Electrostatic self-assembled nanoparticles based on spherical polyelectrolyte brushes for magnetic resonance imaging

Abstract

Magnetic resonance imaging (MRI) is one of the most important medical imaging techniques for clinical diagnosis. Contrast agents (CAs) are commonly necessarily used to enhance the imaging quality of MRI and differentiate diseased tissues from normal ones. Herein, we introduced a macromolecular carrier, spherical polyelectrolyte brushes (SPBs), which consists of a solid polystyrene (PS) core and polyacrylic acid (PAA) chains as a brush layer to host Gd(iii) complexes. The cationic Gd(iii) complex Gd-DTPA-NO-C4 was synthesized through a 6-step approach and then formed electrostatic self-assemblies with SPBs to afford magnetic assemblies. The regular appearance of the core-shell type structure of the assemblies was confirmed by TEM and SEM. Besides, a remarkable enhancement in relaxivity up to 62 mM-1 s-1 of these assemblies was determined, much higher than that of clinically used small molecule CAs (4-5 mM-1 s-1). It is noteworthy that the assemblies exhibit non-cytotoxicity even at the concentration of Gd(iii) up to 150 μM, showing great potential for clinical MRI applications.

Integration of gadolinium in nanostructure for contrast enhanced‐magnetic resonance imaging

“…This higher circulation half‐life and enhanced relaxivity offers opportunity for larger diagnostic imaging window for detection of possible pathological site. In a study conducted by Qian et al (), the applicability of electrostatic self‐assembly of spherical polyelectrolyte brushes (SBP) into hybrid magnetic nanoparticles (core‐shell type) with the positively charged Gd 3+ complex based on diethylenetriamine‐ N ‐oxide pentaacetic acid (DTPA‐NO‐C 4 ) was demonstrated. The methodology involves twinning of SPB first into a carboxylated form followed by the electrostatic self‐assemblies with the Gd 3+ complexes forming a core‐shell structure.…”

Interaction among Spherical Polyelectrolyte Brushes in Concentrated Aqueous Solution

“…It has been proposed that the charges of polyelectrolytes and the osmotic pressure in SPB are increased with pH, , which causes the expansion of the brush layer. To characterize SPB, a series of characterization methods, including neutron scattering, light scattering, X-ray scattering, − and transmission electron micrography (TEM), − have been employed. Much efforts have been made to investigate the effects of grafting density, pH, and ionic strength on electrostatic interactions of SPB. − But, the literature is still lacking with regard to studies on the systematic interactions among concentrated SPB.…”

Recent advances in development of nanomedicines for multiple sclerosis diagnosis

“…Gd-based polymeric nanoparticles have been the main workhorse for novel MRI contrast agents. With a high water solubility, high biodegradability, a longer circulation time and excellent biocompatibility and biosafety, lipids-polymer amphiphilic molecule micelles [77], pH-responsive polymeric micelles [78], fluorescent polymeric nanoparticles [79] and diethylenetriamine-N-oxide pentaacetic acid (DTPA-NO-C4) [80] have already been applied to the integration of the Gd complex to construct a nanocontrast agent. Similar to Gd-based liposomes, these Gd-based polymeric nanoparticles could significantly increase the r 1 relaxicity, which could be used for the diagnosis of early stage MS and the identification of small lesions.…”