Phosphorescent Carbon-Nanodots-Assisted Förster Resonant Energy Transfer for Achieving Red Afterglow in an Aqueous Solution

Abstract

Water-soluble red afterglow imaging agents based on ecofriendly nanomaterials have potential application in timegated afterglow bioimaging due to their larger penetration depth and nondurable excitation. Herein, red afterglow imaging agents consisted of Rhodamine B (RhB) and carbon nanodots (CNDs) have been designed and demonstrated. In these agents, CNDs act as energy donors, and RhB acts as an energy acceptor. Both of them are confined into a hydrophilic silica shell to form a CNDs-RhB@silica nanocomposite. The phosphorescence emission spectrum of the CNDs and the absorption spectrum of the RhB match well, and efficient energy transfer from the CNDs to the RhB via Forster resonant energy transfer process can be achieved, with a transfer efficiency can reach 99.2%. Thus, the as-prepared nanocomposite can emit a red afterglow in aqueous solution, and the afterglow spectrum of CNDs-RhB@silica nanocomposite can extend to the first near-infrared window (NIR-I). The luminescence lifetime and afterglow quantum yield (QY) of the CNDs-RhB@silica can reach 0.91 s and 3.56%, respectively, which are the best results in red afterglow region. Time-gated in vivo afterglow imaging has been demonstrated by using the CNDs-RhB@silica as afterglow agents.

Carbon Dots in Bioimaging, Biosensing and Therapeutics: A Comprehensive Review

“…[ 148 ] Afterglow imaging eliminates autofluorescence interference, however, it is usually difficult to prepare liquid‐phase phosphorescence CDs, which greatly limits the development of this imaging method. [ 149,150 ]…”

Millisecond‐Range Time‐Resolved Bioimaging Enabled through Ultralong Aqueous Phosphorescence Probes

“…Mater. 2020 [7d] Conjugated polymer dotsbased probes CNDs-RhB@silica [e] None SBR: � 80 None ACS Nano 2021 [10] TPM [f ]…”

“…[4] Up to now, in virtue of scientists' elegant work, various kinds of phosphorescence probes have been designed and used for time-resolved bioimaging applications. [5][6][7][8][9][10][11][12][13] For examples, Zhao and co-workers employed Asp-Glu-Val-Asp and an iridium(III) complex as phosphorescence probes, allowing the detection of catalytic activity and apoptotic cells with high sensitivity and efficiency. [6a] Li et al fabricated a type of organic phosphorescence probes with a high SBR value of 229, which was useful for time-resolved imaging of the sentinel lymph node.…”

Ultraviolet phosphorescent carbon nanodots

“…Their relatively easy preparation process, unique optical properties, and high biocompatibility make them especially fascinating in the field of bioscience and technology 3 – 5 . To date, room temperature phosphorescent CNDs have facilitated amazing advances in optoelectronics devices, time-resolved imaging, and phosphorescence bioimaging, due to the efforts of scientists 6 – 11 . However, most phosphorescence of CNDs is centered in the visible region, and there remains an issue of limited phosphorescence wavelengths.…”