Ionic liquids: prospects for nucleic acid handling and delivery

A comprehensive dataset on cytotoxicity of ionic liquids

Ionic liquids (ILs) are structurally tunable salts with applications ranging from chemical synthesis to batteries, novel materials and medicine. Despite their potential, the toxicity of ILs poses significant environmental and biological challenges. This study introduces a comprehensive dataset of cytotoxicity of 1227 ILs, compiled from 151 research papers and encompassing 3837 data entries. For each entry, the following information is provided: substance name, empirical formula, CAS, SMILES, molecular weight, cytotoxicity value, details on the experimental setup (incubation time, cell line, assay used, etc.), and reference to the original publication. This dataset can be used for deriving structure‒activity relationships and establishing the major structural elements that govern the cytotoxic effects of ILs on eukaryotic cells. The dataset is available freely to all researchers.

Utilizing ionic liquids as eco-friendly and sustainable carriers for delivering nucleic acids: A review on the revolutionary advancement in nano delivery systems

Ionic liquids (ILs) are an extremely versatile class of chemicals. It has been shown that they can effectively pass through many biological barriers in the human body to deliver medications. ILs are solvents noted for their ecological friendliness; they contain equal amounts of cations and anions and remain liquid at temperatures below 100 °C. Hence, these are ideal for biomedical applications owing to their advantageous properties such as biocompatibility, solubility, and adaptability. ILs are widely reported to improve the solubility and stability of nucleic acids (DNA and RNA) in aqueous conditions, allowing for more effective delivery. Certain ILs have shown the ability to enhance the absorption of nucleic acids into cells. In addition, ILs can also be used to create vectors for gene delivery, such as liposomes and nanoparticles, thereby improving the transfection efficiency of plasmid DNA and siRNA. Subsequently, the application of ILs for nucleic acid delivery has increased significantly in recent years. In this context, we believe that using ILs to enhance the transport of nucleic acids will have a considerable effect as a novel and crucial therapeutic method in the upcoming decades. The use of ILs as solvents to preserve the natural structure of DNA and RNA shows promise for a variety of biotechnological and medical applications. Notably, ILs may be utilized for a variety of functions, including extracting, concentrating, stabilizing, and spreading nucleic acids inside cells. Our review emphasizes the key findings of research works published in this domain, wherein outstanding effectiveness of delivering RNA to the desired areas was achieved, and was made possible through the utilization of ILs.

Ionic liquids and their potential use in development and improvement of drug delivery systems: evidence of their tendency to promote drug accumulation in the brain

Ionic liquids (ILs) are considered salt in liquid state, which is composed of organic cations and anions with low melting points (<100 °C). ILs have become a major scientific area with an extensive range of applications including chemistry, electrochemistry, and pharmaceutics. ILs have received great research interest in the pharmaceutical field as solvents, anti-solvents, co-solvents, and reagents in synthesis and formulation. While therapeutic ILs have been investigated for oral and trans-dermal drug delivery systems showing promising compatibility with a wide range of therapeutics, enhanced drug permeation through the skin, and cell membrane solvation to open channels to facilitate molecular passage, their potential to cross the challenging blood-brain barrier (BBB) remains an unanswered question. IL-based therapies could potentially be a game changer for improving drug delivery to cellular targets both at and across the BBB. In this review, we discuss (1) the tunable physicochemical properties of ILs; (2) the vast and various applications of ILs in the development and improvement of drug delivery systems; and (3) ILs as a potential approach for increasing drug accumulation in the brain tissue.

Subcellular effects of imidazolium-based ionic liquids with varying anions on the marine bivalve Mytilus galloprovincialis

Green Chemistry involves applying a set of principles aimed at minimizing the use of hazardous substances in the design, production, and application of chemical products. In recent decades, Ionic Liquids (ILs) have emerged as more environmentally friendly substitutes for traditional organic solvents. This preference is primarily due to their low vapor pressure, which results in minimal atmospheric pollution and enhanced industrial safety. However, existing literature highlights the toxicity of ILs towards aquatic invertebrates. Consequently, this study points to assess the biochemical effects of a selection of ILs through an in vitro approach. Specifically, digestive gland and gill cellular fractions (S9) of the marine bivalve Mytilus galloprovincialis were exposed to varying concentrations (0.05-2 μM) of three ILs featuring identical cations but different anions. The ILs tested were 1-ethyl-3-methylimidazolium octanoate ([EMIM][Oct]), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), and 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtSO4]). The results indicate that [EMIM][Oct] induces higher toxicity in both S9 tissues, highlighting a strong effect of the anion. Overall, antioxidant and biotransformation defenses were significantly altered for all three ILs assessed. While acetylcholinesterase activity was significantly inhibited of about half of control activity, indicating neurotoxic damage as part of the toxicity mode of action of these ILs, neither lipid peroxidation nor alterations to DNA integrity were observed (≥100 %). This study supports the use of in vitro techniques as important tools capable of generating reliable ecotoxicological data, which can be further considered as a screening before in vivo testing and used for in silico modeling.

