Use of zinc oxide nanoparticles for detection of fluoride in toothpaste gel.

This study aimed to investigate the metal-binding effect of fluoride, contained in different commercial toothpaste gels; the study aimed to determine if the toothpastes contained excessive concentrations of fluoride, which result in white spot lesions. A spectrophotometric method that used spectrophotometric reagents, including zinc oxide nanoparticles and iron chloride, was used to determine fluoride distribution; the analysis was based on the selective attack of fluoride ions on metals. Fluoride concentrations between 0 and 1450 ppm were analyzed. Although the iron-fluoride complex was a more sensitive reagent, the zinc-fluoride complex could serve as a suitable alternative to it for fluoride analysis, partly because the method was less time consuming and more stable. The detection and quantification limits obtained from the linear calibration curves of the zinc-fluoride complexes, in deionized water, were 0.191:1 and 0.579:1 w/w ZnO, respectively. A model calibration curve was suggested to detect the unknown products of fluoride degradation. Dentists could use a fluoride treatment similar to the protocol used in this study, to prevent potential enamel demineralization, and exclude physical cavity preparation and restoration.

Effective detection of ZnO in nicotine using butterfly wing scales.

This study aimed to elucidate the optical functions of naturally butterfly wing scales via precise control of morphology as an effective photonic sensor and confirm the content of metal oxide nanoparticles in surrounding nicotine. Metal oxide nanoparticles mixed with nicotine were deposited on the wing scales through the spin-coating method and hence investigated using optical microscopy and spectroscopy. Experimental results demonstrated that absorption intensities of ZnO and TiO2 mixed with nicotine on Danaus genutia were remarkably enhanced. Due to the relatively high concentration of zinc found in e-cigarette aerosol, the intensity of ZnO/nicotine modelled as aerosol adsorption on Danaus genutia, further held a certain linear relationship with the concentration of ZnO. The limit of detection of ZnO was as low as 1 nM. The working mechanism of our sensor was explained through the molecular adsorption after H-bond formation of ZnO/nicotine molecules as high-index materials on the wing scales of Danaus genutia without aggregation. This photonic sensor is an alternative to the present-day methods for the rapid test of ZnO content, which is very simple without complicated instrumentation. Furthermore, our method might become a starting point for the advancement of portable instruments for onsite ZnO detection.