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Molecularly imprinted polymers (MIPs) for benzylpiperazine (BZP, 1), an illicit designer drug, were developed by using both self-assembly and semi-covalent approaches. From an array of potential functional monomers (FMs) and using a combination of pre-synthetic interaction studies (by molecular modelling and NMR analysis) and binding assays, the highest performing self-assembly 1-MIPs were confirmed to result from methacrylic acid (7) as FM, ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TRIM) as crosslinkers and chloroform as the porogen and rebinding solvent at template (T): FM ratios of 1:1 and 1:2, giving imprinting factors (IF) 3 to 7. The semi-covalent 1-MIPs were designed using benzylpiperazine (4-vinylphenyl) carbamate (16) as the template–monomer adduct in combination with either EDGMA or TRIM. Our comparative analysis showed the semi-covalent polymers to have a stronger affinity for 1 (significantly lower Kd values and higher IFs) and faster uptake than the self-assembly systems. Both approaches have comparable cross-reactivity: marginal to low against cocaine (17) and morphine (18) and high against ephedrine (19) and phenylpiperazine (20). They also have comparable selectivity: highly selective towards 1 against 17, moderate against 18 and non-selective against 19. EGDMA-based self-assembly MIPs displayed a greater imprinting effect (higher IFs and NIP-to-MIP Kd ratios) than TRIM-based MIPs, while the TRIM-based semi-covalent MIP outperformed its EGDMA-based equivalent. By virtue of its modest selectivity against the test illicit drugs, 1-MIPs could potentially be used as a dummy MIP for the broad-based capture and enrichment of illicit drug blends for subsequent laboratory analysis.

Receptors generated by natural evolution in living organisms show an astonishing capacity for specifically recognizing target molecules. If applied as recognition units of biosensors, these receptors provide very high selectivity. However, they suffer from instability under measurement conditions, and low durability. Devising alternative robust artificial receptors circumvents these deficiencies. For instance, an antibody can be successfully replaced by a corresponding molecularly imprinted polymer (MIP), sometimes called a ‘plastic antibody’. Therefore, MIPs used as recognition units in chemical sensors are gaining increasing interest. In this review, we survey selected examples of MIPs used for determining target bioanalytes by mimicking natural recognition. For scientists working with biosensors, MIPs might be considered as alternatives to natural receptors, such as antibodies, enzymes, or histones. MIPs can recognize target analytes not only by their shape and size, because introducing a dedicated set of recognizing sites into the imprinted cavity increases both the affinity of the cavity for the analyte and its selectivity with respect to interferences. Different functional monomers have been introduced to provide selective chemical recognition that involves the formation of covalent bonds, hydrogen bonds, and coulombic and supramolecular interactions, as well as metal chelation and π-π stacking. MIPs are prepared as bulk polymers, which can then be ground, or, alternatively, can be prepared as beads with the desired shape and size. However, for chemosensor fabrication, these MIPs should be deposited as thin films. Electropolymerization or electrochemically inducted polymerization is best suited for depositing both conducting and nonconducting MIP films.

A molecularly imprinted polymer (MIP) is a synthetic polymer that has characteristics such as natural receptors which are able to interact and bind to a specific molecule that is used as a template in the MIP polymerization process. MIPs have been widely developed because of the need for more selective, effective, and efficient methods for sample preparation, identification, isolation, and separation. The MIP compositions consist of a template, monomer, crosslinker, initiator, and porogenic solvent. Generally, MIPs are only synthesized using one type of monomer (mono-functional monomer); however, along with the development of MIPs, MIPs began to be synthesized using two types of monomers to improve the performance of MIPs. MIPs used for identification, separation, and molecular analysis have the most applications in solid-phase extraction (SPE) and as biochemical sensors. Until now, no review article has discussed the various studies carried out in recent years in relation to the synthesis of dual-functional monomer MIPs. This review is necessary, as an improvement in the performance of MIPs still needs to be explored, and a dual-functional monomer strategy is one way of overcoming the current performance limitations. In this review article, we discuss the techniques commonly used in the synthesis of dual-functional monomer MIPs, and the use of dual-functional monomer MIPs as sorbents in the MI-SPE method and as detection elements in biochemical sensors. The application of dual-functional monomer MIPs showed better selectivity and adsorption capacity in these areas when compared to mono-functional monomer MIPs. However, the combination of functional monomers must be selected properly, in order to achieve an effective synergistic effect and produce the ideal MIP characteristics. Therefore, studies regarding the synergistic effect of the MIP combination still need to be carried out to obtain MIPs with superior characteristics.

