Thermoseparating aqueous two-phase systems: Recent trends and mechanisms

Thermosensitive polymer-assisted extraction and purification of fungal laccase from citrus pulp wash effluent

BACKGROUND

This study explores the use of liquid-liquid extraction with thermosensitive polymers for producing laccase (Lac) from Pleurotus sajor-caju. This process leverages liquid waste from the citrus industry, specifically pulp wash. The research delves into extractive fermentation and thermoseparation, both processes being facilitated by a polymer exhibiting a lower critical solution temperature transition.

RESULTS

Key factors considered include the choice of polymer, its concentration, pH, separation temperature, and the behavior of the polymer-rich phase post-extractive fermentation concerning the lower critical solution temperature. Notably, under conditions of 45% by weight of Pluronic L-61 and pH 5.0 at 25 °C, the Lac resulted in an enhancement in the purification factor of 28.4-fold, compared with the Lac obtained directly from the fermentation process on the eighth day. There was an 83.6% recovery of the Lac enzyme in the bottom phase of the system. Additionally, the unique properties of Pluronic L-61, which can induce phase separation and also allow for thermoseparation, led to a secondary fraction (aqueous solution) of Lac with purification factor of 2.1 ± 0.1-fold (at 32 ± 0.9 °C and 30 ± 0.3 min without stirring) from the polymeric phase (top phase). Fourier-transform infrared analysis validated the separation data, particularly highlighting the α-helix content in the amide I region (1600-1700 cm-1 ).

CONCLUSION

In summary, the insights from this study pave the way for broader industrial applications of these techniques, underscoring benefits like streamlined process integration, heightened selectivity, and superior separation efficacy. © 2023 Society of Chemical Industry.

Up/Down Tuning of Poly(ionic liquid)s in Aqueous Two-Phase Systems

Thermally induced reversible up/down migration of poly(ionic liquid)s (PILs) in aqueous two-phase systems (ATPSs) was achieved for the first time in this study. Novel ATPSs were fabricated using azobenzene (Azo)- and benzyl (Bn)-modified PILs, and their upper and lower phases could be easily tuned using the grafting degree (GD) of the Azo and Bn groups. Bn-PIL with higher GD_Bn could go up into the upper phase and Azo-PIL come down to the lower phase when the temperature increased (>65 °C); this behavior was reversed at lower temperatures. Moreover, a reversible two-phase/single-phase transition was realized under UV irradiation. Experimental and simulation results revealed that the difference in the hydration capacity between Bn-PIL and Azo-PIL accounted for their unique phase-separation behavior. A versatile platform for fabricating ATPSs with tunable stimuli-responsive behavior can be realized based on our findings, which can broaden their applications in the fields of smart separation systems and functional material development.

Downstream processing of virus-like particles with aqueous two-phase systems: applications and challenges

The advancement of recombinant virus-like particle-based vaccines has attracted global attention owing to substantially safety and high efficacy in provoking a protective immunity against various chronic and infectious diseases in humans and animals. A robust, low-cost and scalability separation and purification technology is of utmost importance in the downstream processing of recombinant virus-like particles to produce affordable and safe vaccines. Being a relatively simple, environmentally friendly and efficient biomolecules recovery approach, aqueous two-phase systems have received great attention from researchers worldwide. This review aims to highlight the challenges and outlook in addition to the current applications of aqueous two-phase systems in downstream processing of virus-like particles. The efforts will confidently reinforce scholars' knowledge and fill in the valuable research gap in the aspect of concerning recombinant virus-like particle-based vaccines development, particularly related to the virus-like particles downstream production processes. This article is protected by copyright. All rights reserved.

Producing fucoxanthin from algae - Recent advances in cultivation strategies and downstream processing

Fucoxanthin, a brown-colored pigment from algae, is gaining much attention from industries and researchers recently due to its numerous potential health benefits, including anti-oxidant, anti-cancer, anti-obesity functions, and so on. Although current commercial production is mainly from brown macroalgae, microalgae with rapid growth rate and much higher fucoxanthin content demonstrated higher potential as the fucoxanthin producer. Factors such as concentration of nitrogen, iron, silicate as well as light intensity and wavelength play a significant role in fucoxanthin biosynthesis from microalgae. Two-stage cultivation approaches have been proposed to maximize the production of fucoxanthin and other valuable metabolites. Sustainable fucoxanthin production can be achieved by using low-cost substrates as a culture medium in an open pond cultivation system utilizing seawater with nutrient recycling. For downstream processing, the integration of novel "green" solvents with other extraction techniques emerged as a promising extraction technique.

Effective extraction of tylosin and spiramycin from fermentation broth using thermo-responsive ethylene oxide/propylene oxide aqueous two-phase systems

Recyclable aqueous two-phase systems with thermo-responsive phase-forming materials have been employed to separate macromolecules; however, these systems have achieved very limited separation efficiency for small molecules, such as antibiotics. In this study, aqueous two-phase systems composed of the ethylene oxide/propylene oxide copolymer and water were developed to extract alkaline antibiotics from the fermentation broth. In the aqueous two-phase systems with an ethylene oxide ratio of 20 and propylene oxide ratio of 80, the partition coefficients of tylosin and spiramycin reached 16.87 and 20.39, respectively, while the extraction recoveries were 70.67 and 86.70%, respectively. Coupled with mechanism analysis, we demonstrated the feasibility of extracting alkaline antibiotics using this aqueous two-phase system, especially for 16-membered macrolide antibiotics. The molecular dynamic simulation was employed to visualize the process of dual-phase formation and the partition behavior of antibiotics in an aqueous two-phase system. The dynamic simulation revealed the binding energy between the antibiotic and ethylene oxide/propylene oxide copolymers, which provides a simple indicator for screening suitable antibiotics in aqueous two-phase systems. Our recyclable aqueous two-phase systems provide a robust approach for the extraction of 16-membered macrolide antibiotics with ease of operation and high recovery rates, which is appropriate for large-scale extraction in the fermentation industry.

