Sterile 96 well polystyrene flat bottom microtiter plate

Biofilm formation was evaluated by measuring the ability of cells to adhere to a sterile 96-well polystyrene flat-bottom microtiter plate (BD Falcon, Mississauga, Ontario Canada) as described previously 18. Briefly, a suspension of S. epidermidis (MH supplemented with 1% glucose) at the final density of 10⁵ CFU ml-1 was treated with compounds 9, 14, and 20 50 mM. After 24 h at 37°C, planktonic cells were removed, and the wells washed twice with phosphate-buffered saline (PBS) and dried at 60°C for 30 min. Crystal violet solution (150 ml at 0.1%) was added to each well and the plates were incubated at room temperature for 30 min. The wells were then washed with PBS and discolored with 200 ml of 96% ethanol for 20 min. Absorbance was measured at 620 nm using a microtiter plate reader. The percentage of biofilm mass reduction was calculated using the formula [(Ac-At)/Ac] ×100, where Ac is the absorbance value (OD) for control wells and At is the OD value in the presence of a compound.

Biofilm formation was evaluated by measuring the ability of cells to adhere to sterile 96‐well polystyrene flat‐bottom microtiter plate (BD Falcon, Mississauga, Ontario Canada) as described previously.^[57] Briefly, a suspension of S. epidermidis (MH supplemented with 1 % glucose) at the final density of 10⁵ CFU mL⁻¹ was treated with compound (S,S*)‐9, (S,R*)‐11 and 15 at 100 μM. After 24 hours at 37 °C, planktonic cells were removed, and the wells washed twice with phosphate‐buffered saline (PBS) and dried at 60 °C for 30 min. Crystal violet solution (150 mL at 0.1 %) was added to each well and the plates were incubated at room temperature for 30 min. The wells were then washed with PBS and discolored with 200 mL of 96 % ethanol for 20 min. Absorbance was measured at 595 nm using a microtiter plate reader. The percentage of biofilm mass reduction was calculated using the formula: [(Ac−At)/Ac]×100, where Ac is the OD₅₉₅ for control wells and At is OD₅₉₅ in the presence of a compound.