Recent Progress in Fluorescence Imaging of the Near‐Infrared II Window

Abstract

Near‐infrared (NIR) fluorescent materials are considered to be the most promising labeling reagents for sensitive determination and biological imaging due to the advantages of lower background noise, deeper penetrating capacity, and less destructive effects on the biomatrix over those of UV and visible fluorophores. In the past decade, advances in biomedical fluorescence imaging in the NIR region have focused on the traditional NIR window (NIR‐I; λ=700–900 nm), and have recently been extended to the second NIR window (NIR‐II; λ=1000–1700 nm). In vivo NIR‐II fluorescence imaging outperforms imaging in the NIR‐I window as a result of further reduced absorption, tissue autofluorescence, and scattering. In this review, the applications of four types of NIR‐II fluorescent materials, organic fluorophores, quantum dots, rare‐earth compounds, and single‐walled carbon nanotubes, are summarized and future trends are discussed. Some methods to enhance the NIR‐II fluorescence quantum yield are also proposed.

Conjugated‐Polymer‐Based Nanoparticles with Efficient NIR‐II Fluorescent, Photoacoustic and Photothermal Performance

“…Fluorescence imaging (FI) has been widely used in life sciences and biotechnology due to its advantages of real‐time operation, non‐invasive nature, and high spatial and temporal resolution . At present, efforts have focused on using the conventional first near‐infrared (NIR) window (NIR‐I, 700–900 nm) in contrast agents, due to the suitability of NIR‐I fluorescence materials for real‐time monitoring and their high quantum yields (QYs) .…”

Recent Advances on Activatable NIR‐II Fluorescence Probes for Biomedical Imaging

“…[3,26] Currently, various materials, such as carbon nanotubes, [20,27,28] quantum dots, [29][30][31][32] rare-earth nanoparticles, [33][34][35][36][37][38] organic small molecules, [39][40][41][42][43][44][45][46][47][48][49][50][51][52] and polymers, [53,54] have been applied in NIR-II fluorescence bioimaging. Although several reviews of NIR-II fluorescence probe for bio medical imaging have been reported, [3,6,11,15,18,24,55,56] currently no review article focuses on activatable NIR-II fluorescence probes since the first activatable NIR-II fluorescence probe was reported in 2013. [57] Thus, herein, we comprehensively summarized their advances and challenges for biosensing and bio medical imaging in order to promote their development.…”

“…immensely reduces photon scattering, absorption, and autofluorescence of tissues and increases applicable power at longer wavelengths (Figure 1b-e), [13,14] which provides a higher signalto-noise ratio and deeper tissue penetration (Figure 1f). [15][16][17] It further improves sensitivity and specificity of disease detection, exhibiting tremendous potential in disease diagnostic. [3,18] In the whole NIR-II window, we should try not to use the 1400-1500 nm region due to the strong absorbance of water in this region (Figure 1g).…”

Carbon Nanomaterials Applied for the Treatment of Inflammatory Diseases: Preclinical Evidence

“…CNTs are promising carriers for drug delivery and contrast agents for NIR-II fluorescence imaging. [21,[178][179][180][181] But, their clinical translation may be hampered by their perceived biopersistence and toxicity, although evidence of biodegradation and alleviation of their toxicological profile by functionalization, [182,183] as well as their potential for photothermal therapy, provide attractive opportunities. [24] CNTs can be degraded by peroxidases as well as by neutrophils and macrophages, although complete biodegradation in the body was not demonstrated yet.…”