*3.2. Lung Targeting of SLPs*

It is described that SLPs present several advantages in the treatment of pulmonary pathologies, stemming from their adequate size, the potential for deep lung deposition, low toxicity, and prolonged drug release [40].

To study the biodistribution of SLPs after intravenous injection (Figure S3), we administered in lung tissues fluorescent control SLPs particles and analyzed the presence of DiO fluorescence in lung tissue cryosections using fluorescence confocal microscopy. Figure S3a shows confocal Z-projection images of lung slides from SLP-treated mice. The particles are identified as small green spots in the vicinities of the nuclei of the cells. Particles were identified in the lung tissue at both 3 and 8 h after intravenous injection. To confirm this lung distribution after a long period (20 days after injection), we performed an additional biodistribution test quantifying the iron content by ICP-OES. This analysis revealed a broad distribution in the analyzed organs but also lung accumulation of the particles 20 days after injection (Figure S3b). Together, these results confirm that SLPs targeted the lung tissues.
