Supramolecular immobilization

Haag et al. [43] have recently reported on the supramolecular immobilization of a perfluoro-tagged Pd catalyst on a dendritic polyglycerol ester with a perfluorinated shell and they have investigated its activity in Suzuki coup-... 

Hyperbranched polymers can also be used for supramolecular immobilization (Scheme 15). Yet another approach for the noncovalent immobilization has been presented by Tzschucke and coworkers who used interactions between fluorous phase silica (FPS) and perfluoro-tagged palladium... 

This strategy was based on the supramolecular immobilization of alternating layers of HRP (either modified with 1-adamantane or P-cyclodextrin-branched carboxymethylcellulose residues) on Au electrodes coated with polythiolated P-cyclodextrin polymer. Fragoso et al. adopted a similar strategy by the immobilization of a first layer of thiolated cyclodextrin polymer on a gold electrode followed by the supramolecular capture of adamantane-modified HRP (Fig. 6)... 

Fig. 33.14 The proposed supramolecular immobilization of Cgo onto a SAM of p-tert-butylcalix [8]arene thioctic ester derivative 13 (Figure adapted with permission from Ref. [20], Copyright 2005, American Chemical Society)...

In this chapter we describe the basic principles involved in the controlled production and modification of two-dimensional protein crystals. These are synthesized in nature as the outermost cell surface layer (S-layer) of prokaryotic organisms and have been successfully applied as basic building blocks in a biomolecular construction kit. Most importantly, the constituent subunits of the S-layer lattices have the capability to recrystallize into iso-porous closed monolayers in suspension, at liquid-surface interfaces, on lipid films, on liposomes, and on solid supports (e.g., silicon wafers, metals, and polymers). The self-assembled monomolecular lattices have been utilized for the immobilization of functional biomolecules in an ordered fashion and for their controlled confinement in defined areas of nanometer dimension. Thus, S-layers fulfill key requirements for the development of new supramolecular materials and enable the design of a broad spectrum of nanoscale devices, as required in molecular nanotechnology, nanobiotechnology, and biomimetics [1-3]. 

A unique feature of such DNA-directed self-assemblies is their site-selective immobilization, which makes it possible to construct well-defined nanostructures. On the other hand, the possibility of the introduction of a vast number of substitutes (like peptidic sequences, nucleoproteins, of hydrophobic hydrocarbon chains) to an adamantane core (adamantyl) makes such a process capable of designing steric colloidal and supramolecular conformations by setting hydrophobic/hydrophilic and other interactions. In addition, the rigidity of the adamantane structure can provide strength and rigidity to such self-assemblies [150]. 

Abstract The supramolecular composites containing fullerenes C60 immobilized at nanosilica were used for the design of the molecular systems that can be an effective agent in cancer photodynamic therapy (PDT). In particular, it was shown that photoexcited fullerene C60-containing composites decrease viability of transformed cells, intensify the process of lipid peroxidation (LPO) in cell membranes and accumulation of low-molecular weight DNA fragments, and also decrease the activity of electron-transport chain of mitochondria. 

Fig. 7. Schematic representation of the non-covalent immobilization of ligands to a dendrimer support and the actual supramolecular dendritic complex containing 32 phosphine ligands 21).

Moreover, the supramolecular presentation of the ligand could affect the kinetics of the reaction thus allowing, for example, selectins to immobilize leucocytes flowing in the blood-stream [6]. 

Another method for the analysis of aptamer-protein complexes involved the use of a positively charged ferrocene-tethered polythiophene, (19), as redox label reporting unit (Fig. 12.19). The antithrombin aptamer was immobilized on an electrode surface, and the electrostatic binding of the redox polymer (19) to the aptamer monolayer resulted in a supramolecular complex that revealed electrical contact between the polymer and the electrode.74 The formation of the aptamer-thrombin complex removed the polymer from the surface and blocked the electrical contact between the polymer label and the electrode. As a result, higher concentrations of thrombin increased the surface coverage of the aptamer-thrombin complex on the electrode, and this decreased the amperometric responses of the sensing device. 

New Supramolecular Approaches in Transition Metal Catalysis Template-Ligand Assisted Catalyst Encapsulation, Self-Assembled Ligands and Supramolecular Catalyst Immobilization... 

The activities of free and immobilized invertase for various substrate concentrations are plotted in a Lineweaver-Burk graph, from which Vmax and Km values were calculated (Fig. 9). The Km of free enzyme was 40.3 mM, while the apparent Km was 38.2 mM for the immobilized one. These similar Km values for both forms indicate that enzyme-substract interaction is not substantially altered after immobilization. However, the Vmax for immobilized invertase (0.0489 U/mL) was 35% higher than the Vmax for soluble invertase (0.0320 U/mL). Such a difference could be explained by the predominance of supramolecular aggregates (hexamer, octamer forms) guaranteed under the conditions of the immobilization assay. 

From the viewpoint of supramolecular chemistry, behavior of noncovalent supramolecular assemblies confined in mesopores would be a more interesting target. Aida and coworkers reported the first example of immobilization of one-dimensional columnar charge-transfer (CT) assemblies in a mesoporous silica film through sol-gel... 

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