2.5. Bacterial Inhibition Assay in Culture

In this method, bacteria were cultured in the nutrient broth (NB) medium at 37 °C for 16 h with shaking at 190 rpm. The prepared bacteria cultures were suspended in the NB and adjusted to an optical density (OD) at 600 nm of 0.1 ± 0.01 corresponding to 1 × 10⁸ CFU/mL. Next, 100 μL of the bacterial suspension was mixed with 1 mL of 1 mg/mL solution of MSN/Ag, MSNs, or penicillin in a sterilized culture tube. The bacterial suspension without the addition of any antibacterial agent was defined as the control. The tubes were incubated at 37 °C for 16 h in an orbital shaker (MaxQ 4000, Thermo Scientific, Waltham, MA, USA) at 190 rpm. The concentration of the bacterial culture was monitored every 3 h by measuring OD₆₀₀ on a spectrophotometer (Jenway 632621, Fisher Scientific, Waltham, MA, USA).