DNA nanotechnology in ionic liquids and deep eutectic solvents

Nucleic acids have the ability to generate advanced nanostructures in a controlled manner and can interact with target sequences or molecules with high affinity and selectivity. For this reason, they have applications in a variety of nanotechnology applications, from highly specific sensors to smart nanomachines and even in other applications such as enantioselective catalysis or drug delivery systems. However, a common disadvantage is the use of water as the ubiquitous solvent. The use of nucleic acids in non-aqueous solvents offers the opportunity to create a completely new toolbox with unprecedented degrees of freedom. Ionic liquids (ILs) and deep eutectic solvents (DESs) are the most promising alternative solvents due to their unique electrolyte and solvent roles, as well as their ability to maintain the stability and functionality of nucleic acids. This review aims to be a comprehensive, critical, and accessible evaluation of how much this goal has been achieved and what are the most critical parameters for accomplishing a breakthrough.

Mechanisms of Biological Effects of Ionic Liquids: From Single Cells to Multicellular Organisms

The review presents a detailed discussion of the evolving field studying interactions between ionic liquids (ILs) and biological systems. Originating from molten salt electrolytes to present multiapplication substances, ILs have found usage across various fields due to their exceptional physicochemical properties, including excellent tunability. However, their interactions with biological systems and potential influence on living organisms remain largely unexplored. This review examines the cytotoxic effects of ILs on cell cultures, biomolecules, and vertebrate and invertebrate organisms. Our understanding of IL toxicity, while growing in recent years, is yet nascent. The established findings include correlations between harmful effects of ILs and their ability to disturb cellular membranes, their potential to trigger oxidative stress in cells, and their ability to cause cell death via apoptosis. Future research directions proposed in the review include studying the distribution of various ILs within cellular compartments and organelles, investigating metabolic transformations of ILs in cells and organisms, detailed analysis of IL effects on proteins involved in oxidative stress and apoptosis, correlation studies between IL doses, exposure times and resulting adverse effects, and examination of effects of subtoxic concentrations of ILs on various biological objects. This review aims to serve as a critical analysis of the current body of knowledge on IL-related toxicity mechanisms. Furthermore, it can guide researchers toward the design of less toxic ILs and the informed use of ILs in drug development and medicine.

Smart co-delivery of plasmid DNA and doxorubicin using MCM-chitosan-PEG polymerization functionalized with MUC-1 aptamer against breast cancer

This study introduces an innovative co-delivery approach using the MCM-co-polymerized nanosystem, integrating chitosan and polyethylene glycol, and targeted by the MUC-1 aptamer (MCM@CS@PEG-APT). This system enables simultaneous delivery of the GFP plasmid and doxorubicin (DOX). The synthesis of the nanosystem was thoroughly characterized at each step, including FTIR, XRD, BET, DLS, FE-SEM, and HRTEM analyses. The impact of individual polymers (chitosan and PEG) on payload retardation was compared to the co-polymerized MCM@CS@PEG conjugation. Furthermore, the DOX release mechanism was investigated using various kinetic models. The nanosystem's potential for delivering GFP plasmid and DOX separately and simultaneously was assessed through fluorescence microscopy and flow cytometry. The co-polymerized nanosystem exhibited superior payload entrapment (1:100 ratio of Plasmid:NPs) compared to separately polymer-coated counterparts (1:640 ratio of Plasmid:NPs). Besides, the presence of pH-sensitive chitosan creates a smart nanosystem for efficient DOX and GFP plasmid delivery into tumor cells, along with a Higuchi model pattern for drug release. Toxicity assessments against breast tumor cells also indicated reduced off-target effects compared to pure DOX, introducing it as a promising candidate for targeted cancer therapy. Cellular uptake findings demonstrated the nanosystem's ability to deliver GFP plasmid and DOX separately into MCF-7 cells, with rates of 32% and 98%, respectively. Flow cytometry results confirmed efficient co-delivery, with 42.7% of cells showing the presence of both GFP-plasmid and DOX, while 52.2% exclusively contained DOX. Overall, our study explores the co-delivery potential of the MCM@CS@PEG-APT nanosystem in breast cancer therapy. This system's ability to co-deliver multiple agents preciselyopens new avenues for targeted therapeutic strategies.

