A Molecularly Imprinted Polymer on a Plasmonic Plastic Optical Fiber to Detect Perfluorinated Compounds in Water

Abstract

A novel Molecularly Imprinted Polymer (MIP) able to bind perfluorinated compounds, combined with a surface plasmon resonance (SPR) optical fiber platform, is presented. The new MIP receptor has been deposited on a D-shaped plastic optical fiber (POF) covered with a photoresist buffer layer and a thin gold film. The experimental results have shown that the developed SPR-POF-MIP sensor makes it possible to selectively detect the above compounds. In this work, we present the results obtained with perfluorooctanoate (PFOA) compound, and they hold true when obtained with a perfluorinated alkylated substances (PFAs) mixture sample. The sensor’s response is the same for PFOA, perfluorooctanesulfonate (PFOS) or PFA contaminants in the C4–C11 range. We have also tested a sensor based on a non-imprinted polymer (NIP) on the same SPR in a D-shaped POF platform. The limit of detection (LOD) of the developed chemical sensor was 0.13 ppb. It is similar to the one obtained by the configuration based on a specific antibody for PFOA/PFOS exploiting the same SPR-POF platform, already reported in literature. The advantage of an MIP receptor is that it presents a better stability out of the native environment, very good reproducibility, low cost and, furthermore, it can be directly deposited on the gold layer, without modifying the metal surface by functionalizing procedures.

A Simple and Low-Cost Optical Fiber Intensity-Based Configuration for Perfluorinated Compounds in Water Solution

“…The polishing process is very important in the performances of the sensor platform. This analysis has been widely reported in several works [ 26 , 29 ].…”

“…The MIP receptor exploited in the present work is the same used in [ 26 ]. Nevertheless, in order to make this paper self-contained, we reported, in the following, all the information about the MIP preparation along with those relative to the optical sensor’s configuration.…”

“…The obtained results have shown good performance in terms of sensitivity and limit of detection (LOD) of this novel approach. The LOD of this sensor system, obtained by approximating the Hill equation to the Langmuir equation [ 26 , 27 , 28 ], is completely comparable to the configuration based on a surface plasmon resonance (SPR) sensor in D-shaped POF (0.13 ppb) [ 26 ], but with the advantage of an easier and low-cost preparation procedure and experimental setup.…”

“…This synthetic receptor is designed to recognize C4 to C12 PFAs, even if we will show only PFOA response. Actually, we already demonstrated, exploiting the SPR approach, that the MIP response is similar to PFOA or C4 to C12 PFAs [ 26 ]. Thus, for the sake of comparison, we deposited the same MIP receptor on an SPR-POF configuration, as already done in [ 26 ].…”

“…Actually, we already demonstrated, exploiting the SPR approach, that the MIP response is similar to PFOA or C4 to C12 PFAs [ 26 ]. Thus, for the sake of comparison, we deposited the same MIP receptor on an SPR-POF configuration, as already done in [ 26 ]. In summary, in the present work, we show two transmission POF chemical sensors, both based on the same MIP receptor for PFAs, one based on evanescent field sensing and another one (reference sensor [ 26 ]) on plasmonic sensing.…”