The potential of C-60 as a nucleic acid base (NAB) optical sensor is theoretically explored. We investigate the adsorption of four NABs, namely, adenine, cytosine, guanine, and thymine, on C-60 in the gas phase. For the optimal NAB@C-60 adsorption configurations, obtained using a dispersion-corrected density functional, we calculate the vis-near-ultraviolet optical response using time-dependent density functional theory. While the isolated C-60 and NAB molecules do not exhibit visible optical excitation, we find that C-60/NAB conjugation gives rise to distinct spectral features in the visible range. These results suggest that C-60 conjugation can be applied for photodetection of individual NABS.