Ultrastable and Biocompatible NIR‐II Quantum Dots for Functional Bioimaging

Abstract

Fluorescence bioimaging in the second near‐infrared spectral region (NIR‐II, 1000–1700 nm) can provide advantages of high spatial resolution and large penetration depth, due to low light scattering. However, NIR‐II fluorophores simultaneously possessing high brightness, good stability, and biocompatibility are very rare. Hydrophobic NIR‐II emissive PbS@CdS quantum dots (QDs) are surface‐functionalized, via a silica and amphiphilic polymer (Pluronic F‐127) dual‐layer coating method. The as‐synthesized PbS@CdS@SiO2@F‐127 nanoparticles (NPs) are aqueously dispersible and possess a quantum yield of ≈5.79%, which is much larger than those of most existing NIR‐II fluorophores. Thanks to the dual‐layer protection, PbS@CdS@SiO2@F‐127 NPs show excellent chemical stability in a wide range of pH values. The biocompatibility of PbS@CdS@SiO2@F‐127 NPs is studied, and the results show that the toxicity of the NPs in vivo could be minimal. PbS@CdS@SiO2@F‐127 NPs are then utilized for in vivo and real‐time NIR‐II fluorescence microscopic imaging of mouse brain. The architecture of blood vessels is visualized and the imaging depth reaches 950 µm. Furthermore, in vivo NIR‐II fluorescence imaging of gastrointestinal tract is achieved, by perfusing PbS@CdS@SiO2@F‐127 NPs into mice at a rather low dosage. This work illustrates the potential of ultrastable, biocompatible, and bright NIR‐II QDs in biomedical and clinical applications, which require deep tissue imaging.

Multiplexed NIR‐II Probes for Lymph Node‐Invaded Cancer Detection and Imaging‐Guided Surgery

“…Although the peak emission of donor–acceptor–donor (D‐A‐D) dyes and the tail emission of cyanine dyes can be both used for NIR‐II imaging, the benefit of NIR‐II imaging is better realized in the NIR‐IIb sub‐window (>1500 nm), where light can penetrate nearly all tissues . Imaging in the NIR‐IIb window can minimize photon scattering and simultaneously avoid high absorbance by water, affording high resolution of mouse vasculature at depths of several millimeter in the brain or other tissues . Thus, the challenge for NIR‐II imaging is the limited availability of NIR‐IIb fluorophores with both high brightness and biocompatibility .…”

“…[22] Imaging in the NIR-IIb window can minimize photon scattering and simultaneously avoid high absorbance by water, affording high resolution of mouse vasculature at depths of several millimeter in the brain or other tissues. [23][24][25][26][27][28] Thus, the challenge for NIR-II imaging is the limited availability of NIR-IIb fluorophores with both high brightness and biocompatibility. [29][30][31][32][33] Multicolored NIR-II imaging probes with high brightness, photostability, and biosafety will greatly benefit the biomedical research and intraoperative image-guided surgery.…”

NIR-II fluorescence microscopic imaging of cortical vasculature in non-human primates

“…These advantages have made NIR-II fluorescence bioimaging a method of choice for functional applications in mice, including whole-body angiography, organ visualization, as well as diagnosis and imaging-guided treatment of tumours [10][11][12][14][15][16][17][18][19][20][21][22] .…”

Tm3+‐Sensitized NIR‐II Fluorescent Nanocrystals for In Vivo Information Storage and Decoding

“…[1] However,o wing to the large absorption and scattering of photons traversing biological tissues in the visible (400-700 nm) and traditional nearinfrared (NIR-I, 700-1000 nm) regions,i nvivo fluorescence imaging often suffers from low penetration depth and resolution. [5] Compared to these NIR-II probes,r are-earth-doped nanocrystals with superior photostability and lower biotoxicity are also capable of generating intense NIR-II emissions with large Stokes shifts. [5] Compared to these NIR-II probes,r are-earth-doped nanocrystals with superior photostability and lower biotoxicity are also capable of generating intense NIR-II emissions with large Stokes shifts.…”

“…[2] Recently,s cientists have achieved deep-tissue and high-resolution imaging in the second near-infrared window (NIR-II, 1000-1700 nm) resulting from reduced autofluorescence and scattering.U pt on ow,g reat efforts have been dedicated to developing NIR-II-emitting probes, including single-walled carbon nanotubes and carbon dots, [3] small-molecule organic fluorophores, [4] and quantum dots. [5] Compared to these NIR-II probes,r are-earth-doped nanocrystals with superior photostability and lower biotoxicity are also capable of generating intense NIR-II emissions with large Stokes shifts. [6] Within the NIR-II window,several studies have confirmed increased imaging resolution by using NIR-II b( 1500-1700 nm) emitting probes.…”