State-of-the-art applications of cyclodextrins as functional monomers in molecular imprinting techniques: a review

Assessing the greenification potential of cyclodextrin-based molecularly imprinted polymers for pesticides detection

Cyclodextrins, with their unparalleled attributes of eco-friendliness, natural abundance, versatile utility, and facile functionalization, make a paramount contribution to the field of molecular imprinting. Leveraging the unique properties of cyclodextrins in molecularly imprinted polymers synthesis has revolutionized the performance of molecularly imprinted polymers, resulting in enhanced adsorption selectivity, capacity, and rapid extraction of pesticides, while also circumventing conventional limitations. As the concern for food quality and safety continues to grow, the need for standard analytical methods to detect pesticides in food and environmental samples has become paramount. Cyclodextrins, being non-toxic and biodegradable, present an attractive option for greener reagents in imprinting polymers that can also ensure environmental safety post-application. This review provides a comprehensive summary of the significance of cyclodextrins in molecular imprinting for pesticide detection in food and environmental samples. The recent advancements in the synthesis and application of molecularly imprinted polymers using cyclodextrins have been critically analyzed. Furthermore, the current limitations have been meticulously examined, and potential opportunities for greenification with cyclodextrin applications in this field have been discussed. By harnessing the advantages of cyclodextrins in molecular imprinting, it is possible to develop highly selective and efficient methods for detecting pesticides in food and environmental samples while also addressing the challenges of sustainability and environmental impact.

Synthesis, column packing and liquid chromatography of molecularly imprinted polymers for the acid black 1, acid black 210, and acid Brown 703 dyes

Molecularly imprinted polymers have been synthesized for the acid black 1, acid black 210, and acid brown 703 dyes using methacrylic acid, ethylene glycol, and azobisisobutyronitrile as the monomer, cross-linker, and initiator, respectively, in the ratio of 1 : 10 : 44 (template:monomer:cross-linker). The MIPs were used for the selective removal of their corresponding dyes. The selective nature of the MIPs towards their respective dyes was confirmed by a homemade liquid chromatography system. The resultant polymer materials were packed in a stainless steel column and checked for the separation of mixtures of dyes in liquid chromatography. The dyes complementary in structure to the imprinted cavities in the MIPs had long retention times, showing the highly selective nature of the MIPs. The pH, quantity of the MIPs, time, and concentration of the dyes were optimized for the highly efficient removal of the newly synthesized MIP adsorbents in batch adsorption studies. First-order, second-order, and intra-particle diffusion models were applied to all the three MIP-based adsorbents for their kinetic investigations towards the dyes. All the three MIPs selectively absorbed their target template molecule in the presence of four other template dyes having closely related structures with % RSD < 4% for the three batch experiments. The synthesized MIPs were characterized by FTIR, SEM imaging and liquid chromatography. FTIR results strongly confirmed the presence of hydrogen bonding interactions (600–900) between the template and the individual monomers present in the unwashed MIPs. Liquid chromatography revealed the highly selective nature of the MIPs towards their template molecules. The synthesized polymeric substances possess excellent thermal, chemical, and mechanical stability and can be reused several hundred times. The MIPs were applied in the removal of dyes from spiked water samples (river water, tap water and distilled water) where the % removal of the dyes by their corresponding MIPs was greater than 90%.

MIP synthesis for the recently emerging dyes, a new method for their characterization in liquid chromatography by packing packing the MIP particles in a stainless steel column, and their application in environmental remediation.

Advances in Detection of Antibiotic Pollutants in Aqueous Media Using Molecular Imprinting Technique-A Review

Antibiotics constitute one of the emerging categories of persistent organic pollutants, characterised by their expansion of resistant pathogens. Antibiotic pollutants create a major public health challenge, with already identifiable detrimental effects on human and animal health. A fundamental aspect of controlling and preventing the spread of pollutants is the continuous screening and monitoring of environmental samples. Molecular imprinting is a state-of-the-art technique for designing robust biomimetic receptors called molecularly imprinted polymers (MIPs), which mimic natural biomolecules in target-selective recognition. When integrated with an appropriate sensor transducer, MIP demonstrates a potential for the needed environmental monitoring, thus justifying the observed rise in interest in this field of research. This review examines scientific interventions within the last decade on the determination of antibiotic water pollutants using MIP receptors interfaced with label-free sensing platforms, with an expanded focus on optical, piezoelectric, and electrochemical systems. Following these, the review evaluates the analytical performance of outstanding MIP-based sensors for environmentally significant antibiotics, while highlighting the importance of computational chemistry in functional monomer selection and the strategies for signal amplification and performance improvement. Lastly, the review points out the future trends in antibiotic MIP research, as it transits from a proof of concept to the much demanded commercially available entity.

