Comparison among different "revealers" in the study of accelerated blood clearance phenomenon.

ABSTRACT

The markers are the "revealers" of accelerated blood clearance (ABC) phenomenon. PEGylated nanocarriers labeled with various markers have been used to explore the mechanism of ABC. However, different markers were labeled on different nanocarriers, and the influence of different markers on ABC phenomenon is questionable. In this study, tocopheryl nicotinate (TN), N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt (NBD-DPPE), and 1,1'-dioctadecyl-3,3,3',3'-tetra-methylindotricarbocyanine iodide (DiR) were selected as markers. ABC index(0-30min) was used as an evaluation indicator to reveal ABC phenomenon after repeated injections of PEGylated emulsions (PEs) in Wistar rats. No significant difference was observed in ABC index(0-30min) of PE labeled with the three markers (P>0.05), suggesting that the results of previous studies using these markers were comparable and interchangeable. Of the three markers, TN required tedious analytical method and showed proliferative effect on liver cells, while NBD-DPPE fluorescence was easily interfered by tissues and its phospholipid composition affected ABC analysis. On the contrary, DiR was deemed superior due to its near-infrared fluorescence, high-sensitivity, and convenient analytical detection.