Poly(ionic liquids) as “smart” stabilizers for metal nanoparticles

Synthesis of poly(ionic liquid-OH) mediated deacetylated chitin and its hydrogels: A study on their applications in controlled release of paracetamol and urea

Due to the biodegradable and biocompatible nature of chitin and chitosan, they are extensively used in the synthesis of hydrogels for various applications. In this work, deacetylation of chitin is carried out with alkaline poly(dimethyldiallylammonium-hydroxide) that gave a higher amount of water-soluble chitin (with 84 % of the degree of deacetylation = chitosan0.84) compared to deacetylation using NaOH. The water-soluble chitosan0.84 is used as intercalating chains for the preparation of acrylic acid and vinylimidazole-based hydrogels. The quaternization of imidazole groups is done with 1,ω-dibromoalkanes, which sets off the crosslinking in the above polymer network. A set of three chitosan0.84 intercalated hydrogels, namely Cs-C4-hydrogel, Cs-C5-hydrogel, and Cs-C10-hydrogel are prepared bearing butyl, pentyl, and decyl chains as respective crosslinkers. The swell ratios of these intercalated hydrogels are compared with those of non-intercalated hydrogels (C4-hydrogel, C5-hydrogel, and C10-hydrogel). Chitosan0.84 intercalated Cs-C10-hydrogel has excellent swelling properties (2330 % swelling ratio) among six synthesized hydrogels. SEM analysis reveals that decyl crosslinker-bearing hydrogels are highly porous. The multi-functionality of Cs-C10-hydrogel and C10-hydrogel is explored towards -the controlled release of paracetamol/urea, and methyleneblue dye absorption. These studies disclose that chitosan0.84 intercalated hydrogels are showing superior-swelling behavior, high paracetamol/urea loading capacities and better dye entrapment than their non-intercalated counterparts.

Ionic Liquids in Pharmaceutical and Biomedical Applications: A Review

The unique properties of ionic liquids (ILs), such as structural tunability, good solubility, chemical/thermal stability, favorable biocompatibility, and simplicity of preparation, have led to a wide range of applications in the pharmaceutical and biomedical fields. ILs can not only speed up the chemical reaction process, improve the yield, and reduce environmental pollution but also improve many problems in the field of medicine, such as the poor drug solubility, product crystal instability, poor biological activity, and low drug delivery efficiency. This paper presents a systematic and concise analysis of the recent advancements and further applications of ILs in the pharmaceutical field from the aspects of drug synthesis, drug analysis, drug solubilization, and drug crystal engineering. Additionally, it explores the biomedical field, covering aspects such as drug carriers, stabilization of proteins, antimicrobials, and bioactive ionic liquids.

Design and synthesis of silver nanoparticle anchored poly(ionic liquid)s mesoporous for controlled anticancer drug delivery with antimicrobial effect

Owing to the importance of drug delivery, the synthesis of advanced nanomaterials for targeted drug delivery plays a considerable role in medical treatment. One of the most prominent nanomaterials is PIL, which is used as controlled anticancer drug delivery and significantly improves the half-life and antitumor effect. In this study, a stable and effective drug carrier containing silver nanoparticles was reported for the drug delivery with an antimicrobial effect, and the capability of the drug carrier . PILP was synthesized by radical polymerization, and silver nanoparticles were anchored into PIL voids by in-situ reduction, which developed the adsorption antimicrobial effect and capability of the drug carrier. The synthesized nanocomposite was characterized. The Ag-PILP nanocomposite showed antibacterial activityagainst both E. coli and S. aureus with a MIC of 256 μg/mL, and bactericidal activity against E. coli and S. aureus strains with a MBC of 256 and 512 μg/mL, respectively.

