Hollow Au<sub><i>x</i></sub>Cu<sub>1–<i>x</i></sub> Alloy Nanoshells for Surface-Enhanced Raman-Based Tracking of Bladder Cancer Cells Followed by Triggerable Secretion Removal
Ya-Ting Chuang, Ting-Yu Cheng, Tzu-Lan Kao, Mei‐Yi Liao
Abstract
Here, we utilized inert Cu@poly(styrene-alt-maleic acid) (PSMA) nanoparticles (NPs) as a potential starting material, enabling restrictions on chemical etching and resistance to external toxic surfactant adsorption. Such modulated oxidation–dissolution of Cu allowed preservation of the original nano-Cu shape and facilitated the subsequent deposition of Au atoms to form AuCu nanoshells with a tunable Au/Cu ratio. An increase in the Au concentration fraction at the surface nanolayer of the AuxCu1–x nanoshells (x = 0.41–0.86) could intensify the polarizability at the interface structure to essentially aid both electromagnetic field- and chemical-improved surface-enhanced Raman scattering (SERS). Among the AuxCu1–x composites, Au0.86Cu0.14 nanoshells exhibited boost in SERS with amplification to 2–26-fold that of pure Au nanorods, Ag@ polyvinylpyrrolidone (PVP) NPs, Ag@PVP nanocubes, and AuyAg1–y@PSMA nanoshells. Because of the intended SERS response and lower cytotoxicity, we further conjugated the FGFR3 antibody onto the surface of the Au0.86Cu0.14 nanoshells to first demonstrate SERS detection for the highly selective sensing and recognition of T24 human bladder cells. Time-dependent SERS monitor presented the targeted labeling with a signal increase from 0 to 24 h followed by an endocytosis route. In bladder cancer cell uptake, the Au0.86Cu0.14 nanoshell possessed very slight release of Cu species which could deliver a “secretion signal” to trigger the outward transportation of AuCu hollow NPs to leave bladder living cells, showing an alternative method with the potential Au–Cu composite to overcome previous inorganic SERS NPs that often encounter cellular accumulation and cannot be secreted.