In vitro release was conducted in triplicate using sealed dialysis bags to contain the bacterial subcultures. Briefly, dialysis tubing was sealed at one end, and to this was added: 2 mL of sterile LB (control); or 2 mL of S. aureus subculture in the exponential phase of growth. A filled mini-beaker was added to each bag, the ends were tied, sterilised with 70% ethanol (v/v), and transferred to a Schott bottle (250 mL) containing 200 mL sink volume (LB). Replicates were incubated at 37 ℃ with 180 rpm shaking for 50 h (Eppendorf, Innova 44 New Brunswick). Dye release over time was quantified by taking 1 mL samples of sink volume every 15 min for 1 h r, then every 30 min for the following 6 hr.