Validation of L19-conjugated gold nanoparticles for V targeting: a novel approach to image progressive atherosclerotic lesions in a transgenic mouse mode

Atherosclerosis is a chronic vascular disease and a leading cause of morbidity and mortality. Early identification of inflammatory pathways is crucial for risk stratification, yet conventional imaging modalities (CT, PET, MRI) remain limited by high costs, radiation exposure, and insufficient sensitivity for early-stage disease. The extra domain B of fibronectin (FN-EDB), selectively expressed in vasculature during remodeling, has emerged as a promising biomarker of early and progressive atherosclerosis. Its selective expression in unstable lesions makes it an attractive molecular target for precision imaging. Photoacoustic imaging (PA), which integrates optical contrast with ultrasound resolution, offers high sensitivity and adequate penetration depth for detecting inflammatory cues in vivo. Gold nanoparticles (AuNPs), due to their tunable plasmonic properties, represent ideal PA contrast agents.

In this study, we focused on exploiting FN-EDB as a biomarker of progressive atherosclerosis by developing AuNPs conjugated with L19, a recombinant antibody specific to FN-EDB (AuNP-L19), and evaluating their performance as targeting PA tracers in ApoE-/- mice.

AuNP-L19 were synthesized and administered to ApoE-/- mice fed a Western diet to promote atherosclerosis. Optimal imaging wavelengths were selected through phantom and in vivo spectral characterization, minimizing hemoglobin and melanin interference. The established intravenous dose was 100 µL (71.5 ± 5.76 × 10¹⁰ particles/mL).

In vivo PA imaging assessed targeting efficiency, biodistribution, and clearance.

Histology and immunohistochemistry confirmed plaque development and robust FN-EDB expression, validating its role as a relevant and accessible biomarker. PA imaging revealed maximal nanoparticle accumulation in FN-EDB–rich regions (aortic arch and major aortic segments) at 5 h post-injection, with residual signal at 24 h. Ex vivo analyses corroborated in vivo findings and identified the liver as the primary clearance organ.

Overall, AuNP-L19 was demonstrated as an effective PA contrast agent for visualizing FN-EDB-expressing atherosclerotic lesions, supporting FN-EDB as a strategic biomarker for progressive detection. This approach may open the way to novel non-invasive, diagnostics tools both in preclinical and clinical settings, enable personalized risk assessment, and reduce unnecessary surgical interventions in asymptomatic or unstable carotid disease, ultimately lowering the healthcare burden of cardiovascular pathology.For image description, please refer to the figure legend and surrounding text.