Ethylene Oxide-propylene Oxide Copolymer Research Articles

Amphiphilic star block copolymer micelles in saline as effective vehicle for quercetin solubilization

There has been an enormous interest in improving the therapeutic efficacy of hydrophobic flavonoids through enhancement of their bioavailability. A carrier capable to effectively solubilize flavonoids is expected to support the chemical/structural integrity of flavonoid molecule, and hence, its antioxidant properties. In this paper, the effectiveness of saline solutions of an amphiphilic star block ethylene oxide-propylene oxide copolymer (Tetronic®T904) has been investigated for solubilizing quercetin (QN). T904 self-assembles in aqueous solution above its critical micellization temperature (CMT) that depends on solution concentration, temperature, pH and presence of salt. We have studied the solubilization of QN in T904 micelles at different temperature, concentration and salt (sodium chloride) concentration using scattering and spectral techniques. Our findings suggest that, at a given temperature, QN solubility is influenced by the concentration of salt and copolymer. When compared to its linear counterparts (the Pluronics®), T904 solutions offered superior solubilization. 2D NOESY NMR observations revealed that QN occupied the periphery of the hydrophobic core of micelles. Such an environment can protect the drug against oxidation in aqueous phase.

Investigation of organic additives to regulate growth and signal transmission loss of copper interconnection structure

<p indent=0mm>Signal integrity is severely limited by the copper roughness. Plating solution containing different organic additives could influence the roughness of electroplating copper growth. Molecular simulation and electrochemical tests were used to regulate the competitive adsorption behavior of organic additives on the copper surface and understand the possible mechanism on the difference of copper growth. The results show that the plating solution system containing bis-(sodium sulfopropyl)-disulfide (SPS), ethylene oxide-propylene oxide copolymer (EO/PO) and Janus Green B (JGB) can contribute to the copper growth with smooth surface, leading to insertion loss of <sc>−8.9 dB@20 GHz.</sc> Therefore, organic additives could be used to regulate the low-profile growth of copper interconnection structure and reduce transmission loss to effectively ensure the integrity of high-frequency signal transmission.

Purification of xylanase from Aspergillus niger NRRL3 extract by an integrated strategy based on aqueous two-phase systems followed by ion exchange chromatography

Xylanases are enzymes that degrade the linear polysaccharide xylan into xylose, thus breaking down hemicellulose, one of the major components of plant cell walls. Xylanases are applied in a wide range of industrial processes, such as in the pulp and paper industry, which demands a higher purity degree compared to other industries. Processes for the purification of this enzyme has been widely reported using different techniques. However, cases involving the use of a simple combination of unit operations are not common. The objective of this work was to design an integrated bioseparation strategy for the purification of a fungal cellulase-free xylanase. The design consisted of a liquid-liquid extraction using two-combined aqueous two-phase system (ATPS) with an ion exchange chromatography. The effect of different parameters such as polymer type (ethylene oxide-propylene oxide copolymer (UCON) and polyethylene glycol (PEG)), PEG molecular mass (600, 1450, 2000 and 4600 g/mol), volume ratio and the addition of sodium chloride on the enzymes -from the Aspergillus niger NRRL3 extract- partition coefficient were analyzed. The partition behavior of the target product was affected for the type and molecular mass of the polymer used. Extraction using UCON/Citrate system combined with a second extraction using PEG1450/Citrate system proved to be the most suitable for the extraction of xylanase and natural fungal pigments. The enzymatic activity recovery and purification factor achieved were 80% and 4, respectively. The proposed systems have the ability to recycle the UCON and Citrate salt for their reuse in new ATPS. The phases of the combined extraction by ATPS and the elution obtained from ion exchange chromatography were characterized by nano-LC–MS/MS, providing a complete profile of the proteins present. The combination of ATPS with ion exchange chromatography using a Q-Sepharose XL column reached a total enzymatic activity recovery of 79.9% and a purification factor of 11. This is the first time that high-quality xylanase free of cellulolytic enzymes is reported using an integrated bioprocess strategy with potential for industrial adoption.

