| Coenzyme Q10（CoQ10）is the only endogenous lipophilic antioxidant synthesized by the cell itself.It has a strong ability to scavenge free radicals,and can inhibit lipid peroxidation to protect cells from oxidative damage.Therefore,CoQ10 has important applications in anti-aging cosmetics.However,due to its poor water solubility and unstable chemical properties,it greatly affects the antioxidant properties of CoQ10.The novel lipid nanocapsule is a micro-nano carrier in which lipophilic actives are embedded in monolayer phospholipids prepared by mixing water,phospholipid,polyol or carbohydrate by high-pressure homogenization.It has the advantages of small particle size,good stability,and can effectively promote the transdermal absorption of actives.In this study,the ion-stabilized CoQ10-lipid nanocapsules were prepared using phosphatidylcholine（PC60）and decaglycerol monolaurate（P10）as emulsifiers.The effects of solid lipids in oil phase on the stability and transdermal absorption of CoQ10-lipid nanocapsules was investigated,and the antioxidant properties of the system were characterized.First,when using PC60 as an emulsifier,it was found that when the mass ratio of glycerol to water was 18:2,the mass fraction of PC60 was 5%,the mass fraction of CoQ10was 5%,the high-pressure homogenization pressure was 800 bar,and the number of cycles was 7,PC60-CoQ10-lipid nanocapsules had the smallest particle size.The system was transparent and had good storage stability,but it was unstable to ions.After mixing with NaCl and CaCl2,it changed from transparent to opalescent,and the particle size increased significantly.In order to improve the ionic stability of the system,P10-PC60-CoQ10-lipid nanocapsules were prepared by nonionic surfactant P10 and PC60 as emulsifiers,and their stability was studied.It was found that when the mass fraction of P10 was 70%（based on the total mass of P10 and PC60,the same below）,the ionic stability of P10-PC60-CoQ10-lipid nanocapsules was significantly improved compared with PC60-CoQ10-lipid nanocapsules,and it had good storage stability and thermal stability.The particle size of P10-PC60-CoQ10-lipid nanocapsule was（51.9±0.5）nm,and it had a good spherical shape.The encapsulation rate was close to 100%,and its retention rate was（93.35±0.72）%when stored at room temperature and protected from light for 30 days.In addition,P10-PC60-CoQ10-lipid nanocapsules could promote the transdermal absorption of CoQ10more efficient.Compared with CoQ10-GTCC oil solution,the transdermal content increasedfrom（5.32±0.90）μg/cm2 to（44.60±11.68）μg/cm2.Secondly,to further improve the transdermal absorption of P10-PC60-CoQ10-lipid nanocapsules,the effect of the concentration of solid lipids（cetyl palmitate,CP）in the oil phase on the stability and transdermal delivery of lipid nanocapsules was investigated.The results showed that P10-PC60-CoQ10-lipid nanocapsules with different mass fractions of solid lipids all showed a good spherical shape with no obvious difference in particle size.Its encapsulation rate was close to 100%which can well protect CoQ10 from light.In addition,they all had good storage stability and thermal stability.However,when the mass fraction of CP was 95%（based on the total mass of solid and liquid lipids,the same below）,P10-PC60-CoQ10-lipid nanocapsules was unstable to ions and demulsify after mixing with NaCl and CaCl2.The results of transdermal experiments showed that compared with P10-PC60-CoQ10-lipid nanocapsules with CP mass fraction of 0 and 50%,P10-PC60-CoQ10-lipid nanocapsules with CP mass fraction of 70%and 95%could promote the transdermal absorption of CoQ10 more efficient.The transdermal content increased from（48.84±12.79）μg/cm2,（56.03±7.83）μg/cm2 to（91.43±11.17）μg/cm2,（125.64±9.73）μg/cm2,which made the epidermal and dermal layer fluorescence intensity significant increase.According to the results of DSC and occlusion effect,this may be because the solid lipids in P10-PC60-CoQ10-lipid nanocapsules with CP mass fraction of 70%and 95%had high crystallinity.This could reduce the evaporation of skin moisture and loosen the structure of the stratum corneum,thereby facilitating the transdermal absorption of CoQ10.Finally,the chemical and cellular methods were used to study the antioxidant properties of P10-PC60-CoQ10-lipid nanocapsules with a CP mass fraction of 70%.The chemical antioxidant results showed that P10-PC60-CoQ10-lipid nanocapsules had better DPPH free radical scavenging ability and anti-lipid peroxidation ability when compared with free CoQ10.When the concentration of CoQ10 was 5 mg/mL,DPPH free radical scavenging rate increased from（23.98±0.42）%to（34.08±0.19）%,and TBARS inhibition rate increased from（8.23±3.85）%to（86.20±0.34）%.The results of cell antioxidant experiments showed that when the concentration of CoQ10 was 200μg/mL,P10-PC60-CoQ10-lipid nanocapsules was not cytotoxic and could significantly reduce the oxidative damage of UVA to cells.In addition,compared with free CoQ10,P10-PC60-CoQ10-lipid nanocapsules could promote the absorption of CoQ10 by cells and improve their protection against oxidative damage to cells.The cell viability increased from（67.95±6.52）%to（87.92±1.51）%,the level of active oxygen was reduced from（6.06±0.88）times of the control group to（2.78±0.26）times,the activity of SOD increased from（0.52±0.33）U/m L to（1.14±0.20）U/m L,and the content of GSH increased from（15.77±3.28）μmol/L to（26.10±2.98）μmol/L. |
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