Computational design and preparation of water-compatible noncovalent imprinted microspheres.

Herein, 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model template in a rational design strategy to produce water-compatible noncovalent imprinted microspheres. The proposed approach involved computational modelling for screening functional monomers and a simple method for preparing monodisperse and highly cross-linked microspheres. The fabricated non-imprinted polymer (NIP) and 2,4-d-imprinted polymer (2,4-d-MIP) were characterised, and their adsorption capabilities in an aqueous environment were evaluated. Results reveal that the pseudo-second-order kinetics model was appropriate for representing the adsorption of 2,4-D on NIP and 2,4-d-MIP, with R2 values of 0.97 and 0.99, respectively. The amount of 2,4-D adsorbed on 2,4-d-MIP (97.75 mg g-1) was considerably higher than those of phenoxyacetic acid (35.77 mg g-1), chlorogenic acid (9.72 mg g-1), spiramycin (1.56 mg g-1) and tylosin (1.67 mg g-1). Furthermore, it exhibited strong resistance to protein adsorption in an aqueous medium. These findings confirmed the feasibility of the proposed approach, providing a reference for the development of water-compatible noncovalent imprinted polymers.

Repeated Low-Level Red-Light Therapy for Controlling Onset and Progression of Myopia-a Review.

Repeated low-level red-light (RLRL), characterized by increased energy supply and cellular metabolism, thus enhancing metabolic repair processes, has gained persistent worldwide attention in recent years as a new novel scientific approach for therapeutic application in myopia. This therapeutic revolution led by RLRL therapy is due to significant advances in bioenergetics and photobiology, for instance, enormous progresses in photobiomodulation regulated by cytochrome c oxidase, the primary photoreceptor of the light in the red to near infrared regions of the electromagnetic spectrum, as the primary mechanism of action in RLRL therapy. This oxidase is also a key mitochondrial enzyme for cellular bioenergetics, especially for the nerve cells in the retina and brain. In addition, dopamine (DA)-enhanced release of nitric oxide may also be involved in controlling myopia by activation of nitric oxide synthase, enhancing cGMP signaling. Recent evidence has also suggested that RLRL may inhibit myopia progression by inhibiting spherical equivalent refraction (SER) progression and axial elongation without adverse effects. In this review, we provide scientific evidence for RLRL therapy as a unique paradigm to control myopia and support the theory that targeting neuronal energy metabolism may constitute a major target for the neurotherapeutics of myopia, with emphasis on its molecular, cellular, and nervous tissue levels, and the potential benefits of RLRL therapy for myopia.

Prediction and validation of monoclonal antibodies separation in aqueous two-phase system using molecular dynamic simulation.

In order to predict how mAbs partition in 20% ethylene oxide/80% propylene oxide (v/v) random copolymer (EO20PO80)/water aqueous two-phase system (ATPS), a molecular dynamic simulation model was developed using Gromacs and then validated by experiments. The ATPS was applied with seven kinds of salt, including buffer salt and strong dissociation salt that were commonly employed in the purification of protein. Na2SO4 was shown to have the best effects on lowering EO20PO80 content in the aqueous phase and enhancing recovery. The content of EO20PO80 in the sample solution was decreased to 0.62%±0.25% and the recovery of rituximab increased to 97.88%±0.95% by adding 300 mM Na2SO4 into back extraction ATPS. The viability determined by ELISA was 95.57% at the same time. A strategy for constructing a prediction model for the distribution of mAbs in ATPS was proposed in consideration of this finding. Partition of trastuzumab in ATPS was predicted by the model created using this method and the prediction result was further validated by experiments. The recovery of trastuzumab reached 95.63%±2.86% under the ideal extraction conditions suggested by the prediction model.

Optimization of extraction tower structure and extraction conditions for lincomycin separation.

Lincomycin is a widely used aminoglycoside antibiotic. For its separation from fermentation broth in production, solvent extraction is usually applied because of its low cost and high capacity compared to other bioseparation methods. The multistage mixer-settler is a common extraction equipment in commercial production, but it occupies a large area and causes pollution. In this study, a fully enclosed turbine tower was designed and applied in order to replace the mixer-settler. Its structure parameters (turbine diameter, tray porosity) were optimized on the basis of the extraction effect of lincomycin. The results showed that with 35% tray porosity and 28/26 mm turbine diameter of the tower, the extraction rate was kept above 99.0% steadily under 375 rpm/min rotating speed and 60 °C temperature. The extraction effect is much better than mixer-settler and such turbine tower is expected to be applied in the commercial production of lincomycin.

