Nanocrystals for Deep-Tissue In Vivo Luminescence Imaging in the Near-Infrared Region

Abstract

In vivo imaging technologies have emerged as a powerful tool for both fundamental research and clinical practice. In particular, luminescence imaging in the tissuetransparent near-infrared (NIR, 700−1700 nm) region offers tremendous potential for visualizing biological architectures and pathophysiological events in living subjects with deep tissue penetration and high imaging contrast owing to the reduced light−tissue interactions of absorption, scattering, and autofluorescence. The distinctive quantum effects of nanocrystals have been harnessed to achieve exceptional photophysical properties, establishing them as a promising category of luminescent probes. In this comprehensive review, the interactions between light and biological tissues, as well as the advantages of NIR light for in vivo luminescence imaging, are initially elaborated. Subsequently, we focus on achieving deep tissue penetration and improved imaging contrast by optimizing the performance of nanocrystal fluorophores. The ingenious design strategies of NIR nanocrystal probes are discussed, along with their respective biomedical applications in versatile in vivo luminescence imaging modalities. Finally, thought-provoking reflections on the challenges and prospects for future clinical translation of nanocrystal-based in vivo luminescence imaging in the NIR region are wisely provided.

Semiconducting polymer dots for multifunctional integrated nanomedicine carriers

“…Imaging based on electromagnetic radiation in the near-infrared (NIR) spectral range enables the acquisition of detailed information on the surface or interior of an object, rendering it widely applicable across various fields [ 312 , 313 ]. For instance, in medical diagnostics, near-infrared emitting nanoprobes combined with corresponding detectors can obtain images of internal lesions in human tissues or organs.…”

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects

“…Fluorescence bioimaging has undergone rapid development over the past few decades, leading to widespread applications in clinical diagnosis and treatment due to its exceptional attributes of high contrast, superior spatiotemporal resolution, non-invasiveness, and real-time visualization. − Benefiting from advances in imaging equipment and probes, fluorescence bioimaging has provided great help in promoting the development of molecular biology and drug discovery. − Traditionally, fluorescence probes with emission in the ultraviolet and visible region (300–700 nm) have been widely applied for fluorescence bioimaging due to their high brightness and visibility with the naked eye; however, they suffer from limited tissue penetration. , To overcome this problem, first near-infrared window (NIR-I, 700–1000 nm) fluorescent dyes were rapidly developed with high penetration and low tissue interference for fluorescence bioimaging, especially in living bodies. − Therefore, in vivo fluorescence bioimaging has achieved rapid growth and is widely used for visualizing dynamic events in the living body. − How to improve the applicability of fluorescence bioimaging has always been a research hotspot but remains a challenge.…”

Interdiffusion-Enhanced Cation Exchange for HgSe and HgCdSe Nanocrystals with Infrared Bandgaps

“…5,6 NCs with optical bandgap energies in the infrared spectrum are being pursued for applications in infrared photonic devices and deep-tissue bioimaging. 7,8 The most developed binary NC materials with infrared bandgaps include InAs, PbS, PbSe, HgSe, and HgTe, all of which are less advanced compared with their counterparts in the visible spectrum due to distinct challenges in synthesis. III-V InAs NCs are challenging to prepare with homogeneous sizes, especially for larger sizes with narrower bandgaps, while PL QY is limited by interfacial defects at heterovalent interfaces incorporating insulating II-VI shell compounds like CdSe, CdS, and ZnS.…”