Acid-Resistant Near-Infrared II Ag₂Se Quantum Dots for Gastrointestinal Imaging

Abstract

With the development of near-infrared II (NIR-II) fluorescence imaging, Ag2Se quantum dots (QDs) have become promising label candidates due to their negligible toxicity and narrow band gap. Despite their potential for gastrointestinal (GI) imaging, the application of Ag2Se QDs still presents significant challenges due to issues such as fluorescence extinction or poor stability in the complex digestive microenvironment. Herein, we have proposed a novel approach to the continuous production of Se precursors using glutathione (GSH) as the reductant under acidic conditions, realizing the continuous growth of water-dispersible Ag2Se QDs. The Ag2Se QDs emitting at 600–1100 nm have been successfully synthesized. Meanwhile, the silver-rich surface of the synthesized NIR-II Ag2Se QDs has been passivated well with the dense GSH, resulting in exceptional colloidal stability and photostability and endowing them with acid resistance. As a result, the obtained NIR-II Ag2Se QDs have exhibited remarkable stability in gastric acid, thus enabling their utilization for long-term real-time monitoring of GI peristalsis via NIR-II fluorescence imaging. Moreover, in contrast to conventional barium meal-based X-ray imaging, NIR-II fluorescence imaging with as-prepared NIR-II Ag2Se QDs can offer clearer visualization of fine intestinal structures, with a width as small as 1.07 mm. The developed strategy has offered a new opportunity for the synthesis of acid-resistant nanocrystals, and the acid-resistant, low-toxicity, and biocompatible NIR-II Ag2Se QDs synthesized in this work show a great promise for GI imaging and diagnosis of GI diseases in vivo.

Nanodrug delivery materials for digestive system diseases

“…Therefore, the synthesis of NIR silver-sulfur QDs with high fluorescence performance, high stability, and tolerance to strongly acidic environments suitable for GI tract imaging remains a challenging task. Recently, Yang et al 83 have proposed a novel method of generating selenium precursors under acidic conditions using glutathione as a reducing agent and successfully achieved the ongoing expansion of water-dispersed Ag 2 Se QDs. Using this method, they successfully synthesized acid-resistant and biocompatible NIR-II Ag2Se QDs and used them for in vitro intestine fine structure imaging as well as GI motility monitoring.…”

Real-Time Detection of Multiple Intracellular MicroRNAs using an Ultrasound-Propelled Nanomotor-Based Dynamic Fluorescent Probe

“…In contrast to conventional fluorescent dyes, QDs have exceptional fluorescence characteristics (strong fluorescence, light drift resistance, broad absorption, etc. ), − demonstrating unparalleled advantages in the high-sensitivity detection of multiple targets. − However, the construction of a probe based on the combination of US-powered AuNW nanomotors and multicolor QDs for the real-time determination of multiple intracellular miRNAs in one step is still rare.…”

Heteroions Radii Matching Produced Intensely Luminescent Bismuth-Ag2S Nanocrystals for through-Skull NIR-II Imaging of Orthotopic Glioma

“…Capitalizing on its enhanced optical properties, a crucial step toward bioapplication involved the transformation of oil-soluble NCs into a water-dispersible form. , This was achieved through a ligand exchange method, where 3-mercapto­propionic acid (MPA) replaced the original ligands (Figure e). This was confirmed by Fourier-transform infrared (FTIR) spectra, where new absorption peaks around 3500 and 1705 cm –1 appeared, assigned to −OH and C=O stretching vibration in carbonyl, respectively (Figure f).…”