Green Chemistry and Molecularly Imprinted Membranes

Technological progress has made chemistry assume a role of primary importance in our daily life. However, the worsening of the level of environmental pollution is increasingly leading to the realization of more eco-friendly chemical processes due to the advent of green chemistry. The challenge of green chemistry is to produce more and better while consuming and rejecting less. It represents a profitable approach to address environmental problems and the new demands of industrial competitiveness. The concept of green chemistry finds application in several material syntheses such as organic, inorganic, and coordination materials and nanomaterials. One of the different goals pursued in the field of materials science is the application of GC for producing sustainable green polymers and membranes. In this context, extremely relevant is the application of green chemistry in the production of imprinted materials by means of its combination with molecular imprinting technology. Referring to this issue, in the present review, the application of the concept of green chemistry in the production of polymeric materials is discussed. In addition, the principles of green molecular imprinting as well as their application in developing greenificated, imprinted polymers and membranes are presented. In particular, green actions (e.g., the use of harmless chemicals, natural polymers, ultrasound-assisted synthesis and extraction, supercritical CO2, etc.) characterizing the imprinting and the post-imprinting process for producing green molecularly imprinted membranes are highlighted.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

Green Aspects in Molecularly Imprinted Polymers by Biomass Waste Utilization

Molecular Imprinting Polymer (MIP) technology is a technique to design artificial receptors with a predetermined selectivity and specificity for a given analyte, which can be used as ideal materials in various application fields. In the last decades, MIP technology has gained much attention from the scientific world as summarized in several reviews with this topic. Furthermore, green synthesis in chemistry is nowadays one of the essential aspects to be taken into consideration in the development of novel products. In accordance with this feature, the MIP community more recently devoted considerable research and development efforts on eco-friendly processes. Among other materials, biomass waste, which is a big environmental problem because most of it is discarded, can represent a potential sustainable alternative source in green synthesis, which can be addressed to the production of high-value carbon-based materials with different applications. This review aims to focus and explore in detail the recent progress in the use of biomass waste for imprinted polymers preparation. Specifically, different types of biomass waste in MIP preparation will be exploited: chitosan, cellulose, activated carbon, carbon dots, cyclodextrins, and waste extracts, describing the approaches used in the synthesis of MIPs combined with biomass waste derivatives.

Recent Advances of Molecularly Imprinted Polymers Based on Cyclodextrin

Molecular imprinting polymers (MIPs), generally considered as artificial mimics that are comparable to natural receptor, are polymers with tailor-made specific recognition sites complementary to the template molecules in shape and size. As a class of supramolecular compounds, cyclodextrins (CDs) are flourishing in the field of molecular imprinting with their unique structural properties. This review presents recent advances in application of MIPs based on CDs during the past five years. The discussion is grouped according to the different role of CDs in MIPs, that is, functional monomer, carrier modifier, etc. Main focus is the application of CD-based MIP on sample preparation, detection, and sensing. Additionally, drug delivery with CD-based MIP is also briefly discussed. Finally, challenges and future prospects of application of CDs in MIP are elaborated.

Construction of natural polymeric imprinted materials and their applications in water treatment: A review

Molecularly imprinted materials (MIMs) have been widely used in various fields, including water treatment, chemical sensing, and biotechnology, because of their specific recognition and high selectivity. MIMs are usually obtained via two successive steps, namely, (1) copolymerization and crosslinking reactions of the preassembled complex of comonomers and a specific target compound (2) and thorough removal of template molecules. Some functional polymers are directly used as supporting materials and functional groups assembled with target compound are provided to simplify the preparation of MIMs. Natural polymers, such as chitosan, cyclodextrin, sodium alginate, starch, cellulose, lignin and their derivatives, are good candidates because of their environmentally friendly properties, low costs, and abundant active functional groups. In this study, different methods for the preparation of natural polymeric MIMs were reviewed in terms of the construction of microscopic binding cavities and macroscopic visible condensed structures with different shapes. Natural polymeric MIMs in water treatment applications, such as adsorption and detection of various pollutants from aqueous solutions, were summarized. Prospects on the development of novel and high-performance natural polymeric MIMs were discussed to overcome the difficulties in their preparation and applications.

