Barbell-shaped stir bar sorptive extraction using dummy template molecularly imprinted polymer coatings for analysis of bisphenol A in water

Insights into the Imprinting and Rebinding Performance of Molecularly Imprinted Hybrids for Bisphenol A and Bisphenol F

This study investigates the factors influencing the imprinting performance of molecularly imprinted hybrids (MIHs) with various template/monomer associations and their corresponding adsorption ability for three bisphenol analogues, bisphenol A (BPA), 2,2'-bisphenol F (2BPF), and 4,4'-bisphenol F (4BPF). Styrene (St) and methacrylic acid (MAA) were selected as the primary functional monomers for template complexation. Compared with hydrophilic MAA monomers, hydrophobic St monomers were more favorable for BPA imprinting, despite the lower binding energy of π-π interactions compared to hydrogen bonds. However, St monomers were unsuitable for 4BPF imprinting, while 2BPF exhibited limited complexation with MAA monomers. Among the bisphenols, BPA demonstrated the strongest imprinting capability, leading MIHs to exhibit the highest imprinting factor (IF = 14-18), adsorption capacity (Qmax = 43.7-47.6 mg/g), binding affinity (KL = 4.52-6.74 L/mg, ΔHads° = -35.2 to -38.9 kJ/mol, and ΔSads° = -40.5 to -50.6 J mol-1 K-1), and selectivity over 2BPF and 4BPF (2.0-3.5). In contrast, 2BPF- and 4BPF-imprinted hybrids exhibited significantly lower adsorption capacities (Qmax = 19.4-26.7 mg/g) and binding affinities (KL = 1.22-4.35 L/mg) for their respective templates. In competitive adsorption systems, bisphenol rebinding followed the trend BPA > 2BPF > 4BPF, regardless of which template was used for imprinting. Based on NMR analysis, the superior structure-directing and competitive rebinding abilities of BPA are attributed to the restricted rotation of its two phenyl groups, p-OH groups, and additional -CH3 groups on the bridged carbon, which enhance π-π stacking, H-bond, CH-π, and hydrophobic interactions within the imprinted cavities. In contrast, the o-OH groups of 2BPF and the rotational phenyl groups of 4BPF hinder their imprinting and rebinding via H-bond and π-π interactions, respectively.

Molecularly imprinted polymers in the analysis of chlorogenic acid: A review

Chlorogenic acid, a phenolic compound, is prevalent across various plant species and has been known for its pharmacological advantages. Health care experts have identified chlorogenic acid as a potential biomarker for treatment of a wide range of illnesses. Therefore, achieving efficient extraction and analysis of chlorogenic acid from plants and their products has become essential. Molecularly imprinted polymers (MIPs) are highly effective adsorbent for the extraction of chlorogenic acid from complex matrices. Currently, there is a lack of comprehensive review article that consolidate the methods utilized for the purification of chlorogenic acid through molecular imprinting. In this context, we have surveyed the common approaches employed in preparing MIPs specifically designed for the analysis of chlorogenic acid, including both conventional and newly developed. This review discusses the advantages, limitations of polymerization techniques and proposed strategies to produce more efficient MIPs for chlorogenic acid enrichment in complex samples. Additionaly, we present advanced imprinting methods for designing MIPs, which improve the adsorption capacity, sensitivity and selectivity towards chlorogenic acid.

Application of Molecularly Imprinted Polymers in the Analysis of Waters and Wastewaters

The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such as heavy metals, dyes, pesticides, endocrine disrupting compounds (EDCs), and pharmaceuticals, are produced through continuous technical and industrial developments that are emerging with the increasing population. Molecularly imprinted polymers (MIPs) represent a class of synthetic receptors that can be produced from different types of polymerization reactions between a target template and functional monomer(s), having functional groups specifically interacting with the template; such interactions can be tailored according to the purpose of designing the polymer and based on the nature of the target compounds. The removal of the template using suitable knocking out agents renders a recognition cavity that can specifically rebind to the target template which is the main mechanism of the applicability of MIPs in electrochemical sensors and as solid phase extraction sorbents. MIPs have unique properties in terms of stability, selectivity, and resistance to acids and bases besides being of low cost and simple to prepare; thus, they are excellent materials to be used for water analysis. The current review represents the different applications of MIPs in the past five years for the detection of different classes of water and wastewater contaminants and possible approaches for future applications.