Extraction and preliminary purification of polysaccharides from Camellia oleifera Abel. seed cake using a thermoseparating aqueous two-phase system based on EOPO copolymer and deep eutectic solvents

A thermoseparating aqueous two-phase system (ATPS) based on ethylene oxide-propylene oxide (EOPO) copolymer and deep eutectic solvents (DES) was developed for the extraction and preliminary purification of polysaccharides in Camellia oleifera Abel. seed cake. DESs were used as the extraction media for obtaining the crude extract. The maximum extraction yield (Y) of polysaccharides was 152.37 mg/g in the crude extract. Then the crude polysaccharides were extracted and preliminary purified by EOPO/DES ATPS. The maximum extraction efficiency (E.E.) of polysaccharides was 86.91% in EOPO-rich phase by the first ATPS extraction. The EOPO-rich phase was separated and the polysaccharides were recovered by temperature-induced phase separation. The maximum recovery efficiency (R.E.) was 84.92% in aqueous phase by the second ATPS extraction. This thermoseparating ATPS possesses the merits of good environment-friendlies, simple operation, and easy recovery of components, which can be used as an efficient method for the extraction and separation of polysaccharides.

Performance evaluation of a thermoresponsive polyelectrolyte draw solution in a pilot scale forward osmosis seawater desalination system

The current study assesses the technical feasibility of using a thermoresponsive polyelectrolyte draw solution (DS) in a Forward Osmosis (FO) desalination pilot scale system of 10 m3/day capacity. The FO system utilized a commercial spiral wound hollow fiber FO membrane and ethylene oxide-propylene oxide copolymer as DS. This study evaluated the effect of DS flow rate and feed solution flow rates on the net water recovery and product water flow rates of the system. The osmotic pressure distribution of polyelectrolyte DS at different sections of the HF module was greatly influenced by DS flow rate. The study revealed that the DS had great potential to generate the high osmotic pressure (Δπ) difference in the various compartments of the HF module. The reliability of the FO pilot plant was proved over a long run without any severe FO membrane fouling with total dissolved solids of product water at 143 ppm and water recovery of 30%. The selected DS showed its potentiality towards the installation of commercial-scale FO desalination plant by witnessing its low viscosity and easy phase separation at a moderately lower temperature of 85 °C in the coalesce DS regeneration system.

Effects of non-ionic surfactants on formation kinetics of structure H hydrate regarding transportation and storage of natural gas

Clathrate hydrates are one of the proposed mediums for transportation and storage of natural gas. Among the known hydrate structures, structure H seems the most fitting crystal due to its moderate formation pressure and high storage capacity. In the present work, the kinetics of methane hydrate formation is investigated in a high pressure batch stirred reactor with and without additives. Methylcyclohexane (MCH), methylcyclopentane (MCP) and tertbutylmethylether (TBME) were used as large molecule guest substance (LMGS). The effects of one anionic and five non-ionic surfactants on hydrate promotion at 2 °C and 55 bar pressure are experimentally investigated. These surfactants belong to the family of Nonyl Phenol Ethoxylates (NPE), Lauryl Alcohol Ethoxylates (LAE), Ethylene Oxide/Propylene Oxide copolymer (EO/PO), polyoxyethylene sorbitan mono palmitate (Tween®), Butyl Phenol ethoxylates (Triton™X100) and Sodium alkyl sulfate. The results show that while the system with MCH and MCP exhibit high induction times and low formation rates, addition of surfactants can intensely decrease the induction times and increase the formation rates. Among the studied surfactants, Triton™X100 and NPE6EO are the best kinetic promoters of structure H methane hydrate, resulting more than 500% increase in the hydrate formation rate. Also effects of non-ionic surfactants on MCP and TBME follow the same trend. Finally, systems containing two LMGSs (e.g. MCH+TBME) were tested and proved to be better candidates for storage and transportation of natural gas in sH hydrated form.

Experimental investigation on structure H hydrates formation kinetics: Effects of surfactants on interfacial tension

