Gold Nanorods as Photoacoustic Nanoprobes to Detect Proinflammatory Macrophages and Inflammation

Abstract

Key hallmarks of inflammation include proinflammatory (M1) macrophages and production of reactive oxygen species (ROS). Therefore, we developed a ROS-sensitive, photoacoustic (PA) nanoprobe capable of identifying M1 macrophages in vitro. The nanoprobe is a silica-coated gold nanorod (AuNR), which provides a stable PA signal, combined with an adsorbed polyelectrolyte-dye (poly-d-lysine (PDL)-IR775c) coating that exhibits ROS sensitivity. By monitoring the ratio between these two PA intensities, we can determine if ROS is present. Upon loading, then stimulating, macrophages toward an M1 phenotype, we observe a significant decrease in the ratio of dye/AuNR intensities relative to a nonstimulated control. Our nanoprobe is also applied to a mouse model of peripheral artery disease (PAD), where we demonstrate an ability to identify early signs of muscle inflammation before symptoms or histologic evidence. Taken together, our nanoprobe can be a powerful tool for monitoring macrophage phenotype and inflammation in vivo.

Poly-d-lysine coated nanoparticles to identify pro-inflammatory macrophages

“…While the stability of this electrostatically constructed particle may be a concern for ultimate application in vivo , our particle provides an attractive nanoparticle-based platform for ultimate use as a real-time, phenotypic indicator of macrophages for use in ACTs, and we are working on a next-generation thiolated version to improve stability. Future studies will aim to incorporate NIR dyes for in vivo imaging, 37 or translate this system to non-invasive trackable platforms, such as photoacoustic imaging, 38 for a more clinic-ready approach.…”

Nanotheranostics: Molecular Diagnostics and Nanotherapeutic Evaluation by Photoacoustic/Ultrasound Imaging in Small Animals

“…When compared to endogenous contrast agents, an exogenous contrast agent offers better image quality and enhanced signal of contrast agents. Exogenous contrast agents can be divided into dyes-based materials such as indocyanine green, prussian blue, methylene blue, and nanoparticle-based contrast agents such as quantum dots, gold nanoparticles, upconversion nanoparticles, and copper sulfide nanoparticles . Inorganic materials exhibit good photothermal stability and higher photothermal convention efficiency.…”

Ameliorated Skin Inflammation through the Synergistic Effect of Gold Nanorod–Dexamethasone and Photothermal Therapy

“…12 Several studies have demonstrated the efficacy of combining AuNRs and drugs as a strategy against inflammation and cancer. 13,14 This is because, unlike other materials, gold is deemed minimally toxic, rendering it suitable for biological and medical applications. Moreover, gold absorbs near-infrared (NIR) lasers and efficiently converts the absorbed energy into heat.…”