Starch Capped Atomically Thin CuS Nanocrystals for Efficient Photothermal Therapy.

Abstract

Photothermal therapy requires efficient plasmonic nanomaterials with small size, good water dispersibility, and biocompatibility. This work reports a one-pot, 2-min synthesis strategy for ultrathin CuS nanocrystals (NCs) with precisely tunable size and localized surface plasmon resonance (LSPR), where a single-starch-layer coating leads to a high LSPR absorption at the near-IR wavelength 980nm. The CuS NC diameter increases from 4.7 (1nm height along [101]) to 28.6nm (4.9nm height along [001]) accompanied by LSPR redshift from 978 to 1200nm, as the precursor ratio decreases from 1 to 0.125. Photothermal temperature increases by 38.6°C in 50mg L-1 CuS NC solution under laser illumination (980nm, 1.44 W cm-2 ). Notably, 98.4% of human prostate cancer PC-3/Luc+ cells are killed by as little as 5mg L-1 starch-coated CuS NCs with 3-min laser treatment, whereas CuS NCs without starch cause insignificant cell death. LSPR modeling discloses that the starch layer enhances the photothermal effect by significantly increasing the free carrier density and blue-shifting the LSPR toward 980nm. This study not only presents a new type of photothermally highly efficient ultrathin CuS NCs, but also offers in-depth LSPR modeling investigations useful for other photothermal nanomaterial designs.