Evaluation of a chitosan-polyethylene glycol paste as a local antibiotic delivery device

Figure 1 Experimental design flowchart detailing methods for the following studies. A: Biocompatibility; B: Degradation; C: Antibiotic elution; D: Antibiotic eluate activity; E: In vivo functional model. NHDF: Normal human dermal fibroblast; PBS: Phosphate buffered saline; CPP: Chitosan/polyethylene glycol paste; TSB: Trypticase soy broth.

Figure 2 In vitro direct contact biocompatibility normalized to tissue culture plastic control reported as the average ± standard deviation of percent cell viability for 100% acidic chitosan paste, 3A:2N, 1A:1N, and 2A:3N chitosan/polyethylene glycol paste variations, and neutral 1% chitosan sponges after 24 and 72 h (n = 5). (^aP < 0.05 vs all at respective time point, ^cP < 0.05 vs 2A:3N CPP and neutral 1% CS at respective time point). CPP: Chitosan/polyethylene glycol paste.

Figure 3 In vitro enzymatic degradation reported as the average ± standard deviation of weight percent remaining of the sample for 3A:2N, 1A:1N, and 2A:3N chitosan/ polyethylene glycol paste variations and neutral 1% chitosan sponges over 10 d (n = 5). ^aP < 0.05 vs each other at all time points except § for all pastes at day 2 and 2A:3N and 1A:1N at day 1; ^cP < 0.05 showing significant degradation through marked time points.

Figure 4 In vitro release of antibiotics, vancomycin elution group (A), and Amikacin elution group (B), from 3A:2N, 1A:1N, and 2A:3N chitosan/polyethylene glycol paste variations and neutral 1% chitosan sponges over 72 h reported as the average ± standard deviation in concentration of antibiotic in sample retrieved.

Figure 5 Percentage of catheters cleared (A) and average Staphylococcus aureus colony (B) forming units per catheter for those retrieved from mice treated with 1A:1N and 2A:3N chitosan/polyethylene glycol paste variations and neutral 1% chitosan sponges over 48 h (n = 8, 2 catheters per mouse). All samples were loaded with either PBS alone or 4 mg/mL of vancomycin. ^aP < 0.05 vs all vancomycin samples. PBS: Phosphate buffered saline; CPP: Chitosan/polyethylene glycol paste.

Figure 6 Ejection results represented as the average ± standard deviation of force required to eject air and 3A:2N, 1A:1N, and 2A:3N chitosan/polyethylene glycol paste variations from a syringe (n = 3). CPP: Chitosan/polyethylene glycol paste.