Ultra-durable, multi-template molecularly imprinted polymers for ultrasensitive monitoring and multicomponent quantification of trace sulfa antibiotics

Traditional analysis methods are susceptible to interference caused by the complexity of sample matrices, and detector surface fouling arising from nonspecific adsorption of microorganisms (in biological samples) which leads in particular to a gradual loss of sensitivity. Imprinted materials can be used to effectively reduce interference originating in the matrices. However, the poor reproducibility and multicomponent quantification of trace antibiotics represent significant challenges to the detection process. Meanwhile, the high biological risk presented by bacterial antibiotic immunity and the persistence of antibiotics in foodstuffs, especially meat, both caused by the overuse of sulfonamide antibiotics, remain urgent issues. Here, we present the first example of a method for the accurate quantification of trace sulfa antibiotics (SAs) based on multi-template imprinted polymers (MMIPs). Levels of multiple SAs have been simultaneously successfully quantified by applying MMIP extraction coupled with UPLC-MS/MS analysis. This method shows excellent linearity of detection in the range of 0.1-500 μg L^-1, and ultrasensitivity with low limits of detection of 0.03 μg L^-1. The maximum SA residue recovered from sample tissues by using MMIPs was 5.48 μg g^-1. MMIP-coupled UPLC-MS/MS quantification of SAs is an accurate and repeatable method for the monitoring of SA accumulation in mouse tissue samples. It also provides an effective strategy for the tracking and quantification of drugs in other biological samples.

Role of Functional Monomers upon the Properties of Bisphenol A Molecularly Imprinted Silica Films

In this study, two types of bisphenol A molecularly imprinted films (BPA-MIP) were successfully prepared via sol-gel derived methods using two different organosilane functional monomers N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DAMO-T) or (3-mercaptopropyl)trimethoxysilane (MPTES). The physical-chemical characterization of films, in terms of morphology, structure, thermal analysis, and optical features, suggested that thinner films with a homogenous porous structure were more likely to retain BPA molecules. The MIP films revealed the rapid and quantitative adsorption of BPA, registering the most specific binding in the first five minutes of contact with the BPA-MIP film. Silica films were effectively regenerated for further usage for at least five times, demonstrating their high stability and reusability. Even if the performance of films for BPA uptake dropped dramatically after the third adsorption/reconditioning cycle, this synthesis method for BPA-MIP films has proven to be a reliable and cheap way to prepare sensitive films with potential application for re-usable optical sensors.

Application of a new adhesive elastomeric coating and hydrophilic-lipophilic-balanced sorbent for modified stir-bar sorptive extraction

A new polyurethane adhesive was evaluated to fix a hydrophilic-lipophilic-balanced sorbent and to produce modified stir-bars. It presented high mechanical and chemical resistance, indicating that it is an adequate adhesive. The homemade bars were employed to determine bisphenol A, diclofenac, ibuprofen and triclosan in aqueous medium. Satisfactory figures of merit were observed, with LOD between 0.06 and 0.30 ng mL-1 and enrichment factors between 133 and 195 times, using an extraction time of 2 h. The stir-bars were employed to determine the four analytes in water samples, presenting recovery results from 53 to 135% and RSD between 0.7 and 20%. In general, the results observed here indicated that the adhesive is an appropriate alternative material to fix HLB particles, and could probably be applied to other sorbents.

