperature.

Hybrid nanomaterials consisting of functionalized fullerene and gold nanoparticle (NP) have been synthesized. Fullerene was functionalized by citric acid and used as reducing and capping agent for preparation of gold NPs. Functionalization of fullerene by use of citric acid was performed by enzymatic and thermal approaches. The core-shell structures containing gold NPs as core and fullerene as shell (gold/fullerene) were prepared. It was found that method and density of functionalization of fullerene effect final structure and therefore their physicochemical property of hybrid nanomaterial dramatically. Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM) were used to analyze the structure of the synthesized hybrid nanomaterial and also study their self-assembly and physicochemical properties. Effect of the size, structure and morphology (e.g., agglomeration) of the synthesized hybrid nanomaterial on their UV-Vis absorption behavior has been also verified by theoretical modeling.

The reaction under autogenic pressure at elevated temperature (RAPET) technique is proposed for synthesizing a series of metal phosphide nanoparticles such as MoP, MoP₂, Cu₃P and CuP₂ at 850${}^{\circ }$C for 3.50h by reacting selectively the transition metal powders with elemental phosphorus. The obtained products are characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). A reaction mechanism is suggested based on the experimental results.

A simple solvothermal microwave irradiation (SMI) route was used first time for the preparation of pure and different concentrations of cobalt (Co) doped CuO nanocrystals. The structure, morphology and composition of the as-synthesized nanocrystals were investigated by X-ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectral (EDX) analysis. The XRD results confirmed the formation of the single phase monoclinic structure of pure and doped CuO with average crystallite sizes in the range of 10–16nm. The surface morphology of the Co doped CuO nanocrystals did not show much change following the increasing concentration of doping. The EDX analysis showed that the atomic percentage of Cu decreases with the increasing dopant (Co) concentrations, which have proved that the Cu atoms have successfully replaced their Co counterparts as dopant. The optical absorption properties were determined by a UV-Vis spectral analysis and the results showed that the as-prepared pure and Co doped CuO nanoparticles have a larger bandgap values in the range of 2.804–3.193eV. A strong and sharp photoluminescence (PL) emission at 300nm excitation wavelength is reported from the prepared nanoparticles. The results show that the pure and doped CuO nanoparticles have high dispersion and narrow size distribution.