Enhancement of T1 and T2-weighted dual contrast agents based on iron oxide nanoparticles

Abstract

Iron oxide nanoparticles (IONPs) are recognized for their potential in biomedical applications due to their distinctive physicochemical properties. This study explores the synthesis of IONPs with various geometric morphologies, i.e.cubic, star-like, truncated icosahedron, and spherical,and aims to enhance their utility in magnetic resonance imaging (MRI) and targeted drug delivery. X-ray diffraction (XRD) analysis confirmed the Fe₃O₄ phase in all synthesized nanoparticles, affirming the efficacy of the synthesis process. Particle morphologies, well-defined with sizes ranging from 10 to 150 nm, were characterized using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Magnetic evaluations using a vibrating sample magnetometer (VSM-PPMs) demonstrated their superparamagnetic behavior, with larger particles exhibiting greater saturation magnetization. Notably, truncated icosahedron and cubic IONPs displayed superior transverse relaxation rates, with r₂ values of 56.77 s^-1 mM^-1 and 42.67 s^-1 mM^-1, respectively, suggesting their suitability for T₂-weighted imaging applications. The study investigated the surface modification of IONPs using 3-Glycidyloxypropyl)trimethoxysilane (GLYMO) through a silanization process. Comprehensive characterization revealed significant alterations in their morphology, crystallographic structure, thermal properties, and chemical interactions due to silica encapsulation. However, this encapsulation led to a 47.3% reduction in T₂ relaxivity, indicating a diminished effectiveness as MRI contrast agents, suggesting that while the silica coating improved biocompatibility, it adversely affected the functional imaging properties of the IONPs. A novel material was synthesized by functionalizing truncated icosahedron iron oxide nanoparticles with graphene quantum dots (GQDs) and doped GQDs. Spectroscopic analysis demonstrated significant optical changes indicative of successful functionalization, which were corroborated by SEM images showing effective surface conjugation. Relaxivity studies revealed dual T₁ and T₂ contrast-enhancing behaviors, positioning these nanoparticles as superior in some aspects to traditional contrast agents like gadodiamide and ferumoxytol. Phantom imaging studies further validated their efficacy in enhancing MRI contrast, underscoring their potential as dual-mode contrast agents. Cytotoxicity assays indicated that these GQD-coated IONPs are less toxic than conventional contrast agents, with an IC₅₀ value of 49.9 mg/ml at 72 hours, suggesting enhanced biocompatibility. This research highlights the potential of using GQD-coated IONPs as advanced, biocompatible materials for enhanced magnetic resonance imaging, effectively combining diagnostic and therapeutic functionalities into a single platform. The findings pave the way for the development of nanoparticles with optimized properties for improved biomedical applications, particularly in diagnostic imaging and targeted therapy.