Synergistic regulation of longitudinal and transverse relaxivity of extremely small iron oxide nanoparticles (ESIONPs) using pH-responsive nanoassemblies

• Published in: Nanoscale Vol. 12; no. 33; pp. 1752 - 17516
• Main Authors: Cao, Yi, He, Yilin, Mao, Zheng, Kuang, Ye, Liu, Min, Zhang, Ye, Pei, Renjun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 28.08.2020
• Subjects: Contrast agents; Contrast Media; Diagnosis; Gold; Hydrogen-Ion Concentration; Iron oxides; Magnetic cores; Magnetic Iron Oxide Nanoparticles; Magnetic Resonance Imaging; Metal Nanoparticles; Micelles; Nanoparticles; Regulation; Regulations; Stimuli; Tumors
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d0nr04201c

Extremely small iron oxide nanoparticles (ESIONPs), as a kind of the special T 1 magnetic resonance imaging (MRI) contrast agent that can provide T 1 contrasting enhancement since their magnetically disordered shells are dominant compared to their magnetic cores and have powerful potential for constructing stimuli-responsive contrast agents (CAs) to realize precise the tumor diagnosis with high specificity and sensitivity. The stimuli-responsive function of ESIONPs-based CAs can be directly endowed through the synergistic regulation of the longitudinal and transverse relaxivity ( r 1 and r 2 ) of ESIONPs. However, the systematical investigation for the synergistic regulation of r 1 and r 2 of ESIONPs is quite lacking. Herein, based on the relaxivity theories, three kinds of ESIONPs-based nanoassemblies with pH-responsiveness were designed and constructed to explore the possibility of various synergistic regulations on r 1 and r 2 . When three kinds of ESIONPs-based nanoassemblies were converted to dissociated ones under a weak acid environment, ESIONPs micelle could realize a synergistic regulation of the single r 2 decrease along with the stable r 1 , while gold nanoparticles-ESIONPs (AuNPs-ESIONPs) vesicle could provide a synergistic regulation comprising the single r 1 increase along with the stable r 2 , and ESIONPs vesicle could offer a synergistic regulation involving the r 2 decrease together with the r 1 increase. Moreover, all the synergistic regulations on r 1 and r 2 were efficient strategies to fabricate ESIONPs-based CAs with the stimuli-responsive function. These systematic and feasible synergistic regulations of r 1 and r 2 may guide and promote the development of ESIONPs-based stimuli-responsive CAs for the highly sensitive and specific tumor diagnosis. Synergistic regulation of the longitudinal and transverse relaxivity of extremely small iron oxide nanoparticles was systematically investigated to guide the design of responsive contrast agents for the precise tumor diagnosis.