The charge conduction of a single nanowire of radicals-containing vanadium oxides was experimentally studied and found to be modulated by different gas exposures, showing a gating effect by the adsorption and absorption of different gas molecules. After N(2) and O(2) gas are introduced, the nanowires show an abrupt increase of the resistance but show the opposite trend within a longer timescale of several ks. The introduction of N(2) and O(2) can respectively 'write' the nanowire into high and low resistance states, which are metastable in a high vacuum. The long-term gating effect which was attributed to the interlayer diffusion of the gas molecules can be registered on the nanowire in the high vacuum environment.