Short Wavelength Infrared Diimmonium Nano-Agents for Photoacoustic Imaging
Abstract
Photoacoustic imaging (PAI) as an innovative biomedical imaging modality shows high contrast and superior spatial resolution, yet remains limited by underdeveloped second near-infrared (NIR-II, 1000-1700 nm) contrast agents, particularly neglecting the NIR-IIb (1500-1700 nm) window. In this work, we designed a new class of diimmonium (DB)-based dicationic nano-agents (DB·2X, X = TFSI ⁻ , B(C ₂ O ₄ ) ₂ ⁻ , or BF ₄ ⁻ ) for 1700 nm excitation PAI. Density functional theory (DFT) calculations reveal that dicationic DB ²⁺ exhibits a dramatically reduced excitation energy (1.24 eV) and enhanced oscillator strength (f = 1.11) by molecular engineering, attributed to a symmetry-allowed local excitation mechanism for electronic restructuring. Single-crystal X-ray diffraction further demonstrates the intermolecular spacings >5.0 Å in DB·2X aggregates, facilitating optimized non-radiative transitions for amplified PAI signals. In vivo study using different disease models shows that DB·2TFSI nano-agents under 1700 nm excitation can achieve higher signal-to-background ratio and minimized interference from endogenous chromophores compared to conventional 1064 nm excitation. Biocompatibility assessments confirm low cytotoxicity, underscoring potential for further development of DB·2TFSI nano-agents. This work delivers a robust molecular design paradigm for non-radiative decay optimization, and for the first time establishes 1700 nm-excitable PAI nano-agents, paving the way for tissue high-quality biomedical imaging.
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BibTeX
@article{liu2026short,
title = {{Short Wavelength Infrared Diimmonium Nano-Agents for Photoacoustic Imaging}},
author = {Longcai Liu and Yang Chen and Liya Yu and Xiaozhou Mou and Guangxue Feng and Yu Cai},
journal = {Nature Communications},
year = {2026},
month = oct,
doi = {10.1038/s41467-026-78613-7},
url = {https://www.nature.com/articles/s41467-026-78613-7},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Short Wavelength Infrared Diimmonium Nano-Agents for Photoacoustic Imaging
AU - Longcai Liu
AU - Yang Chen
AU - Liya Yu
AU - Xiaozhou Mou
AU - Guangxue Feng
AU - Yu Cai
PY - 2026
DA - 2026/10/12
JO - Nature Communications
DO - 10.1038/s41467-026-78613-7
UR - https://www.nature.com/articles/s41467-026-78613-7
AB - Photoacoustic imaging (PAI) as an innovative biomedical imaging modality shows high contrast and superior spatial resolution, yet remains limited by underdeveloped second near-infrared (NIR-II, 1000-1700 nm) contrast agents, particularly neglecting the NIR-IIb (1500-1700 nm) window. In this work, we designed a new class of diimmonium (DB)-based dicationic nano-agents (DB·2X, X = TFSI ⁻ , B(C ₂ O ₄ ) ₂ ⁻ , or BF ₄ ⁻ ) for 1700 nm excitation PAI. Density functional theory (DFT) calculations reveal that dicationic DB ²⁺ exhibits a dramatically reduced excitation energy (1.24 eV) and enhanced oscillator strength (f = 1.11) by molecular engineering, attributed to a symmetry-allowed local excitation mechanism for electronic restructuring. Single-crystal X-ray diffraction further demonstrates the intermolecular spacings >5.0 Å in DB·2X aggregates, facilitating optimized non-radiative transitions for amplified PAI signals. In vivo study using different disease models shows that DB·2TFSI nano-agents under 1700 nm excitation can achieve higher signal-to-background ratio and minimized interference from endogenous chromophores compared to conventional 1064 nm excitation. Biocompatibility assessments confirm low cytotoxicity, underscoring potential for further development of DB·2TFSI nano-agents. This work delivers a robust molecular design paradigm for non-radiative decay optimization, and for the first time establishes 1700 nm-excitable PAI nano-agents, paving the way for tissue high-quality biomedical imaging.
SN - 2041-1723
ER -