Figure 9.

Proposed mechanism of selective engulfment of negatively-charged, macrophage membrane-encapsulated, antimicrobial-conjugated NPs into infected macrophages through lysozyme-rich scars created during staphylococcal engulfment. I) Sterile macrophages excrete lysozyme to kill extra-cellular planktonic bacteria. II) Positively charged lysozyme molecules are recruited to a partly engulfed, negatively charged staphylococcus. III–V) During recruitment, lysozyme is captured in the membrane upon closure of the phagocytic cup to leave a lysozyme-rich, positively charged membrane scar with dimensions comparable with the bacterial diameter, i.e., much larger than the NPs. VI) Positively-charged lysozyme scars attract negatively charged Me-ANPs to the membrane of an infected cell. Sterile cells only possess scattered lysozyme molecules, embedded in a highly negative-charged membrane repelling negatively charged Me-ANPs.