•A new cryogel with a combination of ion-exchange and hydrophobic functions was prepared.•The cryogel was employed to isolate immunoglobulin G with a purity of 98.2% and albumin with a purity of 96.8% from rabbit blood serum.•A model was developed to describe the protein adsorption and breakthrough through the cryogel.The preparation and characterization of mixed-mode adsorbents for a typical separation purpose are of great importance in bioseparation areas. In this work, we prepared a new monolithic cryogel with a combination of ion-exchange and hydrophobic functions by employing benzyl-quaternary amine groups. The fundamental cryogel properties, protein equilibrium adsorption isotherm and chromatographic adsorption in the cryogel were measured experimentally. The results showed that, by using bovine serum album as the model protein, the dual functional cryogel has protein binding capability even in salt solution and the buffer with pH close or below the protein isoelectric point due to both the electrostatic and hydrophobic interactions. A capillary-based adsorption model was developed, which provided satisfied insights of the microstructure, axial dispersion, mass transfer as well as protein adsorption characteristics within the cryogel bed. The chromatographic isolation of bioactive proteins from rabbit blood serum was carried out by the cryogel. Immunoglobulin G antibody with a purity of 98.2% and albumin with a purity of 96.8% were obtained, indicating that the cryogel could be an interesting and promising adsorbent in bioseparation areas.

A new coumarin–quinoline based sensor 1 has been synthesized. The paramagnetic Cu2+ ion turned off the fluorescence of sensor 1 with a 1:1 binding stoichiometry. The resultant 1–Cu2+ complex could act in situ as an efficient “off–on” fluorescence sensor for the paramagnetic Cr3+ ion triggered by the 1:1 replacement of Cu2+ with Cr3+. This selective fluorescence “on–off–on” sensor was used to identify Cu2+ and Cr3+ in living breast cancer MCF-7 cells using confocal fluorescence microscopy, indicating that sensor 1 has a potential application for the selective detection of Cu2+ and Cr3+ in living cells.

Vapor–liquid equilibrium (VLE) data for methanol + tert-butylamine + N,N-dimethylformamide (DMF) and constituent binary systems containing tert-butylamine at 101.3 kPa were measured. A maximum boiling point azeotrope was observed at the methanol mole fraction of 0.763, corresponding to the temperature of 340.28 K for the binary system methanol + tert-butylamine. The binary equilibrium data were correlated using Wilson, nonrandom two-liquid (NRTL), and universal quasichemical activity coefficient (UNIQUAC) models, respectively. The VLE data of the ternary system were calculated with the binary interaction parameters of the NRTL model, and the average absolute deviations of the equilibrium temperature and the vapor-phase mole fractions for methanol and tert-butylamine were about 0.87 K, 0.014, and 0.018, respectively. The results show that DMF can break the azeotrope of the methanol + tert-butylamine system as a solvent.

An effective cation-exchange chromatographic method for lysozyme isolation from chicken egg white is presented, using supermacroporous cryogel grafted with sulfo functional groups. The chromatographic processes were carried out by one-step and sequential elution, respectively. Sodium phosphate buffer (pH 7.8) containing different concentrations of NaCl is used as elution agent. The corresponding breakthrough characteristics and elution behaviors in the cryogel bed were investigated and analyzed. Purity of lysozyme in the elution effluent was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The maximum purity of the obtained lysozyme was about 96%, and the cryogel is demonstrated as a potential separation medium for purification of high-purity lysozyme from chicken egg white.

The densities and viscosities of ternary systems (Poloxamer 188 + ethanol/acetone + water) were measured at 288.15, 293.15, 298.15, 303.15, 308.15 K and atmospheric pressure for different mass fractions of Poloxamer 188 (0 to 0.02) in aqueous solution and different solvent volume fractions of ethanol/acetone (0 to 0.3) in Poloxamer 188 aqueous solution. The densities were measured by a pycnometer, while the viscosities were measured using two Ubbelohde capillary viscometers. The correlations of density and viscosity of these ternary systems are obtained by fitting the experimental data at different temperatures, mass fractions and volume fractions.

The effects of grafting conditions on the properties of a novel cation-exchange cryogel by grafting of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) onto polyacrylamide-based cryogel (pAAm cryogel) using potassium diperiodatocuprate (Cu(III) solution) as initiator were investigated experimentally. The basic cryogels were saturated with the initiator solution followed by the solution of monomers to get the expected sulfo groups under various grafting conditions, such as concentrations of monomers and initiator, graft reaction time, graft temperature and the volume ratio of Cu(III) to NaOH. The results showed that these factors influenced the liquid dispersion behaviors and the flow resistance as well as the protein binding capacity of the grafted cryogels. Protein binding capacity increased with the increase of concentration of AMPSA and Cu(III), the graft temperature and the graft reaction time in a wide range under the present conditions. Compared with these factors, the volume ratio of Cu(III) to NaOH in the initiator solution in the considered situations had a relatively weaker influence on the cryogel microstructures and protein binding capacity. The maximum binding capacity of lysozyme reached 2.5 mg/mL cryogel in these grafted cryogels.

