# Surface Plasmon Resonance-Based Fiber Optic Sensors Utilizing Molecular Imprinting
## 6 Fiber Optic SPR Sensor Based on MITs
### Developments on FO-SPR-MIP-Based Sensors
#### 6.3.7 Profenofos  
Profenofos is the most common member of the organophosphorus pesticides (OPPs) and is used to control a broad range of pests on cotton, rice, vegetables, sugarcane, etc. OPPs are injurious to human health because OPPs affect the nervous system at very low concentrations [177]. This reason has motivated the development of a sensing method for profenofos detection with high sensitivity and selectivity and low limit of detection. Recently, [PERSON] et al. reported a profenofos detection method using FO-SPR and MIT [144]. The method for the sensing probe fabrication is shown in Figure 15a. The synthesis of MIP was performed by mixing 0.065 mM profenofos (cross-linker), 0.670 mM MAA (monomer) and 0.431 mM TRIM (initiator) in 10 mL DMSO (porogen) in an ultrasonic bath for 10 min and the solution was bubbled under a nitrogen gas environment for 15 min to remove the oxygen from the solution. The solution was then immediately left for pre-polymerization. The unbinding of the profenofos was done by dipping the non-imprinted polymer (NIP)-coated probe in methanol and \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Method** & **Substrate/Sensing Layer** & **Linearity (M)** & **LOD (M)** & **Ref.** \\ \hline Electrochemical & DMF exfoliated graphene & 4 \(\times\) 10\({}^{-4}\)-6 \(\times\) 10\({}^{-3}\) & 1.2 \(\times\) 10\({}^{-4}\) & [167] \\ \hline Electrochemical & \begin{tabular}{c} MIP polypyrrole/pencil \\ graphite electrode \\ \end{tabular} & 2.7 \(\times\) 10\({}^{-4}\)-7 \(\times\) 10\({}^{-3}\) & 7.4 \(\times\) 10\({}^{-5}\) & [168] \\ \hline Electrochemical & MIP PANI/ITO & 5 \(\times\) 10\({}^{-5}\)-4 \(\times\) 10\({}^{-4}\) & 1.8 \(\times\) 10\({}^{-5}\) & [169] \\ \hline Electrochemical & \begin{tabular}{c} Nitrogen doped porous \\ carbon nanopolyhedra \\ \end{tabular} & 8 \(\times\) 10\({}^{-5}\)-2 \(\times\) 10\({}^{-3}\) & 7.4 \(\times\) 10\({}^{-7}\) & [170] \\ \hline Electrochemical & \begin{tabular}{c} Ferricyanide/calcium \\ carbonate microsphere \\ \end{tabular} & 1 \(\times\) 10\({}^{-6}\)-2.1 \(\times\) 10\({}^{-3}\) & 7 \(\times\) 10\({}^{-7}\) & [171] \\ \hline Colorimetric & Ag NPs/artificial neutral network & 2 \(\times\) 10\({}^{-6}\)-4.8 \(\times\) 10\({}^{-5}\) & 6.2 \(\times\) 10\({}^{-7}\) & [172] \\ \hline Electrochemical & \begin{tabular}{c} Reduced graphene \\ oxide-ZnS nanocomposite \\ \end{tabular} & 5 \(\times\) 10\({}^{-5}\)-1 \(\times\) 10\({}^{-3}\) & 3 \(\times\) 10\({}^{-7}\) & [173] \\ \hline Electrochemical & \
\begin{tabular}{c} Graphene-MWCNT \\ nanocomposite/Au nanoclusters \\ \end{tabular} & 1 \(\times\) 10\({}^{-5}\)-1.5 \(\times\) 10\({}^{-4}\) & 2.7 \(\times\) 10\({}^{-7}\) & [174] \\ \hline Fluorescence & Protein modified Au nanoclusters & 1.5 \(\times\) 10\({}^{-6}\)-1 \(\times\) 10\({}^{-5}\) & 2 \(\times\) 10\({}^{-7}\) & [175] \\ \hline Colorimetric &
\begin{tabular}{c} Photocatalytic Ag NPs \\ \end{tabular} & 2.5 \(\times\) 10\({}^{-7}\)-5 \(\times\) 10\({}^{-5}\) & 7.92 \(\times\) 10\({}^{-10}\) & [176] \\ \hline Optical (SPR) & Fiber optic core/PANI MIP & 1 \(\times\) 10\({}^{-8}\)-1 \(\times\) 10\({}^{-7}\) & 1.28 \(\times\) 10\({}^{-10}\) & [166] \\ \hline Optical (LSPR + SPR) & Fiber optic core/Ag/PANI-Ag MIP & 1 \(\times\) 10\({}^{-8}\)-1 \(\times\) 10\({}^{-6}\) & 7.38 \(\times\) 10\({}^{-11}\) & [66] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Linearity and detection limits of various AA detection methods: Reprinted with permission from [66]. Copyright 2016 Institute of Physics. acetic acid solution 9:1 (v/v) for 10 min. The sensor was calibrated for profenofos solution prepared in aqueous medium with concentration range from 10\({}^{-4}\) to 10\({}^{-1}\)\(\upmu\)g/L. A red shift of 18.7 nm was observed for this profenofos concentration change. The variations in resonance wavelength shift and the sensitivity of the probe with the concentration of profenofos are shown in Figure 15b,c, respectively.