Potassium dihydrogen phosphate

The animal study was reviewed and approved by the Hefei University Ethics Committee. Type I collagen was prepared from the tail tendons of rats. Sodium alginate, 75% alcohol, glacial acetic acid, sodium chloride, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, anhydrous sodium carbonate, bovine serum albumin (BSA), 4% paraformaldehyde, Triton X-100, Tween 20 were all purchased from Sangon Biotech Co., Ltd. (Shanghai, China). Beakers, ophthalmic Scissors, and tweezers were all obtained from the school reagent library; primary antibodies and fluorescent-labeled secondary antibodies were purchased from Wuhan Sanying Biology Technology Co., Ltd. Inverted fluorescence microscopes (IX53; Olympus, Japan), CO2 incubators (Thermo 3131), and computer-controlled microfluidic pumps (Harvard Apparatus PUMP33; Harvard Instruments, USA) were employed in this study.

Hydroxyethyl cellulose (3400–5000 mPa.s, 25°C), azone, glycerol, triethanolamine, and ethyl p-hydroxybenzoate were purchased from Aladdin-Reagent Co. Ltd. (Shanghai, China). Centella asiatica total glycosides (47.95%), asiaticoside standard (≥98% pure), and madecassoside standard were obtained from Pusi Biotechnology Co., Ltd. (Chengdu, China). β-Cyclodextrin, propylene glycol, sodium hydroxide, polyethylene glycol, and absolute ethanol were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Acetonitrile was purchased from Tedia (Tedia, Fairfield, OH, USA). 2,4-Dinitrochlorobenzene was purchased from Huamai Technology Co., Ltd. (Wuhan, China). Recombinant human epidermal growth factor solution was purchased from Shenzhen Watsin Genetech Ltd. Dibasic sodium phosphate was purchased from Chengdu Jinshan Chemical Reagent Co., Ltd. Potassium dihydrogen phosphate was purchased from Sangon Biotech (Shanghai) Co., Ltd. Nutrient agar and eosin methylene blue were purchased from Beijing Solarbio Science and Technology Co., Ltd. Phosphoric acid, methanol, n-butanol, acetic anhydride, sulfuric acid, formaldehyde solution, sodium chloride, sodium citrate, and citric acid were purchased from Chengdu Kelong Chemical Reagent Factory (Chengdu, China). The diabetes-inducing agent streptozotocin (STZ) (S0130) was purchased from Sigma-Aldrich (Sigma-Aldrich, Shanghai, China).