Among the known gas hydrate structures, structure H (sH) is the most fitting crystal for storage and transportation of natural gas due to its moderate formation pressure and high storage capacity. In the present work, the kinetics of methane (as help gas) hydrate formation is investigated in a high pressure batch stirred reactor with and without additives. Methylcyclohexane (MCH), methylcyclopentane (MCP) and tertbutylmethylether (TBME) were used as large molecule guest substance (LMGS). The effects of five surfactants on sH hydrate promotion are experimentally investigated. These surfactants belong to the family of Nonyl Phenol Ethoxylates (NPE), Lauryl Alcohol Ethoxylates (LAE), Ethylene Oxide/Propylene Oxide copolymer (EO/PO), polyoxyethylene sorbitan mono palmitate (Tween), Butyl Phenol ethoxylates (TritonX100) and Sodium alkyl sulfate. The results show that while the system with MCH and MCP exhibit high induction times and low formation rates, addition of surfactants can highly decrease the induction times and increase the formation rates. Investigation of the Liquid/Liquid (L/L) interfacial tension (IFT) of these systems in their pure state and in present of surfactants indicates that IFT plays an important role in the kinetic promotion of these systems. Studied surfactants can reduce L/L IFTs dramatically. Furthermore our results indicate that, in general, the systems with lower interfacial tension tend to have higher hydrate formation rates and lower induction times. Among the studied surfactants, TritonX100 and NPE6EO are the best kinetic promoters of structure H methane hydrate. The rate of hydrate formation in MCH system is increased more than 400% and the induction time is lowered to 0.05 its original value. Also effects of non-ionic surfactants on MCP and TBME follow the same trend.

Kinetic promotion of non-ionic surfactants on cyclopentane hydrate formation

Clathrate hydrates are among the most important cold storage materials studied which are known to enhance the coefficient of performance in air conditioning systems. In the present work, the kinetics of cyclopentane (CP) hydrate formation is investigated in an atmospheric stirred reactor, with and without additives. The effects of 14 surfactants and polymers on hydrate promotion are experimentally investigated. These surfactants and polymers belong to the family of Nonyl Phenol ethoxylates (NPE), Lauryl Alcohol Ethoxylates (LAE), Poly Ethylene Glycols (PEG), Ethylene Oxide/Propylene Oxide copolymer (EO/PO), polyoxyethylene sorbitan monopalmitate (Tween), butyl phenol ethoxylates (TritonX-100), and sodium alkyl sulfate. The results indicate that while the CP/water system exhibits high induction time and low formation rate, addition of surfactants can highly decrease the induction time and increase the formation rate. Among the studied surfactants, LAE8EO, TritonX-100 and NPE6EO were the best. The rate of hydrate formation is increased 1533% and the induction time is lowered to 0.04 its original value. Also our studies show that surfactants that form oil in water emulsions in general can promote hydrate formation better than surfactant that forms water in oil emulsions. For better understanding of the promotion mechanism, the interfacial tension (IFT) of CP/water, in the presence of some surfactants, is measured. Results show that addition of TritonX-100 can lower the CP/water IFT from 31.6 to 2.1mN/m. The IFT data along with a simple mass transfer analysis are utilized to uncover the CP hydrate promotion mechanism.

Synergetic effects of polyacrylamide and nonionic surfactants on preventing gas hydrate formation

The aim of this work is to conduct an experimental investigation on the synergetic influence of polyacrylamide (PAM), some non-ionic surfactants and polymers on the ethane hydrate formation kinetics. The surfactants and polymers used in the experiments belong to the family of nonylphenol ethoxylates (NPE), lauryl alcohol ethoxylates (LAE), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and ethylene oxide/propylene oxide copolymer (EO/PO). All experiments have been performed in an isochoric batch reactor under high pressure conditions. It is found that synergism of PAM and surfactants exhibits strong inhibition of ethane hydrate at experimental subcooling temperature of 10.5 °C. The experimental studies prove that the synergism of a very low dosage of PAM and surfactants not only delays the induction time but also dramatically lowers the hydrate formation rate.

Experimental study on the rheology of anisotropic, flocculated and low volume fraction colloids

In this work, we have investigated rheological behavior of colloids with a low particle volume fraction, and anisotropic and flocculated microstructures through measuring their viscosity and electrical resistance under varying shear rates together with utilizing several relevant characterization methods (i.e., Dynamic Light Scattering, Transmission Electron Microscopy, Atomic Force Microscopy, and Capacitance and Electrical resistance measurements). The colloids are formed through the suspension of hydrophilic/phobic fumed silica particle with attractive/repulsive interaction in polyethylene glycol and/or ethylene oxide-propylene oxide copolymer. It is observed that studied suspensions display shear thickening/thinning flow behavior depending on their microstructure (the spatial distribution and arrangements of particles in continuous media) and associated changes in cluster sizes, which are controlled by the break down of densified clusters (due to the shear induced mechanical and hydrodynamical forces) and the interaction forces among particleparticle and particles-polymers (owing to physicochemical effects). The detailed evaluation of the experimental results indicates that the shear thickening phenomena in low volume fraction, anisotropic and flocculated systems can be mainly attributed to the increase in the effective volume fraction of particles due to both hydrodynamic and physicochemical forces.

