Construction Of Chemical Sunscreen/Lignin Microcapsules And Their Applied Fundamental Research

It is urgent to protect our skin from UV radiation because of the destruction of the ozone layer.Lignin is the unique aromatic polymer in the plant.The natural phenylpropane units,phenolic hydroxyl groups and other functional groups endow lignin excellent UV protection and antioxidant properties.However,the industrial lignin is dark brown,be easy to aggregate and has poor compatibility,which limit its application in skin care products.In this paper,the microcapsules were prepared by ultrasonic cavitiation in one-step.The enzymatic hydrolysis lignin?EHL?was used as wall material.The chemical sunscreen octyl methoxycinnamate?OMC?and avobenzone?BMDM?were used as core material.The optimum preparation conditions were as follows:ultrasonic time=3⁴ min,ultrasonic power=750 W,the ratio of EHL to chemical sunscreen=1:1,the concentration of EHL=3 wt%,the concentration of surfactant=1² wt%.The microcapsules could be stored at room temperature for more than 12 months without leakage.The results of FTIR showed that EHL could protect the structure of chemical sunscreen whose sunscreen performance was not affected by ultrasonic cavitation.H₂O₂ could be used to increase the cross-linking degree of EHL.Surfactants had the effects of reducing the particle size of microcapsules to 100¹50 nm,increasing the content of EHL,enhancing the sun protection performance.The results of in-vitro sunscreen performance showed that adding 10 wt%microcapsules encapsulating two kinds of chemical sunscreen into polar cream could prepare a sunscreen with sun protection factor?SPF?of 408,the SPF valus increased by 153%compared with free chemical sunscreen.Due to the photo-resistance of lignin,the sun protection perfprmance of creams added nanocapsules could be maintained at least 8 h under high-intensity UV radiation.The chemical sunscreen in capsules did not show significant leakage and skin penetration.The results of cytotoxicity showed that the microcapsules had good biocompatibility.The microcapsules were prepared by using ultrasonic cavitiation in one-step.The sodium lignosulfonate?LS?was used as wall material.The chemical sunscreen octyl methoxycinnamate?OMC?and avobenzone?BMDM?were used as core material.The optimum preparation conditions were as follows:the ratio of LS to chemical sunscreen=2:1,the concentration of LS=3 wt%,ultrasonic time=3 min,ultrasonic power=600 W,the concentration of surfactant=2 wt%.The microcapsules could also be stored at room temperature for more than 12 months without leakage.The results of FTIR showed that LS could protect the structure of chemical sunscreen.Surfactant had the effects of reducing the particle size of microcapsules to 200²50 nm,increasing the content of LS,enhancing the sun protection performance.The results of in-vitro sunscreen performance showed that adding 10wt%microcapsules encapsulating two kinds of chemical sunscreen into polar cream could prepare a sunscreen with sun protection factor?SPF?of 324,the SPF valus increased by 119%compared with free chemical sunscreen.And the sun protection perfprmance of creams added nanocapsules could be maintained at least 4 h under high-intensity UV radiation.Compared with the performance of Chemical sunscreen/EHL microcapsules,Chemical sunscreen/LS microcapsules had weaker sun protection performance and photo-stability.