Poly(ionic liquid) nanovesicles via polymerization induced self-assembly and their stabilization of Cu nanoparticles for tailored CO2 electroreduction

Herein, we report a straightforward, scalable synthetic route towards poly(ionic liquid) (PIL) homopolymer nanovesicles (NVs) with a tunable particle size of 50 to 120 nm and a shell thickness of 15 to 60 nm via one-step free radical polymerization induced self-assembly. By increasing monomer concentration for polymerization, their nanoscopic morphology can evolve from hollow NVs to dense spheres, and finally to directional worms, in which a multilamellar packing of PIL chains occurred in all samples. The transformation mechanism of NVs' internal morphology is studied in detail by coarse-grained simulations, revealing a correlation between the PIL chain length and the shell thickness of NVs. To explore their potential applications, PIL NVs with varied shell thickness are in situ functionalized with ultra-small (1 ∼ 3 nm in size) copper nanoparticles (CuNPs) and employed as electrocatalysts for CO₂ electroreduction. The composite electrocatalysts exhibit a 2.5-fold enhancement in selectivity towards C₁ products (e.g., CH₄), compared to the pristine CuNPs. This enhancement is attributed to the strong electronic interactions between the CuNPs and the surface functionalities of PIL NVs. This study casts new aspects on using nanostructured PILs as new electrocatalyst supports in CO₂ conversion to C₁ products.

Advanced Formulations Based on Poly(ionic liquid) Materials for Additive Manufacturing

Innovation in materials specially formulated for additive manufacturing is of great interest and can generate new opportunities for designing cost-effective smart materials for next-generation devices and engineering applications. Nevertheless, advanced molecular and nanostructured systems are frequently not possible to integrate into 3D printable materials, thus limiting their technological transferability. In some cases, this challenge can be overcome using polymeric macromolecules of ionic nature, such as polymeric ionic liquids (PILs). Due to their tuneability, wide variety in molecular composition, and macromolecular architecture, they show a remarkable ability to stabilize molecular and nanostructured materials. The technology resulting from 3D-printable PIL-based formulations represents an untapped array of potential applications, including optoelectronic, antimicrobial, catalysis, photoactive, conductive, and redox applications.

Ion channels in sulfonated copolymer-grafted nanoparticles in ionic liquids

The use of ionic liquids as solvents for polymers or polymer-grafted nanoparticles provides an exciting feature to explore electrolyte-polymer interactions. 1-Hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HMIm-TFSI) can have specific interactions with the polymer through ion-dipole forces or hydrogen bonding. In this work, poly(methyl methacrylate)-b-poly(styrene sulfonate) (PMMA-b-PSS) copolymer-grafted Fe₃O₄ nanoparticles with different sulfonation levels (∼4.9 to 10.9 mol% SS) were synthesized, and their concentration dependent ionic conductivities were reported in acetonitrile and HMIm-TFSI/acetonitrile mixtures. We found that conductivity enhancement with the particle concentration in acetonitrile was due to the aggregation of grafted particles, resulting in sulfonic domain connectivity. The ionic conductivity was found to be related to the effective hopping transfer within ionic channels. On the contrary, the conductivity decreased or remained constant with increasing particle concentration in HMIm-TFSI/acetonitrile. This result was attributed to the ion coupling between ionic liquids and copolymer domains.

Surface modifications of Gold Nanoparticles: Stabilization and Recent Applications in Cancer Therapy

Gold nanoparticles (GNP) are noble metal nanocarriers that have been recently researched upon for pharmaceutical applications, imaging, and diagnosis. These metallic nanocarriers are easy to synthesize using chemical reduction techniques as their surface can be easily modified. Also, the properties of GNP are significantly affected by its size and shape which mandates its stabilization using suitable techniques of surface modification. Over the past decade, research has focused on surface modification of GNP and its stabilization using polymers, polysaccharides, proteins, dendrimers, and phase-stabilizers like gel phase or ionic liquid phase. The use of GNP for pharmaceutical applications requires its surface modification using biocompatible and inert surface modifiers. The stabilizers used, interact with the surface of GNP to provide either electrostatic stabilization or steric stabilization. This review extensively discusses the surface modification techniques for GNP and the related molecular level interactions involved in the same. The influence of various factors like the concentration of stabilizers used their characteristics like chain length and thickness, pH of the surrounding media, etc., on the surface of GNP and resulting to stability have been discussed in detail. Further, this review highlights the recent applications of surface-modified GNP in the management of tumor microenvironment and cancer therapy.

