Optical Properties of Stabilized ZnO Nanoparticles, Perspective for UV-Protection in Sunscreens

ZnO nanoparticles have been synthesized for utilization as UV filter in sunscreens. Optical characteristics of the synthesized ZnO nanoparticles have been investigated. Two methods were used for stabilizing of nanoparticles to prevent coagulation and stabilization of disperse systems: deposition of inert polymer (PVA) during synthesis and surface modification by 3-aminopropyltriethoxysilane (APTES). Presences of PVA layer of 2nm and APTES have modified the optical properties. It was shown that both UV-A and UV-B can be completely blocked by modified ZnO nanoparticles. Surface modification by APTES leads to aggregative stability of the sol dispersion in solution. Level of hemolysis and cytotoxicity activities of all samples was also studied, and the influence of surface modification has been analyzed in details. Addition of PVA (more than 3 wt%) leads to a significant increase in cytotoxicity. Surface modification of nanoparticles by APTES also leads to an increase in level of hemolysis and cytotoxicity, however this level is quite low. Notably we have achieved the stabilized and non-harmful ZnO nanoparticles by not only depositing the PVA but by modifying the PVA capped nanoparticles with APTES. Stabilized ZnO nanoparticles act as UV filters and were transparent in the visible region of the spectrum, which makes the present material promising for use as UV filters in sunscreens, while the effect on cells in case of penetrating the layer of epidermis may be minimal.