Plating Uniformity of Bottom-up Copper Pillars and Patterns for IC Substrates with Additive-assisted Electrodeposition

Electrochemical behaviors of the base electrolyte containing different additives were investigated by galvanostatic potential transient measurements (GM), cyclic voltammetry tests (CV) and potentiostatic measurements. Copper deposits on sputtering copper seed from physical vapor deposition (PVD) were examined by a scanning electron microscope and X-ray diffraction spectra. Cross sections of copper pillars and fine line patterns were observed by metallographic microscope. GM result revealed ethylene oxide-propylene oxide co-polymer (EO/PO) performed a further inhibition on copper deposition in the presence of 60ppm chloride ions as the increment of EO/PO concentration. GM, CV and potentiostatic results indicated that copper deposition was accelerated by synergetic effects of additives in the base electrolyte containing 60ppm chloride ions, 20mg/L EO/PO and 0.7mg/L bis-(sodium sulfopropyl)-disulfide. Sputtering PVD copper seed with even deposit surface was recommended to form the uniformity of copper deposition through increasing the growing density of copper particles. Oscillatory was employed to form uniform distribution of copper deposits in thickness. Copper grain growth was preferentially [111] textured. Bottom-up copper pillars and fine line patterns with plating uniformity were fabricated to meet the requirement of an accurate impedance and the high density interconnection for IC substrates.

Influence of Structural Variations of Demulsifiers on their Performance

Chemical demulsification is the most widely used method for breaking water-in-diluted bitumen emulsions in oil sands processing. In this work, the properties and performance of six samples of ethylene oxide (EO)—propylene oxide (PO) block copolymer demulsifiers from two families were investigated. The demulsifiers were characterized by their relative solubility number (RSN), EO content, PO content, and molecular weight (MW). The results showed that the performance of the demulsifiers is correlated to the starting base compound, EO content, PO content, RSN, MW, degree of cross-linking, interfacial tension (IFT), yield stress of underflow, and bitumen loss. Demulsifiers with higher MW and more EO–PO branching had higher dehydration efficiencies when the EO content was varied from 0% to 40% at constant PO content. An increase in MW by cross-linking EO–PO copolymers improved the dehydration efficiency. In this work, an appropriate rheological method was developed to correlate the properties of the demulsifiers with the properties of the underflow. The yield stress of the underflow, including settled solids, water, and the rag layer, increased with increasing RSN value and dosage of demulsifier. At high dosages, the yield stress values were high because of an increased number of aggregates, which, in turn, restricted underflow. An increase in the RSN value of the demulsifiers led to more bitumen loss to the underflow, which increased the size of the aggregates present in the underflow, resulting in increased immobility and constriction and higher yield stress.

Partitioning of lysozyme in aqueous two-phase systems containing ethylene oxide-propylene oxide copolymer and potassium phosphates

Lysozyme partitioning in EO50PO50/potassium phosphate aqueous two-phase systems (ATPS) was studied. In the work, the influence of EO50PO50, potassium phosphate and sodium chloride concentration in the ATPS on lysozyme partition coefficient and separation yield was examined. In addition, the influence of the pH of potassium phosphate solution was also investigated. A Box–Behnken design was defined, and response surface models for the partition coefficient K and percentage yield of the enzyme in the top phase Y were calculated. Among the examined factors, the NaCl concentration had the highest influence on lysozyme separation parameters. This influence can be explained mainly by the hydrophobic interactions between the protein and the phase-forming components. A maximum partition coefficient KL1, yield YL1 and YL2 were predicted for EO50PO50, potassium phosphate and NaCl concentrations of 17.40, 22.67% and 0.85mol/l, respectively, and for pH 9.0. A good agreement was obtained between the experimental and the predicted results.

