All the reagents used in this study were of analytical grade. Acrylamide (AM), sodium p-styrene sulfonate (SSS), 3-(trimethoxysilyl)propyl methacrylate (MPS), sodium hydroxide (NaOH), hydrochloric acid (HCl, 37wt%) and ammonium persulfate were purchased from Aladdin Reagent Co., Ltd. (Shanghai, China). Anhydrous ethanol (99.7% purity) and tetracycline hydrochloride (TCH) were supplied by Macklin Biochemical Technology Co., Ltd. (Shanghai, China). Deionized Milli-Q water (18 μS cm−1) was used to prepare solutions.