Effect of surface functionality of molecularly imprinted composite nanospheres on specific recognition of proteins

The surface functionality of biomaterial plays a primary role in determining its application in biorecognition and drug delivery. In our work, three types of synthetic tailoring polymer nanospheres with hierarchical architecture were constructed to obtain functional polymer layer with disparate chemical motifs for protein adsorption via surface imprinting and grafting copolymerization. In this polymerization system, the structure stability of template protein bovine serum albumin (BSA) is well maintained within a certain range, which facilitated the accurate imprinting and precise identification. A comprehensive protocol for screening different functional layer is proposed through comparing the adsorption behavior, selectivity, identification and responsiveness to medium pH of three functional layers. Our study demonstrates that surface functionality greatly influences the adsorption capacity and selectivity of adsorption material. The functional layer with ionic liquid structure that could only provide multiple non-covalent binding sites is beneficial to the proteins aggregation and extraction, while the anti-nonspecific binding functional layer of biomaterial with zwitterionic structure for specific protein capture is promising to serve as a preferable antigen-antibody communication network, which shows great potential for protein recognition and separation. In summary, our proposed strategy provides a systematic selection criterion of biomaterials for effective application in biosensors.

Highly sensitive determination of amanita toxins in biological samples using β-cyclodextrin collaborated molecularly imprinted polymers coupled with ultra-high performance liquid chromatography tandem mass spectrometry

In this work, a β-cyclodextrin functional vinyl monomer was synthesized and the common moiety of five amanita toxins was used as the template for preparing molecularly imprinted polymers (MIPs). Chemical calculation was used to evaluate and describe the binding interactions between the template and the functional monomer. The preparation conditions were optimized and the resultant MIPs were characterized and employed as solid-phase extraction (SPE) sorbents. The SPE conditions including the amount of sorbent, extraction solution, and eluting solution were also optimized for the enrichment of the five toxins. Using an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), detection limits ranging from 0.34-0.42 µg/L, 0.16-0.33 µg/L, and 0.035-0.056 µg/kg were achieved for the five toxins in serum, urine and liver samples, respectively. The proposed method was further applied to the determination of the amanita toxins in suspected samples and showed great potential in the diagnosis of mushroom poisoning.

Reasonable design and sifting of microporous carbon nanosphere-based surface molecularly imprinted polymer for selective removal of phenol from wastewater

Highly selective surface molecularly imprinted polymer (SMIP) was prepared on glucose-derived microporous carbon nanospheres (GMCNs) by surface molecular imprinting technology for the removal of phenol from wastewater. GMCNs with rich pore structure and surface oxygenic functional groups were adopted as support materials, on which the active layers were constructed by grafting silane coupling agent 3-(methacryloyloxy) propyltrimethoxysilane. Then with phenol as template molecule, different types and amounts of functional monomer (including methacrylic acid and 4-vinylpyridine (4-VP)) were screened for optimizing imprinting conditions suitable for phenol adsorption, and a series of SMIP was obtained through crosslinking polymerization. The adsorption behaviors of SMIP were evaluated by UV spectrophotometry. The results show that, when 4-VP is used as functional monomer, the resultant 4-VP/SMIP exhibites an excellent adsorption capacity of 85.72 mg g^-1. The relative selectivity factor for phenol against hydroquinone, p-nitrophenol and p-tert-butylphenol is 8.38, 7.96 and 6.67, respectively, indicating outstanding adsorption capacity and selectivity of 4-VP/SMIP. The pseudo-second-order model and Langmuir‒Freundlich model fit better than other models for the adsorption of phenol. 4-VP/SMIP is promising for selective removal and enrichment recovery towards phenol in wastewater.