Study on synthesis of ursodeoxycholic acid by reduction of 7-ketolithocholic acid in double aprotic solvents and molecular simulations.

Ursodeoxycholic acid (UDCA) is not only safer than chenodeoxycholic acid in the treatment of hepatobiliary diseases, but also has a wide range of applications in Acute Kidney Injury and Parkinson's Disease. The purpose of this experiment is to improve the conversion rate of 7-ketocholic acid (7K-LCA) and the yield of ursodeoxycholic acid in aprotic solvents during electrochemical reduction process. Three aprotic solvents were investigated as electrolytes. 1,3-Dimethyl-2-imidazolidinone (DMI) has a stable five-membered ring structure, and 7K-LCA has undergone two nucleophilic reactions and "Walden" inversion, the 7K-LCK was stereoselectively reduced to UDCA. Hexamethylphosphoramide (HMPA) and 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU) can be attacked by chloride ions to produce by-products. Molecular orbital theory-based simulations were conducted to study the reducibility of three aprotic solvents [hexamethylphosphoramide (HMPA), 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU), and 1,3-Dimethyl-2-imidazolidinone (DMI)] in combination with experiments. Choose the best solvent based on the simulation results, the electrolysis reaction can be carried out by applying current and voltage when lithium chloride is used as electrolytes. Calculations using Materials Studio showed that Cu, Pb, Hg-Cu, and Ni exhibited the highest binding energies to the substrate in this system. Using Cu as the electrode when the solvent is a 1:1 mix of DMI and HMPA, the conversion rate of 7-ketocholic acid (could reach 98%, the yield of ursodeoxycholic acid was up to 80%. Under the same conditions, linear voltammetry was performed on the electrochemical workstation to study the electrolysis behavior, and the obtained results were consistent with the experiment.

MoS2 and Fe2O3 co-modify g-C3N4 to improve the performance of photocatalytic hydrogen production.

Photocatalytic hydrogen production as a technology to solve energy and environmental problems exhibits great prospect and the exploration of new photocatalytic materials is crucial. In this research, the ternary composite catalyst of MoS2/Fe2O3/g-C3N4 was successfully prepared by a hydrothermal method, and then a series of characterizations were conducted. The characterization results demonstrated that the composite catalyst had better photocatalytic performance and experiment results had confirmed that the MoS2/Fe2O3/g-C3N4 composite catalyst had a higher hydrogen production rate than the single-component catalyst g-C3N4, which was 7.82 mmol g-1 h-1, about 5 times higher than the catalyst g-C3N4 (1.56 mmol g-1 h-1). The improvement of its photocatalytic activity can be mainly attributed to its enhanced absorption of visible light and the increase of the specific surface area, which provided more reactive sites for the composite catalyst. The successful preparation of composite catalyst provided more channels for carrier migration and reduced the recombination of photogenerated electrons and holes. Meanwhile, the composite catalyst also showed higher stability and repeatability.

Conversion of Calcium Citrate to Citric Acid with Compressed CO2.

Citric acid is mainly produced in the fermentation industry, which needs complex processes and produces a high amount of CaSO4 as waste. In this study, CO2 has been used to convert calcium citrate to citric acid and CaCO3 by controlling the reaction parameters (reactants ratio, temperature, and pressure). The CaCO3 produced in this conversion could further be used in the fermentation industry for citric acid production. The transformation condition has been optimized by controlling temperature, pressure, reaction time, and mass ratio of calcium citrate and water. The highest conversion could reach up to 94.7% under optimal experimental conditions of 18 MPa of pressure, 65 °C of reaction temperature, 4 h of reaction time, and 2 g/L of calcium citrate/water suspension solution. This method features simple process, easy separation of citric acid, and environmentally friendly process, which could be a potentially alternative route for downstream treatment in fermentation production of citric acid.

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.

Dosage-dependent antimicrobial activity of DNA-histone microwebs against Staphylococcus aureus.