Homogeneous liquid-liquid extraction as an alternative sample preparation technique for biomedical analysis

Liquid-liquid extraction is a widely used technique of sample preparation in biomedical analysis. In spite of the high pre-concentration capacities of liquid-liquid extraction, it suffers from a number of limitations including time and effort consumption, large organic solvent utilization, and poor performance in highly polar analytes. Homogeneous liquid-liquid extraction is an alternative sample preparation technique that overcomes some drawbacks of conventional liquid-liquid extraction, and allows employing greener organic solvents in sample treatment. In homogeneous liquid-liquid extraction, a homogeneous phase is formed between the aqueous sample and the water-miscible extractant, followed by chemically or physically induced phase separation. To form the homogeneous phase, aqueous samples are mixed with water-miscible organic solvents, water-immiscible solvents/cosolvents, surfactants, or smart polymers. Then, phase separation is induced chemically (adding salt, sugar, or buffer) or physically (changing temperature or pH). This mode is rapid, sustainable, and cost-effective in comparison with other sample preparation techniques. Moreover, homogeneous liquid-liquid extraction is more suitable for the extraction of delicate macromolecules such as enzymes, hormones, and proteins and it is more compatible with liquid chromatography with tandem mass spectrometry, which is a vital technique in metabolomics and proteomics. In this review, the principle, types, applications, automation, and technical aspects of homogeneous liquid-liquid extraction are discussed.

Liquid Biphasic System: A Recent Bioseparation Technology

A well-known bioseparation technique namely liquid biphasic system (LBS) has attracted many researchers’ interest for being an alternative bioseparation technology for various kinds of biomolecules. The present review begins with an in-depth discussion on the fundamental principle of LBS and this is followed by the discussion on further development of various phase-forming components in LBS. Additionally, the implementation of various advance technologies to the LBS that is beneficial towards the efficiency of LBS for the extraction, separation, and purification of biomolecules was discussed. The key parameters affecting the LBS were presented and evaluated. Moreover, future prospect and challenges were highlighted to be a useful guide for future development of LBS. The efforts presented in this review will provide an insight for future researches in liquid-liquid separation techniques.

Thermo-separating polymer-based aqueous two-phase systems for the recovery of PEGylated lysozyme species

Fractionation of native, mono and di-PEGylated lysozyme was performed in 36 different polymer-polymer aqueous two-phase systems using UCON as a phase-forming component. After a discrete partition analysis, dextran 75 kDa-UCON, volume ratio 3, tie-line length 35% w/w; ficoll 70 kDa-UCON, volume ratio 1, tie-line length 45% w/w and a PEG 8 kDa-UCON volume ratio 3, tie-line length 65% w/w systems were selected for optimization via salt addition and to observe the behavior of the lysozyme species in mixtures. The dextran-UCON and the PEG-UCON systems with 75 mM NaCl showed effectiveness in separating 75% and 87% of mono-PEGylated lysozyme from the rest of the lysozyme species in the top and bottom phases, respectively. These results are an advancement in incorporating these extractions in different processes since the use of UCON simplifies the removal of the polymers, providing the opportunity of recycling it to the operation.

Ionophore-Based Titrimetric Detection of Alkali Metal Ions in Serum

While the titrimetric assay is one of the most precise analytical techniques available, only a limited list of complexometric chelators is available, as many otherwise promising reagents are not water-soluble. Recent work demonstrated successful titrimetry with ion-exchanging polymeric nanospheres containing hydrophobic complexing agents, so-called ionophores, opening an exciting avenue in this field. However, this method was limited to ionophores of very high affinity to the analyte and exhibited a relatively limited titration capacity. To overcome these two limitations, we report here on solvent based titration reagents. This heterogeneous titration principle is based on the dissolution of all hydrophobic recognition components in a solvent such as dichloromethane (CH₂Cl₂) where the ionophores are shown to maintain a high affinity to the target ions. HSV (hue, saturation, value) analysis of the images captured with a digital camera provides a convenient and inexpensive way to determine the end point. This approach is combined with an automated titration setup. The titrations of the alkali metals K⁺, Na⁺, and Li⁺ in aqueous solution are successfully demonstrated. The potassium concentration in human serum without pretreatment was precisely and accurately determined as 4.38 mM ± 0.10 mM (automated titration), which compares favorably with atomic emission spectroscopy (4.47 mM ± 0.20 mM).

Determination of photoinitiator 4-methylbenzophenone in milk by cloud point extraction

An efficient and easy sample pretreatment methodology was proposed for the detection of photoinitiator 4-methylbenzophenone from milk before high-performance liquid chromatography. Appropriate conditions for demulsification were studied. The parameters affecting cloud point extraction, such as concentration of Tween-20, electrolyte salt, equilibration temperature, and time, have been investigated. When the spiked level was 200-1000 μg/kg, the average addition standard recovery was 99.14-105.98% with the optimum cloud point extraction conditions (concentration of Tween-20, 138 g/L; mass of anhydrous sodium sulfate, 0.75 g; equilibration temperature, 65°C; equilibration time, 30 min). To decrease the detection limits, further work about the organic solvent, shaking time, and ultrasonic parameters was carried. When the spiked level was 10-100 μg/kg, the average addition standard recovery was 70.40-106.91% with the optimum cloud point extraction and enrichment conditions (optimum cloud point extraction conditions; volume of cyclohexane, 30 mL; shaking time, 20 min; time of ultrasonic, 20 min; temperature of ultrasonic bath, 45°C).