Tuning the activity and selectivity of polymerised ionic liquid-stabilised ruthenium nanoparticles through anion exchange reactions

The development of highly active and selective heterogeneous-based catalysts with tailorable properties is not only a fundamental challenge, but is also crucial in the context of energy savings and sustainable chemistry. Here, we show that ruthenium nanoparticles (RuNPs) stabilised with simple polymerised ionic liquids (PILs) based on N-vinyl imidazolium led to highly active and robust nano-catalysts in hydrogenation reactions, both in water and organic media. Of particular interest, their activity and selectivity could simply be manipulated through counter-anion exchange reactions. Hence, as a proof of concept, the activity of RuNPs could be reversibly turned on and off in the hydrogenation of toluene, while in the case of styrene, the hydrogenation could be selectively switched from ethylbenzene to ethylcyclohexane upon anion metathesis. According to X-ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS) analyses, these effects could originate not only from the relative hydrophobicity and solvation of the PIL corona but also from the nature and strength of the PIL-Ru interactions.

Novel Poly(ionic liquid) Augmented Membranes for Unconventional Aqueous Phase Applications in Fractionation of Dyes and Sugar

Poly(ionic) liquid (PIL) augmented membranes were fabricated through self-polymerization of 2-vinyl pyridine and 4-vinyl pyridine followed by dopamine triggered polymerization and bridging with inert polyamide support. The resulting membranes acquired a positive surface charge with a high degree of hydrophilicity. Fourier transformed Infra-red (FTIR) and Energy dispersive X-ray (EDX) spectroscopic investigation revealed the successful augmentation of PIL surface layer, whereas surface morphology was investigated through scanning electron microscopy (SEM) imaging. This manuscript demonstrates pi electron-induced separation of dyes with the trend in permeability: Coomassie Brilliant Blue G (CBBHG) > Remazol Brilliant Blue R (RBBR) > Eichrome Black T (EBT) > Congo Red (CR). CBBG exhibited extended conjugation over large aromatic domain. RBBR and EBT were associated withtheelectron-donating -NH2 group and electron-withdrawing -NO2 group, respectively, hence pi electron density on aromatic ring varied. The steric repulsion between two pairs of ortho hydrogens (Hs) in biphenyl moieties of CR resulted in deviation of planarity and hence aromaticity leading to the lowest permeability. The sugar fractionation followed the trend: Galactose > Mannose > Fructose > Glucose > Xylose. More hydroxyl (-OH) groups in sugars and their conformational alignment in the same direction, exhibited more lone pair of electrons leading to more interaction with PIL and hence better permeability. Pentose showed poorer permeation than hexose, whereas aldose showed better permeation than ketose.

Poly(ionic liquid) composites

This review highlights recent advances in the development of poly(ionic liquid)-based composites for diverse materials applications.

Surface modification of cerasomes with AuNPs@poly(ionic liquid)s for an enhanced stereo biomimetic membrane electrochemical platform

A novel liposomal nanocomposite, Au@PIL-cerasome, with biocompatibility and conductivity was fabricated via the self-assembly of cerasomes and gold nanoparticles (AuNPs) stabilized by poly(ionic liquid)s (PILs). The surface charge, morphology and chemical composition of the nanocomposites were characterized by the zeta potential, UV-vis, TEM, SEM and EDS. The nanocomposites exhibited structural stability directly on the surface of solid electrodes, without fusion. Electrochemical impedance experiments demonstrated that the nanocomposites had an enhanced conductivity compared with unmodified cerasomes. Horseradish peroxidase (HRP), as a reporter, was immobilized on the nanocomposites without denaturation or inactivation. The direct electron transfer of HRP was achieved, and the HRP/Au@PIL-cerasome/GCE exhibited an amplified current and improved electrocatalytic activity. Activity towards H₂O₂ displayed a linear range over 10-70 μM and a detection limit of 3.3 μM. Activity towards NO₂^- displayed linear ranges over 1-5 mM and 5-1280 mM, and the limit of detection was 0.11 mM. In addition, the electrode was stable and reproducible, with 6% RSD. Such multi-component liposomal nanocomposites with an enhanced electrical performance pave a better way for building novel and straightforward 3D stereo biomimetic electrochemical platforms and even molecular communication systems to investigate information transduction between cells.

