Development of Amino Acids Functionalized SBA-15 for the Improvement of Protein Adsorption

Ordered mesoporous materials and their modification with multiple functional groups are of wide scientific interest for many applications involving interaction with biological systems and biomolecules (e.g., catalysis, separation, sensor design, nano-science or drug delivery). In particular, the immobilization of enzymes onto solid supports is highly attractive for industry and synthetic chemistry, as it allows the development of stable and cheap biocatalysts. In this context, we developed novel silylated amino acid derivatives (Si-AA-NH2) that have been immobilized onto SBA-15 materials in biocompatible conditions avoiding the use of toxic catalyst, solvents or reagents. The resulting amino acid-functionalized materials (SBA-15@AA) were characterized by XRD, TGA, EA, Zeta potential, nitrogen sorption and FT-IR. Differences of the physical properties (e.g., charges) were observed while the structural ones remained unchanged. The adsorption of the enzyme lysozyme (Lyz) onto the resulting functionalized SBA-15@AA materials was evaluated at different pHs. The presence of different functional groups compared with bare SBA-15 showed better adsorption results, for example, 79.6 nmol of Lyz adsorbed per m2 of SBA-15@Tyr compared with the 44.9 nmol/m2 of the bare SBA-15.

Ordered Mesoporous Photocatalysts for CO2 Photoreduction

Artificial photosynthesis is the process that converts solar energy and CO2 to valuable chemicals over a photocatalyst through CO2 photoreduction (CO2PR). Ordered mesoporous materials (OMMs) highly improve photocatalytic activity and...

Controlling Particle Morphology and Pore Size in the Synthesis of Ordered Mesoporous Materials

Ordered mesoporous materials have attracted considerable attention due to their potential applications in catalysis, adsorption, and separation technologies, as well as biomedical applications. In the present manuscript, we aim at a rational design to obtain the desired surface functionality (Ti and/or hydrophobic groups) while obtaining short channels (short diffusion paths) and large pore size (>10 nm). Santa Barbara Amorphous material SBA-15 and periodic mesoporous organosilica PMO materials are synthesized using Pluronic PE 10400 (P104) surfactant under mild acidic conditions to obtain hexagonal platelet-like particles with very short mesochannels (300–450 nm). The use of expanders, such as 1, 3, 5-trimethylbenzene (TMB) and 1, 3, 5-triisopropylbenzene (TIPB) were tested in order to increase the pore size. TMB yielded in the formation of vesicles in all the syntheses attempted, whereas P104 combined with TIPB resulted both in expanded (E) E-SBA-15 and E-PMO with 12.3 nm pore size short channel particles in both cases. Furthermore, the synthesis method was expanded to the incorporation of small amount of Ti via co-condensation method using titanocene as titanium source. As a result, Ti-E-SBA-15 was obtained with 15.5 nm pore size and isolated Ti-sites maintaining platelet hexagonal morphology. Ti-PMO was obtained with 7.8 nm and short channels, although the pore size under the tried synthesis conditions could not be expanded further without losing the structural ordering.

Porous materials: microporosity induced by the shape and length of the pores

There are insufficient parameters to explain the appearance of microporosity in porous materials. One of the parameters associated with micropores is the generalized pore shape factor F, which includes, as special cases, the known slit, circular and spherical model pore shapes. F covers the shapes between the slit (F = 2000) and spherical (F = 6000), as well as beyond. For the intermediate shape, one can estimate proportions of model motifs. The transition of the shape from one model to another is accompanied by the appearance of micropores (or vice versa); corresponding dependencies are given. Nanotechnologies, such as self-assembly of ordered mesoporous materials (OMMs), the production of carbon OMMs as replicas of silica matrixes, supercapacitors made of carbon nanofibres (CNF), a hybrid CNF/MWCNT for use in lithium-ion batteries, carbon xerogels with Ni additive for storage of H2, catalysis and others are discussed; they cover materials with F in the range 1,100 ÷ 32,600. A pore surface length index Lsi is proposed for any pore shape; it supplements the generalized parameters causing stresses, deformations and micropores. Using F and Lsi, it was discovered, that activated carbon, obtained as a replica of non-circular matrix of silica, behaves like a compressed spring, which, after removal of silica, expands and its pores become circular. A concept of molecular sieving based on the shape of molecules is proposed and demonstrated by the example of lipase immobilization. Application of the proposed parameters improves understanding of many published and new results.

Mathematical Modeling of Heat, Mass and Moisture Transfer in Catalytic Porous Media

The discovery of ordered mesoporous materials has opened great opportunities for new applications in heterogeneous catalysis e.g. in soil purification processes. The focus of this study is the development of a mathematical model to simulate heat, mass and moisture transfer in soil arrays tacking into account catalytic micro- or nanoparticles. The nonlinear mathematical model of contaminant distribution in unsaturated catalytic porous media to the filter-trap in non-isothermal conditions is presented. The finite differences method was used to find the numerical solution of the corresponding boundary value problem and the analytical solution for mass transfer in catalytic micro- or nanoparticles was presented as well. Numerical experiments and their analysis were conducted using NanoSurface software complex.