Conventional antimicrobials are becoming increasingly ineffective for treating
bacterial infection due to the emergence of multi-drug resistant (MDR) pathogens. In addition, the biofilm-mode-of-growth of infecting bacteria impedes antimicrobial penetration in biofilms. Here, we report on poly(
ethylene)glycol-poly(β-amino
esters) (PEG-PAE)
micelles with conjugated antimicrobials, that can uniquely penetrate biofilms, target themselves to bacterial cell surfaces once inside the low-pH environment of a biofilm and release conjugated antimicrobials through degradation of their
ester-linkage with PAE by bacterial lipases. In vitro, PEG-PAE
micelles with conjugated
Triclosan (PEG-PAE-
Triclosan) yielded no inadvertent leakage of their antimicrobial cargo and better killing of MDR Staphylococcus aureus, Escherichia coli and oral streptococcal biofilms than
Triclosan in
solution. In mice, PEG-PAE-
Triclosan micelles with conjugated
Triclosan yielded better eradication efficacy towards a MDR S. aureus-
infection compared with
Triclosan in
solution and
Triclosan-loaded
micelles at equal
Triclosan-equivalent concentrations. Ex vivo exposure of multi-species oral biofilms collected from orthodontic patients to PEG-PAE-
Triclosan micelles, demonstrated effective bacterial killing at 30-40 fold lower
Triclosan-equivalent concentrations than achieved by
Triclosan in
solution. Importantly, Streptococcus mutans, the main causative organism of
dental caries, was preferentially killed by PEG-PAE-
Triclosan micelles. Thus PEG-PAE-
Triclosan micelles present a promising addendum to the decreasing armamentarium available to combat
infection in diverse sites of the body. STATEMENT OF SIGNIFICANCE: pH-adaptive polymeric
micelles with conjugated antimicrobials can efficiently eradicate infectious biofilms from diverse body sites in mice and men. An antimicrobial was conjugated through an
ester-linkage to a poly(
ethylene glycol) (PEG)/poly(β-amino
ester) block copolymer to create micellar nanocarriers. Stable
micelle structures were formed by the hydrophobic poly(β-amino
ester) inner core and a hydrophilic PEG outer shell. Thus formed PEG-PAE-
Triclosan micelles do not lose their antimicrobial cargo underway to an
infection site through the blood circulation, but penetrate and accumulate in biofilms to release antimicrobials once inside a biofilm through degradation of its
ester-linkage by bacterial lipases, to kill biofilm-embedded bacteria at lower antimicrobial concentrations than when applied in
solution. PEG-PAE-
Triclosan micelles effectively eradicate biofilms of multi-drug-resistant pathogens and oral bacteria, most notably highly cariogenic Streptococcus mutans, in mice and men respectively, and possess excellent clinical translation possibilities.