Compositional Analysis of the High Molecular Weight Ethylene Oxide-Propylene-Oxide Copolymer by MALDI Mass Spectrometry

The composition of narrow distribution poly ethylene oxide-propylene oxide copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide copolymer produced oligomers separated by 14 Da. The average resolving power over the entire spectrum was 28,000. Approximately 448 isotopically resolved peaks representing about 56 oligomers are identified. Although agreement between experimental and calculated isotopic distributions was strong, the compositional assignment was difficult. This is due to the large number of possible isobaric components. The purpose of this research is to resolve and study the composition of high mass copolymer such as ethylene oxide-propylene oxide.

Primary recovery of lipase derived from Burkholderia cenocepacia strain ST8 and recycling of phase components in an aqueous two-phase system

The recovery of Burkholderia cenocepacia ( B. cenocepacia) strain ST8 lipase has been investigated using a recycling aqueous two-phase system (ATPS) consisting of the thermoseparating random copolymer ethylene oxide–propylene oxide (EOPO) and potassium phosphate. In the primary ATPS, lipase was satisfactorily partitioned to the polymer-rich top phase in the system composed of EOPO 3900 with a tie-line length (TLL) of 48.5% (w/w), a volume ratio ( V R ) of 2.3 and a crude load of 20% (w/w) at pH 7. In the secondary system, the polymer-rich top phase from the primary ATPS was isolated and subjected to thermo-induced phase separation. After thermoseparating, a concentrated solution of EOPO copolymer was formed in the bottom phase, and a water solution containing lipase was formed in the top phase of this secondary two-phase system. Recycling of the components was accomplished by mixing the concentrated polymer recovered from the secondary system and the phosphate solution recovered from the primary system. The average purification factor of lipase and the yield obtained from the four successive purifications were 14 and 99%, respectively. There was no significant difference in the purification factor, yield or partitioning efficiency of purified lipase obtained using fresh or recycled chemicals in the ATPS.

Experimental Study of Surfactant Retention on Kaolinite Clay

Abstract We measured equilibrium surfactant retention on kaolinite clay for a large array of surfactants. We demonstrate that the mass balance measurements we used are a rapid way to screen surfactants in terms of their potential to be used in enhanced oil recovery applications. Surfactant classes investigated include: alkyl(aryl) sulfonates, ethylene oxide-propylene oxide copolymers, ethoxylated alkylphenols, alkyl polyglucosides, sorbitan ester ethoxylates, alkyl alcohol propoxylated sulfate sodium salts, gemini surfactants, sulfosuccinates and organo silicone-ethylene oxide-propylene oxide terpolymers. We identified several surfactants which had zero retention under the test conditions and which may therefore be suitable as enhanced oil recovery chemicals in surfactant flooding schemes. We discuss surfactant retention mechanisms on kaolinite clay and analyze surfactant structure-retention relationships for several surfactant classes.

Abstracts: Polyoxyethylene/polyoxypropylene dimethyl ether improves the structure of intercellular lipids in SDS‐induced dry skin

pp. 39–48 The dimethyl ether of an amphiphilic random ethylene oxide/propylene oxide copolymer (EPDME) is useful for the preparation of finely dispersed micro‐emulsions. We examined whether EPDME is effective for skin moisturization by means of electron paramagnetic resonance (EPR) studies of ex vivo specimens of stratum corneum (SC) obtained by successive stripping. The values of the order parameter S obtained by EPR measurement indicated that EPDME treatment improved sodium dodecyl sulfate (SDS)‐induced disruption of SC lipid structures. This effect appeared to be related to improved hydration of the epidermis, not occlusion by EPDME, since there was no significant change in transepidermal water loss (TEWL).

Removal of polyether-polyols by means of ultrafiltration

The removal of diethyleneglycol (DEG) and several polyether-polyols of different molecular weights and nature by ultrafiltration was studied. These polyether-polyols are polyethyleneglycols (PEG) of different molecular weights (800 and 6,000) and two ethylene oxide-propylene oxide copolymers: Pluronic PE6100 and Alcupol F4811. Rejection coefficients and permeate fluxes were measured for these compounds and for mixtures of PEG-6000+SDS, glycols + Pluronic and glycols + Alcupol. The main purpose of working with these mixtures is to study how the addition of SDS, Pluronic or Alcupol can enhance rejection coefficients observed for total organic matter present in the target effluent. In a first stage, 0.1% w/w solutions of DEG, PEG-800 and PEG-6000 were ultrafiltered using a CARBOSEP M5 ceramic membrane (MWCO = 10 kDa). No significant retention was obtained for DEG and PEG-800, but for PEG-6000, rejection coefficients higher than 80% were reached. The effects of temperature, transmembrane pressure and feed rate on both permeate flux and rejection coefficient were also studied. Secondly, the same procedure was followed for 0.1% w/w solutions of Alcupol and Pluronic, obtaining rejection coefficients of almost 100%. With respect to the above-mentioned mixtures, total organic carbon (TOC) retention was not enhanced by the addition of either SDS or Pluronic. However, a clear increase was obtained for TOC rejection when Alcupol was added due to the distribution of the PEG-6000 molecules between the aqueous phase and the organic phase formed by the Alcupol emulsion.

