Reproducible Quantification of Pseudomonas aeruginosa via MIP-Functionalized SPR-FPI Optical Fiber Sensor

A reusable optical fiber surface plasmon resonance (SPR) sensor for quantitative detection of Pseudomonas aeruginosa is presented. To achieve repeatable measurement, this study used aptamer DNA as the functional monomer and polydopamine as the cross-linking agent to construct a molecularly imprinted nanofilm on the sensing surface. After elution treatment, molecularly imprinted cavities with high matching shape and size to the target molecule are formed in the nanofilm. Experimental results demonstrated that the sensors enhanced by molecular imprinting technology achieved an increase in resonance wavelength response from 10.677 nm to 24.98 nm, a reduction in response time from 22 minutes to 16 minutes, and an improvement in detection limit from 0.00985 OD to 0.00105 OD, compared with sensors only modified with functional monomers. Moreover, to address the problem of temperature interference in practical applications, a Fabry-Perot interferometer (FPI) is innovatively integrated. By taking advantage of the temperature sensitivity but bacterial insensitivity of FPI, the influence of temperature changes on SPR measurement is quantified, effectively providing temperature compensation and further improving the environmental adaptability of the sensor. This study provides a novel, reliable, and cost-effective detection solution for marine environmental microbial monitoring.