Primary capture of high molecular weight nucleic acids using aqueous two-phase systems

Water-in-water droplets selectively uptake self-assembled DNA nano/microstructures: a versatile method for purification in DNA nanotechnology

DNA is an excellent material for constructing self-assembled nano/microstructures. Owing to the widespread use of DNA as a building block in laboratories and industry, it is desirable to increase the efficiency of all steps involved in producing self-assembled DNA structures. One of the bottlenecks is the purification required to separate the excess components from the target structures. This paper describes a purification method based on the fractionation by water-in-water (W/W) droplets composed of phase-separated dextran-rich droplets in a polyethylene glycol (PEG)-rich continuous phase. The dextran-rich droplets facilitate the selective uptake of self-assembled DNA nano/microstructures and allow the separation of the target structure. This study investigates the ability to purify DNA origami, DNA hydrogels, and DNA microtubes. The W/W-droplet fractionation allows the purification of structures of a broad size spectrum without changes to the protocol. By quantifying the activity of deoxyribozyme-modified DNA origami after W/W-droplet purification, this study demonstrates that this method sufficiently preserves the accessibility to the surface of a functional DNA nanostructure. It is considered that the W/W-droplet fractionation could become one of the standard methods for the purification of self-assembled DNA nano/microstructures for biomedical and nanotechnology applications owing to its low cost and simplicity.

Enhancing the Sensitivity of DNA and Aptamer Probes in the Dextran/PEG Aqueous Two-Phase System

Increasing the local concentration of DNA-based probes is a convenient way to improve the sensitivity of biosensors. Instead of using organic solvents or ionic liquids that phase-separate with water based on hydrophobic interactions, we herein studied a classic aqueous two-phase system (ATPS) comprising polyethylene glycol (PEG) and dextran. Polymers of higher molecular weights and higher concentrations favored phase separation. DNA oligonucleotides are selectively enriched in the dextran-rich phase unless the pH was increased to 12. A higher volume ratio of PEG-to-dextran and a higher concentration of PEG also enrich more DNA probes in the dextran-rich phase. The partition efficiency of the T₁₅ DNA was enriched around seven times in the dextran phase when the volume ratio of dextran and PEG reached 1:10. The detection of limit improved by 3.6-fold in a molecular beacon-based DNA detection system with the ATPS. The ATPS also increased the sensitivity for the detection of Hg²⁺ and adenosine triphosphate, although these target molecules alone distributed equally in the two phases. This work demonstrates a simple method using water soluble polymers to improve biosensors.

Exploring New Horizons in Liquid Compartmentalization via Microfluidics

Spatial organization of cellular processes is crucial to efficiently regulate life's essential reactions. Nature does this by compartmentalization, either using membranes, such as the cell and nuclear membrane, or by liquid-like droplets formed by aqueous liquid-liquid phase separation. Aqueous liquid-liquid phase separation can be divided in two different phenomena, associative and segregative phase separation, of which both are studied for their membraneless compartmentalization abilities. For centuries, segregative phase separation has been used for the extraction and purification of biomolecules. With the emergence of microfluidic techniques, further exciting possibilities were explored because of their ability to fine-tune phase separation within emulsions of various compositions and morphologies and achieve one of the simplest forms of compartmentalization. Lately, interest in aqueous liquid-liquid phase separation has been revived due to the discovery of membraneless phases within the cell. In this Perspective we focus on segregative aqueous phase separation, discuss the theory of this interesting phenomenon, and give an overview of the evolution of aqueous phase separation in microfluidics.

Purification of a lectin from Cratylia mollis crude extract seed by a single step PEG/phosphate aqueous two-phase system

The partitioning and purification of lectins from the crude extract of Cratylia mollis seeds (Cramoll 1,4) was investigated in aqueous two-phase systems (ATPS). A factorial design model (2⁴) was used to evaluate the influence of polyethylene glycol (PEG) molar mass (1500-8000 g/mol), PEG concentration (12.5-17.5% w/w), phosphate (10-15% w/w) concentration, and pH (6-8) on the differential partitioning, purification factor, and yield of the lectin. Polymer and salt concentration were the most important variables affecting partition of lectin and used to find optimum purification factor by experimental Box-Behnken design together with the response surface methodology (RSM). ATPS showed best conditions composed by 13.9% PEG1500, 15.3% phosphate buffer at pH 6, which ensured purification factor of 4.70. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a single band of protein with 26.1 kDa. Furthermore, results demonstrated a thermostable lectin presenting activity until 60 °C and lost hemagglutinating activity at 80 °C. According to the obtained data it can be inferred that the ATPS optimization using RSM approach can be applied for recovery and purification of lectins.

