Functional Thin Films using Dendrimers

The layer formation was initiated by the deposition of avidin on a hydrophobic quartz slide, yielding a homogeneous monomolecular layer [66]. Subse- 

Alonso et al. prepared ferrocenyl silicon dendrimers [67], which could be used as mediators in glucose biosensors, based on glucose oxidase [68, 69], The ferrocenyl units are located at the end of long, flexible, silicon containing branches and serve to electrically connect the enzyme to the electrode. The flexibility of the dendrimer is proposed to play an important role in the interaction with the redox center of glucose oxidase. 

Moreover, these dendrimers proved to be good hosts for anionic dye molecules. Films prepared from these host-guest complexes showed efficient ( 90%) energy transfer from the OPV units to the encapsulated dye molecules 

Dendrimers have also been found useful in the construction of thin films containing isolated fullerenes [85, 86]. Such materials could eventually find practical application in sensors and/or optoelectronic devices [87]. Generally, monolayers prepared from C60 are ill-defined due to the aggregation tendency of fullerenes. The covalent attachement of C60 to bulky dendritic frameworks 

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The preparation of thin films and layers from dendrimers by self-assembly is a topic of great current interest since it allows the construction of functional interfaces that use specific dendritic properties such as size, shape, porosity, end-group density and multifunctionality. It is also an area of research that benefits substantially from the flexible character intrinsic to most dendrimers. 

Scheme 6 Formation of hyperbranched thin film nanocomposites using an electrophilic polymeric reagent 14 and a nucleophilic amine-functionalized PAMAM dendrimer 15...

PAMAM]. The final step of this functionalization relied on activation and cross-linking of attached dendrimers with a homobifunctional spacer (DSG or PDITC). Alternatively, after attachment of dendrimers to the surface, glutaric anhydride activated with V-h ydrox vsucc i n i m i de can be used. This surface modification yields a thin, chemically reactive polymer film, which is covalently attached to the glass support and can be directly used for the covalent attachment of amino-modified components, such as DNA or peptides (Fig. 14.2b). 

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