Figure 3

Structure-activity relationships in anti-biofilm capacities of C − S conjugate.

(A–C) L. monocytogenes biofilms were exposed to the following conjugates (C − S) and the respective mixtures (C + S) at 0.25 mg/mL for 24 h. Biofilms incubated in TSB containing phosphate-buffered saline were used as control. Biofilm mass and viable cells were quantified. (A) ~13 k chitosan derived C − S conjugates containing 0.3%, 15%, 23% and 32% (w/w) streptomycin; (B) C − S conjugates which contain similar levels of streptomycin and were derived from chitosan with different molecular mass: ~3 k (streptomycin: 30%), ~13 k (streptomycin: 28%) and ~180 k Da (streptomycin: 30%); (C) C − S conjugates which contain similar levels of streptomycin and were derived from chitosan (~13 k Da) with different N-deacetylation degrees: 50% DD (streptomycin: 25%), 75% DD (streptomycin: 23%) and 88% DD (streptomycin: 26%); (D) L. monocytogenes biofilms were exposed to 0.25 mg/mL of L-S conjugate containing 42% streptomycin, equivalent epoly-L-lysine (L, 2 ~ 3 kDa) or streptomycin (S) alone and the respective mixture (L + S) for 24 h. These experiments were performed three times with similar results each time. Error bars represent SD.