A novel amphiphilic pH-responsive AIEgen for highly sensitive detection of protamine and heparin

• Published in: Sensors and actuators. B, Chemical Vol. 261; pp. 233 - 240
• Main Authors: Wang, Xuefeng, Jiang, Qin, Man, Yuecuo, Feng, Shengyu, Lee, Yong-Ill, Liu, Hong-Guo
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.05.2018; Elsevier Science Ltd
• Subjects: Aggregates; AIE; Aqueous solutions; Dispersions; Fluorescence; Fluorescent indicators; Fluorescent probe; Hexanoic acid; Hydrogen; Hydrogen bonding; Molecular chains; Molecules; Protamine; Proteins; Studies; Tetraphenylbenzene; Tetraphenylbenzene; Protamine; AIE; Fluorescent probe
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2018.01.130

The fluorescence and aggregate states of TPHA can be tuned reversibly through adjusting pH of the solutions. TPHA can be used as probes for detection of Pro. (protamine) and Hep. (heparin) in alkaline conditions. [Display omitted] •The fluorescence intensity of TPHA increased as the water content increased.•The fluorescence and aggregate states can be turned through adjusting pH.•TPHA showed high sensitivity and selectivity for protamine and heparin detection. An amphiphilic aggregation-induced emission (AIE) tetraphenylbenzene derivative, namely 6-(1,3-dioxo-4,5,6,7-tetraphenylisoindolin-2-yl) hexanoic acid (TPHA), was designed. TPHA exhibits pH-responsive AIE properties in aqueous solutions. Its fluorescence intensity in dispersed systems of acidic THF/water increased with an increasing volume ratio of water due to the formation of aggregates, while only very weak fluorescence was observed in basic THF/water dispersions. The formation of aggregates in acidic dispersions could be attributed to the hydrophobic effect, intermolecular π-π interaction, and possible hydrogen bonding between the carboxyl groups. Deprotonation of the carboxyl moieties in basic dispersions resulted in the formation of molecularly dispersed systems. The fluorescence intensity of the dispersions in basic media increased dramatically (turn-on signals) when adding protamine, due to the formation of aggregates via electrostatic interactions between the deprotonated carboxyl groups and protein molecules. A good linear relationship between the fluorescence intensities and the protein concentrations in the range of 0–6 μg/mL was obtained, and the detection limit was calculated to be 4.78 ng/mL. In addition, heparin was found to quench the fluorescence (turn-off signals) of the TPHA-protamine system effectively. Therefore, this strategy can be used as fluorescence probes for both protamine and heparin detection.