Neutrophil extracellular traps (NETs) is an antimicrobial cobweb-structured material produced by immune cells for clearance of pathogens in the body, but paradoxically associated with biofilm formation and exacerbated lung infections. To provide a better materials perspective on the pleiotropic roles played by NETs at diverse compositions/concentrations, a NETs-like material (called 'microwebs', abbreviated as µwebs) is synthesized for decoding the antimicrobial activity of NETs against Staphylococcus aureus in infection-relevant conditions. We show that µwebs composed of low-to-intermediate concentrations of DNA-histone complexes successfully trap and inhibit S. aureus growth and biofilm formation. However, with growing concentrations and histone proportions, the resulting microwebs appear gel-like structures accompanied by reduced antimicrobial activity that can even promote formation of S. aureus biofilms. Our simplified model of NETs provides a materials-based evidence on NETs-relevant pathology in the development of biofilms.

Synthesis of ursodeoxycholic acid by electrochemical stereoselective reduction of 7-ketolithocholic acid in aprotic solvents.

A novel method of producing ursodeoxycholic acid was developed through electrochemical stereoselective reduction of 7-ketolithocholic acid (7K-LCA) in a undivided electrolytic cell and aprotic solvents as electrolyte. Five aprotic solvents were investigated as electrolytes, the simple structure of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) were easily attacked by chloride ions and undergo nucleophilic reactions, resulting in no target reactions. The structure of hexamethylphosphoric triamide (HMPA) and 1,3-methyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone (DMPU) is relatively complex, but chloride ions can still attack them, and it was easier for 7K-LCA to directly undergo a reduction reaction under the action of electric current, because of the small steric hindrance of chenodeoxycholic acid (CDCA), 7K-LCA was stereoselectively reduced to CDCA. Due to the stable structure of the five-membered imidazole ring of 1,3-dimethyl-2-imidazolidinone (DMI), 7K-LCA undergoes two nucleophilic and a "Walden inversion", thereby stereoselective reduction of 7K-LCA to UDCA. In DMI, the highest conversion rate of 7K-LCA was 58.3%, the yield of UDCA was 34.9%, ee value was 100%. Linear sweep voltammetry was used to explore the electrochemical behavior of the reaction, and the electrolysis results were consistent with the linear sweep voltammetry. The product was characterized by using IR, 1H NMR and 13C NMR, it confirm the product was UDCA. The method developed in this paper provides a relatively environmentally friendly and low-consumption method for large-scale production of ursodeoxycholic acid, and provides a valuable reference for the asymmetric electrochemical reduction of ketone groups.

Partition of Tea Saponin with a Novel Recyclable Thermo-pH Aqueous Two-Phase Systems.

Aqueous two-phase systems (ATPS) have the advantages of environmentally friendly, high mass transfer efficiency, and mild extraction conditions. However, it is difficult to recycle these polymers, which limits the large-scale application of ATPS. In this study, a novel recyclable ATPS was constructed with thermo-responsive polymer PN and pH-responsive polymer PADB4.78 for the partition of tea saponin. PN represents poly-(N-isopropylacrylamide), and PADB4.78 represents poly-(acrylic acid-dimethylamine ethyl methacrylate-butyl methacrylate), where 4.78 in the subscript indicate the isoelectric point of the polymer. The recoveries of PN and PADB4.78 were 95.36% and 93.48%, respectively, after two cycles. Meanwhile, the phase formation mechanism of ATPS was studied by surface tension and low-field nuclear magnetic resonance (LF-NMR). The effects of polymer concentration, pH, temperature, types and concentrations of salt were investigated on tea saponin partition. In the 1.5% (w/v) PN/3.5% (w/v) PADB4.78 ATPS, the optimal partition coefficient (K) of crude tea saponin were 0.15 in the presence of 1.5 mM KCl at pH 7.6 and 25 °C while the extraction recovery (ERb) reached 92.13%. The K and ERb of tea saponin from tea seeds were 0.12 and 94.50% with 7.5 mM LiBr at pH 8.0 and 25 °C, respectively.

Synthesis of molecularly imprinted polymers based on boronate affinity for diol-containing macrolide antibiotics with hydrophobicity-balanced and pH-responsive cavities.

