Pseudomonas aeruginosa (P. aeruginosa) infections lead to a high mortality rate for cystic fibrosis or immunocompromised patients. The alginate of the biofilm was believed to be the key factor disabling immune therapy and antibiotic treatments. A silver nanocomposite consisting of silver nanoparticles and a mesoporous organosilica layer was created to deliver two pharmaceutical compounds (alginate lyase and ceftazidime) to degrade the alginate and eradicate P. aeruginosa from the lungs. The introduction of thioether-bridged mesoporous organosilica into the nanocomposites greatly benefited the conjunction of foreign functional molecules such as alginate lyase and increased their hemocompatibility and drug-loading capacity. Silver nanocomposites with a uniform diameter (∼39 nm) exhibited a high dispersity, good biocompatibility, and high ceftazidime-loading capacity (380.96 mg/g). Notably, the silver nanocomposites displayed a low pH-dependent drug release and degradation profiles (pH 6.4), guaranteeing the targeted release of the drugs in the acidic niches of the P. aeruginosa biofilm. Indeed, particles loaded with alginate lyase and ceftazidime exhibited high inhibitory and degradation effects on the biofilm of P. aeruginosa PAO1 based on the specific catalytic activity of the enzyme to the alginate and antibacterial function of their loaded ceftazidime and silver ions. It should be noted that the enzyme-decorated nanocomposites succeeded in eradicating P. aeruginosa PAO1 from the mouse lungs and decreasing the lung injuries. No deaths or serious side effects were observed during the experiments. We believe that the silver nanocomposites with high biocompatibility and organic group-incorporated framework have the potential to be used to deliver multiple functional molecules for antibacterial therapy in clinical application.
Keywords: Pseudomonas aeruginosa; alginate; biofilm; mesoporous organosilica; silver nanocomposites.