Ionic liquids and deep eutectic solvents for the stabilization of biopharmaceuticals: A review

Biopharmaceuticals have allowed the control of previously untreatable diseases. However, their low solubility and stability still hinder their application, transport, and storage. Hence, researchers have applied different compounds to preserve and enhance the delivery of biopharmaceuticals, such as ionic liquids (ILs) and deep eutectic solvents (DESs). Although the biopharmaceutical industry can employ various substances for enhancing formulations, their effect will change depending on the properties of the target biomolecule and environmental conditions. Hence, this review organized the current state-of-the-art on the application of ILs and DESs to stabilize biopharmaceuticals, considering the properties of the biomolecules, ILs, and DESs classes, concentration range, types of stability, and effect. We also provided a critical discussion regarding the potential utilization of ILs and DESs in pharmaceutical formulations, considering the restrictions in this field, as well as the advantages and drawbacks of these substances for medical applications. Overall, the most applied IL and DES classes for stabilizing biopharmaceuticals were cholinium-, imidazolium-, and ammonium-based, with cholinium ILs also employed to improve their delivery. Interestingly, dilute and concentrated ILs and DESs solutions presented similar results regarding the stabilization of biopharmaceuticals. With additional investigation, ILs and DESs have the potential to overcome current challenges in biopharmaceutical formulation.

Alkyl-templated cocrystallization of long-chain 1-bromoalkanes by lipid-like ionic liquids

The serendipitous discovery of an unorthodox ionic cocrystallization system using 2-mercaptothiazolium-based ionic liquids as a crystallization milieu paves the way for the first report of crystal structures of long-chain 1-bromoalkanes. We used single crystal X-ray diffraction to determine the structures of 1-bromo-hexadecane and 1-octadecane with the aid of ionic liquids with alkyl side chains of equivalent length to the bromoalkane at room temperature. Long alkyl chains in combination with σ-hole interactions from strategically placed sulfur motifs synergistically function to crystallize the 1-bromoalkanes.

In vitro screening of imidazolium and pyrrolidinium based ionic liquids toxicity on subcellular fractions of the Mediterranean mussel Mytilus galloprovincialis

Ionic liquids (ILs) have been considered eco-friendly alternatives to conventional organic solvents. However, several studies have reported that ILs exert toxicity towards aquatic invertebrates. Applying in vitro methodology, the aim of the present study was to evaluate the potential effect of three ILs on the biochemical performance of exposed Mytilus galloprovincialis digestive gland and gills cellular fractions. Carboxylesterase might be involved in the derived toxicity mechanism of ILs as activity levels increased significantly in digestive gland exposed fractions. This group of ILs did not seem to induce genotoxicity, except in gills cellular fractions exposed to 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. In the literature, in vitro methodology has been suggested as an important complement to animal testing and in silico studies. The present research underlines its efficacy as a quick pre-screening before in vivo testing, particularly with heterogenic groups of substances with high variability in composition, such as ILs and deep eutectic solvents.

Ionic Liquids: New Forms of Active Pharmaceutical Ingredients with Unique, Tunable Properties

This Review aims to summarize advances over the last 15 years in the development of active pharmaceutical ingredient ionic liquids (API-ILs), which make up a prospective game-changing strategy to overcome multiple problems with conventional solid-state drugs, for example, polymorphism. A critical part of the present Review is the collection of API-ILs and deep eutectic solvents (DESs) prepared to date. The Review covers rules for rational design of API-ILs and tools for API-IL formation, syntheses, and characterization. Nomenclature and ionic speciation, and the confusion that these may cause, are highlighted, particularly for speciation in both ILs and DESs of intermediate ionicity. We also highlight in vivo and in vitro pharmaceutical activity studies, with differences in pharmacokinetic/pharmacodynamic depending on ionicity of API-ILs. A brief overview is provided for the ILs used to deliver drugs, and the Review concludes with key prospects and roadblocks in translating API-ILs into pharmaceutical manufacturing.

