Solid–liquid-core optical fiber biosensor for highly sensitive and selective detection of 4-chlorophenol in water

A novel solid–liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water. The sensor comprised horseradish peroxidase (HRP)-coated U-shaped liquid-core optical fiber (LCOF) and 4-chlorophenol permselective polymer membrane. The U-shaped LCOF was filled with ethanol suspension of SiO2 particles and the polymer membrane was composed of molecularly imprinted polymer, sulfonated polyethersulfone, and polysulfone. The morphology, composition, and surface luminous properties of the sensing region were examined. The effects of the diameter and content of SiO2 particles and temperature of 4-chlorophenol solutions on the sensitivity of the biosensors were investigated. Further, the sensitivity, selectivity, response time, and limit of detection (LOD) of the biosensors was investigated. In addition, the effects of fiber core materials on the light transmission in sensing region were investigated and a biosensor sensing model was established. The proposed sensor exhibited high selectivity for 4-chlorophenol with satisfactory sensitivity, LOD, and response time: -1.18 (µg/L)−1, 30 µg/L, and 400 s, respectively. The results are expected to aid in the development of methods for enhancing sensitivity of fiber-optic sensors and surface luminous intensity of optical fibers.