DNA hybridization detection using graphene-MoSe2-Ag heterostructure-based surface plasmon resonance biosensor

As detection of specific deoxyribonucleic acid (DNA) sequences is of great importance in diagnosing many fatal and genetic diseases, there have been renewed interests in designing highly sensitive label-free DNA detection platforms. This paper presents a molybdenum diselenide (MoSe2)-graphene hybrid structure-based surface plasmon resonance (SPR) biosensor with capability of detecting single-nucleotide polymorphism (SNP) and DNA hybridization events. Because of its better absorption capability the MoSe2 layer provides strong excitation energy which induces huge charge carrier transfer while the graphene layer serves as a biomolecular recognition element to capture bio-analytes through pi-stacking force. The silver (Ag) layer is attached to the BK7 prism by a very thin titanium (Ti) adhesion film which also serves as oxidization and corrosion protection layer. The biosensor is optimized by numerical modeling and the optimum structure has an excellent sensitivity of 215.5 degrees/RIU which is better than other reported works. It has been demonstrated that when target DNAs are attached to the probe DNAs pre-immobilized on the sensing surface the change of SPR angle is insignificant for mismatched DNA strands while it is highly prominent for complementary DNA strands. Thus, the proposed sensor can effectively distinguish hybridization event and SNP by examining the level of changes in resonance angle and reflectance spectrum.