  The interaction of DNA nucleobases with monolayer GaSe has been studied with
in DFT framework using vdW functional. We found that nucleobases are
physisorbed on the GaSe monolayer. The order of binding energy per atom is C >
T > G > A. The room temperature recovery time estimated to be maximum of 113.88
micro sec. for T+GaSe indicting reusability of the GaSe based devices. The
modulation in the electronic structures of GaSe has been clearly captured
within the simulated STM measurements. We also demonstrate quantum capacitance
as a key parameter for sensing applications. Furthermore, in optical
properties, electron energy loss (EEL) spectra show red shift in photon energy
on nucleobase adsorption in UV region. In nutshell, GaSe monolayer exhibit
anisotropic optical response in UV-region which can be highly beneficial for
developing polarized optical sensors. Our results demonstrate that GaSe
monolayer can be utilized to fabricate reusable DNA sequencing devices for
biotechnology and medical science.
