Bimodal MRI/Fluorescence Nanoparticle Imaging Contrast Agent Targeting Prostate Cancer.

Area of Science:

• Nanotechnology
• Biomedical Imaging
• Oncology

Background:

• Gastrin-releasing peptide receptors (GRPrs) are overexpressed in aggressive prostate cancers.
• Targeted imaging agents are crucial for early and accurate diagnosis of prostate cancer.
• Developing multimodal contrast agents can improve diagnostic sensitivity.

Purpose of the Study:

• To develop and characterize a novel bimodal magnetic resonance imaging (MRI)/fluorescence nanoparticle contrast agent.
• To target gastrin-releasing peptide receptors (GRPrs) for site-specific imaging of aggressive prostate cancer.
• To evaluate the in vitro and in vivo efficacy of the developed nanoparticle agent.

Main Methods:

• Synthesis of biocompatible ultra-small superparamagnetic iron oxide (USPIO) nanoparticles coated with glucose and casein.
• Conjugation of USPIO nanoparticles with a Cy7.5-K-8AOC-BBN peptide for GRPr targeting.
• Characterization using TEM, DLS, FTIR, and MRI relaxivity measurements.
• In vitro and in vivo evaluation of binding specificity and imaging efficacy in prostate cancer cells and xenograft models.

Main Results:

• USPIO(Cy7.5)-BBN nanoparticles exhibited a core diameter of ~5 nm and hydrodynamic diameter of ~36 nm.
• High r₂ relaxivity (70.2 ± 2.5 s^-1 mM^-1) and high binding affinity (IC₅₀ = 2.5 ± 0.7 nM) to GRPr.
• Significant tumor-to-muscle contrast enhancement in vivo via MRI (up to 31.1%) and increased fluorescence via NIRF imaging.

Conclusions:

• The bimodal USPIO(Cy7.5)-BBN nanoparticles demonstrate high specificity for GRPr-expressing prostate cancer cells.
• The developed agent shows promising potential for targeted imaging of aggressive prostate cancer.
• This nanoparticle offers a novel tool for enhanced diagnostic capabilities in oncology.