(A–D): Growth reduction of MRSA (A), VRE (B), S. aureus (C) and E. coli (D) by [CEL+CS] composite materials; 100% CS (red circle), 40% CS (green triangle), 29% CS (blue square), 0% CS (i.e., 100% CEL) (orange cross), and 100% lyophilized CS (purple diamond); and (E and F): Growth reduction of MRSA (A) and E. coli (B) by pH-treated [CEL+CS] composite materials; 100% CS pH 3.5 (red, closed circle), pH 5.0 (blue, closed square), pH 7.0 (green, closed triangle), 50% CS pH 3.5 (red, open circle), pH 5.0 (blue, open square), pH 7.0 (green, open triangle).