Crystal-amorphous Core-shell Structure synergistically Enabling TiO2 Nanoparticles Remarkable SERS Sensitivity for Cancer Cells Imaging

Exploring novel surface-enhanced Raman scattering (SERS)-active materials with high detection sensitivity, excellent biocompatibility, low biotoxicity, and good spectral stability is urgently required for efficacious cancer cell diagnosis. Herein, black TiO2 nanoparticles (B-TiO2 NPs) with crystal-amorphous core-shell structure are successfully developed. Remarkable SERS activity is derived from the synergistic effect of the promising crystal-amorphous core-shell structure. Abundant excitons can be generated by high-efficiency exciton transitions in the crystal core; a feature that provides sufficient charge source. Significantly, the novel crystal-amorphous heterojunction enables the efficient exciton separation at the crystal-amorphous interface, which can effectively facilitate charge transfer from crystal core to amorphous shell and results in exciton enrichment at the amorphous shell. Kelvin probe force microscopy (KPFM) confirms the Fermi level of amorphous layer shifting to relatively low position ...