Supermacroporous composite cryogels embedded with SiO2 nanoparticles were prepared by radical cryogenic copolymerization of the reactive monomer mixture of acrylamide (AAm) and N, N-methylene-bis-acrylamide (MBAAm) containing SiO2 nanoparticles (mass ratios of nanoparticles to the monomer AAm from 0.01 to 0.08) under the freezing-temperature variation condition in glass columns. The properties of these composite cryogels were measured. The height equivalent to theoretical plate (HETP) of the cryogel beds at different liquid flow rates was determined by residence time distribution (RTD) using tracer pulse-response method. The composite cryogel matrix embedded with the mass fraction of SiO2 nanoparticles of 0.02 presented the best properties and was employed in the following graft polymerization. Chromatographic process of lysozyme in the composite cryogel grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) was carried out to evaluate the protein breakthrough and elution characteristics. The chromatography can be carried out at relatively high superficial velocity, i.e., 15 cm·min−1, indicating the satisfactory mechanical strength due to the embedded nanoparticles.

The slug flow of an inert gas and two miscible liquids in microchannels has found its applications in the preparation of solid lipid nanoparticles (SLNs) by the liquid flow-focusing together with Taylor bubbles in microchannel systems, synthesis of metal nanoparticles or colloid silica in microreactors and enhancement of micro-mixing by interaction using gas bubbles in microfluidic devices. In this work, the flow characteristics of the slug flow generated by nitrogen gas and two miscible liquids (the aqueous surfactant solution and acetone or ethanol) flowing in a rectangular microchannel were investigated experimentally by using the high-speed optical imaging method. The microchannel system has a straight main channel for introducing one of the miscible liquids, a cross-junction for injecting of the other miscible liquid, and a T-junction for feeding the gas phase. The pressure drops were measured and images of Taylor bubbles and slug units at various velocities were obtained, from which other flow parameters were determined. Correlations for the velocity and length of Taylor bubbles, the bubble nose length, the bubble tail length, the liquid slug length, the maximum and minimum thicknesses of the liquid films around bubbles, as well as the pressure drop, were proposed. The calculated values of these parameters by using the correlations were compared with the experimental data. The results showed that the proposed correlations are in a good or reasonable agreement with experimental data and then expected to be available in the estimation of the slug flow parameters of the inert gas and two miscible liquids in rectangular microchannels.

The liquid flow-focusing and gas displacing method is developed to produce solid lipid nanoparticles (SLNs) continuously in a microchannel, which has a cross-junction for the focus of lipid and aqueous solutions and a T-junction for the injection of gas bubbles. The liquid flow-focusing was achieved by introducing a lipid solution with a water-miscible organic solvent and an aqueous surfactant solution simultaneously through the two branches of the cross-junction into the main channel, while the gas displacing was accomplished by injecting an inert gas (N2) through the T-junction at the downstream of the cross-junction into the main flow streams upward to form gas–liquid slug flow. Solid lipid nanoparticles were formed due to the local supersaturation of lipid induced by the diffusion of the solvent from the lipid solution stream into the aqueous phase. The liquid suspension containing solid lipid nanoparticles then passed freely through the microchannel without any blockage by the contribution of gas slug flow. The flow behaviors were observed by a digital inversion microscope system and the hydrodynamics of the liquid flow-focusing streams and the gas slug flow were investigated. Particle size distributions of the solid lipid nanoparticles obtained under various conditions were measured by dynamic light scattering and the particle morphology was examined by transmission electron microscopy. The influences of liquid velocity and lipid concentration under the gas displacing condition on the properties of solid lipid nanoparticles were studied experimentally. The solid lipid nanoparticles with small size (the mean size in the range of 120–200 nm) and narrow particle size distribution (with values of polydispersity index in the range of 0.14–0.19) had been produced by this method. The crucial roles of Taylor bubbles and liquid slugs in the formation of solid lipid nanoparticles were considered and the transfer mechanism of slug flow on the formation and passage of solid lipid nanoparticles in the microchannel were also discussed. Compared with other production methods for SLNs (e.g., hot homogenization, warm microemulsions and supercritical fluid technique), the proposed method in this work is simple and no overcritical operations are needed during the preparing process. Therefore, it can be employed to prepare SLNs with small sizes and a narrow diameter distribution.