We present a facile strategy to prepare grape-like silica-based hierarchical porous interlocked microcapsules (HPIMs) by polystyrene colloidal crystals templates, whose structure is the subtle integration of open mouthed structure, hierarchical porous nanostructure and interlocked architecture. HPIMs are fabricated by replicating colloidal crystals templates that have a hexagonal close-packed structure; thus, theoretically, each microcapsule has 12 open mouths, and these open mouths with mesoporous microcapsule wall construct the hierarchical porous structure. Furthermore, the interlocked architecture of the microcapsules can endow HPIMs with excellent mechanical stability and recyclability. By adjusting sulfonation time, the morphology, shell thickness, and even mesporous size of the HPIMs can be precisely controlled. In addition, HPIMs with various compositions are obtained via this method, such as silica and aminopropyl polysilsesquioxane (APSQ). All these unique features derived from a readily available method will give products with a broader range of applications.

A facile and novel method was developed to fabricate silica-based hierarchical porous Janus microcapsules (HPJMs SiO2) for catalysis. The resulting Au@HPJMs SiO2 nanocomposites showed enhanced catalysis, great stability, convenient recovery and reuse without losing catalytic efficiency.

This study describes a general strategy using norepinephrine (NE) as a stable anchor for the immobilization of enzyme onto three-dimensionally ordered macroporous (3DOM) silica. Penicillin G acylase (PGA) was chosen as a model enzyme. The effect of pH and temperature on the activity of PGA@PN–SiO2 (PGA immobilized on poly(norepinephrine)-modified 3DOM silica) was investigated. The operational stability, storage stability and kinetic properties of the PGA@PN–SiO2 were also examined. Compared with free PGA and PGA@SiO2 (PGA immobilized on blank 3DOM silica through physical adsorption), the stabilities of PGA@PN–SiO2 were improved significantly. PGA@PN–SiO2 retained high activity during the hydrolysis in a continuous packed-bed reactor (PBR) after 30 catalytic cycles, which demonstrated that PGA@PN–SiO2 can bear endurance of continuous catalysis. The method presented in this study has broad potential for immobilizing enzymes and other biomolecules.

A novel 3-D ordered macroporous (3DOM) adsorbent with a cationic polymer chain (poly(N,N-dimethylaminoethyl methacrylate), PDMAEMA) tethered on the pore wall was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) for the removal of toxic Cr(VI) ions from aqueous solution. In comparison with recently reported adsorbents, the adsorbent remarkably stands out owing to large adsorption capacity, relatively fast kinetics, and high stability in the regeneration process. The adsorption capacity significantly depended on the solution pH and there was a wide working pH range that is much convenient in practical application. Kinetics of Cr(VI) adsorption by the 3DOM adsorbent was studied in batch experiments, in the temperature range 298–318 K. The equilibriums were arrived within 120–130 min and a pseudo-second order model can be described well. In the adsorption isotherm study, experimental data followed the Langmuir adsorption model. The maximum adsorption capacity increased with the increase of temperature, and reached the high value of 431.0 mg/g at 308 K. Thermodynamic parameters revealed spontaneous and endothermic adsorption processes. Furthermore, the 3DOM adsorbent remained high adsorption capacity (above 90% of the original Cr(VI) loading capacity) after 15 adsorption–desorption cycles by simply using sodium hydroxide solution as the desorption liquid, which ensured the reusability of 3DOM adsorbent.

With the aim to provide a highly stable and active biocatalyst, cross-linked enzyme aggregates (CLEAs) of lipase Candida sp. 99-125 were prepared in three-dimensionally ordered macroporous silica materials (CLEAs-LP@3DOM-SiO2). Lipase Candida sp. 99-125 was first precipitated in the pores of 3DOM SiO2 (named EAs-LP@3DOM-SiO2), and further cross-linked by glutaraldehyde to form CLEAs-LP@3DOM-SiO2. Saturated ammonium sulfate was used as a precipitant and glutaraldehyde with a concentration of 0.25% (w/w) was employed as a cross-linker. Compared with EAs-LP@3DOM-SiO2 and native lipase, CLEAs-LP@3DOM-SiO2 exhibited excellent thermal and mechanical stability, and could maintain more than 85% of initial activity after 16 days of shaking in organic and aqueous phase. When CLEAs-LP@3DOM-SiO2 was applied in esterification and transesterification reactions, improved activity and reusability were achieved. This method can be used for the immobilization of other enzymes of interest.Keywords: biodiesel; cross-linked enzyme aggregates; enzyme immobilization; lipase; Three-dimensionally ordered macroporous materials;

