A Nanographene-Porphyrin Hybrid for Near-Infrared-Ii Phototheranostics

Abstract

Photoacoustic imaging (PAI)-guided photothermal therapy (PTT) in the second near-infrared (NIR-II, 1000-1700 nm) window has been attracting attention as a promising cancer theranostic platform. Here, it is reported that the π-extended porphyrins fused with one or two nanographene units (NGP-1 and NGP-2) can serve as a new class of NIR-responsive organic agents, displaying absorption extending to ≈1000 and ≈1400 nm in the NIR-I and NIR-II windows, respectively. NGP-1 and NGP-2 are dispersed in water through encapsulation into self-assembled nanoparticles (NPs), achieving high photothermal conversion efficiency of 60% and 69%, respectively, under 808 and 1064 nm laser irradiation. Moreover, the NIR-II-active NGP-2-NPs demonstrated promising photoacoustic responses, along with high photostability and biocompatibility, enabling PAI and efficient NIR-II PTT of cancer in vivo.

Keywords: NIR‐II absorption; nanographene; photoacoustic imaging; photothermal therapy; porphyrin.

Figure 1

a) Chemical structures of DMP, NGP‐1, and NGP‐2. Schematic and conceptual illustration of b) the preparation of NGP‐NPs by a nanoprecipitation method and c) the PAI‐guided PTT based on NGP‐NPs. d) Normalized absorption spectra of DMP and NGP molecules in THF, as well as the NGP‐NPs in water. Inset: photographs of NGP‐1‐NPs (left) and NGP‐2‐NPs (right) solutions. e) Size distribution of NGP‐NPs by DLS experiments. f) TEM images of NGP‐NPs. Data shown in panel e are presented as mean ± standard deviation (n = 3).

Figure 2

Photothermal curves of a) NGP‐1‐NPs under 808 nm laser irradiation (1 W cm⁻²), b) NGP‐2‐NPs under 1064 nm laser irradiation (1 W cm⁻²) for 10 min, and c) infrared images of NGP‐NPs with the extension of irradiation time. d) Photothermal stability of NGP‐2‐NPs and IR1048‐NPs under 1064 nm laser irradiation (1 W cm⁻²) for five on/off cycles. e) Absorption spectra of NGP‐1‐NPs and NGP‐2‐NPs before and after 808 nm (1 W cm⁻²) or 1064 nm (1 W cm⁻²) laser irradiation, respectively. The concentration of NGP‐1‐NPs and NGP‐2‐NPs was 30 µg mL⁻¹, based on the amount of NGP‐1 or NGP‐2 molecule without DSPE‐PEG2000. f) Photothermal performance of NGP‐2‐NPs (30 µg mL⁻¹, based on the amount of NGP‐2 without DSPE‐PEG2000) by cooling to room temperature with linear analysis. g) In vitro PA images of a glass capillary filled with NGP‐2‐NPs or NGP‐1‐NPs of different concentrations. h) PA signals of NGP‐2‐NPs or NGP‐1‐NPs showing a proportional relationship to concentration.

Figure 3

a) Co‐localization of NGP‐2‐NPs with DAPI and LysoTracker after incubating with 4T1 cancer cells for 4 h. Scale bar: 40 µm. Cell viability of b) 4T1 cells and c) MCF‐7 cells treated with various concentrations of NGP‐2‐NPs with or without 1064 nm laser irradiation (1 W cm⁻²) for 10 min. d) Live/dead images of 4T1 cells costained with AM (green fluorescence for live cells) and PI (red fluorescence for dead cells) after incubation with PBS or NGP‐2‐NPs with or without 1064 nm laser irradiation (1 W cm⁻²) for 10 min. Scale bar: 100 µm. The corresponding enlarged images for the white box region were also shown, Scale bar: 50 µm. Data shown in panels b and c are presented as mean ± standard deviation (n = 3). Probability (P)‐values are calculated by using one‐way ANOVA with Tukey test; ns: not significant, *p < 0.05, **p < 0.01, ***p < 0.001.

Figure 4

a) In vivo PA images of 4T1 tumor at different times post‐injection of NGP‐2‐NP through the tail vein. b) PA intensity from a) plotted as a function of time post‐injection. c) Infrared thermal images of tumor sites and d) corresponding temperature profiles of 4T1 tumor‐bearing mice with or without 1064 nm laser irradiation (1 W cm⁻²) for 10 min at 6 h post‐injection of PBS or NGP‐2‐NPs. e) Mice and h) tumor images at day 14 of different treatment groups. e) Tumor growth curves of different treatment groups for 14 days. f) Tumor volume and g) tumor weight of mice in different treatment groups during the therapy period. i) H&E, Ki67, and TUNEL staining of tumor tissue, as well as j) H&E staining of major organs excised from mice in different treatment groups. Scale bar: 100 µm. Data shown in panels f and g are presented as mean ± standard deviation (n = 5). P‐values are calculated by using one‐way ANOVA with Tukey test; ns: not significant, *p < 0.05, **p < 0.01, ***p < 0.001.