Eu(III) Functionalized Crystalline Polyimide Hydrogel Film as a Multifunctional Platform for Consecutive Sensing of Spermine and Copper Ions

In this study, a novel Eu(III) functionalized crystalline polyimide hydrogel film (Eu-1) is fabricated by incorporating highly stable polyimide (PI) into a sodium alginate (SA) matrix, followed by cross-linking reaction with Eu3+ ions. Based on different fluorescence responses, Eu-1 is used for the consecutive detection of spermine (Spm) and copper ions (Cu2+). Eu-1 can be employed as a sensor for polyamine, especially for Spm with significant fluorescence enhancement based on the turn on mode. The fluorescent sensor Eu-1@Spm constructed by the Eu-1 and Spm can be further used as a turn off sensor to quantitatively monitor Cu2+. The good selectivity combined with the low detection limit of the sensor meets the requirements for monitoring Cu2+. The possible luminescence response mechanisms to Spm and Cu2+ have been studied through experimental data and theoretical calculations. In addition, a back-propagation neural network (BPNN) model based on an Eu-1@Spm sensor is constructed, which can accurately distinguish Cu2+ concentrations by deep machine learning (ML). This work not only puts forward a facile method to prepare a novel Eu-functionalized PI-based hybrid film but also demonstrates the potential of PI-based film materials for fluorescence detection.

Automated summary

In this study, a novel Eu(III) functionalized crystalline polyimide hydrogel film is synthesized and used for the consecutive detection of spermine and copper ions. The film shows significant fluorescence enhancement in the presence of spermine and can be used as a turn off sensor to quantitatively monitor copper ions. The luminescence response mechanisms to spermine and copper ions have been studied, and a neural network model is constructed to accurately distinguish copper ion concentrations. This work demonstrates the potential of polyimide-based film materials for fluorescence detection.