A Cross-Linker-Based Poly(Ionic Liquid) for Sensitive Electrochemical Detection of 4-Nonylphenol

Polymerized and Colloidal Ionic Liquids─Syntheses and Applications

The breadth and importance of polymerized ionic liquids (PILs) are steadily expanding, and this review updates advances and trends in syntheses, properties, and applications over the past five to six years. We begin with an historical overview of the genesis and growth of the PIL field as a subset of materials science. The genesis of ionic liquids (ILs) over nano to meso length-scales exhibiting 0D, 1D, 2D, and 3D topologies defines colloidal ionic liquids, CILs, which compose a subclass of PILs and provide a synthetic bridge between IL monomers (ILMs) and micro to macro-scale PIL materials. The second focus of this review addresses design and syntheses of ILMs and their polymerization reactions to yield PILs and PIL-based materials. A burgeoning diversity of ILMs reflects increasing use of nonimidazolium nuclei and an expanding use of step-growth chemistries in synthesizing PIL materials. Radical chain polymerization remains a primary method of making PILs and reflects an increasing use of controlled polymerization methods. Step-growth chemistries used in creating some CILs utilize extensive cross-linking. This cross-linking is enabled by incorporating reactive functionalities in CILs and PILs, and some of these CILs and PILs may be viewed as exotic cross-linking agents. The third part of this update focuses upon some advances in key properties, including molecular weight, thermal properties, rheology, ion transport, self-healing, and stimuli-responsiveness. Glass transitions, critical solution temperatures, and liquidity are key thermal properties that tie to PIL rheology and viscoelasticity. These properties in turn modulate mechanical properties and ion transport, which are foundational in increasing applications of PILs. Cross-linking in gelation and ionogels and reversible step-growth chemistries are essential for self-healing PILs. Stimuli-responsiveness distinguishes PILs from many other classes of polymers, and it emphasizes the importance of segmentally controlling and tuning solvation in CILs and PILs. The fourth part of this review addresses development of applications, and the diverse scope of such applications supports the increasing importance of PILs in materials science. Adhesion applications are supported by ionogel properties, especially cross-linking and solvation tunable interactions with adjacent phases. Antimicrobial and antifouling applications are consequences of the cationic nature of PILs. Similarly, emulsion and dispersion applications rely on tunable solvation of functional groups and on how such groups interact with continuous phases and substrates. Catalysis is another significant application, and this is an historical tie between ILs and PILs. This component also provides a connection to diverse and porous carbon phases templated by PILs that are catalysts or serve as supports for catalysts. Devices, including sensors and actuators, also rely on solvation tuning and stimuli-responsiveness that include photo and electrochemical stimuli. We conclude our view of applications with 3D printing. The largest components of these applications are energy related and include developments for supercapacitors, batteries, fuel cells, and solar cells. We conclude with our vision of how PIL development will evolve over the next decade.

Synthesis and Evaluation of Rutin–Hydroxypropyl β-Cyclodextrin Inclusion Complexes Embedded in Xanthan Gum-Based (HPMC-g-AMPS) Hydrogels for Oral Controlled Drug Delivery

Oxidants play a significant role in causing oxidative stress in the body, which contributes to the development of diseases. Rutin—a powerful antioxidant—may be useful in the prevention and treatment of various diseases by scavenging oxidants and reducing oxidative stress. However, low solubility and oral bioavailability have restricted its use. Due to the hydrophobic nature of rutin, it cannot be easily loaded inside hydrogels. Therefore, first rutin inclusion complexes (RIC) with hydroxypropyl-β-cyclodextrin (HP-βCD) were prepared to improve its solubility, followed by incorporation into xanthan gum-based (hydroxypropyl methylcellulose-grafted-2-acrylamido -2-methyl-1-propane sulfonic acid) hydrogels for controlled drug release in order to improve the bioavailability. Rutin inclusion complexes and hydrogels were validated by FTIR, XRD, SEM, TGA, and DSC. The highest swelling ratio and drug release occurred at pH 1.2 (28% swelling ratio and 70% drug release) versus pH 7.4 (22% swelling ratio, 65% drug release) after 48 h. Hydrogels showed high porosity (94%) and biodegradation (9% in 1 week in phosphate buffer saline). Moreover, in vitro antioxidative and antibacterial studies (Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli) confirmed the antioxidative and antibacterial potential of the developed hydrogels.

