# Enhanced Antimicrobial Activity of Ciprofloxacin Encapsulated in Sophorolipid-Based Nano-Assemblies Against Ciprofloxacin-/Methicillin-Resistant Staphylococcus aureus (MRSA)

## TL;DR

This paper explores using sophorolipid-based niosomes to improve ciprofloxacin's effectiveness against drug-resistant MRSA bacteria.

## Contribution

The study introduces sophorolipid-based niosomes as a green alternative for encapsulating ciprofloxacin to combat resistant MRSA strains.

## Key findings

- SL-based niosomes showed enhanced antimicrobial activity against MRSA compared to free ciprofloxacin.
- Ciprofloxacin-loaded niosomes had lower minimum inhibitory and biofilm inhibitory concentrations than free drug.
- Positively charged niosomes exhibited better morphology and stability.

## Abstract

Background: Drug delivery against ciprofloxacin-resistant microbial strains is one of the most challenging areas of research in the pharmaceutical industry. The broad-spectrum antibiotic ciprofloxacin often faces challenges due to its poor bioavailability; thus, the activity of this drug is generally compromised against resistant strains. Traditional drug delivery systems, such as liposomes, are utilized to address this issue; however, niosomes have surfaced as a promising successor to their liposomal counterparts due to their superior attributes, such as enhanced stability and reduced toxicity. However, owing to environmental and toxicological concerns over commonly used chemical surfactants in niosomes, there is a pressing need to explore greener and safer alternatives. This study is focused on the application of sophorolipids (SLs), a biosurfactant that is synthesized by the yeast Starmerella bombicola, as a vesicular assembly for ciprofloxacin encapsulation. Methods: The SL-based niosomal formulation was characterized for particle size, zeta potential, and polydispersity index (PDI), while transmission electron microscopy (TEM) was employed to determine the morphology of niosomes. Agar well diffusion, broth dilution, and biofilm inhibition assays were performed to assess efficacy. Results: The niosomal formulations were successfully prepared; among them, the (+)vely charged formulation exhibited a more organized morphology, and their size and zeta potential values were found to be around ~371 nm and 63 mV for the blank niosomes (without the loaded drug) and ~269 nm and 51 mV for the ciprofloxacin-loaded niosomes. The minimum inhibitory concentration and biofilm inhibitory concentration against the MRSA strain were 5 µg/mL and 25 µg/mL, respectively, for the ciprofloxacin-loaded, (+)vely charged SL niosomes—for free ciprofloxacin these values were 40 µg/mL and 100 µg/mL—presenting remarkable potential for biofilm inhibition. Conclusion: This study highlights the promising therapeutic potential of SL-based ciprofloxacin-loaded niosomes against the emerging health threat of the MRSA strain.