Poly(dopamine) coated H-aggregates of amphoteric charged near-infrared absorbing cyanine dyes for enhanced photothermal tumor imaging and therapy

Abstract

Cancer and tumors pose a formidable danger to health, with clinical treatments often beset by adversities such as deleterious side effects, suboptimal therapeutic outcomes, and the propensity for subsequent recurrence and metastasis. In this work, we present a self-assembled organic dyes as an innovative approach for the photothermal imaging and therapy for tumors. Cyanine aggregation nanoparticles (Cy-aggregate) were prepared by autonomous aggregation of amphoteric charged cyanine dyes in the near-infrared spectral range, and after the formation of aggregates, a new absorption peak of H-aggregates appeared around 808 nm, which were subsequently modified with dopamine to obtain cyanine aggregate@PDA nanoparticles (Cy-aggregate@PDA). The nanoparticle exhibits distinctive electrostatic gravitation-mediated H-type aggregation, resulting in the quenching of near-infrared fluorescence. Upon exposure to 808 nm laser irradiation, the self-aggregated cyanine dyes do not emit the absorbed energy through fluorescence as conventional organic dyes do, but efficiently converts the energy into heat, with a photothermal conversion efficiency of up to 51.4%, which can facilitate photothermal therapy and imaging. The inclusion of poly(dopamine) engenders heightened photothermal conversion efficiency, improved stability, and diminished cytotoxicity within the nanoparticles. Moreover, the nanoparticles manifest remarkable dispersion, biocompatibility, and stable photothermal properties, thus bestowing upon them a novel avenue for the photothermal treatment of tumors.