Schematic depiction of bacterial membrane surface properties. (A) Simplified model of a bacterial cell and its surrounding electrostatic layers. The membrane surface carries fixed charges, followed by the Stern layer with tightly bound counterions and the diffusive layer with a dynamic ion distribution. The ζ-potential, measured at the slipping plane, reflects the effective surface charge, influencing bacterial adhesion and interactions. (B) Schematic representation of the bacterial cell envelope components in gram-positive and gram-negative bacteria. Gram-positive bacteria possess a thick PGN layer, decorated with WTA and LTA, as well as surface-exposed adhesins, membrane proteins, and capsular polysaccharides. In contrast, gram-negative bacteria feature a thinner PGN layer located within the periplasmic space, an OM containing LPS, and the absence of TAs. Both bacterial types contain cytoplasmic membranes and can express adhesins and capsular polysaccharides, which contribute to interactions with host cells and immune evasion. OM, outer membrane.