Advanced surface-functionalized optical fiber biosensing platform for ultrasensitive fructose quantification in...

The human blood's concentration evaluation of fructose demonstrates significant clinical importance due to that it is closely associated with various diseases. However, current clinical technologies face challenges in achieving rapid quantitative analysis of fructose. The cascaded fiber sensor was proposed by fabricating microsphere cavities through the sequential fusion of single-mode fibers and seven-core fiber, followed by flame tapering of the seven-core fiber. Through optimization of the tapering length parameters, a structure with high refractive index sensitivity was obtained. By chemically immobilizing ketohexokinase (KHK) onto the fiber sensor surface, we established a specific biological functional layer that provides targeted binding sites. Spectral measurements of fructose standards at gradient concentrations demonstrated sensing sensitivity of 5.98 nm/(μg/mL) and detection limit of 12.6 ng/mL. Subsequent measurements of fructose solutions at gradient concentrations in human serum samples revealed that the sensor exhibits strong specificity and anti-interference capabilities in serum. Moreover, we performed the Bland-Altman analysis by comparing the quantitative analysis results of fiber sensor with liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS) method. The analysis confirmed the validity and accuracy of the sensor's detection capability towards clinically unknown serum samples. This method offers several advantages, including minimal sample volume requirements, label-free, rapid analysis and low cost, demonstrating significant potential for clinical applications in fructose detection.