Difunctional Hydrogel Optical Fiber Fluorescence Sensor for Continuous and Simultaneous Monitoring of Glucose and pH

Abstract

It is significant for people with diabetes to know their body’s real-time glucose level, which can guide the diagnosis and treatment. Therefore, it is necessary to research continuous glucose monitoring (CGM) as it gives us real-time information about our health condition and its dynamic changes. Here, we report a novel hydrogel optical fiber fluorescence sensor segmentally functionalized with fluorescein derivative and CdTe QDs/3-APBA, which can continuously monitor pH and glucose simultaneously. In the glucose detection section, the complexation of PBA and glucose will expand the local hydrogel and decrease the fluorescence of the quantum dots. The fluorescence can be transmitted to the detector by the hydrogel optical fiber in real time. As the complexation reaction and the swelling–deswelling of the hydrogel are all reversible, the dynamic change of glucose concentration can be monitored. For pH detection, the fluorescein attached to another segment of the hydrogel exhibits different protolytic forms when pH changes and the fluorescence changes correspondingly. The significance of pH detection is compensation for pH errors in glucose detection because the reaction between PBA and glucose is sensitive to pH. The emission peaks of the two detection units are 517 nm and 594 nm, respectively, so there is no signal interference between them. The sensor can continuously monitor glucose in 0–20 mM and pH in 5.4–7.8. The advantages of this sensor are multi-parameter simultaneous detection, transmission-detection integration, real-time dynamic detection, and good biocompatibility.

Biosensors Based on Inorganic Composite Fluorescent Hydrogels

“…By ratiometric detection of the intensities of fluorescence of the two NC types, quantitative and selective detection of Fe 3+ ions was achieved in a linear range of 0-3.5 µM, with a detection limit of 14 nM. A similar approach was used by Li et al [100] for engineering a difunctional hydrogel optical fiber fluorescence sensor for continuous and simultaneous monitoring of the glucose level and pH.…”

Probing quantum phenomena using fiber Bragg grating sensor

“…Optical fibers have been explored substantially for fluorescence spectrometry as well as for obtaining high resolution fluorescence imaging useful for in vivo disease diagnosis applications [2][3][4] . Fluorescent reagents coated on the tip or on the surface of the optical fiber can be used for detection of desired analyte in the sample based on change in the fluorescence properties, mostly fluctuations in fluorescence intensity where the emitted light coupled into the same or different fiber reaches the detector [5][6][7][8][9][10] . However, the measurement of fluorescence intensity suffers from certain limitations such as requirement for filtering of weak fluorescence signal from the source of excitation as well as low sensitivity to molecular change.…”

Nanocomposite Hydrogel‐Based Optical Fiber Probe for Continuous Glucose Sensing

“…For example, Li et al recently reported a fluorescence glucose sensor based on a functionalized hydrogel OF. [ 31 ] The hydrogel was functionalized with fluorescein derivative CdTe QDs/3‐APBA. The hydrogel matrix swells because of the interaction between PBA and glucose molecules, which decreases the fluorescence of quantum dots.…”

“…The sensors also showed an equilibrium time of 25 min. [31] Similarly, Ahmed et al reported a PBA-based hydrogel sensor with nanostructure imprinted on the OF tip. [36] Aztec nanostructures were introduced to enhance the sensitivity and detection limit of the sensors.…”

“…This binding induces the reversible volumetric change in the hydrogel matrix. [28] Therefore, PBA-based hydrogel sensors can be exploited for different optical sensing approaches, including fluorescence, [29][30][31] holographic, [32,33] and surface plasmon resonance (SPR) sensing. [34,35] These different approaches were explored to achieve higher sensitivity, faster response time, and lower detection limits.…”