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