Insights on the DNA stability in aqueous solutions of ionic liquids

Deoxyribonucleic acid (DNA) carries the genetic information essential for the growth and functioning of living organisms, playing a significant role in life sciences research. However, the long-term storage and preservation of DNA, while ensuring its bioactivity, are still current challenges to overcome. In this work, aqueous solutions of ionic liquids (ILs) were investigated as potential preservation media for double stranded (dsDNA). A screening of several ILs, by combining the cholinium, tetrabutylammonium, tetrabutylphosphonium, and 1-ethyl-3-methylimidazolium, cations with the anions bromide, chloride, dihydrogen phosphate, acetate, and glycolate, was carried out in order to gather fundamental knowledge on the molecular features of ILs that improve the dsDNA stability. Different IL concentrations and the pH effect were also addressed. Circular dichroism (CD) spectroscopy was used to evaluate the conformational structure and stability of dsDNA. IL-DNA interactions were appraised by UV-Vis absorption spectrophotometry and 31P nuclear magnetic resonance (NMR) spectroscopy. The results obtained demonstrate that pH has a significant effect towards the dsDNA stability. Amongst the ILs investigated, cholinium-based ILs are the most promising class of ILs to preserve the dsDNA structure, in which electrostatic interactions between the cholinium cation and the DNA phosphate groups play a significant role as demonstrated by the 31P NMR data, being more relevant at higher IL concentrations. On the other hand, the denaturation of dsDNA mainly occurs with ILs composed of more hydrophobic cations and able to establish dispersive interactions with the nucleobases environment. Furthermore, the IL anion has a weaker impact when compared to the IL cation effect to interact with DNA molecules. The experimental data of this work provide relevant fundamental knowledge for the application of ILs in the preservation of nucleic acids, being of high relevance in the biotechnology field.publishe

Integrated platform resorting to ionic liquids comprising the extraction, purification and preservation of DNA

The large-scale production of therapeutically targeted-deoxyribonucleic acid (DNA) has passed through several challenges, postponing the tangible implementation of an effective, economic and sustainable manufacturing system. Such challenges comprise the need to develop an integrative downstream process able to extract, purify and long-term preserve DNA, whilst reducing the risk of degradation by endonucleases that would compromise their effectiveness as therapeutic products. In this work, three-phase partitioning (TPP) systems formed by the application of aqueous biphasic systems (ABS) composed of several biocompatible cholinium-based ionic liquids (ILs), are proposed for the separation of double stranded DNA (dsDNA) from the endonuclease deoxyribonuclease I (DNase I). By taking advantage of the tailor-made properties of ILs, dsDNA can be completely extracted to the IL-rich phase, whereas DNase I is precipitated at the ABS interphase. The ABS/TPP formed by IL cholinium glycolate ([N 111(2OH) ][Gly]) fulfills the aim of this work, i.e. at ensuring the technical viability of IL-based ABS/ TPP for the “one-pot” extraction, purification and long-term preservation of dsDNA. The results reveal the potential of this system to be applied in the bioprocessing of DNA, particularly relevant when envisioning DNA- based therapeutic products.publishe

Mixtures of polymers and cholinium-based ionic liquids to tailor the phase diagrams and extraction efficiency of aqueous biphasic systems

