A graphene oxide nanolayer was synthesized and characterized. The label free detection of vitamin B12 based on fluorescence spectroscopy was investigated. The graphene oxide was shown to specifically interact with vitamin B12 in comparison with other samples including vitamin B1, vitamin B9, vitamin C, vitamin B6, urea, lauric acid, glucose, and uric acid. The quenching effect of B12 on the fluorescence emission of graphene oxide layer based on a Stern-Volmer type equation was used to detect samples. The limit of detection (3.2 ċ 10−7 M) and limit of quantitation (1.08 ċ 10−6 M) were obtained under optimal condition. L.
