This work presents the development of a MIP-based screen-printed potentiometric cell for sensing the pesticide atrazine. The cell comprises three screen-printed electrodes; the working and the counter are obtained by graphite-ink and the pseudo-reference by silver/silver chloride-ink. All electrodes are printed on the support of polyester. Obviously, only the working and the pseudo-reference electrodes are connected for potentiometric measurements. The prepolymeric mixture was composed of the reagents at the following molar ratio: 1 atrazine (ATZ):5 methacrylic acids (MAA):4 ethylene glycol dimethacrylate (EGDMA). An amount of 7 µL of the prepolymeric solution was drop coated on the graphite working electrode of the cell, and the polymerization was carried out in an oven at 70 °C overnight. The specific sites obtained after polymerization and template elution can be viewed as the ionophore of a usual ISE membrane. The active ion is the atrazine in its protonated form, positively charged, so the determination was carried out in aqueous solutions at pHs1.5. At these conditions, the potential increases linearly with atrazine concentration ranging from 5 × 10−7 to 5 × 10−6 M; the limit of detection obtained is 4 × 10−7 M. The slope of the calibration curve E vs. log c (obtained as an average value of the slope of different standardization performed with several electrodes) is 40(6) mV/dec; the sub-Nernstian behavior can be ascribed to the interference of the anions present in the solution media.

In this study, a molecularly imprinted polymer (MIP)-based screen-printed cell is developed for detecting phenoxy herbicides using 2-methyl-4-chlorophenoxyacetic acid (MCPA) as the template. MCPA is a phenoxy herbicide widely used since 1945 to control broadleaf weeds via growth regulation, primarily in pasture and cereal crops. The potentiometric cell consists of a silver/silver chloride pseudo-reference electrode and a graphite working electrode coated with a MIP film. The polymeric layer is thermally formed after drop-coating of a pre-polymeric mixture composed of the reagents at the following molar ratio: 1 MCPA: 15 MAA (methacrylic acid): 7 EGDMA (ethylene glycol dimethacrylate). After template removal, the recognition cavities function as the ionophore of a classical ion selective electrode (ISE) membrane. The detected ion is the deprotonated MCPA specie, negatively charged, so the measurements were performed in phosphate buffer at pH 5.5. A linear decrease of the potential with MCPA concentration, ranging from 4 × 10−8 to 1 × 10−6 mol L−1, was obtained. The detection limit and the limit of quantification were, respectively, 10 nmol L−1 and 40 nmol L−1. A Nernstian slope of about −59 mV/dec was achieved. The method has precision and LOD required for MCPA determination in contaminated environmental samples.

In recent years, plasmonic sensors have been used in various fields ranging from environmental monitoring, pharmaceutical analysis, medical diagnosis, and food quality assessment to forensics. A significant amount of information on plasmonic sensors and their applications already exists and there is a continuing development of reliable, selective, sensitive, and low-cost sensors. Combining molecularly imprinting technology with plasmonic sensors is an increasingly timely and important challenge to obtain portable, easy-to-use, particularly selective devices helpful in detecting analytes at the trace level. This review proposes an overview of the applications of molecularly imprinted plasmonic chemosensors and biosensors, critically discussing the performances, pros, and cons of the more recently developed devices.

The present study proposes the application of a recently developed optical–chemical sensor system to glyphosate detection. The device probes the refractive index variation in a chip based on a plastic optical fiber (POF) in which three orthogonal micro-holes were created and filled with an acrylic-based molecularly imprinted polymer (MIP). This sensitive chip, connected in series to a gold-coated SPR-POF platform, can modify the surface plasmon resonance (SPR) phenomena by exploiting the multimode characteristic of the POFs. Therefore, the gold film of the SPR-POF platform is not covered by the MIP layer, improving the sensor’s performance because the interaction between the analyte (glyphosate) and the polymer recognition cavities occurs in the core and not in the cladding of the waveguide. Indeed, the sample solution is dropped on the MIP-based chip while a water drop is constantly maintained above the gold surface of the reference SPR-POF platform to excite the surface plasmons, modulated by the MIP interaction with the target analyte. The device is here for the first time applied for glyphosate sensing in water samples. The high sensitivity and selectivity are proven, and tests on real samples highlight the good performances of the developed sensors.