In order to obtain a magnetic polyamine microsphere, a magnetic oil–water-in-oil multiple emulsion droplet was used as the micro-reactor and template for polymerization. The influences of magnetite (NanoFe3O4) and the polymer precursor polyethyleneimine (PEI) on the properties of an emulsion were investigated. After using hydrophobic CaCO3 nanoparticles (SM-CaCO3) in the emulsification, the liquid paraffin-in-water emulsion stabilized by NanoFe3O4 and PEI was changed to an O/W/O Pickering emulsion. The investigation found that suspensions of 2 wt% SM-CaCO3 in liquid paraffin should be emulsified with 1 wt% NanoFe3O4 in 20 wt% PEI solution at a ϕw of 0.5 in order to incorporate as much PEI as possible, in emulsion droplets, while avoiding the phase inversion of emulsion. After the crosslinking of PEI in the emulsion droplets by glutaraldehyde, a magnetic Fe3O4/polyamine microsphere with both hydrophilic and hydrophobic characteristics was obtained. The microsphere demonstrated an isoelectric point of 9.6. The magnetic capacity of NanoFe3O4 decreased as a result of being trapped in the polyamine matrix of the microsphere.

•PEG-400 showed a stronger promoting effect on the operation of BAA than TEPA.•Intrinsic fluorescence of BAA was quenched or enhanced by TEPA or PEG-400.•PEG-400 reduced the polarity in surrounding of Tyr residues.•TEPA enhanced the polarity in the regions around Trp residues.•PEG-400-BAA interaction was due to hydrophobic interaction and hydrogen bonding.•TEPA-BAA interaction was due to van der waals force and electrostatic interaction.The activity of BAA can be maximally increased about 1.68 times and 1.23 times in the presence of 3.6% (w/v) PEG-400 and 0.2% (w/v) TEPA, respectively. Compared to TEPA, PEG-400 addition can improve the activity of BAA at higher temperature. The addition of PEG can result in enhanced fluorescence of BAA but showed no influence on the UV spectra. Whereas, the presence of TEPA can not only reduce the fluorescence of BAA through dynamic quenching mechanism but also enhance the UV adsorption of BAA at 220 nm and shifted absorption peak from 265 nm to 290 nm. Synchronous fluorescence studies found PEG-400 can reduce the polarity in the environment around the Tyr residues, while TEPA addition can enhance the polarity in the microenvironment around the Trp residues. The hydrophobic interaction and hydrogen binding existed in the interaction between BAA and PEG-400 rendered the enzyme more stable. The ionic interaction and van der waals force between TEPA and BAA can maintain the optimum enzyme activity in a wider pH range. The addition of PEG-400 demonstrated a larger promoting effect on the activity of BAA compared to that of TEPA addition.

•The purity of C-PC in ATPS was increased by 2.1 times in the presence of TMA-PEG.•The promoting effect of TMA-PEG addition was based on the electrostatic attraction.•The purity of C-PC was increased by 18.9% using RSM optimization.•C-PC with a purity of 6.7 can be obtained in the CCD operation of 2-stage ATPS.A novel aqueous two phase system (ATPS) using trimethylamine-polyethylene glycols (TMA-PEG) to promote the extraction of C-phycocyanin (C-PC) from S.platensis was introduced. The purity of C-PC (EP) obtained in the ATPS of PEG1000/Na3PO4 was increased 2.1 times by the addition of TMA-PEG1000. The purification factor was enhanced from 2.9 to 10.1 when 65% TMA-PEG1000 was added in the system. The ATPS operation must be carried out in the pH range of 6.0-7.0 and at temperatures less than 35 °C for maintaining the stability of C-PC. The partition coefficient and recovery ratio of C-PC increased with the increasing concentration of TMA-PEG. The system parameters like TMA-PEG1000 content, tie line length (TLL), pH, temperature and phase volume ratio (Vr) were screened and optimized using the fractional factorial design and Box-Behnken experiment design. The optimized system is composed of 11.8% PEG1000/TMA-PEG1000 (w/w), 64.42% TMA-PEG1000 (w/w PEG1000) and 9.5% Na3PO4 (w/w) with 38.19% TLL (w/w) and 0.89 Vr at pH 6.5 and 25 °C. The obtained value of EP was 5.21 in one-stage ATPS and 6.7 in two-stage ATPS. The recovery ratio of C-PC in the new ATPS extraction system was more than 97%.Download high-res image (122KB)Download full-size image