Cu-Based Tris(chloropropyl) Phosphate MOF Nanosheets for Surface Plasmon Resonance-Based Fiber-Optic Biosensing

Two-dimensional (2D) metal–organic frameworks (MOFs) have promising applications in surface plasmon resonance (SPR) sensing for their intriguing exciton migration and visible light-near infrared absorption properties. In this study, an effective biosensing structure comprising 2D Cu-TCPP MOF nanosheet-capsulated Au film was developed, such that lower molecular-weight dopamine with small changes of refractive index can be identified on the fiber-optic platform. The large areas of ultrathin 2D Cu-TCPP MOF nanosheets were well prepared, the experimental results indicated that the sensitivity (48%) and figure of merit (18%) were increased notably compared with the bare Au film. Moreover, the finite element method was adopted to numerically analyze and verify the excellent charge-transfer ability of MOF nanosheets and the bidirectional gain properties between MOF nanosheets and Au films. Furthermore, the sensitivity [1.24 nm/log(M)] and selectivity of the dopamine were significantly enhanced with a low limit of detection of 1.50 × 10–13 M and linear response with a wide range of concentrations from 5 × 10–12 M to 5 × 10–7 M through ssDNA surface modification and conformation amplification. As revealed by the above-mentioned results, the Cu-TCPP/Au/SMF biosensor can serve as a promising nanoplatform for clinical diagnosis and medical assessment.