Indocyanine Green Assembled Nanobubbles with Enhanced Fluorescence and Photostability
Ning Gu, Bin Huang, Feng Chen, Juan Jin, Zhiguo Qin, Fang Yang, Yan Li, Ning Gu
Abstract
Indocyanine green (ICG) is a near-infrared (NIR) fluorescent dye for extensive biomedical application. However, its fluorescence intensity is limited by its poor aqueous stability and concentration-dependent aggregation. To overcome these limitations, ICG self-assembled nanobubbles (ICG-NBs) with an average size of 244.6 nm are fabricated. In the ICG-NB assembled structures, the ICG molecules are arrayed on the gas-liquid interface by the hydrophobic interaction with the gas core and hydrophilic heads with water. Results show that ICG-NBs exhibited good monodispersity and excellent fluorescence and size stability. Compared with ICG solution, the ICG-NBs indicate the enhanced quantum yield and fluorescence intensity. The surface-enhanced Raman scattering (SERS) spectra and fluorescence lifetime measurement demonstrate that the ICG molecule assembled NBs could result in the changes of molecular vibration and time-resolved intensity decays of ICG. Thus, the ICG-NBs could be more beneficial for optical imaging in clinical applications in the future.