Back to Search Start Over

Amphiphilic branched polymer-nitroxides conjugate as a nanoscale agent for potential magnetic resonance imaging of multiple objects in vivo

Authors :
Xiaoming Wang
Shiwei Guo
Zhiqian Li
Qiang Luo
Yan Dai
Hu Zhang
Yun Ye
Qiyong Gong
Kui Luo
Source :
Journal of Nanobiotechnology, Vol 19, Iss 1, Pp 1-13 (2021)
Publication Year :
2021
Publisher :
BMC, 2021.

Abstract

Abstract Background In order to address the potential toxicity of metal-based magnetic resonance imaging (MRI) contrast agents (CAs), a concept of non-metallic MRI CAs has emerged. Currently, paramagnetic nitroxides (such as (2,2,5,5-tetramethylpyrrolidine-1-oxyl, PROXYL), (2,2,6,6-tetramethylpiperidine-1-oxide, TEMPO), etc.) are being extensively studied because their good stability and imaging mechanism are similar to metal-based contrast agents (such as Gd3+ chelate-based clinical CAs). However, a lower relaxivity and rapid in vivo metabolism of nitroxides remain to be addressed. Previous studies have demonstrated that the construction of macromolecular nitroxides contrast agents (mORCAs) is a promising solution through macromolecularization of nitroxides (i.e., use of large molecules to carry nitroxides). Macromolecular effects not only increase the stability of nitroxides by limiting their exposure to reductive substances in the body, but also improve the overall 1H water relaxation by increasing the concentration of nitroxides and slowing the molecular rotation speed. Results Branched pDHPMA-mPEG-Ppa-PROXYL with a high molecular weight (MW = 160 kDa) and a nitroxides content (0.059 mmol/g) can form a nanoscale (~ 28 nm) self-assembled aggregate in a water environment and hydrophobic PROXYL can be protected by a hydrophilic outer layer to obtain strong reduction resistance in vivo. Compared with a small molecular CA (3-Carboxy-PROXYL (3-CP)), Branched pDHPMA-mPEG-Ppa-PROXYL displays three prominent features: (1) its longitudinal relaxivity (0.50 mM− 1 s− 1) is about three times that of 3-CP (0.17 mM− 1 s− 1); (2) the blood retention time of nitroxides is significantly increased from a few minutes of 3-CP to 6 h; (3) it provides long-term and significant enhancement in MR imaging of the tumor, liver, kidney and cardiovascular system (heart and aortaventralis), and this is the first report on nitroxides-based MRI CAs for imaging the cardiovascular system. Conclusions As a safe and efficient candidate metal-free magnetic resonance contrast agent, Branched pDHPMA-mPEG-Ppa-PROXYL is expected to be used not only in imaging the tumor, liver and kidney, but also the cardiovascular system, which expands the application scope of these CAs. Graphical abstract

Details

Language :
English
ISSN :
14773155
Volume :
19
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Journal of Nanobiotechnology
Publication Type :
Academic Journal
Accession number :
edsdoj.19b879f91f345b18975bac7f5ddadc0
Document Type :
article
Full Text :
https://doi.org/10.1186/s12951-021-00951-z