Polymers imprinted with PAH mixtures—comparing fluorescence and QCM sensors

Sensing Approaches Exploiting Molecularly Imprinted Nanoparticles and Lossy Mode Resonance in Polymer Optical Fibers

In this work, two different lossy mode resonance (LMR) platforms based on plastic optical fibers (POFs) are developed and tested in a biochemical sensing scenario. The LMR platforms are based on the combination of two metal oxides (MOs), i.e., zirconium oxide (ZrO2) and titanium oxide (TiO2), and deposited on the exposed core of D-shaped POF chips. More specifically, two experimental sensor configurations were obtained by swapping the mutual position of the Mos films over to the core of the D-shaped POF probe. The POF-LMR sensors were first characterized as refractometers, proving the bulk sensitivities. Then, both the POF-LMR platforms were functionalized using molecularly imprinted nanoparticles (nanoMIPs) specific for human transferrin (HTR) in order to carry out binding tests. The achieved results report a bulk sensitivity equal to about 148 nm/RIU in the best sensor configuration, namely the POF-TiO2-ZrO2. In contrast, both optical configurations combined with nanoMIPs showed an ultra-low detection limit (fM), demonstrating excellent efficiency of the used receptor (nanoMIPs) and paving the way to disposable POF-LMR biochemical sensors that are easy-to-use, low-cost, and highly sensitive.

Molecularly Imprinted Polymer-Based Sensors for Priority Pollutants

Globally, there is growing concern about the health risks of water and air pollution. The U.S. Environmental Protection Agency (EPA) has developed a list of priority pollutants containing 129 different chemical compounds. All of these chemicals are of significant interest due to their serious health and safety issues. Permanent exposure to some concentrations of these chemicals can cause severe and irrecoverable health effects, which can be easily prevented by their early identification. Molecularly imprinted polymers (MIPs) offer great potential for selective adsorption of chemicals from water and air samples. These selective artificial bio(mimetic) receptors are promising candidates for modification of sensors, especially disposable sensors, due to their low-cost, long-term stability, ease of engineering, simplicity of production and their applicability for a wide range of targets. Herein, innovative strategies used to develop MIP-based sensors for EPA priority pollutants will be reviewed.

Highly selective electrochemical nanofilm sensor for detection of carcinogenic PAHs in environmental samples

A highly sensitive sensor based on molecularly imprinted polymer film was devised for determination of polycyclic aromatic hydrocarbon (PAHs) in aquatic solutions. In this paper we report, electro-polymerisation of 4-vinyl pyridine (4VP) and target, pyrene, using cyclic voltammeter in electrolyte medium, forming the pyrene imprinted polymer. After polymerisation, the pyrene was removed from imprinted polymer using methanol to produce sensory nanofilm characterised by infrared spectrometer, optical and atomic force microscopy. The mechanism of nanofilm sensing was established using atomic models and electrochemical response by differential pulse voltammeter with the redox system of ([Fe(CN)₆]^3-/[Fe(CN)₆]^4-). The π-π interaction between pyrene and 4VP was primary cause for pyrene recognition in aqueous solutions and the model binding score for this interaction was -5.10 kcal mol^-1. The electrochemical sensor determined pyrene in the concentration range of 1 × 10^-4 - 1 ng L^-1, resulting best linear regression (r² > 0.9) and detection limit of 0.001 ng L^-1. The recovery percentage of pyrene from the nanofilm was 83-110% in water samples and the imprinting factor value was 2.67. Therefore, the novel imprinted polymer nanofilm sensor showed highest sensitivity for target pyrene in aqueous samples compared to reported sensors.

Diazonium Salt-Based Surface-Enhanced Raman Spectroscopy Nanosensor: Detection and Quantitation of Aromatic Hydrocarbons in Water Samples