A facile and promising approach was developed to fabricate enzyme-based 3D-ordered macroporous biocatalysts (enzyme-based inverse opals) by using the colloidal crystal templating method. Horseradish peroxidase- and amylase-based inverse opals were prepared, which verified that this method is suitable for various enzymes.

3-D ordered macroporous (3DOM) materials have exhibited advantages in the adsorption field. Their monodisperse macropores undergo facile modification, and the interconnected cavities enhance accessibility to the active sites, while the short diffusion path of the thin pore walls accelerates material exchange. A 3DOM material can increase the number of adsorption sites by the grafting of a polymer chain with functional groups from the pore wall of the 3DOM resin. In this study, different amounts of the cationic polymer poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) were grafted from the pore wall of a 3DOM cross-linked polystyrene (3DOM CLPS-g-PDMAEMA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and salicylic acid (SA) was employed as the model adsorbate. PDMAEMA chains can adopt a more extended conformation in water. Therefore, the adsorption capacity increases with the grafted amount due to the increasing number of adsorption sites and the extended chain conformation. The 3DOM CLPS-g-PDMAEMA exhibits a very high adsorption capacity towards SA (390 mg g−1 when the initial concentration of SA is 500 mg L−1) which is even higher than that of activated carbon. Moreover, the 3DOM adsorbent also exhibits a high adsorption selectivity between SA and phenol, and the selectivity coefficient for SA reaches 45.8 in the presence of phenol. The 3DOM adsorbent is also reusable and can be regenerated by sodium hydroxide solution. The results of fifteen adsorption–desorption cycles show that all the adsorption capacities maintain above 85% of the original SA loading capacity. We envision that novel 3DOM polymeric adsorption will play a significant role in developing a new generation adsorbent.

Three-dimensionally ordered macroporous (3DOM) materials have a large pore volume and a uniformly distributed pore size. The macropores are interconnected with each other via “window” channels. A novel pH-responsive carrier system based on 3DOM material has been constructed by grafting pH-responsive polymeric chains from the pore wall of 3DOM cross-linked polystyrene (3DOM CLPS) via surface-initiated atom transfer radical polymerization to control the on–off action of the “window” channels. The grafted amounts can be controlled by variation of the solvent and the graft polymerization time. The functionalized 3DOM CLPS has a high pore volume and can store more guest molecules. Guest molecules such as vancomycin can be stored and released from the macropores of the functionalized 3DOM CLPS by changing pH values at will. The on–off action of “windows” at different pH values was confirmed by the storage–release experiments, which demonstrate that the level of vancomycin release from the functionalized 3DOM CLPS is strongly dependent on the pH value. The storage–release experiments of 3DOM CLPS-g-PAA with different grafted amounts and the 3DOM CLPS without grafting a polymer chain indicate that the introduced pH-responsive polymer chains act as a permeation valve on the connected windows. We envision that the new 3DOM material equipped with pH-responsive switchable windows can play a significant role in developing new generations of intelligent delivery materials, intelligent chromatographic sampling, and other molecular machines.

Three-dimensionally ordered macroporous cross-linked polystyrenes (3DOM CLPS) attached polyethylene glycols (PEGs) with different molecular weights were prepared for use as a novel tri-phase transfer catalyst. The 3DOM catalysts were characterized by FTIR and SEM. The catalytic activity of functionalized 3DOM CLPS was evaluated using α-butylation reaction of phenylacetonitrile in organic phase and potassium hydroxide aqueous solution in water phase as a model system. The effects of various factors on the phase transfer catalysis reaction of liquid-solid-liquid were investigated. Reusing performance of the catalyst was also examined. The results show that the 3DOM CLPS attached PEG400 is an effective and stable tri-phase catalyst for α-butylation reaction. The reaction yield increases with the increasing of temperature and extension of time. After reusing for eight times, the PEG chains did not run off and the ordered structure was well preserved, and the yield of α-butyl phenylacetonitrile was still above 90%.