Selective Near-Infrared Blood Detection Driven by Ionic Liquid-Dye-Albumin Nanointeractions

Due to its abundance in blood, a great deal of research has been undertaken to develop efficient biosensors for serum albumin and provide insight into the interactions that take place between these biosensing molecules and the protein. Near-infrared (NIR, >700 nm) organic dyes have been shown to be effective biosensors of serum albumin, but their effectiveness is diminished in whole blood. Herein, it is shown that an NIR sulfonate indolizine-donor-based squaraine dye, SO3SQ, can be strengthened as a biosensor of albumin through the addition of biocompatible ionic liquids (ILs). Specifically, the IL choline glycolate (1:1), at a concentration of 160 mM, results in the enhanced fluorescence emission ("switch-on") of the dye in the presence of blood. The origin of the fluorescence enhancement was investigated via methods, including DLS, ITC, and molecular dynamics. Further, fluorescence measurements were conducted to see the impact the dye-IL system had on the fluorescence of the tryptophan residue of human serum albumin (HSA), as well as to determine its apparent association constants in relation to albumin. Circular dichroism (CD) spectroscopy was used to provide evidence that the dye-IL system does not alter the secondary structures of albumin or DNA. Our results suggest that the enhanced fluorescence of the dye in the presence of IL and blood is due to diversification of binding sites in albumin, controlled by the interaction of the IL-dye-albumin complex.

Complexation of Oligo- and Polynucleotides with Methoxyphenyl-Functionalized Imidazolium Surfactants

Interaction between cationic surfactants and nucleic acids attracts much attention due to the possibility of using such systems for gene delivery. Herein, the lipoplexes based on cationic surfactants with imidazolium head group bearing methoxyphenyl fragment (MPI-n, n = 10, 12, 14, 16) and nucleic acids (oligonucleotide and plasmid DNA) were explored. The complex formation was confirmed by dynamic/electrophoretic light scattering, transmission electron microscopy, fluorescence spectroscopy, circular dichroism, and gel electrophoresis. The nanosized lipoplex formation (of about 100-200 nm), contributed by electrostatic, hydrophobic interactions, and intercalation mechanism, has been shown. Significant effects of the hydrocarbon tail length of surfactant and the type of nucleic acid on their interaction was revealed. The cytotoxic effect and transfection ability of lipoplexes studied were determined using M-HeLa, A549 cancer cell lines, and normal Chang liver cells. A selective reduced cytotoxic effect of the complexes on M-HeLa cancer cells was established, as well as a high ability of the systems to be transfected into cancer cells. MPI-n/DNA complexes showed a pronounced transfection activity equal to the commercial preparation Lipofectamine 3000. Thus, it has been shown that MPI-n surfactants are effective agents for nucleic acid condensation and can be considered as potential non-viral vectors for gene delivery.

Molecule(s) of Interest: I. Ionic Liquids-Gateway to Newer Nanotechnology Applications: Advanced Nanobiotechnical Uses', Current Status, Emerging Trends, Challenges, and Prospects

Ionic liquids are a potent class of organic compounds exhibiting unique physico-chemical properties and structural compositions that are different from the classical dipolar organic liquids. These molecules have found diverse applications in different chemical, biochemical, biophysical fields, and a number of industrial usages. The ionic liquids-based products and procedural applications are being developed for a number of newer industrial purposes, and academic uses in nanotechnology related procedures, processes, and products, especially in nanobiotechnology and nanomedicine. The current article overviews their uses in different fields, including applications, functions, and as parts of products and processes at primary and advanced levels. The application and product examples, and prospects in various fields of nanotechnology, domains of nanosystem syntheses, nano-scale product development, the process of membrane filtering, biofilm formation, and bio-separations are prominently discussed. The applications in carbon nanotubes; quantum dots; and drug, gene, and other payload delivery vehicle developments in the nanobiotechnology field are also covered. The broader scopes of applications of ionic liquids, future developmental possibilities in chemistry and different bio-aspects, promises in the newer genres of nanobiotechnology products, certain bioprocesses controls, and toxicity, together with emerging trends, challenges, and prospects are also elaborated.

Macrocyclic Ionic Liquids with Amino Acid Residues: Synthesis and Influence of Thiacalix[4]arene Conformation on Thermal Stability

Novel thiacalix[4]arene based ammonium ionic liquids (ILs) containing amino acid residues (glycine and L-phenylalanine) in cone, partial cone, and 1,3-alternate conformations were synthesized by alkylation of macrocyclic tertiary amines with N-bromoacetyl-amino acids ethyl ester followed by replacing bromide anions with bis(trifluoromethylsulfonyl)imide ions. The melting temperature of the obtained ILs was found in the range of 50−75 °C. The effect of macrocyclic core conformation on the synthesized ILs’ melting points was shown, i.e., the ILs in partial cone conformation have the lowest melting points. Thermal stability of the obtained macrocyclic ILs was determined via thermogravimetry and differential scanning calorimetry. The onset of decomposition of the synthesized compounds was established at 305−327 °C. The compounds with L-phenylalanine residues are less thermally stable by 3−19 °C than the same glycine-containing derivatives.