In this research, in order to separate and purify diol-containing macrolide antibiotics, like tylosin, from complex biological samples, molecularly imprinted polymer (MIP) based on boronate affinity for tylosin was synthesized by using precipitation polymerization method with 4-vinylphenylboronic acid (VPBA) and dimethyl aminoethyl methacrylate (DMAEMA) as pH-responsive functional monomers, and N,N'-methylene bisacrylamide (MBAA)/ ethylene glycol dimethacrylate (EGDMA) as the co-crosslinkers that balance the hydrophobicity of the MIP. The synthesized tylosin-MIP had the advantages of high adsorption capacity (120 mg/g), fast pH-responsiveness responsible for the accessibility of imprinted cavities, and high selectivity coefficient towards tylosin versus its analogues (2.8 versus spiramycin, 7.3 versus desmycosin) in an aqueous environment. The mechanism of boronate affinity between tylosin and VPBA in the form of charged hydrogen bonding was analyzed via density functional theory (DFT). MIPs were used to successfully separate diol-containing macrolides through molecularly imprinted solid phase extraction (MISPE). The results show that MIPs prepared in this method have a good application prospect in the separation and purification of the diol-containing macrolide antibiotics.

Preemptive analgesia using selective cyclooxygenase-2 inhibitors alleviates postoperative pain in patients undergoing total knee arthroplasty: A protocol for PRISMA guided meta-analysis of randomized controlled trials.

BACKGROUND: The postoperative pain associated with total knee arthroplasty (TKA) is severe for most patients. The analgesic efficacy and safety of preoperative use of selective cyclooxygenase-2 (COX-2) inhibitors for patients undergoing TKA are unclear. OBJECTIVES: We conducted a systematic review and meta-analysis to assess whether the use of selective COX-2 inhibitors before TKA decreases the postoperative pain intensity. METHODS: Data sources: The PubMed, Embase, EBSCO, Web of Science, and Cochrane Controlled Register of Trials databases from inception to January 2020. STUDY ELIGIBILITY CRITERIA: All randomized controlled trials (RCTs) in which the intervention treatment was preoperative selective COX-2 vs placebo in patients undergoing TKA and that had at least one of the quantitative outcomes mentioned in the following section of this paper were included. Letters, review articles, case reports, editorials, animal experimental studies, and retrospective studies were excluded. INTERVENTIONS: All RCTs in which the intervention treatment was preoperative selective COX-2 vs placebo in patients undergoing TKA. STUDY APPRAISAL AND SYNTHESIS METHODS: The quality of the RCTs was quantified using the Newcastle-Ottawa quality assessment scale. RevMan 5.3 software was used for the meta-analysis. RESULTS: Six RCTs that had enrolled a total of 574 patients were included in the meta-analysis. The visual analog scale pain score at rest was significantly different between the experimental group and control group at 24 hours (P < .05) and 72 hours (P < .05) postoperatively. The experimental group exhibited a significant visual analog scale pain score during flexion at 24 hours postoperatively (P < .05), and it was not different at 72 hours postoperatively (P = .08). There was a significant difference in opioid consumption (P < .05), but there was no difference in the operation time (P = .24) or postoperative nausea/vomiting (P = .64) between the groups. CONCLUSION: The efficacy of preoperative administration of selective COX-2 inhibitors to reduce postoperative pain and opioid consumption after TKA is validated. SYSTEMATIC REVIEW REGISTRATION NUMBER: INPLASY202090101.

Migration inhibitory factor in spinal tuberculosis: -173G/C polymorphisms, and transcript and protein levels in a northern province of China.

The aim of this study was to elucidate the possible association between migration inhibitory factor (MIF)-173G/C gene polymorphisms and transcript and plasma levels of MIF in spinal tuberculosis (TB) patients. Clinical data were collected from 254 spinal TB patients and 262 healthy controls participating in the study. The genotype of the MIF-173G/C gene was amplified by polymerase chain reaction and genotyped by DNA sequencing technology. The level of mRNA expression was determined by real-time polymerase chain reaction and MIF plasma levels were measured by a solid-phase enzyme-linked immunosorbent assay. The frequency of the C allele and GC+CC genotype in MIF-173G/C was over-represented in spinal TB patients. The mean MIF mRNA level in spinal TB patients and patients with the GG and GC+CC genotype were significantly lower than controls; however, our study also indicated that the MIF concentration in spinal TB patients and patients with the GG and GC+CC genotypes were significantly higher than controls. Spinal TB patients with the GG genotype had higher MIF plasma levels than patients with the GC+CC genotype. The C-reactive protein level and erythrocyte sedimentation rate was correlated with the MIF plasma level. In summary, the association between the MIF-173G/C genetic polymorphism, reduced transcript and increased plasma levels of MIF in spinal TB patients, and MIF may play an important role in the occurrence, development, and damage of spinal TB in the northern Province population of China.

