Predicting protein partition coefficients in aqueous two phase system

Review of recent applications and modifications of aqueous two-phase system for the separation of biomolecules

Biomolecules, specifically proteins, polysaccharides, and secondary metabolites are potential lead compounds due to their remarkable pharmacological properties. However, the complex molecular structure of the biomolecules makes their separation processes of great challenges. The conventional downstream processes require multistep protocols that are less efficient, high solvent consumption, expensive, time-consuming, and laborious. Hence, aqueous two-phase system (ATPS) is a reliable technique for the extraction and purification of biomolecules from a complex mixture. ATPS is an environmentally friendly, simple, cost effective, and easily scalable process. It requires a short processing time to separate biomolecules of industrial values simultaneously in a single process. Modifications have also been performed by introducing deep eutectic solvents, ionic liquids, carbohydrates, amino acids or copolymers to enhance the process efficiency with an increased yield, purity and bioactivity of recovered biomolecules. This review attempts to review the recent developed ATPSs and their efficiency to extract, isolate, and purify biomolecules such as proteins, polysaccharides, secondary metabolites and other biological substances. The review provides insights into the feasibility and reliability of ATPS for biomolecule recovery.

Affinity-Controlled Partitioning of Biomolecules at Aqueous Interfaces and Their Bioanalytic Applications

All-aqueous phase separation systems play essential roles in bioanalytical and biochemical applications. Compared to conventional oil and organic solvent-based systems, these systems are characterized by their rich bulk and interfacial properties, offering superior biocompatibility. In particular, phase separation in all-aqueous systems facilitates the creation of compartments with specific physicochemical properties, and therefore largely enhances the accessibility of the systems. In addition, the all-aqueous compartments have diverse affinities, with an important property known as partitioning, which can concentrate (bio)molecules toward distinct immiscible phases. This partitioning affinity imparts all-aqueous interfaces with selective permeability, enabling the controlled enrichment of target (bio)molecules. This review introduces the basic principles and applications of partitioning-induced interfacial phenomena in a typical all-aqueous system, namely aqueous two-phase systems (ATPSs); these applications include interfacial chemical reactions, bioprinting, and assembly, as well as bio-sensing and detection. The primary challenges associated with designing all-aqueous phase separation systems and several future directions are also discussed, such as the stabilization of aqueous interfaces, the handling of low-volume samples, and exploration of suitable ATPSs compositions with the efficient protocol.

Extraction of Gallic Acid and Ferulic Acid for Application in Hair Supplements

Food supplements based on antioxidants and vitamins are often prescribed to correct inefficiencies in the human diet and delay diseases such as premature aging and alopecia (temporary or permanent hair loss), given the free radical scavenging activity of these biomolecules. By reducing the concentration of reactive oxygen species (ROS), which promote abnormal hair follicle cycling and morphology, follicle inflammation and oxidative stress are reduced, minimising the effects of these health issues. Gallic acid (GA), which is significantly present in gallnuts and in pomegranate root bark, and ferulic acid (FA), commonly found in brown rice and coffee seeds, are very important antioxidants for the preservation of hair colour, strength and growth. In this work, these two secondary phenolic metabolites were successfully extracted in the Aqueous Two-Phase Systems (ATPS) {ethyl lactate (1) + trisodium citrate (2) + water (3)} and {ethyl lactate (1) + tripotassium citrate (2) + water (3)} at 298.15 K and 0.1 MPa, moving towards the application of these ternary systems in extracting antioxidants from biowaste and their a posteriori processing as food supplements for hair fortification. The studied ATPS provided biocompatible and sustainable media for the extraction of gallic acid and ferulic acid, yielding low mass losses (<3%) and contributing to an eco-friendlier production of therapeutics. The most promising results were obtained for ferulic acid, which attained maximum partition coefficients (K) of 15 ± 5 and (3 ± 2) · 10¹ and maximum extraction efficiencies (E) of (92.7 ± 0.4)% and (96.7 ± 0.4)% for the longest tie-lines (TLL = 69.68 and 77.66 m%) in {ethyl lactate (1) + trisodium citrate (2) + water (3)} and {ethyl lactate (1) + tripotassium citrate (2) + water (3)}, respectively. Moreover, the effect of pH on the UV-Vis absorbance spectra was studied for all the biomolecules to minimise errors in solute quantification. Both GA and FA were found to be stable at the used extractive conditions.

Separation and Purification of Astragalus membranaceus Polysaccharides by Deep Eutectic Solvents-Based Aqueous Two-Phase System

(1) Background: Aqueous two-phase systems (ATPSs) have been widely used in the separation and purification of bioactive substances in recent years. (2) Methods: In this study, deep eutectic solvents (DESs)-based ATPSs were employed for the extraction and separation of Astragalus membranaceus polysaccharides (AMP). The optimal DES (choline chloride:urea = 1:1) was first screened to extract AMP, and the effect of DES concentration, solid-liquid ratio, pH, extraction temperature, and extraction time on the extraction yield of AMP were investigated. (3) Results: The maximum extraction yield was 141.11 mg/g under the optimum conditions. AMP was then preliminarily purified by ATPS, to further realize the recycling and reuse of DES. The effect of type of salts, salt concentration, and extraction temperature on extraction efficiency was investigated. The extraction efficiency was 97.85% for AMP under the optimum ATPS conditions. Finally, the obtained AMP was studied by molecular weight determination, infrared spectroscopy analysis, and monosaccharide composition analysis. (4) Conclusions: This ATPS extraction based on DESs is simple, environmentally friendly, low-cost, and has high extraction efficiency, which provides new ideas for the extraction of plant polysaccharides and other bioactive compounds.

