Sensitive pH Monitoring Using a Polyaniline-Functionalized Fiber Optic—Surface Plasmon Resonance Detector

Abstract

In this work, we report results on the fabrication and characterization of a surface plasmon resonance (SPR) pH sensor using platinum (Pt) and polyaniline (PANI) layers successively coated over an unclad core of an optical fiber (FO). The plasmonic thin Pt layer was deposited using a magnetron sputtering technique, while the pH-sensitive PANI layer was synthesized using an electroless polymerization method. Moreover, the formation of PANI film was confirmed by X-ray photoelectron spectroscopy (XPS) technique and its surface morphology was investigated using scanning electron microscopy (SEM). It was found that the PANI/Pt-coated FO-SPR pH sensor exhibits a fast and linear response in either acid or alkali solutions (pH operational range: 1 to 14). The proposed FO-SPR sensor could be used for biomedical applications, environmental monitoring or any remote, real-time on-site measurements.

Synthesis and Anti-Melanoma Activity of L-Cysteine-Coated Iron Oxide Nanoparticles Loaded with Doxorubicin

“…Every binding event at the gold surface will generate a shift in the signal response. A detailed description of the FO-SPR setup can be found in our previous articles [ 33 , 34 , 35 , 36 , 37 , 38 ]. Here, the freshly prepared gold-coated FO-SPR sensors were first immersed in a solution of L-Cys (0.1 M in ethanol) for four hours and then immersed in Dox (0.1 mM in ethanol) for 15 min.…”

Cadmium Ions’ Trace-Level Detection Using a Portable Fiber Optic—Surface Plasmon Resonance Sensor

“…The FO-SPR portable sensing system is schematically represented in Figure 1 and it is already well described in our previous work [ 25 , 26 ]. Briefly, an UV–VIS (Ultraviolet–Visible) spectrophotometer (AvaSpec ULS2048, Avantes, Apeldoorn, The Netherlands), a tungsten halogen light source (AvaLight, Avantes, Apeldoorn, The Netherlands), a bifurcated FO (Avantes, Apeldoorn, The Netherlands), as well as an interchangeable FO-SPR sensor, are included in the system.…”

“…Any event that occurs at this interface (i.e., the interaction between a receptor and its specific target molecule) will trigger a change in the SPR signal, which can be further processed in a graph [ 23 ]. This is the reason that FO-SPR sensors have been widely used in medical diagnostic and environmental monitoring applications, in order to study molecular interactions and their binding specificity [ 24 , 25 , 26 , 27 ]. In the last few years, the FO-SPR sensors have been used for the detection of heavy metal ions in contaminated water [ 28 , 29 , 30 ].…”

Hydrogel-integrated optical fiber sensors and their applications: a comprehensive review

“…115,116 Measuring the changes in the reflected light's intensity, angle, or spectrum facilitates SPR-based detection in various applications. 109 The general applications are pH sensing, [117][118][119] temperature sensing, 118,120,121 RI sensing, 121,122 and ion concentration sensing. 123,124 The optical fiber integrated SPR sensors demonstrate advantages in the detection process along with high spatial resolution, on-line distributed measurement, remote sensing, and low cost.…”