Molecularly Imprinted Polymers and Surface Imprinted Polymers Based Electrochemical Biosensor for Infectious Diseases

Owing to their merits of simple, fast, sensitive, and low cost, electrochemical biosensors have been widely used for the diagnosis of infectious diseases. As a critical element, the receptor determines the selectivity, stability, and accuracy of the electrochemical biosensors. Molecularly imprinted polymers (MIPs) and surface imprinted polymers (SIPs) have great potential to be robust artificial receptors. Therefore, extensive studies have been reported to develop MIPs/SIPs for the detection of infectious diseases with high selectivity and reliability. In this review, we discuss mechanisms of recognition events between imprinted polymers with different biomarkers, such as signaling molecules, microbial toxins, viruses, and bacterial and fungal cells. Then, various preparation methods of MIPs/SIPs for electrochemical biosensors are summarized. Especially, the methods of electropolymerization and micro-contact imprinting are emphasized. Furthermore, applications of MIPs/SIPs based electrochemical biosensors for infectious disease detection are highlighted. At last, challenges and perspectives are discussed.

Progress in Molecularly Imprinted Polymers for Biomedical Applications

Background:

Molecularly Imprinted Polymers (MIPs), a type of biomimetic materials have attracted considerable interest owing to their cost-effectiveness, good physiochemical stability, favorable specificity and selectivity for target analytes, and long shelf life. These materials are able to mimic natural recognition entities, including biological receptors and antibodies, providing a versatile platform to achieve the desirable functionality for various biomedical applications.

Objective:

In this review article, we introduce the most recent development of MIPs to date. We first highlight the advantages of using MIPs for a broad range of biomedical applications. We then review their various methods of synthesis along with their latest progress in biomedical applications, including biosensing, drug delivery, cell imaging and drug discovery. Lastly, the existing challenges and future perspectives of MIPs for biomedical applications are briefly discussed.

Conclusion:

We envision that MIPs may be used as potential materials for diverse biomedical applications in the near future.

Cytotoxicity of novel fluoride solutions and their influence on mineral loss from enamel exposed to a Streptococcus mutans biofilm

OBJECTIVE

This study evaluated the cytotoxicity, antimicrobial activity and in vitro influence of new fluoridated nanocomplexes on dental demineralization.

DESIGN

The nanocomplexes hydroxypropyl-β-cyclodextrin with 1% titanium tetrafluoride (TiF₄) and γ-cyclodextrin with TiF₄ were compared to a positive control (TiF₄), a blank control (without treatment) and negative controls (hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, deionized water), following 12- and 72-hour complexation periods. The cytotoxicity was assessed using the neutral red dye uptake assay at T1-15 min, T2-30 min and T3-24 h. A minimum bactericidal concentration (MBC) against Streptococcus mutans (ATCC 25175) was performed. Enamel blocks were exposed to an S. mutans biofilm, and the percentage of surface microhardness loss was obtained. Biocompatibility and microhardness data were analysed using ANOVA/Tukey tests (p < 0.05).

RESULTS

At T1, the cell viability results of the nanocomplexes were similar to that of the blank control. At T2 and T3, the 72 h nanocomplexes demonstrated cell viability results similar to that of the blank, while the 12 h solutions showed results different from that of the blank (p < 0.05). All fluoridated nanocompounds inhibited S. mutans (MBC = 0.25%), while the MBC of TiF₄ alone was 0.13%. All fluoridated compounds presented a percentage of surface microhardness loss lower than that of deionized water (p < 0.05).

CONCLUSIONS

The new fluoridated nanocomplexes did not induce critical cytotoxic effects during the experimental periods, whilst they did show bactericidal potential against S. mutans and inhibited enamel mineral loss.

Synthesis and application of selective adsorbent for pirimicarb pesticides in aqueous media using allyl-β-cyclodextrin based binary functional monomers

BACKGROUND

Binary functional monomers, allyl-β-cyclodextrin (allyl-β-CD) and methacrylic acid (MAA) or allyl-β-CD and acrylonitrile (AN), were exploited in a fabrication of molecularly imprinted polymers (MIPs) for selective recognition and large enrichment of pirimicarb from aqueous media.

RESULTS

Special attention was paid to the computational simulation of the imprinting molecular and functional monomers. The morphological characteristics of MIPs made of allyl-β-CD and MAA (M-MAA) were characterised by scanning electron microscopy. The effect of binding capacity of MAA-linked allyl-β-CD MIPs (M-MAA) demonstrated higher efficiency than that of AN-linked allyl-β-CD MIPs (M-AN) when tested in binding specificity. Finally, M-MAA was chosen to run through molecularly imprinted solid-phase extraction (MISPE) to analyse the spiked fresh leafy vegetables of pirimicarb.

