Fluorescence sensing of heparin and heparin-like glycosaminoglycans by stabilizing intramolecular charge transfer state of dansyl acid-labeled AG73 peptides with glutathione-capped gold nanoclusters

• Published in: Biosensors & bioelectronics 2021-12, Vol.193, p.113522-113522, Article 113522
• Main Authors: Tseng, Wei-Bin, Chou, Yi-Shiuan, Lu, Cheng-Zong, Madhu, Manivannan, Lu, Chi‐Yu, Tseng, Wei-Lung
• Format: Article
• Language: English
• Subjects: AG73 peptide; Dansyl acid; Fluorescence lifetime; Heparan sulfate; Heparin; Intramolecular charge transfer
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2021.113522

Sensors that can specifically and accurately detect glycosaminoglycans are rare. Here, a dual-mode platform for fluorescence intensity and lifetime sensing of plasma heparin and fluorescence imaging of heparan sulfate proteoglycan-expressed cancer cells was developed by stabilizing the intramolecular charge transfer (ICT) state of dansyl acid-labeling AG73 (DA-AG73) peptide with glutathione-capped gold nanoclusters (GSH-AuNCs). DA-AG73 peptides, including an electron-donor dimethylamino group and an electron-withdrawing sulfonamide moiety in the labeled DA molecules, emitted weak fluorescence due to the formation of the twisted ICT excited state. The complexation of heparin with DA-AG73 peptides followed by interacting with the GSH-AuNCs could restrict the rotation of the dimethylamino groups of the labeled DA molecules, triggering the transition from their twisted ICT state to ICT excited state. As a result, the fluorescence intensity and lifetime of the labeled DA molecules in DA-AG73 peptides were gradually enhanced with increasing the heparin concentration. The proposed platform provided excellent selectivity toward heparin and heparan sulfate and exhibited two linear calibration curves for quantifying 20–800 nM and 20–1000 nM heparin in the fluorescence intensity and lifetime modes, respectively. The proposed platform was practically applied for the fluorescence intensity and lifetime determination of plasma heparin and for the selective imaging of heparan sulfate proteoglycan-expressed cells. •Dual-mode fluorescence intensity/lifetime sensing of 10 nM level of heparin.•GSH-AuNCs stabilized ICT state of dansyl acid-AG73 peptide complexing with heparin.•GSH-AuNCs enhanced the fluorescence lifetime of dansyl acid-AG73-heparin complexes.•The proposed system was exploited to image heparan sulfate-expressed HeLa cells.