The solvent side of proteinaceous membrane-less organelles in light of aqueous two-phase systems

Water represents a common denominator for liquid-liquid phase transitions leading to the formation of the polymer-based aqueous two-phase systems (ATPSs) and a set of the proteinaceous membrane-less organelles (PMLOs). ATPSs have a broad range of biotechnological applications, whereas PMLOs play a number of crucial roles in cellular compartmentalization and often represent a cellular response to the stress. Since ATPSs and PMLOs contain high concentrations of polymers (such as polyethylene glycol (PEG), polypropylene glycol (PPG), Ucon, and polyvinylpyrrolidone (PVP), Dextran, or Ficoll) or biopolymers (peptides, proteins and nucleic acids), it is expected that the separated phases of these systems are characterized by the noticeable changes in the solvent properties of water. These changes in solvent properties can drive partitioning of various compounds (proteins, nucleic acids, organic low-molecular weight molecules, metal ions, etc.) between the phases of ATPSs or between the PMLOs and their surroundings. Although there is a sizable literature on the properties of the ATPS phases, much less is currently known about PMLOs. In this perspective article, we first represent liquid-liquid phase transitions in water, discuss different types of biphasic (or multiphasic) systems in water, and introduce various PMLOs and some of their properties. Then, some basic characteristics of polymer-based ATPSs are presented, with the major focus being on the current understanding of various properties of ATPS phases and solvent properties of water inside them. Finally, similarities and differences between the polymer-based ATPSs and biological PMLOs are discussed.

Synchronized separation, concentration and determination of trace sulfadiazine and sulfamethazine in food and environment by using polyoxyethylene lauryl ether-salt aqueous two-phase system coupled to high-performance liquid chromatography

Polyoxyethylene lauryl ether (POELE10)-Na2C4H4O6 aqueous two-phase extraction system (ATPES) is a novel and green pretreatment technique to trace samples. ATPES coupled with high-performance liquid chromatography (HPLC) is used to analyze synchronously sulfadiazine (SDZ) and sulfamethazine (SMT) in animal by-products (i.e., egg and milk) and environmental water sample. It was found that the extraction efficiency (E%) and the enrichment factor (F) of SDZ and SMT were influenced by the types of salts, the concentration of salt, the concentration of POELE10 and the temperature. The orthogonal experimental design (OED) was adopted in the multi-factor experiment to determine the optimized conditions. The final optimal condition was as following: the concentration of POELE10 is 0.027gmL(-1), the concentration of Na2C4H4O6 is 0.180gmL(-1) and the temperature is 35°C. This POELE10-Na2C4H4O6 ATPS was applied to separate and enrich SDZ and SMT in real samples (i.e., water, egg and milk) under the optimal conditions, and it was found that the recovery of SDZ and SMT was 96.20-99.52% with RSD of 0.35-3.41%. The limit of detection (LOD) of this method for the SDZ and SMT in spiked samples was 2.52-3.64pgmL(-1), and the limit of quantitation (LOQ) of this method for the SDZ and SMT in spiked samples was 8.41-12.15pgmL(-1).

Coupling purification and in situ immobilization process of monoclonal antibodies to clenbuterol for immunosensor application

Clenbuterol (CL), which promotes the growth of muscular tissue and the reduction of body fat in pigs and cattle, has been confirmed to be a potential hazard to human health. In this study, a monoclonal antibody to clenbuterol (CL mAb) from a hybridoma culture supernatant was purified by an aqueous two-phase system (ATPS) at different polyethylene glycol (PEG) concentrations, PEG molecular weights, pH values, and NaCl concentrations. Then the CL mAb was immobilized in situ by directly adding polystyrene microspheres (PSMSs) into a PEG phase containing CL mAb. Using the immobilized antibody, an immunosensor was constructed to detect the CL residues in pork samples. The results showed that using an ATPS composed of 15% (w/w) PEG6000, 15% (w/w) phosphate, and 15% (w/w) NaCl at pH 8.0, the partition coefficient was 7.24, the activity recovery was 87.86%, and the purification fold was 2.88. The PEG-CL mAb-PSMS retained approximately 98% of its initial activity after 30-ml phosphate buffer (PBS) washings. After 30days of storage, the CL mAb-PSMS lost nearly 75% of its activity, whereas the PEG-CL mAb-PSMS retained as much as 95% of its initial activity. Furthermore, the constructed immunosensor obtained recoveries of 90.5 to 102.6% when applied to pork samples spiked with CL.

Redefinition of working aqueous two-phase systems: a generic description for prediction of the effective phase chemical composition for process control and biorecovery

Aqueous two-phase systems (ATPS) have been widely adopted for the combined purpose of solid liquid separation, and recovery and purification of bioproducts such as proteins, viruses and organelles from biological feedstocks and fermentation broth. However, in spite of potential advantages over other techniques applied to concentrated biological feedstocks, ATPS have been applied at process scale only by a few industries and research establishments. ATPS are sensitive to loading with modest to extreme quantities of biological feedstock due to the contribution of that material to phase formation in combination with the conventional phase-forming chemicals. This causes problem associated with the definition and manipulation of loaded working systems, which may be addresses as in the present study with the aid of distribution analysis of radiolabel led analytes (DARA) in representative process samples. The present study focussed on establishing a generic description for characterising ATPS loaded with biological feedstocks and the redefinition of the biological feedstock loaded system composition in terms of phase forming chemical equivalents. This evaluation will be useful to achieve ATPS process implementation where phase recycle/reuse is adopted without compromise to process operations and consistent protein recovery performance.