MgF2–Au–MgF2-polydopamine based surface plasmon resonance sensor and its application in biomedical systems

Abstract

We report a MgF₂–Au–MgF₂-polydopamine based surface plasmon resonance (SPR) sensor and its biomedical applications. The symmetrical MgF₂–Au–MgF₂ geometry induced a minimum loss of surface plasmons leading to, so far, the best refractive index resolution of 2.2 × 10⁻⁸ refractive index units (RIU) in a glucose solution protocol. Meanwhile, a high detection performance could be maintained in the sensed medium with a refractive index ranging from 1.03 to 1.33 RIU. In order to solve the problem of surface functionalization on MgF_2, which was thought to be inert, we managed to form adherent polydopamine films onto the MgF₂–Au–MgF₂ surface by dopamine self-polymerization, and found that secondary reactions could be used to create a variety of ad-layers for further biological uses. Finally, a model experiment on a chip detecting cellular mediators in human aqueous humor demonstrated the biomedical application of this system.