The therapeutic effect of florfenicol-loaded carboxymethyl chitosan-gelatin shell nanogels against Escherichia coli infection in mice

To improve the therapeutic effect of Escherichia coli infections, the florfenicol-loaded CMCh-gelatin double-shell nanogels have been formulated by inclusion action and electrostatic interaction. The optimal formula of florfenicol nanogels was 100 mg polyethylene glycol, 150 mg gelatin, 100 mg carboxymethyl chitosan, and 1.0 mg/mL sodium tripolyphosphate, meanwhile, the loading capacity and encapsulation efficiency of the optimal formula were 29.7%±1.2% and 52.1%±1.7%, respectively. The mean particle diameter, polydispersity index, and zeta potential were 161.7±2.2 nm, 161.7±2.2 nm, and -23.8±1.6 mV, respectively. Scanning electron microscopy images showed uniformly distributed spherical florfenicol nanogels particles. The X-ray diffraction and fourier transform infrared of the powder showed that florfenicol nanogels were successfully formulated by complexation and electrostatic interaction. The minimum inhibitory concentration of florfenicol standard, commercial florfenicol solution, and florfenicol nanogels against Escherichia coli were 2, 4, and 2 μg/ml. In vitro time-killing curves and Live/Dead bacterial staining suggested that the florfenicol standard, commercial florfenicol solution, and florfenicol nanogels against Escherichia coli had a concentration-dependent bactericidal effect. With the help of H&E staining, florfenicol nanogels were demonstrated to be more effective than commercialized florfenicol solution for the treatment of Escherichia coli infections.