Biofilms are prevalent in chronic wounds and once formed are very hard to remove, which is associated with poor outcomes and high mortality rates. Biofilms are comprised of surface-attached bacteria embedded in an extracellular polymeric substance (EPS) matrix, which confers increased antibiotic resistance and host immune evasion. Disruption of this matrix is essential to tackle the biofilm-embedded bacteria. Here, we propose several novel nanotechnologies [1,2] to do this, based on protease-functionalized nanogel carriers of antibiotics. Such active antibiotic nanocarriers, surface coated with the protease Alcalase, “digest” their way through the biofilm EPS matrix, reach the buried bacteria and deliver a high dose of antibiotic directly on their cell walls, which overwhelms their defenses. We demonstrated their effectiveness against six wound biofilm-forming bacteria, S. aureus, P. aeruginosa, S. epidermidis, K. pneumoniae, E. coli and E. faecalis. We confirmed a 6-fold decrease in the biofilm mass and a substantial reduction in bacterial cell density. We showed that co-treatments of ciprofloxacin and Alcalase-coated Carbopol nanogels led to a 3-log reduction in viable biofilm-forming cells when compared to ciprofloxacin treatments alone. Encapsulating an equivalent concentration of ciprofloxacin into the Alcalase-coated nanogel particles boosted their antibacterial effect much further, reducing the bacterial cell viability to below detectable amounts. The Alcalase-coated nanogel particles were non-cytotoxic to human adult keratinocyte cells (HaCaT), inducing a very low apoptotic response in these cells. Overall, we demonstrated that the Alcalase-coated nanogels loaded with a cationic antibiotic elicit very strong biofilm-clearing effects against wound-associated biofilm-forming pathogenic bacteria. This approach may breathe new life into a wide variety of existing antibiotics, helping to overcome antibiotic resistance. It has the potential to become a very powerful treatment of chronically infected wounds with biofilm forming bacteria
References
[1] P.J. Weldrick, S. Iveson, M.J. Hardman and V.N. Paunov, Nanoscale, 2019, 11, 10472.
YChem2021