Tetrabutylammonium hydrogen sulfate

Diquafosol
sodium eye drops was provided from Santen Pharmaceutical Co., Ltd.
Placebo was provided by Fuan Pharmaceutical Group Ningbo Team Pharmaceutical
Co., Ltd. Active pharmaceutical ingredients (API), impurity A, impurity
B, and impurity C were bought from Hang Zhou Chemipanda Bio-Tech Co.,
Ltd. Potassium dihydrogen phosphate, tetrabutylammonium hydrogen sulfate,
and potassium hydroxide (AR grade) were purchased from Sinopharm Chemical
Reagent Co., Ltd. The HPLC grade methanol was obtained from Tedia
Company, Inc. Millipore milli-Q plus water purification system was
used for the preparation of high purity water. Figure 1 shows the structures of diquafosol sodium,
impurity A, impurity B, and impurity C.

Carbon disulfide, chloroform, dimethyl sulphoxide (DMSO), acetonitrile, acetone, SOCl₂, dichloromethane, tetrahydrofuran, ethyl acetate. tetrabutylammonium hydrogen sulfate, o-phenylenediamine, 2,2′-Azobis(2-methylpropionitrile) (AIBN), propynol ethoxylate, N,N-dimethyl-p-phenylene diamine 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide (EDC·HCl), Tris(2-carboxyethyl) phosphine hydrochloride (TCEP-HCl), 3,3′-dithiobis(propanoic dihydrazide) (DTPHY) were purchased from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Poly(ethylene glycol) methyl ether acrylate(pegma, Mn = 480), HA sodium salt, lipopolysaccharide (LPS) and griess reagent were purchased from Sigma-Aldrich (St. Louis, MO, USA), WSP-5 and DAF-2 were obtained from APExBIO Technology LLC (Houston, USA). RANKL and m-CSF were purchased from Peprotech Inc.