Antiaggregation 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, 1000-1700 nm) fluorescence (FL) 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, the Br-modified cyanine dye F-4-Br and the amphiphilic polypeptide poly(oligo[ethylene glycol]methacrylate)-b-poly(benzyl-L-aspartic acid) (POEGMA-PBLA) are synthesized. 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, nanoprobe F-4-Br@P-17 with outstanding antiquenching capability is developed. 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 FL 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 antitumor 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 FL imaging-guided photothermal therapy in the NIR-II region.

Automated summary

Due to the excellent deep penetration and high resolution capabilities, the second near-infrared window (NIR-II, 1000-1700 nm) fluorescence (FL) imaging is expected to be useful in clinical applications such as macroscopic imaging for cancer diagnosis and microangiography for vascular-related disease diagnosis. However, most NIR-II fluorescent probes, especially cyanine, are prone to self-quenching in the aggregated state, severely limiting their application in bioimaging.