Anti-aggregation of NIR-II Probe Regulated by Amphiphilic Polypeptide with High Contrast Brightness for Phototheranostics and Vascular Microscopic Imaging under 1064 nm Irradiation.

Thanks to deep penetration and high resolution, the second near-infrared window (NIR-II, 1000nm-1700 nm) fluorescence imaging is expected to gain favor in clinical applications, including macroscopic imaging for cancer diagnosis and microangiography for vascular-related disease diagnosis. Nevertheless, most NIR-II fluorescent probes, especially cyanine, are highly susceptible to self-quenching in the aggregated state, which severely limits their application in bioimaging. Here, we synthesize the Br-modified cyanine dye F 4 -Br and the amphiphilic polypeptide POEGMA-PBLA. By modulating the self-assembly of F 4 -Br and POEGMA-PBLA to effectively inhibit the H-aggregation of F 4 -Br in aqueous solutions, we develop nanoprobe F 4 -Br@P 17 with outstanding anti-quenching capability. This prominent feature allows it to perform vascular microscopic imaging with high spatiotemporal resolution and assess hemodynamic characteristics. F 4 -Br@P 17 nanoparticles (NPs) with good stability and satisfactory biocompatibility also enable high contrast brightness for NIR-II fluorescence imaging of tumors. Given the efficient enrichment at tumor sites and the promising photothermal conversion efficiency (43.5%), F 4 -Br@P 17 NPs successfully conduct photothermal therapy and exhibit superior anti-tumor efficiency under 1064 nm laser irradiation. These remarkable performances reveal the tremendous possibility of F 4 -Br@P 17 NPs for in vivo microscopic imaging and fluorescence imaging (FI)-guided photothermal therapy (PTT) in the NIR-II region. This article is protected by copyright. All rights reserved.