A versatile and effective method for incorporating functional groups on the pore wall of three-dimensionally ordered macroporous cross-linked polystyrene (3DOM CLPS) by hydrophilic spacer arm has been investigated. The 3DOM CLPS with pore size 865 nm was prepared by sacrifice template method. The hydrophilic spacer arm (polyethylene glycol, molecular weight is 600) was grafted to the 3DOM CLPS via nucleophilic substitution reaction. The other side of active hydroxyl can be further converted into a lot of other functional groups. In this report, the chelating ligand 2-mercaptobenzothiazole (MBZ) group was introduced on the end of the PGE chain to evidence the versatile functionalization approach. The functionalized ordered macroporous materials were characterized by FT-IR, element analyzer, SEM. The results reveal that the pores were successfully bonded with 2-mercaptobenzothiazole groups via hydrophilic spacer arms and the original morphology of ordered macroporous materials were remained after functionalization. The MBZ group density is 0.052 mmol/m2. The functionalized 3DOM CLPS are expected to application as heavy metal ions adsorbent.

•Protein-based inverse opals were prepared for the first time.•The properties of the immobilized PGA were investigated.•The immobilized PGA showed improved thermal and pH stability.•The immobilized PGA can be applied in continuous catalysis in packed-bed reactor.In this study, protein-based inverse opals were prepared for the first time by using the colloidal crystal templating method. The preparation process involved three steps including filling the templates with protein molecules, crosslinking, and template removal. The obtained inverse opals were used to immobilize Penicillin G acylase (PGA) because of its intrinsic biocompatible property. The immobilization process was optimized and the properties of the immobilized PGA (PGA@IO) were investigated. PGA@IO exhibited improved thermal and pH stability compared with its free counterpart. After reusing nine times, it retained 70% of the initial activity. Besides, the PGA@IO retained high activity during the hydrolysis reactions in continuous catalysis in packed-bed reactor (PBR) after 15 days.A facile approach was provided to prepare protein-based inverse opals for the first time and the obtained opals were used to immobilize enzyme.Download high-res image (162KB)Download full-size image

•3DOM/m-S was prepared and applied for lipase immobilization.•CALB@3DOM/m-S showed improved stabilities than CALB@3DOM-S.•CALB@3DOM/m-S showed improved usability when applied in esterification.Hierarchically ordered macroporous/mesoporous silica (3DOM/m-S) material was prepared through the dual templating method with polystyrene (PS) colloidal crystals as the hard template and amphiphilic triblock copolymers (P123) as the soft template. The achieved 3DOM/m-S possesses ordered macropores of 400 nm and mesopores of 5.1 nm, which provides a promising platform for enzyme immobilization. Lipase B from Candida antarctica (CALB) was employed as a model enzyme to verify the possibility and advantages of enzyme immobilized on 3DOM/m-S. The immobilized lipase shows excellent stability towards heat even at 80 °C and organic solvents for long-term incubation (288 h). Also, the immobilized CALB could be used for esterification reactions between acids and alcohols with different chain lengths, and 90% of conversion rate could be reached. In examining the reusability in esterification of oleic acid and ethanol, the conversion rate can retain 75% after 10 reaction cycles, indicating a remarkable reusability of the immobilized lipase.Download full-size image

A facile and novel method was developed to fabricate silica-based hierarchical porous Janus microcapsules (HPJMs SiO2) for catalysis. The resulting Au@HPJMs SiO2 nanocomposites showed enhanced catalysis, great stability, convenient recovery and reuse without losing catalytic efficiency.

A facile and promising approach was developed to fabricate enzyme-based 3D-ordered macroporous biocatalysts (enzyme-based inverse opals) by using the colloidal crystal templating method. Horseradish peroxidase- and amylase-based inverse opals were prepared, which verified that this method is suitable for various enzymes.