Understanding Macrophage Interaction with Antimony-Doped Tin Oxide Plasmonic Nanoparticles

Abstract

Antimony-doped tin oxide nanoparticles (ATO NPs) have emerged as a promising tool in biomedical applications, namely robust photothermal effects upon near-infrared (NIR) light exposure, enabling controlled thermal dynamics to induce spatial cell death. This study investigated the interplay between ATO NPs and macrophages, understanding cellular uptake and cytokine release. ATO NPs demonstrated biocompatibility with no impact on macrophage viability and cytokine secretion. These findings highlight the potential of ATO NPs for inducing targeted cell death in cancer treatments, leveraging their feasibility, unique NIR properties, and safe interactions with immune cells. ATO NPs offer a transformative platform with significant potential for future biomedical applications by combining photothermal capabilities and biocompatibility.

Keywords: antimony-doped tin oxide nanoparticles; cellular uptake; macrophages; near-infrared radiation; photothermal effects.

Figure 1

Characterization of ATO NPs. (A): Representative TEM image of ATO NPs Scale bar: 50 nm; (B): XRD patterns of ATO and TO NPs; (C): LIT thermal maps of pristine ATO NPs, spin-casted at 5000 rpm for 30 s on a glass coverslip, subjected to a series of diverse monochrome LED excitations.

Figure 2

Cellular morphology, viability assessment, and cytokine release. (A): Representative phase-contrast images of J774A.1 cells upon exposure to ATO NPs for 24 h at 25 μg/mL and 100 μg/mL; (B): Cell viability was evaluated in J774A.1 macrophages using the WST-1 assay after exposure for 24 h to ATO NPs; (C): Cytokine secretion was assessed in J774A.1 to ATO NPs (25 µg/mL) for 24 h using TNF-α ELISA. Cells were exposed to 0.1 μg/mL LPS as a positive control. Data shown are mean values ± S.D. (n = 3). Scale bars: 100 µm. Data are shown as means ± SD. n = 3. The statistical analysis was conducted using one-way ANOVA followed by Dunnett’s multiple comparisons test with a single pooled variance, p < 0.05 (*).

Figure 3

Cellular uptake of ATO NPs. (A): LIT thermal maps, collected upon irradiation with a 940 nm LED source upon exposure to J774A.1 cells for 24 h at 25 μg/mL and 100 μg/mL; (B): TEM micrographs of J774A.1 cells untreated and exposed for 24 h to ATO NPs (25 μg/mL and 100 μg/mL). The areas in the red boxes were examined at 25 μg/mL and 100 μg/mL to visualize the uptake of ATO NPs. Yellow arrows indicate the ATO NPs inside the vesicles of J774A.1 cells at these concentrations. Scale bars: 2 µm (500 nm on the magnified selected areas).

Figure 4

Imaging cell-ATO nanoparticles interaction by FIB-SEM. (A): SEM image of J774A.1 exposed to ATO nanoparticles (overview) Scale bars: 30 µm indicated. (B): SEM image of J774A.1 cross-section after FIB milling reveals internalized ATO nanoparticles (yellow arrows) Scale bars: 5 µm indicated.

Figure 5

Cell viability of J774A.1 macrophages 24 h after the NIR laser (1064 nm) irradiation using the WST-1 assay. (A): Laser power 1 W/cm², time of irradiation 1 min; (B): Laser power 1 W/cm², time of irradiation 2.5 min; (C): Laser power 5 W/cm², time of irradiation 1 min; (D): Laser power 5 W/cm², time of irradiation 2.5 min. Data are shown as means ± SD. n=3. The statistical analysis was conducted using one-way ANOVA followed by Dunnett’s multiple comparisons test with a single pooled variance, p < 0.05 (*) and p < 0.001 (***) compared to Untreated.