Multifunctional DNA scaffold mediated gap plasmon resonance: Application to sensitive PD-L1 sensor

The introduction of noble metal nanoparticles with good LSPR characteristics can greatly improve the sensitivity of SPR through resonance coupling effect. The plasma resonance response and optical properties of film coupling nanoparticle systems largely depends on the ingenious design of gap structures. Nucleic acid nanostructures have good stability, flexibility, and high biocompatibility, making them ideal materials for gap construction. 2D MOF (Cu-Tcpp) has a large conjugated surface similar to graphene, which can provide a stable substrate for the directional fixation of nucleic acid nanostructures. However, research on gap coupling plasmon based on nucleic acid nanostructures and 2D MOF is still rarely reported. By integrating the advantages of Cu-Tcpp assembled film and DNA tetrahedron immobilization, a nano gap with porous scaffold structure between the gold film and gold nanorod was build. The rigidity of DNA tetrahedron can precisely control the gap size, and its unique programmability allows us to give the coupling structure greater flexibility through the design of nucleic acid chain. The experimental results and FDTD simulation show that the film coupling nanoparticle systems constructed with DNA tetrahedrons greatly enhance the electric field strength near the chip surface and effectively improve the sensitivity of SPR. This research shows the huge potential of nucleic acid nanomaterials in the construction of SPR chip surface microstructures.