Aqueous biphasic systems (ABS) are outstanding alternatives over conventional liquid-liquid extraction processes since it is avoided the use of volatile and hazardous organic solvents (VOCs). ABS are more biocompatible systems formed by two aqueous-rich phases that can be designed by combining different pairs of solutes (polymer-polymer, polymer-salt or salt-salt) above specific concentrations. In the past years, ABS have been studied as powerful techniques for purification, separation and extraction purposes. Ionic liquids (ILs) have been described as interesting fluids towards the development of more sustainable processes. Due to the ILs unique properties, their introduction in ABS led to systems with higher selectivity and extraction performance for a wide plethora of compounds. In fact, it was already shown that ILs allow to overcome the low hydrophilic-hydrophobic range of ABS composed of two polymers or one polymer and one inorganic salt. IL-based ABS formed with polyethylene glycol (PEG) polymers were recently introduced and a successful control of the phase polarities, through the manipulation of the IL chemical structure, was demonstrated. Lately, it was also demonstrated that a new class of natural-derived cholinium-based ILs are capable of undergoing two phase separation by the addition of PEGs with different molecular weights. In the present work, mixtures of PEGs with different molecular weights (400 and 2000 g/mol) were used to ascertain on the formation ability of ABS composed of water and cholinium-based ILs or salts. The results obtained indicate that the formation ability of these ABS increase with the content of PEG2000 over PEG400 (and follow a continuous increase), meaning that a close-fitting control on their phases polarity can be attained. These systems were then evaluated on their performance for extracting a series of alkaloids with different polarities, namely caffeine, theophylline, theobromine and nicotine. In general, the alkaloids partition extent to the most hydrophobic phase (PEG-rich) follows their polarity/hydrophobicity. In summary, it is here demonstrated that mixtures of polymers as phase-forming components of ABS allow to tailor the partition coefficients of different alkaloids and their use in the purification of added-value compounds from biomass extracts is straightforwardly foreseen.publishe

Aqueous biphasic systems composed of ionic liquids: one-step extraction/concentration techniques for water pollution tracers

Emergent micropollutants have become a serious global problem with a large impact in the environment and human health, while their presence in aquatic systems has been registered as ranging from ng/L-1 to ug/L-1. Pharmaceuticals are ubiquitous micropollutants since their continuous consumption and consequent release via human excretions into aqueous systems are inevitable. Due to their usually low concentrations in aqueous samples, the development of a pre-concentration technique in order to continuously quantify and to monitor these components in aqueous streams is of major relevance. Aqueous biphasic systems (ABS) composed of ionic liquids (ILs) can be seen as more sustainable separation processes since they avoid the use of volatile and hazardous organic solvents (VOCs). As liquid-liquid systems, ABS can be used as extraction, purification and concentration platforms. Due to the outstanding tunable properties of ILs, IL-based ABS provide higher and more selective extraction efficiencies for a wide range of compounds when compared to traditional polymer-based ABS. IL-based ABS were already employed and adequately characterized for the extraction and concentration of endocrine disruptors, either from biological fluids or aqueous matrices. The aim of this work is to demonstrate the applicability of IL-based ABS to completely extract and concentrate, in one-step, two different and representative pharmaceutical pollution tracers, namely caffeine (CAF) and carbamazepine (CBZ). The low concentration of these persistent pollutants (usually found in ug/L-1 and ng/L-1 levels) does not allow a proper detection and quantification by conventional analytical equipment without a previous concentration step. However, pre-concentration methods commonly applied are costly, time-consuming, provide irregular recoveries and/or use VOCs. In this work, ABS composed of the IL tetrabutylammonium chloride ([N4444]Cl) and the salt K3C6H5O7 was investigated, demonstrating to be able to completely extract and concentrate CAF and CBZ in a single-step. Moreover, with this pre-treatment step it was demonstrated to be possible to overcome the detection limits of a high performance liquid chromatography coupled to an UV-Vis detector equipment. The results obtained demonstrate that IL-based ABS are versatile pre-concentration techniques, and can be used for the extraction and concentration of a large plethora of other micropollutants from environmental aqueous matrices.publishe

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species

Advances Brought by Hydrophilic Ionic Liquids in Fields Involving Pharmaceuticals

The negligible volatility and high tunable nature of ionic liquids (ILs) have been the main drivers of their investigation in a wide diversity of fields, among which is their application in areas involving pharmaceuticals. Although most literature dealing with ILs is still majorly devoted to hydrophobic ILs, evidence on the potential of hydrophilic ILs have been increasingly provided in the past decade, viz., ILs with improved therapeutic efficiency and bioavailability, ILs with the ability to increase drugs’ aqueous solubility, ILs with enhanced extraction performance for pharmaceuticals when employed in biphasic systems and other techniques, and ILs displaying low eco/cyto/toxicity and beneficial biological activities. Given their relevance, it is here overviewed the applications of hydrophilic ILs in fields involving pharmaceuticals, particularly focusing on achievements and advances witnessed during the last decade. The application of hydrophilic ILs within fields involving pharmaceuticals is here critically discussed according to four categories: (i) to improve pharmaceuticals solubility, envisioning improved bioavailability; (ii) as IL-based drug delivery systems; (iii) as pretreatment techniques to improve analytical methods performance dealing with pharmaceuticals, and (iv) in the recovery and purification of pharmaceuticals using IL-based systems. Key factors in the selection of appropriate ILs are identified. Insights and perspectives to bring renewed and effective solutions involving ILs able to compete with current commercial technologies are finally provided