CONCLUSION

The present proposed technique is a promising tool for the preparation of the receptors which could recognise pirimicarb pesticide in aqueous media. © 2017 Society of Chemical Industry.

Metallocyclodextrins in medicinal chemistry

This review focuses on metal complexes of cyclodextrin (CyD) derivatives designed for application as therapeutics or diagnostics. We discuss examples of metalloprotein models (hemoglobin, superoxide dismutase and catalase) based on cyclodextrins. The hydrophobic microenvironment of CyDs stabilizes the Fe(II) porphyrin system that can reversibly bind O₂ or CO in water. Superoxide dismutase/catalase mimetics exploit functionalization with CyDs, which increase their solubility and biological activity. Furthermore, CyDs have been used as scaffolds to obtain multicenter metal complexes: paramagnetic systems act as high-performance contrast agents for magnetic resonance imaging applications. Finally, we review CyD ligands, whose use appears promising in metal chelation therapy, as CyD moiety confers additional properties to the ligands.

Azo group(s) in selected macrocyclic compounds

Azobenzene derivatives due to their photo- and electroactive properties are an important group of compounds finding applications in diverse fields. Due to the possibility of controlling the trans-cis isomerization, azo-bearing structures are ideal building blocks for development of e.g. nanomaterials, smart polymers, molecular containers, photoswitches, and sensors. Important role play also macrocyclic compounds well known for their interesting binding properties. In this article selected macrocyclic compounds bearing azo group(s) are comprehensively described. Here, the relationship between compounds' structure and their properties (as e.g. ability to guest complexation, supramolecular structure formation, switching and motion) is reviewed.

Synthesis of molecularly imprinted polymers using acrylamide-β-cyclodextrin as a cofunctional monomer for the specific capture of tea saponins from the defatted cake extract of Camellia oleifera

Molecularly imprinted polymers were synthesized using mixed tea saponins as a template and acrylamide-β-cyclodextrin as a cofunctional monomer for the specific binding and purification of tea saponins from the defatted cake extract of Camellia oleifera. The adsorption properties of the prepared polymers were systematically evaluated including adsorption kinetics, adsorption isotherms, and selective recognition characteristics. It showed that the adsorption kinetics followed the pseudo first-order kinetic model (R² = 0.995) with an equilibrium time of 3 h, adsorption isotherm data fitted well with the Langmuir-Freundlich model (R² = 0.984) with an adsorption capacity of 14.23 mg/g. The relative selectivity coefficient (k´) in the presence of the analogues glycyrrhizic acid and glycyrrhetinic acid were 1.16 and 17.21, respectively. The performance of the molecularly imprinted polymers as solid-phase extraction materials was investigated and the results indicated that using acrylamide-β-cyclodextrin as a cofunctional monomer improved both the adsorption capacity and active sites stability of the imprinted polymers. The solid-phase extraction using the polymers as packing materials was subsequently applied for the separation of tea saponins in raw C. oleifera press extract, and targets were obtained with a purity reaching 89%.

Synergetic recognition and separation of kelthane and pyridaben base on magnetic molecularly imprinted polymer nanospheres

We present novel magnetic composite nanospheres for the preparation of a nanoiron oxide/carbon dots/β-cyclodextrin/molecularly imprinted polymer for the selective solid-phase extraction kelthane and pyridaben from vegetables. The molecularly imprinted polymer was synthesized on the surface of nano-iron oxide/carbon dots via a chemical polymerization procedure, where kelthane-β-cyclodextrin and pyridaben-β-cyclodextrin inclusion complexes were used as template molecules, and their adsorption behavior was investigated in detail. Characterization analysis and binding experiments revealed that magnetic composite nanospheres had outstanding magnetic properties, a large adsorption capacity, and high competitive selectivity for kelthane and pyridaben. The magnetic composite nanospheres were employed as an adsorbent in solid-phase extraction for the determination of kelthane and pyridaben in vegetable samples. The recoveries of kelthane and pyridaben were 92.8-105.2 and 94.4-104.6%, respectively.