Preparation And Characterization Of HA-AgIn₅S₈ Composite Nanoparticles And Their Application In Sunscreen

Objective:The UV-visible light shielding ability of AgIn₅S₈,and the irritation and allergy effect of AgIn₅S₈ to skin were studied.Hyaluronic acid（HA）combined with AgIn₅S₈（expressed as HA-AgIn₅S₈）to improve the safety,moisture retention,hygroscopicity and water dispersion stability of AgIn₅S₈.The shielding performance of HA-AgIn₅S₈and Ti O₂ for UV-visible light was compared.Methods:1.AgIn₅S₈ was prepared with reaction time of 15h by low temperature water bathmethod.The AgIn₅S₈ was characterized by X-ray diffraction（XRD）,X-rayphotoelectron spectroscopy（XPS）,scanning electron microscope（SEM）,highresolution transmission electron microscope（HRTEM）and the specific surface area（BET）.The photocatalytic activity of AgIn₅S₈ was studied by using Rhodamine B（Rh B）as a model pollutant.2.Guinea pigs were used as tested animals to study the irritation and allergy ofAgIn₅S₈ to skin.The skin irritation test was divided into complete skin group anddamaged skin group.Both groups were smeared with deionized water and AgIn₅S₈suspension solution on both sides of the left and right spines of the same guinea pig.The left side was coated with deionized water as the negative control group,and theright side was applied with 1 m L of 5 mg/m L AgIn₅S₈ suspension solution.After 24hours of complete contact with the skin,the samples were washed away.Thechanges of erythema and edema in the tested area were recorded at 0 h,24 h,48 hand 72 h after washing.Skin anaphylaxis test was divided into deionized watergroup,2,4-dinitrochlorobenzene group and AgIn₅S₈ group.Each group wassmeared with 1 m L,5 mg/m L samples on both sides of the test area.After threetimes of sensitizing and one sensitizing test,the samples were washed away,andthe skin allergies were observed for 0 h,24 h,48 h,72 h and 72 h,respectively.3.AgIn₅S₈was combined with HA to compare the moisture retention,hygroscopicityand water dispersion stability of the samples before and after compounding.Thechanges of photocatalytic activity before and after AgIn₅S₈ compounding werestudied by degradation of Rh B pollutants.Using UVA as light source and 8-methoxypsoralan as positive control group,the phototoxicity of samples to skinbefore and after combination was studied.4.The optimum matrix formulation process of sunscreen was selected by Box-Behnken response surface method.The ratio of oil to water,emulsification temperature,emulsification time and emulsification speed were taken as response factors,andthe longest centrifugal time was taken as response values.The prepared AgIn₅S₈and HA-AgIn₅S₈were separately applied to the self-made matrix to compare withthe commercially available rutile Ti O₂,the protective properties and stability ofHA-AgIn₅S₈ sunscreen at different concentrations were investigated.Results:1.The sample prepared at 15h by a lower temperature water bath method was amixture of AgIn₅S₈ and Ag In S₂,and the nanoparticle size is about 79 nm,thespecific surface area is about 87.876 m²/g.2.AgIn₅S₈ has no erythema and edema reaction on intact skin of guinea pigs,andslight edema on damaged skin.It was found by HE staining that AgIn₅S₈ had noeffect on the normal skin,while the skin was thickened and the number offibroblasts was reduced in damaged skin.3.The photocatalytic activity and the skin phototoxicity of AgIn₅S₈ were significantlyreduced and the water-dispersion stability,moisture retention and moistureabsorption of AgIn₅S₈ were enhanced after the HA combined with AgIn₅S₈.4.The best formula of sunscreen cream was screened by Box-Behnken responsesurface method.The results showed that the response factors to the response valuewere oil-water ratio>emulsification temperature>emulsification time>emulsification speed.The optimum formulation process is oil-water ratio,emulsification temperature,emulsification time and emulsification speed of 1:1.08,80.5℃,7 min,1025 r/min.Compared with the protection performance of sunscreen,HA-AgIn₅S₈ sunscreen has better protection effect than that of Ti O₂ sunscreen,andthe 2.0%HA-AgIn₅S₈ sunscreen has the best stability and UV-visible light protection effect.Conclusion:The sample prepared at 15h by a low temperature water bath method was a mixture of AgIn₅S₈ and Ag In S₂,and the sample is non-irritating and allergenic to intact skin,but slightly irritating to the damaged skin.HA-AgIn₅S₈ modified by HA has better water dispersion stability,moisture retention,moisture absorption and safety than AgIn₅S₈.The sunscreen base formulation screened by Box-Bnhnken response surface method has good stability.The prepared HA-AgIn₅S₈ sunscreen has better UV-visible light protection effect than that of Ti O₂ sunscreen,and the 2.0%HA-AgIn₅S₈ sunscreen has the best stability and UV-visible light protection effect.