Study of Microbial Transglutaminase Partitioning in Thermo-pH-Responsive Aqueous Two-Phase Systems.

The recyclable aqueous two-phase systems (ATPS) responding to environmental stimuli have been widely studied in the purification of biologics. In this study, a thermo-responsive polymer PNE was copolymerized after optimization of monomer ratio. In addition, its lower critical solution temperature (LCST, 31 °C) and first recovery (99.43%) were determined. Then, PNE was used to form two recyclable ATPS with another thermo-responsive polymer PNDBN and a pH-responsive polymer PADB4.91, which were polymers already prepared in the lab. Meanwhile, the partition behavior of microbial transglutaminase (MTG) was explored using these two ATPS. The result showed that the PNE/PADB4.91 ATPS was superior to PNDBN/PNE ATPS owing to its faster phase formation and better partition performance. In order to optimize the partition behavior, several parameters were investigated based on PNE/PADB4.91 ATPS. In the ATPS constructed with 2.5% (w/v) PNE and 3.5% (w/v) PADB4.91, the maximal partition coefficient (1/KE) and enzymatic recovery (ERB) of MTG were 12.9 and 95.21% in the presence of 10 mM KCl when the temperature, pH, and the addition amount of MTG were 25 °C, 7.0, and 2 mg/mL, respectively.

A rare case of inflammation after total hip arthroplasty due to a malpositioned prosthesis: A case report.

RATIONALE: Although prosthetic loosening caused by poor prosthesis positioning is common after total hip arthroplasty (THA), an inflammation caused by poor prosthesis positioning is rare. We report a case in which a THA-related inflammation was indeed caused by poor prosthesis positioning. PATIENT CONCERNS: A 64-year-old woman was admitted to our hospital with a history of persistent hip pain that had started after she had undergone THA 4 years previously. In addition, she complained of swelling of the hip that had begun 2 months ago. DIAGNOSIS: Her pain and swelling was initially thought to be caused by an infection, but was eventually diagnosed as inflammation caused by prosthesis loosening, that was in line with finding that her preoperative and intraoperative cultures showed no bacterial or fungal growth. This case posed many questions and difficulties during the diagnostic and treatment stages. INTERVENTIONS: Routine diagnosis of periprosthetic suspected infection includes blood test, erythrocyte sedimentation rate, C-reactive protein level, bacterial and fungal cultures, and pathology examinations, which were performed. Finally, this case was eventually diagnosed as inflammation, the prosthesis was removed and antibiotics administered. It was replaced 6 months later. OUTCOMES: Except for the erythrocyte sedimentation rate and C-reactive protein levels, X rays, routine blood tests, bacterial and fungal cultures (3 times), and other tests were within the normal range. Positive pathological examinations of synovium during and after the operation indicated chronic inflammation and eliminated inflammation in other areas. Postoperative effect of the second-stage THA was good, with the patient highly satisfied after 6 months. LESSONS: The operative method and position of a joint prosthesis are extremely important. A poorly positioned prosthesis worsens with wear. Wear particles then lead to long-term localized aseptic inflammation with swelling and fever and eventually to low-virulence infection. Prosthetic loosening may be found even at long-term follow-up evaluations after THA in patients with a poorly positioned prosthesis, eventually leading to the need for revision. We had 2 questions: should early revision be considered when a prosthesis had not been properly positioned? In the absence of any confirmation of infection, should a patient suspected of having a periprosthetic infection be treated as early as possible?

Computational design of a molecularly imprinted polymer compatible with an aqueous environment for solid phase extraction of chenodeoxycholic acid.

