Chromatography grade acetonitrile

Anhydrous ethanol was acquired from Tianjin Fuyu Fine Chemicals (Tianjin, China). Formic acid was obtained from Tianjin Yongsheng Fine Chemicals (Tianjin, China). Hydrochloric acid was sourced from Chengdu Cologne Chemicals (Chengdu, China). Sodium hydroxide was bought from Tianjin Yongsheng Fine Chemicals (Tianjin, China). Chromatography-grade acetonitrile was from Thermo Fisher Scientific (Waltham, MA, USA). Potassium hydroxide was bought from Tianjin Sheng’ao Chemical Reagents (Tianjin, China).
An ultraviolet (UV) spectrophotometer (UV-2600) was purchased from Shimadzu (Kyoto, Japan). An H-Class ultrahigh pressure liquid chromatography (UPLC) system (Acquity) was obtained from Waters (Milford, MA, USA). A tangential-flow nanofiltration membrane system was sourced from Guxin Biotechnology (Shanghai, China). A constant-temperature oscillator (SHZ-82) was acquired from Jinyi Instrument Technology (Jiangsu, China). A rotary evaporator (RE-2000A) was sourced from Yarong Biochemical Instruments (Shanghai, China). The circulating water-type multi-purpose vacuum pump (SHZ-D) was obtained from Kerui Instruments (Gongyi, China). An ultrasonic cleaner (KQ-500DE CNC) was purchased from Ultrasonic Instruments (Kunshan, China). A vacuum drying oven (DZF-6050) was obtained from Xinmiao Medical Equipment Manufacturing (Shanghai, China).

MTX was purchased from Xingheng Chemical Technology Co., Ltd. (Wuhan, China), whereas dopamine (DA) was acquired from Biotopped (Beijing, China). Cetyltrimethylammonium chloride (CTAC), trifluoroacetic acid (TFA), and tetraethyl orthosilicate (TEOS) were bought from Sigma-Aldrich (St. Louis, MO, USA), MREDA (Beijing, China), and Bailingwei Technology Co., Ltd. (Beijing, China), respectively. Triethanolamine (TEA) and cyclohexane were purchased from Xilong Chemical Co., Ltd. (Foshan, China). Chromatography-grade acetonitrile, DMEM, and FBS were purchased from Thermo Fisher (Waltham, MA, USA). All other reagents were analytically pure.