Progress in all-aqueous droplets generation with microfluidics: Mechanisms of formation and stability improvements

All-aqueous systems have attracted intensive attention as a promising platform for applications in cell separation, protein partitioning, and DNA extraction, due to their selective separation capability, rapid mass transfer, and good biocompatibility. Reliable generation of all-aqueous droplets with accurate control over their size and size distribution is vital to meet the increasingly growing demands in emulsion-based applications. However, the ultra-low interfacial tension and large effective interfacial thickness of the water-water interface pose challenges for the generation and stabilization of uniform all-aqueous droplets, respectively. Microfluidics technology has emerged as a versatile platform for the precision generation of all-aqueous droplets with improved stability. This review aims to systematize the controllable generation of all-aqueous droplets and summarize various strategies to improve their stability with microfluidics. We first provide a comprehensive review on the recent progress of all-aqueous droplets generation with microfluidics by detailing the properties of all-aqueous systems, mechanisms of droplet formation, active and passive methods for droplet generation, and the property of droplets. We then review the various strategies used to improve the stability of all-aqueous droplets and discuss the fabrication of biomaterials using all-aqueous droplets as liquid templates. We envision that this review will benefit the future development of all-aqueous droplet generation and its applications in developing biomaterials, which will be useful for researchers working in the field of all-aqueous systems and those who are new and interested in the field.

Selective separation of Cu, Ni and Ag from printed circuit board waste using an environmentally safe technique

Printed circuit boards (PCBs) make up a large part of e-waste and include high concentrations of high-value metals. Therefore, the recovery of these metals is interesting from both the environmental and economic points of view. Here, the extraction/separation of copper, nickel and silver from PCB leachate was studied using an aqueous two-phase system (ATPS) formed by triblock copolymers with an electrolyte and water, which is in compliance with the principles of green chemistry. The best conditions for the selective extraction consisted of 1-(2-pyridylazo)-2-naphthol (3.5 mmol kg^-1) at pH = 6.0 in 6 sequential steps for the Cu(II), dimethylglyoxime (5.00 mmol kg^-1) at pH = 9.0 for the Ni(II) and thiocyanate (5.20 mmol kg^-1) at pH = 9.0 for the Ag(I). These conditions were applied sequentially for extraction of Cu, Ni and Ag from the PCB leachate, obtaining high separation factor (S) values between the analyte and the metallic concomitants (S_Cu,Ni = 1,460, S_Cu,Fe = 15,500, S_Cu,Ag = 15,900, S_Ni,Fe = 32,700, S_Ni,Ag = 34,700 and S_Ag,Fe = 4800). The maximum extraction percentages (%E) for Cu, Ni and Ag were 99.9%, 99.9% and 99.8%, respectively. After the extraction, a single step stripping process was performed, resulting in more than 82% of the ion available in a clean lower phase. For the first time, an ATPS has been used for sequential extraction of several metal analytes from a real sample.

Aqueous Two-Phase Systems at Large Scale: Challenges and Opportunities

Aqueous two-phase systems (ATPS) have proved to be an efficient and integrative operation to enhance recovery of industrially relevant bioproducts. After ATPS discovery, a variety of works have been published regarding their scaling from 10 to 1000 L. Although ATPS have achieved high recovery and purity yields, there is still a gap between their bench-scale use and potential industrial applications. In this context, this review paper critically analyzes ATPS scale-up strategies to enhance the potential industrial adoption. In particular, large-scale operation considerations, different phase separation procedures, the available optimization techniques (univariate, response surface methodology, and genetic algorithms) to maximize recovery and purity and economic modeling to predict large-scale costs, are discussed. ATPS intensification to increase the amount of sample to process at each system, developing recycling strategies and creating highly efficient predictive models, are still areas of great significance that can be further exploited with the use of high-throughput techniques. Moreover, the development of novel ATPS can maximize their specificity increasing the possibilities for the future industry adoption of ATPS. This review work attempts to present the areas of opportunity to increase ATPS attractiveness at industrial levels.

Integration of Aqueous Two-Phase Extraction as Cell Harvest and Capture Operation in the Manufacturing Process of Monoclonal Antibodies

Substantial improvements have been made to cell culturing processes (e.g., higher product titer) in recent years by raising cell densities and optimizing cultivation time. However, this has been accompanied by an increase in product-related impurities and therefore greater challenges in subsequent clarification and capture operations. Considering the paradigm shift towards the design of continuously operating dedicated plants at smaller scales—with or without disposable technology—for treating smaller patient populations due to new indications or personalized medicine approaches, the rising need for new, innovative strategies for both clarification and capture technology becomes evident. Aqueous two-phase extraction (ATPE) is now considered to be a feasible unit operation, e.g., for the capture of monoclonal antibodies or recombinant proteins. However, most of the published work so far investigates the applicability of ATPE in antibody-manufacturing processes at the lab-scale and for the most part, only during the capture step. This work shows the integration of ATPE as a combined harvest and capture step into a downstream process. Additionally, a model is applied that allows early prediction of settler dimensions with high prediction accuracy. Finally, a reliable process development concept, which guides through the necessary steps, starting from the definition of the separation task to the final stages of integration and scale-up, is presented.