Synthesis of Gallic Acid-Loaded Chitosan-Grafted-2-Acrylamido-2-Methylpropane Sulfonic Acid Hydrogels for Oral Controlled Drug Delivery: In Vitro Biodegradation, Antioxidant, and Antibacterial Effects

In this study, chitosan (CS) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS)-based hydrogels were formulated by the free radical polymerization technique for the controlled release of gallic acid. Fourier transform infrared spectroscopy (FTIR) confirmed the successful preparation and loading of gallic acid within the hydrogel network. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the increased thermal stability of the hydrogels following the crosslinking and polymerization of chitosan and AMPS. In X-ray diffraction analysis (XRD), the crystallinity of the raw materials decreased, indicating strong crosslinking of the reagents and the formation of a new polymeric network of hydrogels. Scanning electron microscopy (SEM) revealed that the hydrogel had a rough, dense, and porous surface, which is consistent with the highly polymerized composition of the hydrogel. After 48 h, the hydrogels exhibited higher swelling at pH 1.2 (swelling ratio of 19.93%) than at pH 7.4 (swelling ratio of 15.65%). The drug release was analyzed using ultraviolet-visible (UV-Vis) spectrophotometer and demonstrated that after 48 h, gallic acid release was maximum at pH 1.2 (85.27%) compared to pH 7.4 (75.19%). The percent porosity (78.36%) and drug loading increased with the increasing concentration of chitosan and AMPS, while a decrease was observed with the increasing concentration of ethylene glycol dimethyl methacrylate (EGDMA). Crosslinking of the hydrogels increased with concentrations of chitosan and EGDMA but decreased with AMPS. In vitro studies demonstrated that the developed hydrogels were biodegradable (8.6% degradation/week) and had antimicrobial (zone of inhibition of 21 and 16 mm against Gram-positive bacteria Escherichia coli and Staphylococcus aureus as well as 13 mm against Gram-negative bacteria Pseudomonas aeruginosa, respectively) and antioxidant (73% DPPH and 70% ABTS) properties. Therefore, the prepared hydrogels could be used as an effective controlled drug delivery system.

Recent advances in poly(ionic liquid)s for biomedical application

Poly(ionic liquid)s (PILs) are polymers containing ions in their side-chain or backbone, and the designability and outstanding physicochemical properties of PILs have attracted widespread attention from researchers. PILs have specific characteristics, including negligible vapor pressure, high thermal and chemical stability, non-flammability, and self-assembly capabilities. PILs can be well combined with advanced analytical instruments and technology and have made outstanding contributions to the development of biomedicine aiding in the continuous advancement of science and technology. Here we reviewed the advances of PILs in the biomedical field in the past five years with a focus on applications in proteomics, drug delivery, and development. This paper aims to engage pharmaceutical and biomedical scientists to full understand PILs and accelerate the progress from laboratory research to industrialization.

Melamine Recognition: Molecularly Imprinted Polymer for Selective and Sensitive Determination of Melamine in Food Samples

In this study, a sensitive and selective sensor is constructed to measure the melamine (MEL) using molecular imprinting polymer (MIP) technique. Chemical and electrochemical techniques are used to construct the MIP and quantitative measurements. The constructed sensor was modified with GO-Fe₃O₄@SiO₂ nanocomposite. Screening and optimization of factors are done using statistical methods, including Plackett–Burman design (PBD) and central composite design (CCD). Under the optimized conditions, an MIP sensor showed a linear range from 5.0 × 10⁻⁷ to 1.0 × 10⁻⁵ M MEL concentration with a correlation coefficient (R²) of 0.9997. The limit of detection was obtained (0.028 µM) with a highly reproducible response (RSD 2.15%, n = 4). The electrochemical sensor showed good results for the determination of MEL in food samples.

Determination of Volatile Water Pollutants Using Cross-Linked Polymeric Ionic Liquid as Solid Phase Micro-Extraction Coatings

Ionic liquids found a wide application in catalysis and extraction due to their unique properties. Herein, ethylene glycol dimethacrylate as the cross-linker and 1-vinyl-3- butylimidazolium tetrafluoroborate as functional monomer via thermally initiated free-radical polymerization was prepared as a novel copolymer solid phase micro-extraction (SPME) coating. A surface modified stainless-steel wire was implemented as the substrate. Factors affecting the extraction performances of the copolymer, including the molar ratio of monomers to cross-linkers, the amount of porogen agent, and polymerization time were evaluated and optimized. To evaluate the extraction performance, five commonly seen polycyclic aromatic hydrocarbons (PAHs) were taken as the analytical targets. The potential factors affecting extraction efficiency were optimized. The as-prepared SPME device, coupled with gas chromatography, was successfully applied for the determination of PAHs in water samples. The wide linear range, low detection limit, good reproducibility, selectivity, and excellent thermal stability indicate the promising application of the newly developed SPME fiber in environmental monitoring as well as in other samples having complex matrices.