Synthesis of a highly dispersive sinapinic acid@graphene oxide (SA@GO) and its applications as a novel surface assisted laser desorption/ionization mass spectrometry for proteomics and pathogenic bacteria biosensing

Graphene oxide (GO)-modified sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid, SA) (SA@GO) was synthesized and characterized; it was then investigated as a new surface assisted laser desorption/ionization mass spectrometry (SALDI-MS) for proteomics and pathogenic bacteria biosensing. SA@GO could effectively decrease the time necessary for sweet spotting searching, reducing the amount of organic matrix and solvent and enhance the sensitivity. SA@GO shows high performance as a matrix alone without the need to add trifluoroacetic acid (TFA). However, the analysis of the intact bacteria cells shows improvement in the signal intensity (2–5 fold) and offers a low limit of detection. All these analyses could be performed with low concentrations (1–10 fmol) and tiny volumes (0.5–1 μL). This study demonstrated that the exploration of new hybrid materials is pivotal to achieve high performance and high ionization. Because of the plane of GO, it assists protein–protein interactions that make it undergo softer ionization.