# Aerosol Delivery of Polyelectrolyte Surfactant—Antimicrobial Nanoparticles to the Lungs

## TL;DR

This study explores using nanoparticles to deliver antimicrobial drugs to the lungs of cystic fibrosis patients, showing they are effective and not toxic.

## Contribution

The study introduces polyelectrolyte surfactant-based nanoparticles as a novel delivery system for cationic antimicrobials in pulmonary treatments.

## Key findings

- Nanoparticles retained their size and antimicrobial activity after nebulization.
- The formulation showed a mucolytic effect on an artificial cystic fibrosis mucus model.
- Nanoparticles were mostly retained in the lungs of mice with minimal toxicity and minor inflammatory responses.

## Abstract

Lung infections affect over 80% of adults with cystic fibrosis, with Pseudomonas aeruginosa being a leading pathogen. Although antibiotics are frequently nebulized as standard treatments, the physicochemical environment of the diseased lung often limits their diffusion and overall effectiveness. Our previous studies showed polyelectrolyte surfactants (PS) to be a promising delivery system for cationic antimicrobials in vitro. This study seeks to expand that knowledge by evaluating their potential for nebulized delivery.

To achieve this, we evaluated their size and antimicrobial activity following nebulization; in vitro toxicity against epithelial cells and erythrocytes; and biodistribution and expression of inflammation markers following administration to healthy mice.

The nanoparticle formulation exhibited a mucolytic effect on an artificial mucus model of cystic fibrosis mucus. Following nebulization, nanoparticles retained both their size and biological activity. Additionally, they displayed no observable toxicity in vitro against either human lung epithelial cells or erythrocytes; instead, epithelial cells treated with PS-based nanoparticles showed increased cell viability. Following administration of these formulations to mice via inhalation, over 70% of the recovered nanoparticles were retained in the lungs 24 h after treatment, with a small fraction being uniformly distributed to other tissues. A screen of key inflammatory cytokines revealed that inhalation treatment led to a slight increase of IL-6 in the liver and IL-18 in the spleen. These increases seem to be consistent with a minor inflammatory response.

Overall, the results suggest that PS are a promising nanotechnology for the pulmonary delivery of cationic drugs.

The online version contains supplementary material available at 10.1007/s11095-025-03985-2.