Development of a triple-response system for surface plasmon-coupled emission (SPCE) based on metal-organic frameworks...

Surface plasmon-coupled emission (SPCE) is a promising fluorescence analysis technique that uses a unique near-field coupling interaction to enhance fluorescence emission. As a type of metal-organic frameworks (MOFs), zeolitic imidazolate framework-8 (ZIF-8) was employed as a carrier to encapsulate fluorophore (Rhodamine B, RhB@ZIF-8) and successfully introduced into the SPCE platform to establish a system that integrates the superior optical performance of SPCE with the structural advantages of ZIF-8. The feasibility of the system was verified through pH and ATP stimulus responses, and such dual stimulus-response designs are highly innovative for SPCE. The shifts of the SPCE angle and signal intensity were attributed to the collapse of RhB@ZIF-8 induced by external stimuli. This system exhibited a pH detection range of 4.0-7.4 with desirable sensing performance and good reproducibility. A satisfactory linear correlation between angular displacement and ATP concentration was established as y = 1.52 x + 0.14 in the concentration range of 0.5-6.0 mM, with a detection limit of 0.039 mM. Most notably, the triple response of response time, angle displacement and signal modulation is achieved, which overcomes the limitation that the conventional SPCE depends on the change of fluorescence signal and provides a more flexible and efficient option for sensing.