The main problem of poor water compatibility of molecularly imprinted polymers (MIPs) has been addressed in this study. A new facile and highly efficient approach was developed to obtain well-defined hydrophilic molecularly imprinted polymer microsphere with excellent specific recognition ability toward Chenodeoxycholic acid (CDCA) in crude bile. Particularly, it involved computational modeling to obtain a polymer network with high affinity for CDCA and addition of a hydrophilic crosslinker (polyethylene glycol (PEG) diacrylate∼200) to increase the hydrophilicity of the polymer surface. To our knowledge, this study first report splitting method in molecular imprinting technology. By using the splitting method, simulation time can be saved under the premise of ensuring accuracy. The adsorption experiments revealed that an optimized CDCA-MIP exhibited better selectivity toward CDCA with inhibition of the nonspecific adsorption. The CDCA-MIP possessed adsorption capacity of 49.86 mg g-1 for CDCA and the imprinting factor was 2.72. Solid-phase extraction (SPE) using the prepared CDCA-MIP as adsorbent was optimized regarding loading and elution conditions, and it was used to extract CDCA from crude bile, resulting in recoveries in the range 94.2-96.1%.

Separation of transglutaminase using aqueous two-phase systems composed of two pH-response polymers.

Aqueous two-phase systems (ATPS) have been effectively used as a rapid and economical method for the separation and purification of many enzymes or proteins. However, a key problem is the recovery of the polymers forming ATPS and there are rarely available studies about ATPS for the transglutaminase. In this study, a pH-responsive ATPS has been established by two pH-responsive polymers (PADB4.91 and PADB4.06) that can be recycled by changing the pH values, with high recovery of over 96%. And partitioning of the crude transglutaminase in this new ATPS was investigated for the first time. The main parameters, such as crude TGase feedstock load, the pH of system (pH 6.50-7.80), polymers concentration, and the types and concentration of salts, were studied to optimize partition conditions. In the 3% PADB4.91/2% PADB4.06 ATPS, enzyme recovery of 96.51%, partition coefficient of 4.23 and purification factor of 3.73 for TGase were obtained in the presence of 60 mmol/L MgSO4 and at pH 7.00. The result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that TGase can be well separated from crude extract.

Recyclable aqueous two-phase system based on two pH-responsive copolymers and its application to porcine circovirus type 2 Cap protein purification.

Aqueous two-phase system (ATPS) has great potential in industrial applications of bio-separations and bio-reactions. However, its large-scale application is limited by recovery difficulty of phase systems. In this paper, a recyclable ATPS was prepared by two pH-responsive copolymers (PADB4.99 and PMDM7.08) and applied for purification of porcine circovirus type 2 Cap protein fermentation broth (PCV2 Cap protein). Phase separation mechanism was studied by using low-field nuclear magnetic resonance (LF-NMR). The results showed that relatively desirable ATPS were formed successfully when two copolymer concentrations were 4%-6% (w/w) with pH 7.5-8.6. The main parameters, such as copolymer concentration, temperature, pH, type and concentration of salts, were investigated. The results demonstrated that the best ATPS consisted of 4% (w/w) PADB4.99 and 6% (w/w) PMDM7.08, the optimal partition coefficient (K) and extraction recovery (ER) of PCV2 cap protein were 0.25 and 94.2% in the presence of 50 mM Li2SO4, 3.53 and 93.4% in the presence of 40 mM KCl, respectively, at 30 °C, pH 8.1. The maximum purity of PCV2 Cap protein was 88.4%. In addition, the two phase-forming copolymers could be recycled by adjusting solution pH to their isoelectric points (pI), with recoveries of over 97.5%.

Development of pH-responsive polymer and citrate aqueous two-phase system for extractive bioconversion of cefprozil.

A pH-responsive aqueous two-phase system (pH-ATPS) has been developed by sodium citrate and a recyclable pH-responsive polymer PADB6.8 that can response to the change of pH values. Phase separation mechanism is studied through Low field-NMR. All variables affecting the phase separation are evaluated. Phase characteristics (viscosity, density, interfacial tension) and phase separation kinetic are studied for understanding of separation process and operational parameters in applications. This pH-ATPS has the characters of low interfacial tension, high recovery leading efficient mass transfer and low cost. The proposed system can be used as a mild medium for extractive bioconversion with low cost. We applied this pH-ATPS in extractive bioconversion of cefprozil. Cefprozil is partitioned towards the polymer-rich phase while the substrates tended to be partitioned in the salt-rich phase. Extractive bioconversion of cefprozil in this pH-ATPS can improve yield of the enzymatic process and reduce the product hydrolysis in optimal conditions. The maximal conversion yield of cefprozil in the studied system is 91.0%.