Here, we present a surface-enhanced Raman spectroscopy (SERS) nanosensor for environmental pollutants detection. This study was conducted on three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BaP), fluoranthene (FL), and naphthalene (NAP). SERS substrates were chemically functionalized using 4-dodecyl benzenediazonium-tetrafluoroborate and SERS analyses were conducted to detect the pollutants alone and in mixtures. Compounds were first measured in water-methanol (9:1 volume ratio) samples. Investigation on solutions containing concentrations ranging from 10⁻⁶ g L⁻¹ to 10⁻³ g L⁻¹ provided data to plot calibration curves and to determine the performance of the sensor. The calculated limit of detection (LOD) was 0.026 mg L⁻¹ (10⁻⁷ mol L⁻¹) for BaP, 0.064 mg L⁻¹ (3.2 × 10⁻⁷ mol L⁻¹) for FL, and 3.94 mg L⁻¹ (3.1 × 10⁻⁵ mol L⁻¹) for NAP, respectively. The correlation between the calculated LOD values and the octanol-water partition coefficient (K_ow) of the investigated PAHs suggests that the developed nanosensor is particularly suitable for detecting highly non-polar PAH compounds. Measurements conducted on a mixture of the three analytes (i) demonstrated the ability of the developed technology to detect and identify the three analytes in the mixture; (ii) provided the exact quantitation of pollutants in a mixture. Moreover, we optimized the surface regeneration step for the nanosensor.

Molecularly imprinted polymers for the analysis and removal of polychlorinated aromatic compounds in the environment: a review

Molecularly imprinted polymers selective to polychlorinated aromatic compounds for application in environmental studies.

Molecularly imprinted polymeric micro- and nano-particles for the targeted delivery of active molecules

Molecular imprinting (MI) represents a strategy to introduce a 'molecular memory' in a polymeric system obtaining materials with specific recognition properties. MI particles can be used as drug delivery systems providing a targeted release and thus reducing the side effects. The introduction of molecular recognition properties on a polymeric drug carrier represents a challenge in the development of targeted delivery systems to increase their efficiency. This review will summarize the limited number of drug delivery MI particles described in the literature along with an overview of potential solutions for a larger exploitation of MI particles as targeted drug delivery carriers. Molecularly imprinted drug carriers can be considered interesting candidates to significantly improve the efficiency of a controlled drug treatment.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Analysis of benzo[a]pyrene in vegetable oils using molecularly imprinted solid phase extraction (MISPE) coupled with enzyme-linked immunosorbent assay (ELISA)

This paper describes the development of a molecularly imprinted polymer-based solid phase extraction (MISPE) method coupled with enzyme-linked immunosorbent assay (ELISA) for determination of the PAH benzo[a]pyrene (B[a]P) in vegetable oils. Different molecularly imprinted polymers (MIPs) were prepared using non-covalent 4-vinylpyridine/divinylbenzene co-polymerization at different ratios and dichloromethane as porogen. Imprinting was done with a template mixture of phenanthrene and pyrene yielding a broad-specific polymer for PAHs with a maximum binding capacity (Q) of ~32 μg B[a]P per 50 mg of polymer. The vegetable oil/n-hexane mixture (1:1, (v/v)) was pre-extracted with acetonitrile, the solvent evaporated, the residue reconstituted in n-hexane and subjected to MISPE. The successive washing with n-hexane and isopropanol revealed most suitable to remove lipid matrix constituents. After elution of bound PAHs from MISPE column with dichloromethane, the solvent was evaporated, the residue reconstituted with dimethyl sulfoxide and diluted 100-fold with methanol/water (10:90, (v/v)) for analysis of B[a]P equivalents with an ELISA. The B[a]P recovery rates in spiked vegetable oil samples of different fatty acid composition were determined between 63% and 114%. The presence of multiple PAHs in the oil sample, because of MIP selectivity and cross-reactivity of the ELISA, could yield overestimated B[a]P values.

Supramolecular complexation for environmental control

Supramolecular complexes offer a new and efficient way for the monitoring and removal of many substances emanating from technical processes, fertilization, plant and animal protection, or e.g. chemotherapy. Such pollutants range from toxic or radioactive metal ions and anions to chemical side products, herbicides, pesticides to drugs including steroids, and include degradation products from natural sources. The applications involve usually fast and reversible complex formation, due to prevailing non-covalent interactions. This is of importance for sensing as well as for separation techniques, where the often expensive host compounds can then be reused almost indefinitely. Immobilization of host compounds, e.g. on exchange resins or on membranes, and their implementation in smart new materials hold particular promise. The review illustrates how the design of suitable host compounds in combination with modern sensing and separation methods can contribute to solve some of the biggest problems facing chemistry, which arise from the everyday increasing pollution of the environment.