In vivo activation of NCL probe by luciferase and nitroredictase expressing E.coli in a mouse model of thigh infection.
(A). Luminescence over 4 h from E. coli luc+ infected quadriceps (5 × 104–5 × 107 bacteria) after IP injection of 0.8 mg NCL probe (200 μL of 10 mM solution in PBS). (B). Luminescence over 4 h from E. coli luc+ infected quadriceps (5 × 107 bacteria) following IP injection of 0.8 mg of probe or 0.63 mg of luciferin (200 μL of 10 mM solution in PBS). (C). Luminescence imaging of mice over 24 h bearing 5 × 107 bacteria, treated with various (0.08, 0.8 and 1.6 mg) NCL probe concentrations (200 μL of 1, 10 and 20 mM solutions of NCL in PBS). As a positive control, mice were injected with equal amounts of E. coli MG1655 expressing lux luciferase that doesn't require exogenous substrate for light production [44]. The signal was collected over 24 h, n = 3 per group.