Localized surface plasmon resonance–based fiber-optic sensor for the detection of triacylglycerides using silver nanoparticles

Abstract

A label-free technique for the detection of triacylglycerides by a localized surface plasmon resonance (LSPR)-based biosensor is demonstrated. An LSPR-based fiber-optic sensor probe is fabricated by immobilizing lipase enzyme on silver nanoparticles (Ag-NPs) coated on an unclad segment of a plastic clad optical fiber. The size and shape of nanoparticles were characterized by high-resolution transmission electron microscopy and UV-visible spectroscopy. The peak absorbance wavelength changes with concentration of triacylglycerides surrounding the sensor probe, and sensitivity is estimated from shift in the peak absorbance wavelength as a function of concentration. The fabricated sensor was characterized for the concentration of triacylglyceride solution in the range 0 to 7 mM. The sensor shows the best sensitivity at a temperature of 37°C and pH 7.4 of the triacylglycerides emulsion with a response time of 40 s. A sensitivity of 28.5 nm/mM of triacylglyceride solution is obtained with a limit of detection of 0.016 mM in the entire range of triacylglycerides. This compact biosensor shows good selectivity, stability, and reproducibility in the entire physiological range of triacylglycerides and is well-suited to real-time online monitoring and remote sensing.

Overview of Recent Advances in the Design of Plasmonic Fiber-Optic Biosensors

“…The plasmonic nanoparticles/nanofilms can be then deposited on the surface of unclad section of fiber. Then, biomolecules can be attached to plasmonic nanoparticles or nanofilm surfaces at the final stage [26][27][28]. The schematic of such sensors and the required setup for biosensing is demonstrated in Figure 2.…”

“…The most straightforward configuration for conventional optical fiber-based plasmonic biosensing consist of an optical fiber, which has a partial or entirely naked core by removing the fiber cladding using for example a sharp blade [26][27][28] (followed by a cleaning procedure with de-ionized water and acetone). To facilitate the process of cladding removal, polymer or plastic based fiber-optics are the desired type of fiber for this type of biosensor [26][27][28]. The plasmonic nanoparticles/nanofilms can be then deposited on the surface of unclad section of fiber.…”

“…To deposit NPs, the fiber probe was coated by using a dip coating method. In this method, the fiber was dipped vertically into a long narrow cylindrical vessel containing the Ag-NPs solution [26]. To functionalize the probe, plasmonic-coated fiber was dipped in 10% ethanolic solution of 3-Aminopropyl triethoxysilane (3-APTES) for two minutes to create the amino functional group on the surface of NPs.…”

“…To functionalize the probe, plasmonic-coated fiber was dipped in 10% ethanolic solution of 3-Aminopropyl triethoxysilane (3-APTES) for two minutes to create the amino functional group on the surface of NPs. Finally, the functionalized optical fiber probe was immersed into lipase enzyme solution which can be immobilized by the interaction with amine groups of APTES on the surface of plasmonic-coated fiber [26]. The schematic of the immobilization method proposed by Baliyan et al [26] to create the biorecognition layer on the fiber probe is demonstrated in Figure 3 (top panel).…”

Preparation and Application of Metal Nanoparticals Elaborated Fiber Sensors

“…The concentration of enzyme and the size of NPs should also be considered in the fabrication of fiber-optic biosensors. Too low concentration of enzyme and too small size (<15 nm) of metal NPs may lead to the failure of the enzyme modification [ 118 ]. In the fiber optic SPR biosensor probe, both markers, and metal NPs contribute to the high sensitivity and low LOD [ 119 ].…”