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

Abstract

Probes featuring room-temperature phosphorescence (RTP) are promising tools for time-resolved imaging. It is worth noting that the time scale of timeresolved bioimaging generally ranges around the microsecond level, because of the short-lived emission. Herein, the first example of millisecond-range time-resolved bioimaging is illustrated, which is enabled through a kind of ultralong aqueous phosphorescence probes (i.e., cyclo-(Arg-Gly-AspD-Tyr-Cys)-conjugated zinc-doped silica nanospheres), with a RTP emission lasting for � 5 s and a lifetime as long as 743.7 ms. We demonstrate that live cells and deep tumor tissue in mice can be specifically targeted through immune-phosphorescence imaging, with a high signal-to-background ratio (SBR) value of � 69 for in vitro imaging, and � 627 for in vivo imaging, respectively. We further show that, compared to that of fluorescence imaging, the SBR enhancement of millisecond-range time-resolved in vivo bioimaging is up to 105 times.

Cross‐linking enhanced room‐temperature phosphorescence of carbon dots

“…[1][2][3] Although inorganic RTP materials with prolonged light emission are actively being sought for many applications including optoelectronic devices, photocatalysis, and emergency signage, [4][5][6][7] they are less suitable for applications such as anticounterfeiting and bioimaging materials, where bright, subsecond afterglow is required. [8][9][10] In general, RTP is difficult to achieve at room temperature due to the spin prohibition of triplet exciton transitions and the fact that triplet excitons are easily quenched by oxygen and other nonradiative processes. [11][12][13] Researchers would achieve RTP by the following methods: (1) doping rare earth metal ions or heteroatoms into the phosphors to facilitate intersystem crossing (ISC) processes; (2) embedding phosphors into rigid substrates, such as polymers, ionic crystals, amorphous materials, and macrocyclic molecules to suppress vibration and rotation; and (3) selecting rigid precursors and using self-assembly to regulate molecular stacking patterns, restricting nonradiative processes and protecting triplet excitons.…”

“…Room‐temperature phosphorescence (RTP) is traditionally associated with inorganic materials (including some minerals), where their afterglow lifetimes can extend from minutes to hours following photoexcitation 1–3 4–7 they are less suitable for applications such as anticounterfeiting and bioimaging materials, where bright, subsecond afterglow is required 8–10 . In general, RTP is difficult to achieve at room temperature due to the spin prohibition of triplet exciton transitions and the fact that triplet excitons are easily quenched by oxygen and other nonradiative processes 11–13 .…”