Novel hierarchical flower-and nanorod-shaped ZnO nanoparticles with uniform morphological features were successfully synthesized through controlled precipitation method in aqueous media without using any surfactant or...Novel hierarchical flower-and nanorod-shaped ZnO nanoparticles with uniform morphological features were successfully synthesized through controlled precipitation method in aqueous media without using any surfactant or template.To elucidate the growth mechanism of the synthesized nanoparticles,the effects of pH,reaction time and temperature were studied systematically.Selected ZnO samples were then subjected to SEM,FT-IR and XRD analysis.XRD patterns confirmed well crystalline nature of the as-synthesized powders.Furthermore,synthesized nanoparticles(hierarchical flowers as ZnO-1 and nanorods as ZnO-2),as well as commercial ZnO(ZnO-Com),were then investigated for in-vitro evaluation of antibacterial activity against various bacterial strains of clinical importance.Results showed that ZnO-2 exhibited higher antibacterial activity to all tested strains than ZnO-1,while ZnO-Com showed no antibacterial response in the applied experimental conditions.In addition,ZnO concentration-dependent antibacterial study unfolded that size of inhibition zones increased significantly from^30 to 33 mm against Streptococcus mutans and from^28 to 30 mm against Escherichia coli with increasing ZnO-2 concentration from 0.25 to 0.75μg/μL.The present study,therefore,suggests that the application of synthesized ZnO nanoparticles as the antibacterial agent may be effective for inhibiting certain pathogenic bacteria in biomedical sides.展开更多
Zinc oxide uniform nanostructures with novel morphologies were synthesized through simple and fast ammonia based controlled precipitation method in aqueous media and in the absence of any additive. Selected batches of...Zinc oxide uniform nanostructures with novel morphologies were synthesized through simple and fast ammonia based controlled precipitation method in aqueous media and in the absence of any additive. Selected batches of the synthesized solids were characterized by SEM, XRD, FTIR and TG/DTA. FTIR analysis revealed that the morphology of nanostructures had little effect on their IR spectral profile of the synthesized material. The as-prepared, calcined and commercial ZnO nanostructures (ZnO-AP, ZnO-Cal and ZnO-Com) were then employed as gas sensors for the detection of ammonia, acetone and ethanol. ZnO-AP and ZnO-Cal based sensors showed superior and reproducible performance towards 1×10^-6 ammonia with gas response of 63.79% and 66.87% and response/recovery time of 13 and 3 s, respectively, at room temperature (29℃). This was attributed to the unique morphology and remarkable uniformity in shape and size of the synthesized nanostructures. In contrast, the ZnO-Com based sensor did not respond to ammonia concentration less than 200×10^-6. In addition, ZnO-Cal showed high selectivity to ammonia as compared to acetone and ethanol at room temperature. Moreover, the lowest detection limit was 1×10^-6, which demonstrates excellent ammonia sensing characteristics of the synthesized ZnO.展开更多
文摘Novel hierarchical flower-and nanorod-shaped ZnO nanoparticles with uniform morphological features were successfully synthesized through controlled precipitation method in aqueous media without using any surfactant or template.To elucidate the growth mechanism of the synthesized nanoparticles,the effects of pH,reaction time and temperature were studied systematically.Selected ZnO samples were then subjected to SEM,FT-IR and XRD analysis.XRD patterns confirmed well crystalline nature of the as-synthesized powders.Furthermore,synthesized nanoparticles(hierarchical flowers as ZnO-1 and nanorods as ZnO-2),as well as commercial ZnO(ZnO-Com),were then investigated for in-vitro evaluation of antibacterial activity against various bacterial strains of clinical importance.Results showed that ZnO-2 exhibited higher antibacterial activity to all tested strains than ZnO-1,while ZnO-Com showed no antibacterial response in the applied experimental conditions.In addition,ZnO concentration-dependent antibacterial study unfolded that size of inhibition zones increased significantly from^30 to 33 mm against Streptococcus mutans and from^28 to 30 mm against Escherichia coli with increasing ZnO-2 concentration from 0.25 to 0.75μg/μL.The present study,therefore,suggests that the application of synthesized ZnO nanoparticles as the antibacterial agent may be effective for inhibiting certain pathogenic bacteria in biomedical sides.
文摘Zinc oxide uniform nanostructures with novel morphologies were synthesized through simple and fast ammonia based controlled precipitation method in aqueous media and in the absence of any additive. Selected batches of the synthesized solids were characterized by SEM, XRD, FTIR and TG/DTA. FTIR analysis revealed that the morphology of nanostructures had little effect on their IR spectral profile of the synthesized material. The as-prepared, calcined and commercial ZnO nanostructures (ZnO-AP, ZnO-Cal and ZnO-Com) were then employed as gas sensors for the detection of ammonia, acetone and ethanol. ZnO-AP and ZnO-Cal based sensors showed superior and reproducible performance towards 1×10^-6 ammonia with gas response of 63.79% and 66.87% and response/recovery time of 13 and 3 s, respectively, at room temperature (29℃). This was attributed to the unique morphology and remarkable uniformity in shape and size of the synthesized nanostructures. In contrast, the ZnO-Com based sensor did not respond to ammonia concentration less than 200×10^-6. In addition, ZnO-Cal showed high selectivity to ammonia as compared to acetone and ethanol at room temperature. Moreover, the lowest detection limit was 1×10^-6, which demonstrates excellent ammonia sensing characteristics of the synthesized ZnO.
