Ti-Si-Zr-Zn Nanometallic Glass Substrate with a Tunable Zinc Composition for Surface-Enhanced Raman Scattering of Cytochrome c

As a remarkably powerful analytical technique, surface-enhancedRaman scattering (SERS) continues to find applications from molecularbiology and chemistry to environmental and food sciences. In searchof reliable and affordable SERS substrates, the development has movedfrom noble metals to other diverse types of structures, e.g., nano-engineered semiconductor materials, but the cost of the enhancementfactors (EF) substantially decreasing. In this work, we employ biocompatiblethin films of Ti-Si-Zr-Zn nanometallic glassesas the SERS substrates, while tuning the Zn composition. Aided byquartz crystal microbalance, we find that the composition of 4.3%Zn (Ti-Si-Zr-Zn-4.3) gives an ultrasensitivedetection of Cytochrome c (Cyt c) with an EF of 1.38 x 10(4), 10-fold higher than thepreviously reported EF in the semiconducting metal oxide nanomaterials,such as TiO2, and even comparable to the reported noble-metal-assistedsemiconducting tungsten oxide hydrate. Ti-Si-Zr-Zn-4.3 exhibits a stronger adhesion force toward Cyt c, which ensures the strong binding of Cyt c to thesurface, facilitating the Cyt c adsorption onto thesurface and thus enhancing the SERS signal. The high separation efficiencyof photoinduced electrons and holes in Ti-Si-Zr-Zn-4.3 is also acknowledged for promoting the SERS activity.