Fig. 1

Galactose analysis based on the reaction of o-phenylene diamine (OPD). a Diagram representing the reactions in the assay for galactose using OPD as a substrate. b Preparation of the TiO₂ nanowire chip. c FE-SEM image of the TiO₂ nanowire chip. d XRD pattern of the TiO₂ nanowire. e Raman spectrum of the TiO₂ nanowire. f Diffuse reflectance UV–vis spectra and Tauc plot of (F(R_∞) × \(h\nu\))^1/2 versus \(h\nu\) of the TiO₂ nanowire. g Mass spectra of galactose, OPD, and DA using MALDI-TOF MS based on conventional organic matrices (CHCA, DHB) and the TiO₂ nanowire chip