Improving ciprofloxacin antimicrobial activity through lipid nanoencapsulation or non-thermal plasma on Pseudomonas aeruginosa biofilms

Antibiotic resistance is a significant challenge in the clinical practice. Pseudomonas aeruginosa is a multidrug-resistant opportunistic pathogen prevalent in hospital settings. Besides, P. aeruginosa forms biofilms that aggravate the problem since biofilms are more resilient to conventional decontamination methods than their planktonic counterparts. Due to the lack of novel antibiotics, the emergence of multidrug-resistant strains, and the resilience of biofilms to antimicrobials, new approaches based on the combination of agents are desirable. Non-thermal plasma (NTP) and nanotechnology-based strategies are an alternative to conventional decontamination/sterilization methods. NTP causes microbial cell damage or death, and it has been proved effective to inactivate more than 99% of biofilm cells after a short exposure to plasma. Nanotechnology is a promising strategy to overcome antibiotic resistance/tolerance of microbial biofilms and nanotechnology-based drug delivery systems may interact with the biofilm matrix and help remove bacterial biofilms. Nanoparticles known as "nanostructured lipid carriers" (NLCs) have been proposed as efficient and tailorable drug delivery systems since their physicochemical properties facilitate their penetrability. The aim of this study was to assess the effectiveness of ciprofloxacin-loaded NLC formulations and their potential synergy with plasma on P. aeruginosa biofilms. A decrease in the minimum inhibitory concentration was reported for biofilms exposed to plasma and free ciprofloxacin, and for biofilms treated with NLCs. The synergy between NLCs and NTP was not found under the experimental conditions used, and further research is needed to test other conditions that might result in synergy. Results show the potential of nanoparticles and plasma for biofilm inactivation.