A New Class of NIR‐II Gold Nanocluster‐Based Protein Biolabels for In Vivo Tumor‐Targeted Imaging

Abstract

The design of bright NIR-II luminescent nanomaterials that enable efficient labelling of proteins without disturbing their physiological properties in vivo is challenging. We developed an efficient strategy to synthesizebright NIR-II gold nanoclusters (AuN Cs) protected by biocompatible cyclodextrin (CD). Leveraging the ultrasmall sizeo fA uN Cs (< 2nm) and strong macrocycle-based host-guest chemistry, the as-synthesized CD-AuN Cs can readily label proteins/ antibodies.M oreover,t he labelled proteins/antibodies enable highly efficient in vivo trackingd uring blood circulation, without disturbing their biodistribution and tumor targeting ability,thus leading to asensitive tumor-targeted imaging. CD-Au NCs are stable in the harsh biological environment and show good biocompatibility and high renal clearance efficiency.T herefore,t he NIR-II biolabels developed in this study provideapromising platform to monitor the physiological behavior of biomolecules in living organisms.

Bright NIR‐II Photoluminescence in Rod‐Shaped Icosahedral Gold Nanoclusters

“…Gold nanoclusters, with their superior biocompatibility, high stability, and rapid excretion, are good candidates for biomedical and bioimaging applications. [4,5] However, while bright near-infrared PL from ≈750-900 nm (the first near-infrared window, NIR-I) has been reported in several gold nanoclusters, [6][7][8][9][10][11][12] the reported NIR-II emissions from gold nanoclusters [13][14][15][16][17][18] still suffer from low QYs (<3%) and limited spectral range (peak wavelength less than ≈1100 nm). More importantly, the underlying electronic transitions, atomic-level structure-property relations, and the fundamental mechanisms for improvement of the performance of the NIR-II PL in gold nanoclusters still remain unexplored.…”

Ag44(EBT)26(TPP)4 Nanoclusters With Tailored Molecular and Electronic Structure

“…[23b,28] TheP Le xcitation spectrum for emission at % 1270 nm well matches with the absorption spectrum ( Figure S12), indicating the origin of the PL from the NCs.F urthermore,t he PL quantum yield (PLQY) of Ag 44 (EBT) 26 (TPP) 4 is found to be % 0.26 %, which is enhanced by > 25-and > 10-folds compared to the reported [Ag 44 (SR) 30 ] 4À ( % 0.01 %) [1b] and [Ag 44 (EBT) 30 ] 4À ( % 0.02 %), respectively.I mportantly,t he PLQY of Ag 44 -(EBT) 26 (TPP) 4 is > 5-folds higher compared to that of the standard dye IR26 (0.05 %) and also comparable to PLQY of cyclodextrin-protected gold NCs ( % 0.11 %). [29] Thei ncrease of PLQY of Ag 44 (EBT) 26 (TPP) 4 NCs is attributed to the Figure 4. Analysis of the computed optical spectrum of Ag 44 (EBT) 26 -(TPP) 4 .Panels (A, C, and E) show the transition contributionm aps (TCMs) for peaks at 775, 530 and 415 nm, respectively,and panels (B, D, and F) show the corresponding transition-induced hole-electron densities.…”

Activatable NIR‐II Fluorescent Probes Applied in Biomedicine: Progress and Perspectives

“…Recently, Yang et al. synthesized cyclodextrin‐protected NIR‐II AuNCs with superior biocompatibility [69] . The biological imaging of synthesized AuNCs can be achieved through somatic or protein labeling, which couldtrack the physiological behavior of proteins and used for tumor targeting visualization.…”