Overcoming the non-kinetic activity of EGFR1 using multi-functionalized mesoporous silica nanocarrier for in vitro delivery of siRNA

Triple-negative breast cancer (TNBC) does not respond to HER2-targeted and hormone-based medicines. Epidermal growth factor receptor 1 (EGFR1) is commonly overexpressed in up to 70% of TNBC cases, so targeting cancer cells via this receptor could emerge as a favored modality for TNBC therapy due to its target specificity. The development of mesoporous silica nanoparticles (MSNs) as carriers for siRNAs remains a rapidly growing area of research. For this purpose, a multi-functionalized KIT-6 containing the guanidinium ionic liquid (GuIL), PEI and PEGylated folic acid (FA-PEG) was designed. Accordingly, KIT-6 was fabricated and modified with FA-PEG and PEI polymers attached on the surface and the GuIL placed in the mesopores. Subsequent to confirming the structure of this multi-functionalized KIT-6- based nanocarrier using TEM, SEM, AFM, BET, BJH, DLS and Zeta Potential, it was investigated for uploading and transferring the anti-EGFR1 siRNAs to the MD-MBA-231 cell line. The rate of cellular uptake, cellular localization and endolysosomal escape was evaluated based on the fluorescent intensity of FAM-labelled siRNA using flowcytometry analysis and confocal laser scanning microscopy (CLSM). The 64% cellular uptake after 4 h incubation, clearly suggested the successful delivery of siRNA into the cells and, CLSM demonstrated that siRNA@[FA-PEGylated/PEI@GuIL@KIT-6] may escape endosomal entrapment after 6 h incubation. Using qPCR, quantitative evaluation of EGFR1 gene expression, a knockdown of 82% was found, which resulted in a functional change in the expression of EGFR1 targets. Co-treatment of chemotherapy drug "carboplatin" in combination with siRNA@[FA-PEGylated/PEI@GuIL@KIT-6] exhibited a remarkable cytotoxic effect in comparison to carboplatin alone.

Ionic Liquid-Assisted Fabrication of Bioactive Heterogeneous Magnetic Nanocatalyst with Antioxidant and Antibacterial Activities for the Synthesis of Polyhydroquinoline Derivatives

Antibacterial materials have obtained much attention in recent years due to the presence of hazardous agents causing oxidative stress and observation of pathogens. However, materials with antioxidant and antibacterial activities can cause toxicity due to their low biocompatibility and safety profile, urging scientists to follow new ways in the synthesis of such materials. Ionic liquids have been employed as a green and environmentally solvent for the fabrication of electrically conductive polymers. In the present study, an antibacterial poly(p-phenylenediamine)@Fe3O4 (PpPDA@Fe3O4) nanocomposite was fabricated using [HPy][HSO4] ionic liquid. The chemical preparation of PpPDA@Fe3O4 nanocomposite was initiated through the oxidative polymerization of p-phenylenediamine by ammonium persulfate in the presence of [HPy][HSO4]. The PpPDA@Fe3O4 nanocomposite exhibited antibacterial properties against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria. The PpPDA@Fe3O4 nanocomposite was employed as a heterogeneous nanocatalysis for one-pot synthesis of polyhydroquinoline derivatives using aromatic aldehyde, dimedone, benzyl acetoacetate, and ammonium acetate. Polyhydroquinoline derivatives were synthesized in significant yields (90-97%) without a difficult work-up procedure in short reaction times. Additionally, PpPDA@Fe3O4 nanocatalyst was recycled for at least five consecutive catalytic runs with a minor decrease in the catalytic activity. In this case, 11 derivatives of polyhydroquinoline showed in vitro antioxidant activity between 70-98%.

