Abstract
A long-range surface plasmonic resonance (LR-SPR) biosensor modified with double-antibody sandwich immunoassay and plasmonic coupling is demonstrated for human-immunoglobulin G detection with a low limit of detection (LOD). The double-antibody sandwich immunoassay dramatically changes the average refractive index of the medium layer on the sensor surface. The near-field electron coupling between the localized surface plasmon and the long-range surface plasmon leads to a significant perturbation of the evanescent field. The large penetration depth and the long propagation distance of the long-range surface plasmonic waves facilitate the LR-SPR sensor in the detection of biological macromolecules. The unique light absorption characteristic of the nanocomposite material in the sensor provides the in situ self-compensation for the disturbance. Therefore, besides the inherent advantages of optical fiber sensors, the developed biosensor can realize the detection of biomolecules with high sensitivity, low LOD and high accuracy and reliability. Experimental results demonstrate that the LOD of the biosensor is as low as 0.11 μg/mL in the detection of the phosphate-buffered saline sample, and the spike-and-repetition rate is 105.56% in the detection of the real serum sample, which partly shows the practicability of the biosensor. This indicates that the LR-SPR biosensor provides better response compared with existing similar sensors and can be regarded as a valuable method for biochemical analysis and disease detection.
Highlights
Surface plasmonic resonance (SPR) biosensors based on optical fiber have been widely studied in immunoassay, analytical chemistry and disease examination due to their outstanding properties of compact size, anti-electromagnetic interference, high sensitivity and label-free detection
Traditional fiber based SPR sensors have limited ability in further reducing the limit of detection (LOD) because the relatively shallow penetration of the evanescent field prevents the effective detection of the refractive index variation of biomolecules
Controlled experiment has has implemented implemented to to investigate investigate the the practicability practicability of of the the developed sensor. 10 μg/mL human-immunoglobulin G (H-IgG) solutions are separately prepared by phosphate-buffered saline (PBS) and donkey developed sensor. 10 μg/mL H−IgG solutions are separately prepared by PBS and donkey serum
Summary
Surface plasmonic resonance (SPR) biosensors based on optical fiber have been widely studied in immunoassay, analytical chemistry and disease examination due to their outstanding properties of compact size, anti-electromagnetic interference, high sensitivity and label-free detection. Zerodimensional materials such as noble metal nanoparticles [1], one-dimensional materials such as halloysite nanotubes [2] and two-dimensional materials such as black phosphorus [3] are applied to modify the sensor surface These materials are used to concentrate target biomolecules, to promote the transmission of electrons between the metallic layer and nanomaterials, and to strengthen the confined electric field. The coupling between plasmons can lead to an obvious enhancement in the localized electromagnetic field and a significant perturbation in the evanescent field This will increase the penetration depth of the evanescent field in the surrounding medium and make the sensor be more sensitive to the change of surrounding refractive index [1,6]. Change of the refractive index in the medium layer on the sensor surface
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