Bovine lactoferrin blf

The materials used in this project, including bovine lactoferrin (bLf, purity ≥85%, 80 kDa) from bovine whey, were purchased from the Sigma Chemical Company (St. Louis, MO, USA). Tetracycline hydrochloride (TCH, Mr: 480.90 Da) was bought from Aladdin Industrial Corporation (Shanghai, China). 8-Anilino-1-naphthalenesulfonic acid (ANS, purity ≥95%, Mr: 299.34 Da) was supplied by TCI chemicals Company (Tokyo, Japan). They were used without further purification. bLf was stored at 4 °C and TCH was stored −20 °C until use. All other reagents and solvents were of analytical reagent grade. Double distilled water was used in the whole experiment.
TCH and bLf were prepared with phosphate buffer solution (PBS) (0.05 M, pH 6.6) to get the stock solutions (1.0 × 10⁻⁴ mol/L), which would be diluted to obtain the different concentrations of working solutions with PBS buffer. Stock solution of 1.0 × 10⁻³ mol/L ANS was prepared in 0.1 M PBS buffer (pH 6.6). ANS stock solution was stored in a screw-capped container and wrapped in aluminum foil to avoid exposure to light. Metal ion stock solution preparation: FeCl₃·6H₂O was dissolved in double distilled water to get Fe³⁺ ion stock solution (1.0 × 10⁻³ mol/L). All solutions were used freshly after preparation and stored in a refrigerator at 4 °C.

Sodium alginate (C₆H₇NaO₆)_n (molecular weight 196 kDa), calcium chloride (CaCl₂), and disodium hydrogen phosphate dodecahydrate (Na₂HPO₄.12H₂O) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Xanthan gum was provided by Lavendersoap (New York, NY, USA). Tween 20 was purchased from Duksan Pharmaceutical Co., Ltd. (Ansan-si, South Korea). Bovine lactoferrin (bLf) was supplied by Sigma-Aldrich (St. Louis, MO, USA). Agar and de Man–Rogosa–Sharpe (MRS) broth were supplied by Solar-Bio Science and Technology Co., Ltd. (Beijing, China). All other reagents and chemicals used were of analytical grade and used without further processing unless otherwise stated.