Pseudomonas aeruginosa is the leading nosocomial and community-acquired pathogen causing a plethora of acute and chronic infections. The Centers for Disease Control and Prevention has designated multidrug-resistant isolates of P. aeruginosa as a serious threat. A novel delivery vehicle capable of specifically targeting  P. aeruginosa, and encapsulating antimicrobials, may address the challenges associated with these infections. We have developed hetero-multivalent targeted liposomes functionalized with host cell glycans to increase the delivery of antibiotics to the site of infection. Previously, we have demonstrated that compared with monovalent liposomes, these hetero-multivalent liposomes bind with higher affinity to P. aeruginosa. Here, compared with nontargeted liposomes, we have shown that greater numbers of targeted liposomes are found in the circulation, as well as at the site of P. aeruginosa (PAO1) infection in the thighs of CD-1 mice. No significant difference was found in the uptake of targeted, nontargeted, and PEGylated liposomes by J774.A1 macrophages. Ciprofloxacin-loaded liposomes were formulated and characterized for size, encapsulation, loading, and drug release. In vitro antimicrobial efficacy was assessed using CLSI broth microdilution assays and time-kill kinetics. Lastly, PAO1-inoculated mice treated with ciprofloxacin-loaded, hetero-multivalent targeted liposomes survived longer than mice treated with ciprofloxacin-loaded, monovalent targeted, or nontargeted liposomes and free ciprofloxacin. Thus, liposomes functionalized with host cell glycans target P. aeruginosa resulting in increased retention of the liposomes in the circulation, accumulation at the site of infection, and increased survival time in a mouse surgical site infection model. Consequently, this formulation strategy may improve outcomes in patients infected with P. aeruginosa.

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Chronic wounds affect more than 5 million Americans annually with an associated cost of $10 – 20 billion. These wounds provide perfect environments for bacterial growth, and are prone to infections, especially from multi‐drug resistant (MDR) pathogens. The current silver‐based bandages used to treat wounds exhibit a high toxicity toward fibroblasts, and lack anti‐inflammatory and analgesic activity. Our work focuses on the development of bandages to address these unmet clinical needs. We have fabricated electrospun polycaprolactone (PCL) scaffolds, capable of aiding in the wound healing process, and with incorporation of Ag+IBU, a novel therapeutic. These scaffolds deliver the drug locally at a controlled rate to impede bacterial infections. We have further functionalized PCL scaffolds with addition of polyethylene glycol (PEG) to accelerate drug release. Scanning electron microscopy images have revealed that our drug loaded scaffolds have a smooth fiber morphology and fiber diameter that is ~1 mm. Loading and release experiments were conducted by generating a standard curve for Ag+IBU using a Cytation 5 plate reader. Scaffolds loaded with either 5% or 10% Ag+IBU (w/w) release 40% of the drug within the first 24 hours. We have determined the antimicrobial efficacy of drug loaded scaffolds against planktonic and biofilm growth mode bacteria by measuring bacterial inhibition after incubation with scaffold for 24 hours. Microbiological assays have revealed that Ag+IBU‐loaded scaffolds are bactericidal against bacteria in both planktonic and biofilm growth mode. Cellular toxicity was determined against Human Dermal Fibroblasts using alamarBlue assay. Cytotoxicity assays have revealed that Ag+IBU‐loaded scaffolds exhibit toxicity toward human dermal fibroblasts at high concentrations. However, pre‐incubation with N‐acetyl cysteine (NAC), an antioxidant metabolite, abrogates this toxicity and significantly increases cell viability. We have fabricated two‐layer scaffolds with one layer rapidly delivering NAC and the second layer slowly releasing Ag+IBU. Compared with the commercially available bandages with antimicrobial properties currently used for wounds, our non‐toxic, antimicrobial, anti‐inflammatory, and analgesic scaffolds offer a more comprehensive treatment option.