Ionic Liquid-Polymer Nanoparticle Hybrid Systems as New Tools to Deliver Poorly Soluble Drugs

The use of functional excipients such as ionic liquids (ILs) and the encapsulation of drugs into nanocarriers are useful strategies to overcome poor drug solubility. The aim of this work was to evaluate the potential of IL-polymer nanoparticle hybrid systems as tools to deliver poorly soluble drugs. These systems were obtained using a methodology previously developed by our group and improved herein to produce IL-polymer nanoparticle hybrid systems. Two different choline-based ILs and poly (lactic-co-glycolic acid) (PLGA) 50:50 or PLGA 75:25 were used to load rutin into the delivery system. The resulting rutin-loaded IL-polymer nanoparticle hybrid systems presented a diameter of 250-300 nm, with a low polydispersity index and a zeta potential of about -40 mV. The drug association efficiency ranged from 51% to 76%, which represents a good achievement considering the poor solubility of rutin. No significant particle aggregation was obtained upon freeze-drying. The presence of the IL in the nanosystem does not affect its sustained release properties, achieving about 85% of rutin released after 72 h. The cytotoxicity studies showed that the delivery system was not toxic to HaCat cells. Our findings may open a new paradigm on the therapy improvement of diseases treated with poorly soluble drugs.

Synthesis of a novel graphene-based gold nanocomposite using PVEIM-b-PNIPAM as a stabilizer and its thermosensitivity for the catalytic reduction of 4-nitrophenol

Fabrication of a graphene-based gold nanocomposite using PVEIM-b-PNIPAM as a stabilizer and its thermosensitivity for the reduction of 4-nitrophenol.

Polyoxometalate-coupled MXene nanohybrid via poly(ionic liquid) linkers and its electrode for enhanced supercapacitive performance

MXenes are novel 2D transition metal carbides with metallic conductivity and hydrophilic surfaces, which have highly active 2D surfaces and can act as a promising new type of electrode material; however, their low capacity and irreversible self-restacking limit their practicality and development. This paper presents a novel method for preparing an MXene-polyoxometalate (POM) nanohybrid using poly(ionic liquid) (PIL) as the linker. The electrostatic interactions, chemical structure, and morphology of this nanohybrid are systematically characterized and have indicated that the MXene-PIL-POM nanohybrid provides the uniform distribution of POM nanoparticles on the MXene nanosheets and exhibits excellent electrochemical activity and stability due to the use of PIL as the linker and stabilizer. The prepared MXene-PIL-POM nanohybrid, used as an electrode, displayed a definite improvement in electrochemical performance with the specific capacitance of 384.6 F g-1 at a current density of 1 A g-1, which is about three-fold higher than that of the MXene electrode. The MXene-PIL-POM electrode also achieved a good rate performance (90.5% retention at 10 A g-1) and a long cycling life (91.7% maintenance of specific capacitance at a constant current density of 4 A g-1 after 2000 cycles). The proposed nanohybrid structure capitalizes on the enhancement of the redox reactions of POM through the PIL linkers to facilitate charge transfer and provide efficient ion transfer channels in the nanohybrid.

An emerging integration between ionic liquids and nanotechnology: general uses and future prospects in drug delivery

There is a growing need to develop drug-delivery systems that overcome drawbacks such as poor drug solubility/loading/release, systemic side effects and limited stability. Ionic liquids (ILs) offer many advantages and their tailoring represents a valuable tuning tool. Nano-based systems are also prized materials that prevent drug degradation, enhance their transport/distribution and extend their release. Consequently, structures containing ILs and nanoparticles (NPs) have been developed to attain synergistic effects. This overview on the properties of ILs, NPs and of their combined structures, reveals the recent advances in these areas through a review of pertinent literature. The IL-NP structures present enhanced properties and the subsequent performance upgrade proves to be useful in drug delivery, although much is yet to be done.

