Ultraviolet Protection Properties of Commercial Sunscreens and Sunscreens Containing Zno Nanorods

Zinc oxide nanorods were used as the main ultraviolet agent in the development of sunscreens. Four commercial sunscreens containing organic and inorganic UV agents were studied for their UV performances and SPF determinations. From FESEM and TEM micrographs of ZnO powder, the dominant structure was rod structure with width range 61-70 nm. Sunscreens containing different concentrations of ZnO nanorods were characterized using UV-Vis spectrophotometer and X-ray diffraction (XRD). The absorbance spectra for commercial sunscreens showed a good protection in range of UVB (280-320nm), while sunscreens containing 20-40% (weight percentage) of ZnO nanorods showed a greater UV absorbance in UVA and UVB (280-400 nm). The strong UVA absorbance of ZnO nanorod can offer extra UV protection for commercial sunscreens. The average crystallite sizes of the sunscreen samples calculated from the XRD spectra were in the range 45.27 to 47.36 nm. In vitro sun protection factor (SPF) method was carried out to determine the SPF value of sunscreen specimens. SPF values of sunscreens containing ZnO nanorods were 29.50 to 43.48, whereby these SPF values indicated more than 93% of UVB blocking capability. The SPF values found of commercial sunscreens were slightly different from the SPF values in the product labels. In conclusion, incorporation of ZnO nanorods into sunscreen can greatly enhanced the UV blocking performance of sunscreens. (paper)