Tracking tumor heterogeneity and progression with near‐infrared II fluorophores

Abstract

Heterogeneous cells are the main feature of tumors with unique genetic and phenotypic characteristics, which can stimulate differentially the progression, metastasis, and drug resistance. Importantly, heterogeneity is pervasive in human malignant tumors, and identification of the degree of tumor heterogeneity in individual tumors and progression is a critical task for tumor treatment. However, current medical tests cannot meet these needs; in particular, the need for noninvasive visualization of single‐cell heterogeneity. Near‐infrared II (NIR‐II, 1000–1700 nm) imaging exhibits an exciting prospect for non‐invasive monitoring due to the high temporal‐spatial resolution. More importantly, NIR‐II imaging displays more extended tissue penetration depths and reduced tissue backgrounds because of the significantly lower photon scattering and tissue autofluorescence than traditional the near‐infrared I (NIR‐I) imaging. In this review, we summarize systematically the advances made in NIR‐II in tumor imaging, especially in the detection of tumor heterogeneity and progression as well as in tumor treatment. As a non‐invasive visual inspection modality, NIR‐II imaging shows promising prospects for understanding the differences in tumor heterogeneity and progression and is envisioned to have the potential to be used clinically.

Mesoporous Manganese Dioxide-Coated Upconversion Nanoparticles for Smart Photoluminescence and Drug Delivery

“…The near-infrared (NIR) light-triggered photoluminescence is ideal for visualizing living organisms with high spatiotemporal resolution. − Benefiting from their unique photophysical properties, upconversion nanoparticles (UCNPs) have sparked considerable interest in biological imaging, diagnosis, and photodynamic therapy. , Upconversion luminescent material is a photoluminescence material that absorbs two or more low-frequency photons and emits a high-frequency photon. , In recent years, rare-earth-doped NaYF 4 upconversion fluorescent materials have become a research hotspot due to excellent chemical and luminescent properties, including narrow emission peaks, long fluorescence lifetime, strong photostability, and low toxicity. Especially, Ln-doped UCNPs can effectively absorb near-infrared light and convert it into visible/ultraviolet light, which avoids the fluorescence of biomolecules and light scattering of tissues, making UCNPs an effective platform for constructing photoluminescent materials. , In addition, UCNPs have good biocompatibility as they do not contain toxic elements, thus having enormous potential for application in the biomedical field. , Due to these distinctive advantages, the successful combination of various functional components, such as photoluminescent materials and drug delivery carriers, into a unique nanoplatform, and the design of tumor imaging based on the unique microenvironment of tumors, thereby achieving simultaneous diagnosis and real-time treatment tracking of in vivo imaging and drug delivery, are important challenges that need to be addressed urgently. , …”

Ligand Engineering of Gold Nanoclusters for NIR-II Imaging

“…Near-infrared-II (NIR-II, 1000–1700 nm) imaging is widely used for biomedical detection from molecular diagnosis to whole-body imaging owing to its high spatial and temporal resolution. − Light in this range can penetrate deeper tissues due to the reduced scattering, absorption, and autofluorescence interference of the biological tissues, which strongly restrain the resolutions of traditional near-infrared-I (NIR-I, 750–900 nm) imaging. ,− In the past few decades, diverse NIR-II fluorophores were developed including organic dyes and inorganic materials, such as single-walled carbon nanotubes (CNTs), semiconductor quantum dots, rare earth nanoparticles, and small nanoclusters. ,,,,− However, there are some limitations on the fluorophores; for instance, organic fluorophores typically have low quantum yields (QYs) and brightness, and inorganic nanomaterials customarily raise a safety concern. Thus, developing more efficient and biosafe probes is still a crucial challenge.…”

Beyond traditional light: NIR-II light-activated photosensitizers for cancer therapy

“…[35][36][37] Notably, compared with short-wavelength light, excitation in the second near-infrared window (NIR-II; 1000-1700 nm) shows a very weak interaction with biological tissues as well as minimal phototoxicity. [38][39][40][41][42][43] More importantly, compared with shorter-wavelength light sources (0.33 W cm À2 at 808 nm), NIR-II light has a higher maximum permissible exposure (1 W cm À2 at 1064 nm) and shows deeper tissue penetration (5-20 mm), and is thus emerging as a more preferable light source for PDT. [44][45][46] On account of the above advantages, photosensitizers stimulated by NIR-II light are particularly suitable for the treatment of deep-seated cancers.…”