Molecular imprinting is a technique for creating artificial recognition sites on polymer matrices that complement the template in terms of size, shape, and spatial arrangement of functional groups. The main advantage of Molecularly Imprinted Polymers (MIP) as the polymer for use with a molecular imprinting technique is that they have high selectivity and affinity for the target molecules used in the molding process. The components of a Molecularly Imprinted Polymer are template, functional monomer, cross-linker, solvent, and initiator. Many things determine the success of a Molecularly Imprinted Polymer, but the Molecularly Imprinted Polymer component and the interaction between template-monomers are the most critical factors. This review will discuss how to find the interaction between template and monomer in Molecularly Imprinted Polymer before polymerization and after polymerization and choose the suitable component for MIP development. Computer simulation, UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Proton-Nuclear Magnetic Resonance (1H-NMR) are generally used to determine the type and strength of intermolecular interaction on pre-polymerization stage. In turn, Suspended State Saturation Transfer Difference High Resolution/Magic Angle Spinning (STD HR/MAS) NMR, Raman Spectroscopy, and Surface-Enhanced Raman Scattering (SERS) and Fluorescence Spectroscopy are used to detect chemical interaction after polymerization. Hydrogen bonding is the type of interaction that is becoming a focus to find on all methods as this interaction strongly contributes to the affinity of molecularly imprinted polymers (MIPs).

In this study, molecular imprinted polymer (MIP)-based impedimetric sensor has been developed to detect dengue infection at an early stage. Screen-printed carbon electrode (SPCE) was modified with electrospun nanofibers of polysulfone (PS) and then, coated with dopamine while using NS1 (non-structural protein 1—a specific and sensitive biomarker for dengue virus infection) as template during polymerization. The self-polymerization of dopamine at room temperature helps to retain exact structure of template (NS1) which results in generating geometrically fit imprinted sites for specific detection of target analyte. The electrochemical properties of MIP-modified SPCEs were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) at every step of modification. Under optimal conditions, impedimetric measurements showed linear response in the range from 1 to 200 ng/mL. The developed sensor can selectively detect NS1 concentrations as low as 0.3 ng/mL. Moreover, impedimetric sensor system was also employed for NS1 determination in real human serum samples and satisfying recoveries varying from 95 to 97.14% were obtained with standard deviations of less than 5%.

The magnitude and spatial pattern of anomalous net biome exchange (NBE) induced by the 2015/16 El Niño over Amazonian rainforests remain uncertain. We here investigated them using multi‐model posterior NBE products in the Orbiting Carbon Observatory‐2 (OCO‐2) version 10 modeling intercomparison project. Results suggest that relative to the annual NBE average in 2017/18, larger anomalous carbon release occurred over the eastern and northern Amazonian rainforests in 2015/16, with a total flux of approximately 0.4 PgC yr−1 after assimilating satellite‐observed column CO2 concentrations (XCO2) over land. We further find that this anomalous spatial pattern was predominantly determined by soil dryness, while the total positive NBE anomaly was dominated by higher temperature with its contribution of approximately 68～70%. We believe that atmospheric inversions assimilating more satellite‐observed XCO2 in future can provide us more comprehensive understanding how Amazonian rainforests cope with the abiotic stresses induced by El Niño events. Plain Language Summary Interannual variability of carbon flux associated with its drivers over Amazonian rainforests are not fully understood. We here used several groups' newly available posterior CO2 flux estimates to comprehensively investigate the net carbon flux anomaly induced by the 2015/16 extreme El Niño. A total net carbon flux anomaly of approximately 0.4 PgC yr−1 was estimated, which showed larger carbon release over the eastern and northern Amazonian rainforests. We further suggest that although dry conditions greatly shaped the spatial pattern of the anomalous carbon flux, the total carbon flux anomaly was controlled by the higher temperature, with its contribution of approximately 68∼70%. Key Points Net biome exchange (NBE) anomalies over Amazonian rainforests induced by the 2015/16 El Niño were investigated based on multiple atmospheric inversions The spatial pattern of NBE anomaly was regulated by soil water with larger anomalies over the eastern and northern Amazonian rainforests The total NBE anomaly was estimated at about 0.4 PgC yr−1 in 2015/16 relative to the average in 2017/18, dominated by higher temperature

