The PH-responsive Tan Ⅱ_A Nanoemulsion Hydrogel Drug Delivery System Based On The Self-assembly Behavior Of Carboxymethyl Chitosan-oxidized Hyaluronic Acid

Acne is a widespread skin disease,especially among teenagers with rates up to 85%,including 30%moderate and 10%severe acne.The pathogenesis of acne is complex,and it was thought that the development of acne is mainly related to androgenic sebum production,altered sebum composition,abnormal keratinization of the follicular sebaceous ducts,colonization by Propionibacterium acnes(P.acnes)and Staphylococcus aureus(S.aureus),inflammatory response and immunity.Clinically,tanshinone capsules can be applied to treat acne,with significant efficacy.Regardless of any potential efficacy and safety issues,there is a high potential for poor patient compliance due to the high number of large pills that are required to be taken.Topical and transdermal preparations are a common means of drug delivery for the treatment of skin diseases.Compared with oral administration,topical administration reduced gastrointestinal reactions and liver and kidney toxicities,and avoided the first-pass effect of the liver;in addition,the blood concentration remained constant and this form required less frequent administration.Tanshinone II_A(Tan Ⅱ_A)is a major constituent of Salvia miltiorrhiza and has been reported to have anti-tumour activity.Accumulating evidence has shown that Tan Ⅱ_A has an anti-inflammatory effect on various diseases.However,Tan Ⅱ_A had poor aqueous solubility which limited its therapeutic efficacy and clinical application.As a result,the aim of this study was to construct a pH-responsive nanoemulsion hydrogel drug delivery system based on the self-assembly behavior of carboxymethyl chitosan(CMC)-oxidized hyaluronic acid(OHA)for transdermal delivery of Tan Ⅱ_A and enhancing its acne treatment effect.Tan Ⅱ_A nanoemulsion was prepared by self-emulsification method and its formulation was optimized.OHA was prepared by sodium periodate oxidation and self-assembled with CMC solution to form CMC-OHA Tan Ⅱ_A nanoemulsion-based hydrogels(CMC-OHA/Tan Ⅱ_A-NBHs).In addition,the physicochemical properties,transdermal properties,safety,and efficacy of CMC-OHA/Tan Ⅱ_A-NBHs were evaluated.Concentrations of Tan Ⅱ_A were determined by high performance liquid chromatography(HPLC)asdescribed with optimization.The optimum prescription of nanoemulsion was determined according to the amount of Tan Ⅱ_A dissolved in various excipients.The pseudo-ternary phase diagram and the physicochemical properties of the nanoemulsion were investigated.The mean particle size of the prepared Tan Ⅱ_Ananoemulsion was(52.18±0.21)nm and Polydispersity Index(PDI)was 0.165±0.012.The appearance of Tan Ⅱ_A nanoemulsion remained clear and transparent,and transmission electron microscopy showed nanoemulsion droplets to be spherical with a homogeneous distribution.Furthermore,OHA was prepared by sodium periodate oxidation and the concentration of CMC and OHA is optimized by using the gel formation time as an indicator.CMC-OHA/Tan Ⅱ_A-NBHs was prepared by dissolving OHA in nanoemulsion and self-assembling the mixture with CMC solution.The content of Tan Ⅱ_A in CMC-OHA/Tan Ⅱ_A-NBHs after determination and optimization was 1.0 mg/g.Moreover,stability,in vitro release,and in vitro transdermal permeation properties of the CMC-OHA/Tan Ⅱ_A-NBHs were also evaluated.Collectively,CMC-OHA/Tan Ⅱ_A-NBHs showed much better centrifugal stability and photostability compared to Tan Ⅱ_A.The long-term stability test shows that GNPs stored at 4℃ had better stability compared with those stored at 25℃ or 40℃.Finally,the toxicity of CMC-OHA/Tan Ⅱ_A-NBHs was evaluated by Cell Counting Kit-8(CCK-8)method.The results showed that CMC-OHA/Tan Ⅱ_A-NBHs in the concentration range of 25-400 g/mL had no toxicity to the mouse embryo fibroblast 3T3-L1 cells.The bacterial inhibition test showed that CMC-OHA/Tan ⅡA-NBHs could significantly inhibit the growth of Propionibacterium acnes and Staphylococcus aureus in vitro.Herein,with the advantages of simple preparation and good stability,CMC-OHA/Tan Ⅱ_A-NBHs could effectively improve the in vitro dissolution behaviour of insoluble drugs,providing a new idea and method for topical delivery of poorly soluble drugs by nanoemulsion.