Current developments and future perspectives on biotechnology applications of natural deep eutectic systems

Funding Information: This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme, under grant agreement No ERC-2016-CoG 725034. This work was also supported by the Associate Laboratory for Green Chemistry – LAQV, financed by national funds from FCT/MCTES (UID/QUI/50006/2019) and by FCT/MCTES through the project CryoDES (PTDC/EQU-EQU/29851/2017). Publisher Copyright: © 2022 Elsevier B.V.Natural Deep Eutectic Systems (NADES) have emerged in the past years as alternative solvents to traditional organic solvents and ionic liquids. NADES are easy to produce, sustainable, biocompatible, eco-friendly, remarkable solubilizing agents, and highly task-specific. The outstanding properties of this new liquid media have attracted the attention of researchers in the last decade in many fields and biotechnology is probably one of the fields where NADES have gained more relevance. Nonetheless, the progress beyond the state of the art in this field is not yet fully explored. Most research papers regarding the use of NADES in biotechnology are related to their use as solubility enhancers for poorly soluble active ingredients, particularly for pharmaceutical applications. However, the applicability of NADES in applications such as cryopreservation, stabilization of proteins and DNA, as well as other biomedical applications, has only recently been explored and presents still a plethora of discoveries to be unravelled. The current developments in this scientific field and future perspectives will be discussed herein.publishersversionpublishe

Application of Green Technologies for Recovering Aromatic Compounds From Natural Resources

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Using Natural Deep Eutectic Systems as Alternative Media for Ocular Applications

Funding Information: This research was funded by European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme, under grant agreement No ERC-2016-CoG 725034 and CryoDES ERC-2022-POC2 101101088. This work was also supported by the Associate Laboratory for Green Chemistry—LAQV, financed by national funds from FCT/MCTES (UID/QUI/50006/2019) and by FCT/MCTES through the project CryoDES (PTDC/EQU-EQU/29851/2017). The authors also acknowledge the PhD grant from Fundação para a Ciência e Tecnologia (2021.07457.BD). Publisher Copyright: © 2023 by the authors.The major goal of this work was to study the potential of natural deep eutectic systems (NADES) as new media for ocular formulations. In formulating eye drops, it is important to increase the retention time of the drug on the surface of eye; hence, due to their high viscosity, NADES may be interesting candidates for formulation. Different systems composed of combinations of sugars, polyols, amino acids, and choline derivatives were prepared and then characterized in terms of rheological and physicochemical properties. Our results showed that 5–10% (w/v) aqueous solutions of NADES have a good profile in terms of viscosity (0.8 to 1.2 mPa.s), osmolarity (412 to 1883 mOsmol), and pH (7.4) for their incorporation of ocular drops. Additionally, contact angle and refractive index were determined. Acetazolamide (ACZ), a highly insoluble drug used to treat glaucoma, was used as proof-of-concept. Herein, we show that NADES can increase the solubility of ACZ in aqueous solutions by at least up to 3 times, making it useful for the formulation of ACZ into ocular drops and thereby enabling more efficient treatment. The cytotoxicity assays demonstrated that NADES are biocompatible up to 5% (w/v) in aqueous media, promoting cell viability (above 80%) when compared to the control after 24 h incubation in ARPE-19 cells. Furthermore, when ACZ is dissolved in aqueous solutions of NADES, the cytotoxicity is not affected in this range of concentrations. Although further studies are necessary to design an optimal formulation incorporating NADES, this study shows that these eutectics can be powerful tools in the formulation of ocular drugs.publishersversionpublishe

Organic salts based on isoniazid drug: Synthesis, bioavailability and cytotoxicity studies