Formation and Properties of Poly(Ionic Liquid)-Carbene Nanogels Containing Individually Stabilized Silver Species

Imidazolium-based ionic liquids have the ability to undergo a variety of chemical reactions through an N-heterocyclic carbene (NHC) intermediate, which has expanded the chemical toolbox for new applications. Despite their uses and exploration, the carbene-forming properties and applications of their polymeric congeners, poly(ionic liquid)s (PILs), is still underdeveloped. Herein, we explore the NHC-forming properties of a theophylline-derived PIL for nanogel synthesis. Using silver oxide as both the carbene-forming reagent and cross-linker, nanogels containing individually stabilized ions can be created with different sizes and morphology, including large "galaxy-like" superstructures. Using high-resolution TEM techniques, we directly observed the sub-nanometer structure of these constructs. These features combined exemplify the unique chemistry of poly-NHCs for single-metal-ion-stabilization nanogel design.

Frontiers in poly(ionic liquid)s: syntheses and applications

We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed. Furthermore, the near-term applications of PILs in multiple fields, such as their use in electrochemical energy materials, stimuli-responsive materials, carbon materials, and antimicrobial materials, in catalysis, in sensors, in absorption and in separation materials, as well as several special-interest applications, are described in detail. We also discuss the limitations of PIL applications, efforts to improve PIL physics, and likely future developments.

General Synthetic Route toward Highly Dispersed Ultrafine Pd-Au Alloy Nanoparticles Enabled by Imidazolium-Based Organic Polymers

Bimetallic Pd-Au nanoparticles (NPs) usually show superior catalytic performances over their single-component counterparts, the general and facile synthesis of subnanometer-scaled Pd-Au NPs still remains a great challenge, especially for electronegative ultrafine bimetallic NPs. Here, we develop an anion-exchange strategy for the synthesis of ultrafine Pd-Au alloy NPs. Simple treatment of main-chain imidazolium-based organic polymer (IOP) with HAuCl₄ and Na₂PdCl₄, followed by reduction with NaBH₄ generated Pd-Au alloy NPs (Pd-Au/IOP). These NPs possess an unprecedented tiny size of 1.50 ± 0.20 nm and are uniformly dispersed over IOP. The electronic structure of the surface Pd and Au atoms is optimized via electron exchange during alloying, a net charge flowing resulting from counteranions is injected into Au and Pd to form a strong ensemble effect, which is responsible for a remarkably higher catalytic activity of Pd-Au/IOP in the hydrolytic dehydrogenation of ammonia borane than those of monometallic counterparts.

Ionic liquid and nanoparticle hybrid systems: Emerging applications

Having novel electronic and optical properties that emanate from their nano-scale dimensions, nanoparticles are central to numerous applications. Ionic liquids can confer to nanoparticle chemical protection and physicochemical property enhancement through intermolecular interactions and can consequently improve the stability and reusability of nanoparticle for various operations. With an aim to combine the novel properties of nanoparticles and ionic liquids, different structures have been generated, based on a balance of several intermolecular interactions. Such ionic liquid and nanoparticle hybrids are showing great potential in diverse applications. In this review, we first introduce various types of ionic liquid and nanoparticle hybrids, including nanoparticle colloidal dispersions in ionic liquids, ionic liquid-grafted nanoparticles, and nanoparticle-stabilized ionic liquid-based emulsions. Such hybrid materials exhibit interesting synergisms. We then highlight representative applications of ionic liquid and nanoparticle hybrids in the catalysis, electrochemistry and separations fields. Such hybrids can attain better stability and higher efficiency under a broad range of conditions. Novel and enhanced performance can be achieved in these applications by combining desired properties of ionic liquids and of nanoparticles within an appropriate hybrid nanostructure.

Chiral anion-triggered helical poly(ionic liquids)

Anion-triggered chirality and helicity in PILs.

Self-assembly of poly(ionic liquid) (PIL)-based amphiphilic homopolymers into vesicles and supramolecular structures with dyes and silver nanoparticles

Self assembly of amphiphilic homo-PILs.