Hydrogen bond basicity of ionic liquids and molar entropy of hydration of salts as major descriptors in the formation of aqueous biphasic systems

Aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and conventional salts have been largely investigated and successfully used in separation processes, for which the determination of the corresponding ternary phase diagrams is a prerequisite. However, due the large number of ILs that can be prepared and their high structural versatility, it is impossible to experimentally cover and characterize all possible combinations of ILs and salts that may form ABS. The development of tools for the prediction and design of IL-based ABS is thus a crucial requirement. Based on a large compilation of experimental data, a correlation describing the formation of IL-based ABS is shown here, based on the hydrogen-bonding interaction energies of ILs (EHB) obtained by the COnductor-like Screening MOdel for Real Solvents (COSMO-RS) and the molar entropy of hydration of the salt ions. The ability of the proposed model to predict the formation of novel IL-based ABS is further ascertained.publishe

Aqueous biphasic systems formed by cholinium-based ionic liquids and mixtures of polymers

In the past years, the relevance of introducing ionic liquids (ILs) has been shown as phase-forming components of aqueous biphasic systems (ABS), which allow the tailoring of polarity differences between the coexisting phases. Although investigations on the IL chemical structure and polymermolecularweight have been carried out, the use of mixtures of polymers can also be seen as a way of tailoring their two-phase formation ability and separation performance, which was not attempted earlier. In this work, we investigate novel ABS composed of cholinium-based ILs and mixtures of polymers, namely polyethylene glycol (PEG) of 400 and 2,000 g·mol-1, at differentmole fractions, as a way of tailoring the formation of ABS and their separation performance. The respective liquid-liquid phase diagrams were determined, and their ability to separate a set of alkaloids (caffeine, theophylline and theobromine) appraised. An increase on the PEG 2000mole fraction favors the formation of ABS. However, this does not follow a monotonous trend, where mole fractions of PEG 400 up to 0.3 do not display significant impact on the two-phase separation capability. Among the studied alkaloids, nicotine preferentially partitions to the IL-rich phase, while the remaining alkaloids majorly partition to the polymer-rich phase. Different selectivity patterns were verified, depending on the cholinium-based IL used and water content at the IL-rich phase. Overall, by using mixtures of polymers it is possible to decrease the viscosity of the coexisting phases and their toxicity impact, without losing their formation and separation capacities, by the addition of PEGs of lower molecular weight.publishe

Ionic-liquid-based aqueous biphasic systems: enhanced one-step extraction/concentration techniques of water pollution tracers

Pharmaceuticals are ubiquitous micropollutants due to their continuous consumption and consequent release via human excretions into aqueous systems. The low concentrations of these compounds in aqueous samples (from ng·L-1 to μg·L-1) results in the need of developing efficient pre-treatment/concentration techniques to accurately quantify and monitor these components in aqueous streams. As an alternative to the currently used concentration methods, mainly based on solid-phase extractions (SPE), liquid-liquid extraction based on aqueous biphasic systems (ABS) composed of ionic liquids (ILs) can be seen as more sustainable processes. In fact, ABS do not require the use of volatile and hazardous organic solvents (VOCs) typically employed in SPE and liquid-liquid extractions. Furthermore, the tunable properties of ILs are transferred to IL-based ABS, and high extraction efficiencies and selectivities have been reported for a wide range of compounds. In this work, we demonstrate the applicability of IL-based ABS for the concomitant extraction and concentration of several water pollution tracers, namely ethinylestradiol (EE2), caffeine, and carbamazepine, in which concentration factors up to 1000-fold have been gathered in a single-step. The increase in the concentration of pollution tracers from ng·L-1 to μg·L-1 allowed the use of high-performance liquid chromatography with fluorescence detection for their analysis/monitoring.publishe