UIDB/50006/2020 POCI-01-0145-FEDER?007265 PTDC/QUI-QOR/32406/2017 MAR-02.01.01-FEAMP-0042Tuberculosis is one of the ten causes of morbidity and mortality worldwide caused by Mycobacterium tuberculosis complex. Some of the anti-tuberculosis drugs used in clinic studies, despite being effective for the treatment of tuberculosis, present serious adverse effects as well as poor bioavailability, stability, and drug-resistance problems. Thus, it is important to develop approaches that could provide shorter drug regimens, preventing drug resistance, toxicity of the antibiotics, and improve their bioavailability. Herein, we reported the use of organic salts based on the isoniazid drug, which can act as an organic cation combined with suitable organic anions such as alkylsulfonate-based (mesylate, R or S-Camphorsulfonate), carboxylate-based (glycolate, vanylate) and sacharinate. The synthesis, characterization, and cytotoxicity studies comparing with the original isoniazid drug have been performed. The possibility to explore dicationic salts seems promising in order to improve original bioavailability, and promote the elimination of polymorphic forms as well as higher stability, which are relevant characteristics that the pharmaceutical industry pursues.publishersversionpublishe

Viscosity investigations on the binary systems of (1 chcl:2 ethylene glycol) des and methanol or ethanol

Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.In this study, the viscosity behavior of two mixtures of Ethaline (1 ChCl:2 ethylene glycol) with either methanol or ethanol were investigated over the temperature range of 283.15–333.15 K at atmospheric pressure. The measured viscosities of neat Ethaline, methanol, and ethanol showed reliable agreement with the corresponding reported literature values. The mixture viscosities were modeled by an Arrhenius-like model to determine the behavior of viscosity with respect to temperature. The data were also modeled by the four well-known mixture viscosity models of Grunberg–Nissan, Jouyban–Acree, McAllister, and Preferential Solvation. All of the model results were reliable, with the Jouyban–Acree and Preferential Solvation models showing the most accurate agreement with the experimental measurements. The Jones–Dole viscosity model was also investigated for the measured viscosities, and by analyzing the results of this model, strong interactions among Ethaline and the alcohol molecules were proposed for both systems. As a final analysis, viscosity deviations of the investigated systems were calculated to study the deviations of the viscosity behaviors with respect to ideal behavior. Both systems showed negative viscosity deviations at all of the investigated temperatures, with the negative values tending towards zero, and hence more ideal behavior, with increasing temperatures. Moreover, in order to correlate the calculated viscosity deviations, the Redlich–Kister model was successfully used for both systems and at each investigated temperature.publishersversionpublishe

Group contribution and atomic contribution models for the prediction of various physical properties of deep eutectic solvents

Publisher Copyright: © 2021, The Author(s).The urgency of advancing green chemistry from labs and computers into the industries is well-known. The Deep Eutectic Solvents (DESs) are a promising category of novel green solvents which simultaneously have the best advantages of liquids and solids. Furthermore, they can be designed or engineered to have the characteristics desired for a given application. However, since they are rather new, there are no general models available to predict the properties of DESs without requiring other properties as input. This is particularly a setback when screening is required for feasibility studies, since a vast number of DESs are envisioned. For the first time, this study presents five group contribution (GC) and five atomic contribution (AC) models for densities, refractive indices, heat capacities, speeds of sound, and surface tensions of DESs. The models, developed using the most up-to-date databank of various types of DESs, simply decompose the molecular structure into a number of predefined groups or atoms. The resulting AARD% of densities, refractive indices, heat capacities, speeds of sound and surface tensions were, respectively, 1.44, 0.37, 3.26, 1.62, and 7.59% for the GC models, and 2.49, 1.03, 9.93, 4.52 and 7.80% for the AC models. Perhaps, even more importantly for designer solvents, is the predictive capability of the models, which was also shown to be highly reliable. Accordingly, very simple, yet highly accurate models are provided that are global for DESs and needless of any physical property information, making them useful predictive tools for a category of green solvents, which is only starting to show its potentials in green technology.publishersversionpublishe

Selective extraction and stabilization of bioactive compounds from rosemary leaves using a biphasic NADES

