Fluorescent iron oxyhydroxide nanocomposites for near-infrared-light-triggered photothermal killing bacteria

Herein, we reported the fabrication of a core-shell-structured iron oxyhydroxide ( β -FeOOH) nanocomposite, which possessed good near-infrared (NIR) light-triggered photothermal conversion capacity for efficient antibacterial application. The nanocomposite was composed of a shuttle-shaped β -FeOOH nanocrystal core protected by the surrounding carboxyl maltodextrin (CMD) shell modified with green-emissive naphthalic anhydride (NA) dyes, thus named as FeOOH@CMD-NA. The inner β -FeOOH core possessed an average length of 19.0 ± 2.5 nm and a diameter of 6.4 ± 1.6 nm, while the mean size of FeOOH@CMD-NA was 35 ± 8.5 nm. Under an 808 nm laser irradiation, the nanocomposite displayed a good photothermal conversion performance with an efficiency of 40.9 %. The fluorescence experiment proved the effective binding behavior of nanocomposites with Escherichia coli ( E. coli ). Subsequently, the exposure to 808 nm light can efficiently inhibit the growth rate of E. coli via the photothermal effect generated by β -FeOOH nanocrystals. Therefore, we provided a low-cost and efficient photothermal agent for fluorescence imaging-guided elimination of microbial infections.