Bismuth Ferrite Second Harmonic Nanoparticles for Pulmonary Macrophage Tracking.

Area of Science:

• Biomedical Optics
• Nanotechnology
• Pulmonary Research

Background:

• Second harmonic generation (SHG) nanomaterials are effective in near-infrared (NIR) and extended NIR-II windows.
• Multiphoton microscopy allows deep tissue imaging.
• Pulmonary macrophages play a critical role in lung health and disease.

Purpose of the Study:

• To evaluate bismuth ferrite harmonic nanoparticles (BFO-HNPs) for monitoring pulmonary macrophages in mice.
• To assess the efficacy of BFO-HNPs in both healthy and allergic airway inflammation models.
• To determine the feasibility of using SHG imaging for tracking nanoparticle-loaded cells in lung tissue.

Main Methods:

• Intratracheal instillation of BFO-loaded MH-S macrophages or intranasal instillation of BFO-HNPs in mice.
• Preparation of lung sections up to 100 μM thickness.
• Imaging using a two-photon-laser scanning microscope.

Main Results:

• Bright BFO-HNPs signals were detected deep within lung tissue with excellent signal-to-noise ratio and minimal background.
• SHG signals from BFO-HNPs were distinguishable from endogenous collagen.
• BFO-HNPs were primarily taken up by M2 alveolar macrophages in vivo.

Conclusions:

• BFO-HNPs are effective for high-resolution, low-background SHG imaging of pulmonary macrophages in thick lung tissues.
• This SHG imaging approach provides novel insights into macrophage-cell and macrophage-extracellular matrix interactions in lung disease.
• BFO-HNPs offer a promising tool for visualizing and tracking nanoparticle-loaded cells in vivo.