Stir bar sorptive extraction and its application

Recent progress of stir bar sorptive extraction (SBSE) in the past six years is reviewed. The preparation methods including electrodeposition, self-assembly, solvent exchange, physical magnetic adsorption and electrostatic spinning, for the coated stir bar are summarized and compared, specifically for a specific material for coatings fabrication, e.g., carbon-based materials and metal organic frameworks. The emerging materials (e.g., graphene, graphene oxide, carbon nanotubes, monolith, metal-organic frameworks and porous organic polymers) applied for coated stir bar fabrication are one of the focus of this review, along with their respective advantages in extraction process and application in trace analysis. The development and application of extraction apparatus of SBSE are also involved. Based on these information, the development status and prospects of SBSE as an efficient sample pretreatment technique in real sample analysis are discussed.

Synthesis of an organic-inorganic hybrid absorbent for in-tube solid-phase microextraction of bisphenol A

This research is an application of fiber-in-tube solid-phase microextraction followed by high-performance liquid chromatography with UV detection for the extraction and determination of trace amounts of bisphenol A. Nanomagnetic Fe₃ O₄ was formed on the surface of polypropylene porous hollow fibers to increase the surface area and then it was coated with polystyrene. The introduction of polystyrene improves the surface hydrophobicity and is an appropriate extractive phase because it is highly stable in aquatic media. The extraction was carried out in a short capillary packed longitudinally with the fine fibers as the extraction medium. Extraction conditions, including extraction and desorption flow rates, extraction time, pH, and ionic strength of the sample solution, were investigated and optimized. Under optimal conditions, the limit of detection was 0.01 µg/L. This method showed good linearity for bisphenol A in the range of 0.033-1000 µg/L, with the coefficient of determination of 0.9984. The inter- and intraday precisions (RSD%, n = 3) were 7.9 and 6.3%, respectively. Finally, the method was applied to analysis of the analyte in thermal papers, disposable plastic cups, and soft drink bottles.

Chiral molecularly imprinted polymeric stir bar sorptive extraction for naproxen enantiomer detection in PPCPs

Chiral micropollutant analysis in pharmaceuticals and personal care products (PPCPs) is interesting but challenging. We firstly developed a series of chiral molecularly imprinted polymeric (CMIP) stir bar sorptive extraction coatings by combining a chiral template with chiral functional monomers via a click reaction for naproxen enantiomer analysis in PPCPs. Heterochiral selectivity was observed in the molecule recognition of the CMIP coatings, which demonstrated good adsorption capability for the chiral template and its structurally similar chiral compounds. The coatings also exhibited excellent enrichment capability for chiral analytes in an aqueous matrix. The surface morphology and pore structure of the CMIP coatings were characterized. The molecular interactions between the chiral template and chiral functional monomer were investigated through UV-vis spectroscopy and theoretical calculations to prove the effective interactions existing in the heterochiral MIPs. The CMIP coatings were used to enrich naproxen enantiomers in chiral drug and environmental water samples, and satisfactory recoveries (83.98 %-118.88 %) with a relative standard deviation of 3.49 %-13.08 % were achieved. The heterochiral imprinted coating-based method provided a sensitive, selective, and effective enrichment strategy for chiral micropollutant analysis in PPCPs. This technique is critical for chiral molecule recognition and enantiomer analysis in complex samples.

Newest applications of molecularly imprinted polymers for extraction of contaminants from environmental and food matrices: A review

This paper presents an overview of the recent applications of molecularly imprinted polymers (MIPs) to sample preparation. The review is thought to cover analytical procedures for extraction of contaminants (mainly illegal/noxious organic compounds) from food and environmental matrices, with a particular focus on the various pre-concentration/cleanup techniques, that is offline and online solid-phase extraction (SPE), dispersive SPE (d-SPE), magnetic SPE (MSPE), solid-phase microextraction (SPME) and stir-bar sorptive extraction (SBSE), applied before instrumental quantification. The selectivity and extraction efficiency of MIP-based sorbent phases are critically discussed, also in relation to the physical-chemical properties resulting from the synthetic procedures. A variety of molecularly imprinted sorbents is presented, including hybrid composites embedding carbon nanomaterials and ionic liquids. The analytical performance of MIP materials in sample preparation is commented as function of the complexity of the matrix, and it is compared to that exhibited by (commercial) aspecific and/or immunosorbent phases.