Supramolecularly Engineered NIR‐II and Upconversion Nanoparticles In Vivo Assembly and Disassembly to Improve Bioimaging

Abstract

Contrast agents for bioimaging suffer from low accumulation at lesion area and high uptake in the reticuloendothelial system (RES). Assembly of nanoparticles in vivo improves their enrichment at tumors and inflamed areas. However, uncontrollable assembly also occurs at the liver and spleen owing to the uptake of nanoparticles by the RES. This is known to probably cause a higher bioimaging background and more severe health hazards, which may hamper the clinical application. Herein, a new near‐infrared (NIR)‐controlled supramolecular engineering strategy is developed for in vivo assembly and disassembly between lanthanide upconversion nanoparticles and second near‐infrared window (NIR‐II, 1000–1700 nm) nanoprobes to realize precision bioimaging of tumors. A supramolecular structure is designed to realize assembly via host–guest interactions of azobenzene and β‐cyclodextrin to enhance the retention of NIR‐II nanoprobes in the tumor area. Meanwhile NIR‐laser‐controllable nanoprobes disassembly brings about a reduction in the bioimaging background as well as acceleration of their RES clearance rate. This strategy may also be used in other nano‐to‐micro‐scale contrast agents to improve bioimaging signal‐to‐noise ratio and reduce long‐term cytotoxicity.

Excretable Lanthanide Nanoparticle for Biomedical Imaging and Surgical Navigation in the Second Near‐Infrared Window

“…[5,6] As a promising candidate of imaging modality with respect to noninvasive and nonradiation, optical imaging has been an area of intense focus in real-time visualization and monitoring the dynamic pathological processes of diseases. [20][21][22][23][24] However, tedious synthetic procedure and low quantum yield of organic molecules are still the main chemical impediments that make them lie behind the inorganic counterparts. Thus, it has emerged as the next-generation imaging technique for in vivo biomedical imaging.…”

Precise In Vivo Inflammation Imaging Using In Situ Responsive Cross‐linking of Glutathione‐Modified Ultra‐Small NIR‐II Lanthanide Nanoparticles

“…[13] To achieve both high SNR and rapid excretion, an ideal contrast agent should have improved delivery efficiency at inflamed tissues and rapid excretion from healthy organs.O ne possible solution to improving the delivery efficiency of contrast agents is using in vivo nanoparticle cross-linking,i ncluding covalent bonding, [14] hydrogen bonding, [15] biotin-avidin recognition, [16] and supramolecular recognition. [17] However,u npredictable cross-linking in blood, RES,a nd normal tissues would also cause high background signals and possible long-term cytotoxicity. Thus,s everal microenvironment-sensitive cross-linking systems responding to enzymes [14,16b] and pH, [18] amongst others, have been reported for in vivo disease detection and bioimaging.N evertheless,t hey usually need complicated design and organic synthesis to obtain the microenvironmentresponsive surface moieties.…”

Engineered Near‐Infrared Fluorescent Protein Assemblies for Robust Bioimaging and Therapeutic Applications

“…Due to the reduced photon scattering and minimal tissue absorption, fluorescence imaging in the NIR window (700–1700 nm) offers increased tissue penetration depths and a better signal‐to‐noise ratio rendering it ideal for biomedical applications. [ 1–7 ] Currently, NIR fluorescent materials mainly comprise quantum dots, [ 8–10 ] lanthanide‐doped upconverting nanoparticles, [ 11–13 ] organic small molecules, [ 14,15 ] and polymer‐based systems. [ 16 ] However, long‐term toxicity and immunogenicity, non‐biodegradability, as well as photo‐instability of these non‐life‐like materials have restricted their translation into clinical applications.…”