Study of the morphology and the adsorption behavior of molecularly imprinted polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization process based on two functionalized β-cyclodextrin as monomers

Preparation of a Molecularly Imprinted Polymer on Polyethylene Terephthalate Platform Using Reversible Addition-Fragmentation Chain Transfer Polymerization for Tartrazine Analysis via Smartphone

This work describes the preparation of a molecularly imprinted polymer (MIP) platform on polyethylene terephthalate (MIP-PET) via RAFT polymerization for analyzing tartrazine using a smartphone. The MIP-PET platform was characterized using Fourier transform infrared (FTIR) techniques, Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS), and confocal microscopy. The optimal pH and adsorption time conditions were determined. The adsorption capacity of the MIP-PET plates with RAFT treatment (0.057 mg cm-2) was higher than that of the untreated plates (0.028 mg cm-2). The kinetic study revealed a pseudo-first-order model with intraparticle diffusion, while the isotherm study indicated a fit for the Freundlich model. Additionally, the MIP-PET demonstrated durability by maintaining its adsorption capacity over five cycles of reuse without significant loss. To quantify tartrazine, images were captured using a smartphone, and the RGB values were obtained using the ImageJ® free program. A partial least squares regression (PLS) was performed, obtaining a linear range of 0 to 7 mg L-1 of tartrazine. The accuracy of the method was 99.4% (4.97 ± 0.74 mg L-1) for 10 samples of 5 mg L-1. The concentration of tartrazine was determined in two local soft drinks (14.1 mg L-1 and 16.5 mg L-1), with results comparable to the UV-visible spectrophotometric method.

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.

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.

Removal of bisphenol A from aqueous media using a highly selective adsorbent of hybridization cyclodextrin with magnetic molecularly imprinted polymer

In this study, a unique magnetic molecularly imprinted polymer (MMIP) adsorbent towards bisphenol A (BPA) as a template molecule was developed by bulk polymerization using β-cyclodextrin (β-CD) as a co-monomer with methacrylic acid (MAA) to form MMIP MAA-βCD as a new adsorbent. β-CD was hybridized with MAA to obtain water-compactible imprinting sites for the effective removal of BPA from aqueous samples. Benzoyl peroxide and trimethylolpropane trimethacrylate were used as the initiator and cross-linker, respectively. The adsorbents were characterized by Fourier transform infrared spectroscopy, scanning electronic microscopy, transmission electron microscopy, vibrating sample magnetometer, Brunauer-Emmett-Teller and X-ray diffraction. 1H nuclear magnetic resonance spectroscopy was used to characterize the MAA-βCD and BPA-MAA-βCD complex. Several parameters influencing the adsorption efficiency of BPA such as adsorbent dosage, pH of sample solution, contact time, initial concentrations and temperature as well as selectivity and reusability study have been evaluated. MMIP MAA-βCD showed significantly higher removal efficiency and selective binding capacity towards BPA compared to MMIP MAA owing to its unique morphology with the presence of β-CD. The kinetics data can be well described by the pseudo second-order kinetic and Freundlich isotherm and Halsey models best fitted the isotherm data. The thermodynamic studies indicated that the adsorption reaction was a spontaneous and exothermic process. Therefore, MMIP based on the hybrid monomer of MAA-βCD shows good potential of a new monomer in molecularly imprinted polymer preparation and can be used as an effective adsorbent for the removal of BPA from aqueous solutions.

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.

Polymer-Ligated Nanocrystals Enabled by Nonlinear Block Copolymer Nanoreactors: Synthesis, Properties, and Applications

The past several decades have witnessed substantial advances in synthesis and self-assembly of inorganic nanocrystals (NCs) due largely to their size- and shape-dependent properties for use in optics, optoelectronics, catalysis, energy conversion and storage, nanotechnology, and biomedical applications. Among various routes to NCs, the nonlinear block copolymer (BCP) nanoreactor technique has recently emerged as a general yet robust strategy for crafting a rich diversity of NCs of interest with precisely controlled dimensions, compositions, architectures, and surface chemistry. It is notable that nonlinear BCPs are unimolecular micelles, where each block copolymer arm of nonlinear BCP is covalently connected to a central core or polymer backbone. As such, their structures are static and stable, representing a class of functional polymers with complex architecture for directing the synthesis of NCs. In this review, recent progress in synthesizing NCs by capitalizing on two sets of nonlinear BCPs as nanoreactors are discussed. They are star-shaped BCPs for producing 0D spherical nanoparticles, including plain, hollow, and core-shell nanoparticles, and bottlebrush-like BCPs for creating 1D plain and core/shell nanorods (and nanowires) as well as nanotubes. As the surface of these NCs is intimately tethered with the outer blocks of nonlinear BCPs used, they can thus be regarded as polymer-ligated NCs (i.e., hairy NCs). First, the rational design and synthesis of nonlinear BCPs via controlled/living radical polymerizations is introduced. Subsequently, their use as the NC-directing nanoreactors to yield monodisperse nanoparticles and nanorods with judiciously engineered dimensions, compositions, and surface chemistry is examined. Afterward, the intriguing properties of such polymer-ligated NCs, which are found to depend sensitively on their sizes, architectures, and functionalities of surface polymer hairs, are highlighted. Some practical applications of these polymer-ligated NCs for energy conversion and storage and drug delivery are then discussed. Finally, challenges and opportunities in this rapidly evolving field are presented.

A sensitive and visual molecularly imprinted fluorescent sensor incorporating CaF2 quantum dots and β-cyclodextrins for 5-hydroxymethylfurfural detection

Calcium fluoride (CaF₂) quantum dots have many applications in various fields. But there is no report on fluorescent characteristics of CaF₂ quantum dots (CaF₂ QDs). Here, a synthesis of multiple-color emission CaF₂ QDs by changing the temperature, time and raw ratio is reported, by which the CaF₂ QDs with purple, blue, green, and yellow emission can be obtained, respectively. They were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). On this basis, a novel molecular imprinting ratiometric fluorescence sensor (MIR sensor) had been constructed based on the prepared CaF₂ QDs and CdTe QDs, in which the yellow emission CaF₂ QDs was used as a responsive signal material and the red emission CdTe QDs was served as a reference signal material. And the β-CD and methylacrylic acid (MAA) as bifunctional monomers were used for constructing the specific molecularly imprinted polymers (MIPs) in MIR sensor. This MIR sensor was applied for highly selective and excellent sensitive detection of 5-hydroxymethylfurfural (HMF). Under optimum conditions, it exhibited an excellent linear relationship between the fluorescence intensity ratio (I₅₉₉/I₆₂₅) and the concentration of HMF in the range of 0.1-6.0 μg/mL with a detection limit of 0.043 μg/mL. Finally, the established HMF-MIR sensor was successfully utilized to detect HMF in honey with satisfactory results. This work provided a reference for the application of the CaF₂ QDs and the detection of the furfural substances.

Functional materials generated by allying cyclodextrin-based supramolecular chemistry with living polymerization

Cyclodextrin molecules are cyclic oligosaccharides that display a unique structure including an inner side and two faces on their outer sides.