Publisher Copyright: Copyright © 2022 Vieira, Rebocho, Craveiro, Paiva and Duarte.Rosemary (Rosmarinus officinalis) is a natural source of bioactive compounds that have high antioxidant activity. It has been in use as a medicinal herb since ancient times, and it currently is in widespread use due to its inherent pharmacological and therapeutic potential, in the pharmaceutical, food, and cosmetic industries. Natural deep eutectic systems (NADESs) have recently been considered as suitable extraction solvents for bioactive compounds, with high solvent power, low toxicity, biodegradability, and low environmental impact. The present work concerns the extraction of compounds such as rosmarinic acid, carnosol, carnosic acid, and caffeic acid, from rosemary using NADESs. This extraction was carried out using heat and stirring (HS) and ultrasound-assisted extraction (UAE). A NADES composed of menthol and lauric acid at a molar ratio of 2:1 (Me:Lau) extracted carnosic acid and carnosol preferentially, showing that this NADES exhibits selectivity for nonpolar compounds. On the other hand, a system of lactic acid and glucose (LA:Glu (5:1)) extracted preferentially rosmaniric acid, which is a more polar compound. Taking advantage of the different polarities of these NADESs, a simultaneous extraction was carried out, where the two NADESs form a biphasic system. The system LA:Glu (5:1)/Men:Lau (2:1) presented the most promising results, reaching 1.00 ± 0.12 mg of rosmarinic acid/g rosemary and 0.26 ± 0.04 mg caffeic acid/g rosemary in the more polar phase and 2.30 ± 0.18 mg of carnosol/g of rosemary and 17.54 ± 1.88 mg carnosic acid/g rosemary in the nonpolar phase. This work reveals that is possible to use two different systems at the same time and extract different compounds in a single-step process under the same conditions. NADESs are also reported to stabilize bioactive compounds, due to their interactions established with NADES components. To determine the stability of the extracts over time, the compounds of interest were quantified by HPLC at different time points. This allows the conclusion that bioactive compounds from rosemary were stable in NADESs for long periods of time; in particular, carnosic acid presented a decrease of only 25% in its antioxidant activity after 3 months, whereas the carnosic acid extracted and kept in the methanol was no longer detected after 15 days. The stabilizing ability of NADESs to extract phenolic/bioactive compounds shows a great promise for future industrial applications.publishersversionpublishe

A comparison between gravimetric and in-situ spectroscopic methods to measure the sorption of CO₂in a biocompatible polymer

In situ ATR-IR spectroscopy was used to simultaneously measure the sorption and swelling of carbon dioxide at high pressures in a biocompatible acrylate copolymer poly(methylmethacrylate-co-ethylhexylacrylate-co-ethyleneglycoldimethacrylate), P(MMA–EHA–EGDMA). The ν3 band of CO2 dissolved in the polymer (at 2335 cm−1) was used to calculate the sorption data and the polymer swelling was determined by analyzing the changes in the absorbance of the ν(C O) band (at 1730 cm−1) of the polymer. Transmission spectroscopy in the near-IR region was also used to study the sorption of CO2 in the polymer using combinational and overtone bands. The experiments were carried out in a pressure range of 2.0–12.0MPa and in a temperature range of 27–40 ◦C. The data for CO2 sorption in this polymer obtained by in situ spectroscopic methods have been compared to the data obtained by the gravimetric technique

The role of organic solvent on the preparation of chitosan scaffolds by supercritical assisted phase inversion

The aim of this study was to evaluate the possibility of preparing chitosan porous matrixes using supercritical fluid technology. Supercritical immersion precipitation technique was used to prepare scaffolds of a natural biocompatible polymer, chitosan for tissue engineering purposes. The physicochemical and biological properties of chitosan make it an excellent material for the preparation of drug delivery systems and for the development of new biomedical applications in many fields from skin to bone or cartilage. Supercritical assisted phase inversion experiments were carried out and the effect of different organic solvents on the morphology of the scaffolds was assessed. Chitosan scaffold morphology, porosity and pore size were evaluated by SEM and micro-CT. A thermodynamic analysis of the process was carried out and insights on the solubility parameter and Flory–Huggins interaction parameters are given. The preparation of a highly porous and interconnected structure of a natural material, chitosan, using a clean and environmentally friendly technology constitutes a new processing technology for the preparation of scaffolds for tissue engineering using these materials.Ana Rita C. Duarte is grateful for financial support from Fundacao para a Ciencia e Tecnologia (FCT) through the grant SFRH/BPD/34994/2007. The support through the FCT project PTDC/QUI/68804/2006 is also acknowledged