"Space—the final frontier." This preamble to a well-known television series captures the challenge encountered not only in space travel adventures, but also in the field of porous materials, which aims to control the size, shape and uniformity of the porous space and the atoms and molecules that define it. The past decade has seen significant advances in the ability to fabricate new porous solids with ordered structures from a wide range of different materials. This has resulted in materials with unusual properties and broadened their application range beyond the traditional use as catalysts and adsorbents. In fact, porous materials now seem set to contribute to developments in areas ranging from microelectronics to medical diagnosis.

Ordered porous materials for emerging applications

Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

In this review, the progress made in the last ten years concerning the synthesis of porous carbon materials is summarized. Porous carbon materials with various pore sizes and pore structures have been synthesized using several different routes. Microporous activated carbons have been synthesized through the activation process. Ordered microporous carbon materials have been synthesized using zeolites as templates. Mesoporous carbons with a disordered pore structure have been synthesized using various methods, including catalytic activation using metal species, carbonization of polymer/polymer blends, carbonization of organic aerogels, and template synthesis using silica nanoparticles. Ordered mesoporous carbons with various pore structures have been synthesized using mesoporous silica materials such as MCM-48, HMS, SBA-15, MCF, and MSU-X as templates. Ordered mesoporous carbons with graphitic pore walls have been synthesized using soft-carbon sources that can be converted to highly ordered graphite at high temperature. Hierarchically ordered mesoporous carbon materials have been synthesized using various designed silica templates. Some of these mesoporous carbon materials have successfully been used as adsorbents for bulky pollutants, as electrodes for supercapacitors and fuel cells, and as hosts for enzyme immobilization. Ordered macroporous carbon materials have been synthesized using colloidal crystals as templates. One-dimensional carbon nanostructured materials have been fabricated using anodic aluminum oxide (AAO) as a template.

Recent Progress in the Synthesis of Porous Carbon Materials

Immobilization is often the key to optimizing the operational performance of an enzyme in industrial processes, particularly for use in non-aqueous media. Different methods for the immobilization of enzymes are critically reviewed. The methods are divided into three main categories, viz. (i) binding to a prefabricated support (carrier), (ii) entrapment in organic or inorganic polymer matrices, and (iii) cross-linking of enzyme molecules. Emphasis is placed on relatively recent developments, such as the use of novel supports, e.g., mesoporous silicas, hydrogels, and smart polymers, novel entrapment methods and cross-linked enzyme aggregates (CLEAs).

http://largens.com/biochemlab/peroxidase2.pdf

Enzyme immobilization: The quest for optimum performance

Nanosilver: a nanoproduct in medical application.

The layer-by-layer (LbL) templating technique has attracted significant interest as a simple, highly versatile approach that has been widely used to prepare nanostructured materials with tailored properties. The process involves the sequential deposition of species, such as polymers, nanoparticles, lipids, proteins, and dye molecules, onto various templates, which are subsequently removed to yield free-standing structures. Although fine control of the material properties (e.g., size, composition, thickness, permeability, function) is afforded by the type of species LbL-assembled, the morphology and composition of the templates also play a crucial role in determining the properties, and hence potential applications, of the materials generated. In this review, we focus on the two main classes of templates that have been employed to prepare nanostructured materials: planar and colloidal. The use of porous planar and colloidal substrates in LbL templating synthesis is also presented, as this offers opportunit...

Template Synthesis of Nanostructured Materials via Layer-by-Layer Assembly†

We report the immobilization of various enzymes in mesoporous silica (MS) spheres followed by encapsulation via the layer-by-layer assembly of multilayered nanocomposite thin shells. A range of enzymes with different molecular sizes and isoelectric points (pI) (e.g., catalase, peroxidase, cytochrome C, and lysozyme) has been examined in MS particles with a series of pore sizes. MS spheres with a bimodal mesoporous structure (BMS, 2−3 nm and 10−40 nm) show faster immobilization rates and significantly improved enzyme immobilization capacity than similar particles with only the smaller mesopores. High enzyme loadings (20−40 wt %) and rapid uptake (several minutes) were observed in BMS spheres for enzymes with a molecular size ≤ 3 nm and pI ≥ 10. Following immobilization of the enzyme catalase, multilayered polyelectrolyte (PE) [poly(diallyldimethylammonium chloride), PDDA/poly(sodium 4-styrenesulfonate), PSS], or PE/nanoparticle [PDDA/silica nanoparticles, SiNP] shells were deposited onto the enzyme-loaded ...

Mesoporous Silica Spheres as Supports for Enzyme Immobilization and Encapsulation

Stable polydopamine capsules are prepared by the single-step deposition and self-polymerization of dopamine onto a range of colloidal silica template particles with different sizes and porosities. MTT assays reveal negligible cytotoxicity of the capsules toward cells.

Self-Polymerization of Dopamine as a Versatile and Robust Technique to Prepare Polymer Capsules

The preparation of monodisperse polymer (polydopamine, PDA) capsules by a one-step interfacial polymerization of dopamine onto dimethyldiethoxysilane (DMDES) emulsion droplets and removal of the DMDES templates with ethanol is reported. The diameters of the PDA capsules can be tailored from 400 nm to 2.4 μm by varying either the DMDES emulsion condensation time or the emulsion concentration used for templating. Further, capsules with defined nanometer-scale shell thicknesses (ranging from ∼10 to 30 nm) can be prepared by adjusting the emulsion concentration. This shell thickness can be increased by repeated interfacial polymerization of dopamine, with three cycles yielding capsules with a shell thickness of up to 140 nm (for a 0.6% v/v suspension). Functional substances, such as organically stabilized magnetic (Fe3O4) nanoparticles, quantum dots (CdSe/CdS), and hydrophobic drugs (thiocoraline), can be preloaded in the emulsion droplets, and following PDA coating and DMDES removal, these materials remain encapsulated in the polymer capsules. All of the unloaded and loaded PDA capsules are monodisperse and do not aggregate. This work provides new avenues for the preparation of polymer capsules with defined size and shell thickness and for the encapsulation of a range of hydrophobic substances. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Monodisperse Polymer Capsules: Tailoring Size, Shell Thickness, and Hydrophobic Cargo Loading via Emulsion Templating

We report a general and facile approach for the fabrication of a new class of monodispersed, single-component and thick-walled polymer nanocapsules via the single-step assembly of macromolecules in solid core/mesoporous shell (SC/MS) silica particle templates, followed by cross-linking of the macromolecules and removal of the SC/MS templates. The general applicability of this approach is demonstrated by the preparation of nanocapsules using various polymers, including synthetic polyelectrolytes, polypeptides, and polypeptide-drug conjugates. The potential of doxorubicin (Dox)-loaded poly(L-glutamic acid) nanocapsules in tumor therapy applications is demonstrated via in vitro degradation experiments, which show a near-linear release of the Dox in the presence of a lysosomal hydrolase, nanocapsule uptake by human colorectal tumor cells, and delivery of the anticancer drug into the tumor cells, leading to tumor cell death.

https://minerva-access.unimelb.edu.au/bitstream/handle/11343/123336/Manuscript_Revised.pdf

Yajun Wang

Papers

Template Synthesis of Nanostructured Materials via Layer-by-Layer Assembly†

Mesoporous Silica Spheres as Supports for Enzyme Immobilization and Encapsulation

Self-Polymerization of Dopamine as a Versatile and Robust Technique to Prepare Polymer Capsules

Monodisperse Polymer Capsules: Tailoring Size, Shell Thickness, and Hydrophobic Cargo Loading via Emulsion Templating

Templated Synthesis of Single-Component Polymer Capsules and Their Application in Drug Delivery