Ionic liquids for nano- and microstructures preparation. Part 1: Properties and multifunctional role

Ionic liquids (ILs) are a broad group of organic salts of varying structure and properties, used in energy conversion and storage, chemical analysis, separation processes, as well as in the preparation of particles in nano- and microscale. In material engineering, ionic liquids are applied to synthesize mainly metal nanoparticles and 3D semiconductor microparticles. They could generally serve as a structuring agent or as a reaction medium (solvent). This review deals with the resent progress in general understanding of the ILs role in particle growth and stabilization and the application of ionic liquids for nano- and microparticles synthesis. The first part of the paper is focused on the interactions between ionic liquids and growing particles. The stabilization of growing particles by steric hindrance, electrostatic interaction, solvation forces, viscous stabilization, and ability of ILs to serve as a soft template is detailed discussed. For the first time, the miscellaneous role of the ILs in nano- and microparticle preparation composed of metals as well as semiconductors is collected, and the formation mechanisms are graphically presented and discussed based on their structure and selected properties. The second part of the paper gives a comprehensive overview of recent experimental studies dealing with the applications of ionic liquids for preparation of metal and semiconductor-based nano- and microparticles. A wide spectrum of preparation routes using ionic liquids are presented, including precipitation, sol-gel technique, hydrothermal method, nanocasting, and microwave or ultrasound-mediated methods.

Nanoporous ionic organic networks: from synthesis to materials applications

This review highlights the recent progress made in the study of the synthesis of nanoporous ionic organic networks (NIONs) and their promising applications.

Assessment on the antibacterial activity of nanosized silica derived from hypercoordinated silicon(iv) precursors

Silica nanoparticles were synthesized through a versatile sol–gel combustion method from hydrazide based hypercoordinated silicon complexes derived from the reaction of silicon tetrachloride with O-silylated hydrazide derivatives.

Ionic liquids for nano- and microstructures preparation. Part 2: Application in synthesis

Ionic liquids (ILs) are widely applied to prepare metal nanoparticles and 3D semiconductor microparticles. Generally, they serve as a structuring agent or reaction medium (solvent), however it was also demonstrated that ILs can play a role of a co-solvent, metal precursor, reducing as well as surface modifying agent. The crucial role and possible types of interactions between ILs and growing particles have been presented in the Part 1 of this review paper. Part 2 of the paper gives a comprehensive overview of recent experimental studies dealing with application of ionic liquids for preparation of metal and semiconductor based nano- and microparticles. A wide spectrum of preparation routes using ionic liquids is presented, including precipitation, sol-gel technique, hydrothermal method, nanocasting and ray-mediated methods (microwave, ultrasound, UV-radiation and γ-radiation). It was found that ionic liquids formed of a 1-butyl-3-methylimidazolium [BMIM] combined with tetrafluoroborate [BF4], hexafluorophosphate [PF6], and bis(trifluoromethanesulfonyl)imide [Tf2N] are the most often used ILs in the synthesis of nano- and microparticles, due to their low melting temperature, low viscosity and good transportation properties. Nevertheless, examples of other IL classes with intrinsic nanoparticles stabilizing abilities such as phosphonium and ammonium derivatives are also presented. Experimental data revealed that structure of ILs (both anion and cation type) affects the size and shape of formed metal particles, and in some cases may even determine possibility of particles formation. The nature of the metal precursor determines its affinity to polar or nonpolar domains of ionic liquid, and therefore, the size of the nanoparticles depends on the size of these regions. Ability of ionic liquids to form varied extended interactions with particle precursor as well as other compounds presented in the reaction media (water, organic solvents etc.) provides nano- and microstructures with different morphologies (0D nanoparticles, 1D nanowires, rods, 2D layers, sheets, and 3D features of molecules). ILs interact efficiently with microwave irradiation, thus even small amount of IL can be employed to increase the dielectric constant of nonpolar solvents used in the synthesis. Thus, combining the advantages of ionic liquids and ray-mediated methods resulted in the development of new ionic liquid-assisted synthesis routes. One of the recently proposed approaches of semiconductor particles preparation is based on the adsorption of semiconductor precursor molecules at the surface of micelles built of ionic liquid molecules playing a role of a soft template for growing microparticles.