Enzyme-containing silica inverse opals prepared by using water-soluble colloidal crystal templates: Characterization and application

Recent Progress of Three-dimensionally Ordered Macroporous (3DOM) Materials in Photocatalytic Applications: A Review

In recent years, three-dimensionally ordered macroporous (3DOM) materials have attracted tremendous interest in the field of photocatalysis due to the periodic spatial structure and unique physicochemical properties of 3DOM catalysts. In this review, the fundamentals and principles of 3DOM photocatalysts are briefly introduced, including the overview of 3DOM materials, the photocatalytic principles based on 3DOM materials, and the advantages of 3DOM materials in photocatalysis. The preparation methods of 3DOM materials are also presented. The structure and properties of 3DOM materials and their effects on photocatalytic performance are briefly summarized. More importantly, 3DOM materials, as a supported catalyst, are extensively employed to combine with various common materials, including metal nanoparticles, metal oxides, metal sulfides, and carbon materials, to enhance photocatalytic performance. Finally, the prospects and challenges for the development of 3DOM materials in the field of photocatalysis are presented.

From Macro to Mesoporous ZnO Inverse Opals: Synthesis, Characterization and Tracer Diffusion Properties

Oxide inverse opals (IOs) with their high surface area and open porosity are promising candidates for catalyst support applications. Supports with confined mesoporous domains are of added value to heterogeneous catalysis. However, the fabrication of IOs with mesoporous or sub-macroporous voids (<100 nm) continues to be a challenge, and the diffusion of tracers in quasi-mesoporous IOs is yet to be adequately studied. In order to address these two problems, we synthesized ZnO IOs films with tunable pore sizes using chemical bath deposition and template-based approach. By decreasing the size of polystyrene (PS) template particles towards the mesoporous range, ZnO IOs with 50 nm-sized pores and open porosity were synthesized. The effect of the template-removal method on the pore geometry (spherical vs. gyroidal) was studied. The infiltration depth in the template was determined, and the factors influencing infiltration were assessed. The crystallinity and photonic stop-band of the IOs were studied using X-Ray diffraction and UV-Vis, respectively. The infiltration of tracer molecules (Alexa Fluor 488) in multilayered quasi-mesoporous ZnO IOs was confirmed via confocal laser scanning microscopy, while fluorescence correlation spectroscopy analysis revealed two distinct diffusion times in IOs assigned to diffusion through the pores (fast) and adsorption on the pore walls (slow).

Preparation of inverse opal adsorbent by water-soluble colloidal crystal template to obtain ultrahigh adsorption capacity for salicylic acid removal from aqueous solution

Diethylenetriamine (DETA) modified inverse opal (IO) poly (glycidyl methacrylate-co-divinylbenzene) (IO PGMD-DETA) was fabricated through the water-soluble colloidal crystal template and further applied as salicylic acid (SA) adsorbent with the ultrahigh adsorption capacity in aqueous solution. Compared that with the reported adsorbents, IO PGMD-DETA possessed the performance of ultrahigh adsorption capacity, comparatively short equilibration time, and relatively good reusability. The influences of the specific surface area and group content on adsorption capacity showed that the high content of group was favorable to improve the hydrophilicity and polarity of the materials, resulting in high adsorption capacity. IO PGMD-DETA-95 (the number of 95 is the mass ratio of GMA monomer) exhibited the largest adsorption capacity towards SA. Langmuir and Liu models could well fit the data of isothermal adsorption. The maximum adsorption capacity was estimated by the Langmuir and Liu models, which could reach out to an excellent value of 905.0 mg/g and 908.4 mg/g at 40 ℃ respectively. Furthermore, the pseudo-first-order rate equation could describe the kinetic data. The adsorption equilibrium of SA on IO PGMD-DETA-95 could be reached within 30-40 min. After five adsorption-desorption cycles, the excellent performance of IO PGMD-DETA-95 and the morphology were well retained.

Co-immobilization of glucose oxidase and catalase in silica inverse opals for glucose removal from commercial isomaltooligosaccharide

In this work, glucose oxidase (GOD) and catalase (CAT) were co-immobilized on novel silica inverse opals (IO-SiO₂) through sol-gel process. The immobilized bi-enzyme system named GOD/CAT@IO-SiO₂ was successfully fabricated and characterized. Morphology characterization indicated that GOD/CAT@IO-SiO₂ had hierarchical porous structure, and the pore diameter of macroporous and mesoporous were 500±50nm and 6.8nm, respectively. The macrospores were connected through windows of 100±30nm. The results of stability tests indicated that both acid (or base) resistance and thermal tolerance of GOD/CAT@IO-SiO₂ were improved. When GOD/CAT@IO-SiO₂ was used to remove glucose from commercial isomaltooligosaccharide (IMO), the immobilized bi-enzyme system exhibited the good performance. The removal efficiency of glucose reached up to 98.97% under the conditions of GOD/CAT activity ratio of 1:30, the amount of enzyme of 68.8mg, reaction time of 9.39h, reaction temperature of 35.2°C and pH of 7.05. After reused 6 times, 79.19% of removal efficiency could be still retained. The present work demonstrates that the immobilized bi-enzyme (GOD/CAT@IO-SiO₂) is not only a very promising system for glucose removal but also has great potential for applications in production of gluconic acid, preparation of biosensors, enzyme bioreactors, etc.

Multi-enzyme cascade reactions using protein–polymer surfactant self-standing films

Self-supporting bio-catalytically active multi-enzyme films fabricated via hierarchical assembly of enzyme–polymer surfactant nanoconjugates are capable of sustaining cascade reactions.