Nanoplasmonic Au–Ag Alloy Coatings on the Surface of TiO2 Nanotubes for Vitamin B12 Detection by Surface-Enhanced Raman Scattering Spectroscopy - Marcin Pisarek; Robert Ambroziak; Mirosław Krawczyk; Marcin Hołdyński; Jan Krajczewski; Tomasz Płociński (ACS Omega)