A novel two-step extraction method with detergent/polymer systems for primary recovery of the fusion protein endoglucanase I–hydrophobin I

Extraction systems for hydrophobically tagged proteins have been developed based on phase separation in aqueous solutions of non-ionic detergents and polymers. The systems have earlier only been applied for separation of membrane proteins. Here, we examine the partitioning and purification of the amphiphilic fusion protein endoglucanase I core–hydrophobin I (EGI core–HFBI) from culture filtrate originating from a Trichoderma reesei fermentation. The micelle extraction system was formed by mixing the non-ionic detergent Triton X-114 or Triton X-100 with the hydroxypropyl starch polymer, Reppal PES100. The detergent/polymer aqueous two-phase systems resulted in both better separation characteristics and increased robustness compared to cloud point extraction in a Triton X-114/water system. Separation and robustness were characterized for the parameters: temperature, protein and salt additions. In the Triton X-114/Reppal PES100 detergent/polymer system EGI core–HFBI strongly partitioned into the micelle-rich phase with a partition coefficient ( K) of 15 and was separated from hydrophilic proteins, which preferably partitioned to the polymer phase. After the primary recovery step, EGI core–HFBI was quantitatively back-extracted ( K EGIcore–HFBI=150, yield=99%) into a water phase. In this second step, ethylene oxide–propylene oxide (EOPO) copolymers were added to the micelle-rich phase and temperature-induced phase separation at 55°C was performed. Total recovery of EGI core–HFBI after the two separation steps was 90% with a volume reduction of six times. For thermolabile proteins, the back-extraction temperature could be decreased to room temperature by using a hydrophobically modified EOPO copolymer, with slightly lower yield. The addition of thermoseparating co-polymer is a novel approach to remove detergent and effectively releases the fusion protein EGI core–HFBI into a water phase.

Cutinase–peptide fusions in thermoseparating aqueous two-phase systems: Prediction of partitioning and enhanced tag efficiency by detergent addition

It is of increasing importance to develop efficient purification methods for recombinant proteins where the number of steps can be minimised. The aim has been to establish a method for predicting the partitioning of the wild-type target protein in an aqueous two-phase system, and with this as basis, develop fusion tags and optimise the phase system for enhanced partitioning of the target protein. The surface of the lipolytic enzyme cutinase from Fusarium solani pisi was investigated with a computer program, Graphical Representation and Analysis of Surface Properties (GRASP). The accessible surface areas for the different amino acid residues were used together with peptide partitioning data to calculate the partition coefficient for the protein. The separation system was composed of a thermoseparating random copolymer of ethylene oxide and propylene oxide, Breox PAG 50A 1000, as top phase forming polymer and a hydroxypropyl starch polymer, Reppal PES 200, as bottom phase polymer. The calculated partition coefficient for the wild-type protein ( K=1.0) agreed reasonably well with the experimentally determined value ( K=0.85). Genetic engineering was used to construct fusion proteins expressed in Saccharomyces cerevisiae based on cutinase and peptide tags containing tryptophan, to enhance the partitioning in aqueous two-phase systems. The partitioning of the cutinase constructs could qualitatively be predicted from peptide partitioning data, i.e. the trends in partitioning could be predicted. A spacer peptide introduced between protein and tag increased the partitioning of the protein towards the ethylene oxide–propylene oxide (EOPO) copolymer top phase. The aqueous two-phase system was modified by addition of detergent to increase the partitioning of the cutinase variants towards the EOPO copolymer phase. Triton and a series of C 12E n detergents selectively increased the partitioning of cutinase constructs with (WP) 4-based tags up to 14 times compared to wild-type cutinase. The protein partition could almost quantitatively be predicted from the peptide partition data.