Molecular imprinting is the process of template-induced formation of specific recognition sites in a polymer. Synthetic receptors prepared using molecular imprinting possess a unique combination of properties such as robustness, high affinity, specificity, and low-cost production, which makes them attractive alternatives to natural receptors. Improvements in polymer science and nanotechnology have contributed to enhanced performance of molecularly imprinted polymer (MIP) sensors. Encouragingly, recent years have seen an increase in high-quality publications describing MIP sensors for the determination of biomolecules, drugs of abuse, and explosives, driving toward applications of this technology in medical and forensic diagnostics. This review aims to provide a focused overview of the latest achievements made in MIP-based sensor technology, with emphasis on research toward real-life applications. Electrochemical and optical sensing based on molecularly imprinted polymers (MIPs) has particular relevance in real-life applications and point-of-care testing in real human samples. MIPs are a leading technology for sensing molecules where there is no available bioreceptor. MIP nanoparticles can be used for direct and indirect detection (labeled or label free). The sensitivity of MIP-based sensors can be enhanced by coupling with nanomaterials such as graphene oxide, carbon nanotubes, or nanoparticles. The present challenges and perspectives of MIP-based electrochemical and optical sensors include exploring the market niches for MIP sensors and identifying the necessary steps toward commercialization.

Bentonite pellets are recognized as good buffer/backfill materials for sealing technological voids in high-level radioactive waste (HLW) repository. Compared to that of a traditional compacted bentonite block, one of the most important particularities of this material is the initially discrete pellets and the inevitable heterogeneous porosity formed, leading to a distinctive water retention behaviour. In this paper, water retention and mercury intrusion porosimetry (MIP) tests were conducted on pellet mixture (constant volume), single pellet (free swelling) and compacted block (constant volume) of GMZ bentonite, water retention properties and pore structure evolutions of the specimens were comparatively investigated. Results show that the water retention properties of the three specimens are almost similar to each other in the high suction range (> 10 MPa), while the water retention capacity of pellet mixture is lower than those of the compacted block and single pellet in the low suction range (< 10 MPa). Based on the capillary water retention theory (the Young–Laplace equation), a new concept ‘saturated void ratio’ that was positively related to water content and dependent on pore size distribution of the specimen was defined. Then, according to the product of saturated void ratio and water density in saturated void, differences of water retention properties for the three specimens at low suctions were explained. Meanwhile, MIP tests indicate that as suction decreases, the micro- and macrovoid ratios of pellet mixture and compacted block decrease as the mesovoid ratio increases, while all the void ratios of single pellets increase. This could be explained that upon wetting, water is successively adsorbed into the inter-layer, inter-particle and inter-pellet voids, leading to the subdivision of particles and swelling of aggregates and pellets. Under constant volume condition, aggregates and pellets tend to swell and fill into the inter-aggregates or inter-pellets voids. While under free swelling condition, the particles and aggregates in a single pellet tend to swell outward rather than squeezing into the inter-aggregate voids, leading to the expansion of the pores and even formation of cracks. Results including the effects of initial conditions (initial dry density and fabric) and constraint conditions (constant volume or free swelling) on the water retention capacity and pore structure evolution reached in this work are of great importance in designing of engineering barrier systems for the HLW repository.

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.

Here we present the results from an intercomparison of multiple global gridded crop models (GGCMs) within the framework of the Agricultural Model Intercomparison and Improvement Project and the Inter-Sectoral Impacts Model Intercomparison Project. Results indicate strong negative effects of climate change, especially at higher levels of warming and at low latitudes; models that include explicit nitrogen stress project more severe impacts. Across seven GGCMs, five global climate models, and four representative concentration pathways, model agreement on direction of yield changes is found in many major agricultural regions at both low and high latitudes; however, reducing uncertainty in sign of response in mid-latitude regions remains a challenge. Uncertainties related to the representation of carbon dioxide, nitrogen, and high temperature effects demonstrated here show that further research is urgently needed to better understand effects of climate change on agricultural production and to devise targeted adaptation strategies.