Preparation And Evaluation Of Vitamin C Double Emulsions Encapsulated By Hydrogel Beads

As a natural active ingredient,vitamin C has high antioxidant properties as well as the functions of whitening and freckles,strengthening the skin,promoting collagen synthesis,etc.,which has been widely used in the field of cosmetics.However,vitamin C has defects including poor stability,strong sensitivity to temperature,light,oxygen,metal ions,etc.and poor skin absorption capacity,which limits its effectiveness.Therefore,many researchers had tried to use micro/nano carriers such as nano-emulsions,liposomes,double emulsions,etc.to encapsulate vitamin C,but the instability of micro/nano carriers limits its advantages of encapsulation.In this article,hydrogel beads with a three-dimensional structure was used to encapsulate vitamin C double emulsions to achieve double encapsulation of vitamin C,thereby improving vitamin C stability and skin absorption,and it could be a certain reference for the application of vitamin C and other water-soluble active ingredients in the field of cosmetics.Firstly,a two-step emulsification method was used to prepare double emulsions of vitamin C,and the parameters such as lipophilic emulsifiers,solid lipids,and hydrophilic emulsifiers in double emulsions formulations were screened through single-factor inspection to prepare a uniform structure and average particle of vitamin C.The prepared vitamin C double emulsions with a diameter of(7.16 ± 0.45)μm,an encapsulation rate of(81.3 ± 4.1)%,and a loading capacity of(0.813 ± 0.041)%.Secondly,the Ca-alginate hydrogel beads were prepared by the direct-dropping method to encapsulate the vitamin C double emulsions,and the parameter of the Ca-alginate hydrogel beads were screened by a single factor inspection method,and the obtained double emulsions Ca-alginate hydrogel beads’ spherical rate was 0.992 ± 0.006,the vitamin C encapsulation rate was(74.5 ± 0.9)%.The well-structured double emulsions present inside the Ca-alginate hydrogel beads could be observed under an optical microscope.The results of physical and chemical stability investigation showed that the double emulsions Ca-alginate hydrogel beads had good storage stability when stored at 4 ℃ and 25 ℃ for 6 months.In addition,the results of in vitro release studies indicated that the double emulsions Ca-alginate hydrogel beads had a significant sustained release effect on the vitamin C,and the release model was more in line with Weibull equation and the release mechanism was tend to Fickian diffusion mechanism.In vitro transdermal behavior studies were shown that Ca-alginate hydrogel beads had a high promotion effect on skin absorption of vitamin C,and the double emulsions and Ca-alginate hydrogels had a synergistic effect on vitamin C percutaneous absorption.Furthermore,the vitamin C double emulsions gellan gum hydrogel beads were also prepared by the direct-dropping method,and according to the single factor inspection method.The obtained double emulsions gellan gum hydrogel beads’ spherical rate was 0.8420 ± 0.019,the vitamin C encapsulation rate was(63.2 ± 2.3)%.Moreover,The well-structured double emulsions present inside the gellan gum hydrogel beads could be observed under an optical microscope.The physical and chemical stability inspection results showed that the double emulsions gellan gum hydrogel beads could effectively reduce the degradation of vitamin C,and there was no obvious appearance change when stored at 4 ℃ and 25 ℃ for 2 months.The results of in vitro release studies showed that double emulsions gellan gum hydrogel beads had a significant sustained release effect on the vitamin C,and its release model was more in line with Weibull equation and the release mechanism was tend to Fickian diffusion mechanism.In vitro transdermal behavior studies were shown that gellan gum hydrogel beads had a certain promoting effect on vitamin C skin absorption.The double encapsulation of vitamin C was achieved to enhance the stability of vitamin C through the above experimental research,and the advantages and disadvantages of Ca-alginate hydrogel beads and gellan gum hydrogel beads in vitamin C double emulsions encapsulation were also evaluated.It might provide a new dosage form for the use of unstable water-soluble active ingredients such as vitamin C in the cosmetics field.In addition,the evaluation of the physical and chemical stability,release performance,antioxidant performance,and transdermal absorption capacity of the two kind of double emulsions hydrogel beads provided a favorable basis for vitamin C to better exert its efficacy.