The combined action of cations and anions of ionic liquids modulates the formation and stability of G-quadruplex DNA

G-Quadruplex (Gq) formation and stabilization by any molecule is an essential requirement for its application in therapy, especially in oncology. Metal cations have shown higher propensity of the formation of the Gq structure and its stabilization. In this study, the role of both cations and anions of ionic liquids (ILs) on the Gq formation of human telomere (hTeloG) and its stability was investigated using spectroscopic and molecular dynamics simulation techniques. Irrespective of the nature of anions of ILs, tetramethylguanidinium (TMG) cations associated with different anions can form an antiparallel Gq structure in hTeloG. However, the propensity of the formation of an antiparallel Gq structure and its stability depend on the chain length of anions of ILs. Gq is significantly less stable in ILs having longer hydrocarbon chain anions compared to the short chain anions suggesting that the hydrophobicity of the anion plays a critical role in the stability and formation of the Gq structure by ILs. The data indicate that longer hydrocarbon chain anions of ILs preferably interact in the loop region of Gq through hydrophobic interaction which enhances the overall binding of the cation of ILs with Gq causing a decrease in the stacking energy between the G-quartets as well as Hoogsteen hydrogen bonds between the guanine bases leading to the destabilization of the antiparallel Gq structure.

Structural Dynamics of RNA in the Presence of Choline Amino Acid Based Ionic Liquid: A Spectroscopic and Computational Outlook

Ribonucleic acid (RNA) is exceedingly sensitive to degradation compared to DNA. The current protocol for storage of purified RNA requires freezing conditions below -20 °C. Recent advancements in biological chemistry have identified amino acid-based ionic liquids as suitable preservation media for RNA, even in the presence of degrading enzymes. However, the mechanistic insight into the interaction between ILs and RNA is unclear. To the best of our knowledge, no attempts are made so far to provide a molecular view. This work aims to establish a detailed understanding of how ILs enable structural stability to RNA sourced from Torula yeast. Herein, we manifest the hypothesis of multimodal binding of IL and its minimal perturbation to the macromolecular structure, with several spectroscopic techniques such as time-resolved fluorescence and fluorescence correlation spectroscopy (FCS) aided with molecular dynamics at microsecond time scales. Relevant structural and thermodynamic details from biophysical experiments confirm that even long-term RNA preservation with ILs is a possible alternative devoid of any structural deformation. These results establish a unifying mechanism of how ILs are maintaining conformational integrity and thermal stability. The atomistic insights are transferable for their potential applications in drug delivery and biomaterials by considering the advantages of having maximum structural retention and minimum toxicity.

Insight into the thermal stability of DNA in hydrated ionic liquids from multi-wavelength UV resonance Raman experiments

The utility of ionic liquids (ILs) as alternative solvents for stabilizing and preserving the native structure of DNA over the long term may be envisaged for biotechnological and biomedical applications in the near future. The delicate balance between the stabilizing and destabilizing effects of IL-mediated interactions with the structure of DNA is complex and is still not well understood. This work reports a fundamental study dealing with the effect exerted by cations and anions in imidazolium-based ILs on the thermal structural stability of large nucleic acid molecules. Multi-wavelength UV resonance Raman spectroscopy is used for selectively detecting heat-induced structural transitions of DNA localized on specific base tracts. Our study reveals the establishment of preferential interactions between the imidazolium cations of ILs and the guanine bases in the DNA groove that lead to more effective stacking between the guanine bases even at high temperatures. Interestingly, we observe that this trend for ILs sharing the same chloride anion is further enhanced as the alkyl chain on the imidazolium cation gets shorter. The results from the present investigation lead to a more comprehensive view of the IL-mediated interactions with A-T and G-C base pairs during thermal unfolding.

Quaternary Ammonium Compounds (QACs) and Ionic Liquids (ILs) as Biocides: From Simple Antiseptics to Tunable Antimicrobials

Quaternary ammonium compounds (QACs) belong to a well-known class of cationic biocides with a broad spectrum of antimicrobial activity. They are used as essential components in surfactants, personal hygiene products, cosmetics, softeners, dyes, biological dyes, antiseptics, and disinfectants. Simple but varied in their structure, QACs are divided into several subclasses: Mono-, bis-, multi-, and poly-derivatives. Since the beginning of the 20th century, a significant amount of work has been dedicated to the advancement of this class of biocides. Thus, more than 700 articles on QACs were published only in 2020, according to the modern literature. The structural variability and diverse biological activity of ionic liquids (ILs) make them highly prospective for developing new types of biocides. QACs and ILs bear a common key element in the molecular structure-quaternary positively charged nitrogen atoms within a cyclic or acyclic structural framework. The state-of-the-art research level and paramount demand in modern society recall the rapid development of a new generation of tunable antimicrobials. This review focuses on the main QACs exhibiting antimicrobial and antifungal properties, commercial products based on QACs, and the latest discoveries in QACs and ILs connected with biocide development.