Dendrimer activation

Keywords. Polyamidoamine dendrimers. Activation of PAMAM dendrimers. Transfection, Gene transfer, DNA-dendrimer complex... 

Singh, P. (1998) Terminal groups in starburst dendrimers Activation and reactions with proteins. Bioconjugate Chem. 9, 54-63. 

Srikant, P., Singh, A.K., McElhanon, J.R., and Dentinger, P.M. (2004) Dendrimer-activated surfaces for high density and high activity protein chip applications. Langmuir 20(15), 6075-6079. 

Benters, R. Niemeyer, C. M. Wohrle, D., Dendrimer activated solid supports for nucleic acid and protein microarrays, Chembiochem. 2001, 2, 686 694... 

Fig. 8 (a) Influence of dendrimer generation on transfection efficiency, (b) Influence of dendrimer activation on transfection efficiency. The different bar colors represent different amounts of transfection agent used. Reproduced with permission from [117]. Copyright 2002 Elsevier... 

Several years ago, the Qiagen company launched the dendritic transfection reagent Poly-Fect on the market. This is an activated PAMAM dendrimer. Activation consists in thermal treatment, in the course of which individual branches of the dendrimer are cleaved off (Fig. 8.21). Under physiological conditions its... 

Figure 14.2 Schematic illustration of dendrimer-modified glass support, (a) Aldehyde-terminated dendrimers attached onto amino-modified glass slides (dendri-slides). (b) PAMAM dendrimers activated with glutaric anhydride and IV-hydroxysuccinimide.

The density of immobilized proteins was successfully improved when a dendrimer-activated surface was used.24 Poly(propyleneimine) dendrimers were bound to the Si and glass surface that was modified with l,l -carbonyldiimidazole under anhydrous conditions. Due to the high concentration of charged amine groups of dendrimers, this method provides a fine platform for high density protein immobilization. 

Beier M., Hoheisel l.D. Versatile derivatisation of solid support media for covalent bonding on DNA-microchips. Nucleic Acids Res. 1999 27(9) 1970-1977 Renters R., Niemeyer C.M., Wohrle D. Dendrimer-activated-solid supports for nucleic acid and protein microarrays. Chem. BioChem. 2001 2(9) 686-694 BhatiaR.B., Brinker C.I., Gupta A.K., Singh A.K. Aqneons sol-gel process for protein encapsulation. Chem. Mater. 2000 12(8) 2434-2441... 

An interesting case in the perspective of artificial enzymes for enantioselective synthesis is the recently described peptide dendrimer aldolases [36]. These dendrimers utilize the enamine type I aldolase mechanism, which is found in natural aldolases [37] and antibodies [21].These aldolase dendrimers, for example, L2Dl,have multiple N-terminal proline residues as found in catalytic aldolase peptides [38], and display catalytic activity in aqueous medium under conditions where the small molecule catalysts are inactive (Figure 3.8). As most enzyme models, these dendrimers remain very far from natural enzymes in terms ofboth activity and selectivity, and at present should only be considered in the perspective of fundamental studies. 

One example has used a manganese porphyrin and iodobenzene encapsulated within a dendrimer to bring about shape-selective epox-idation of alkenes. The important aspect of catalysts is that the reactants can move rapidly to the active site, and that the products can be removed rapidly from the active site and expelled from the dendrimer. 

Dennig J (2003) Gene Transfer in Eukaryotic Cells Using Activated Dendrimers. 228 ... 

In macromolecular dmg delivery systems, dmgs are attached to polymeric compounds, such as synthetic polymers [60], dendrimers [61], and antibodies [62], in order to enhance the delivery of the active substance to the diseased tissue and to reduce the toxicity to healthy tissue. The use of macromolecular delivery systems provides several advantages extension of the half-life of the dmg, the ability to introduce targeting moieties into the carrier, the possibility of triggered dmg release, and the aforementioned reduced cytotoxicity. 

Reinhoudt et al. also reported water-soluble pseudorotaxane-terminated dendrimers possessing a radio-active metal core for radiotherapeutical applications... 

PBE dendrons bearing a focal bipyridine moiety have been demonstrated to coordinate to Ru + cations, exhibiting luminescence from the metal cation core by the excitation of the dendron subunits [28-30]. The terminal peripheral unit was examined (e.g., phenyl, naphthyl, 4-f-butylphenyl) to control the luminescence. The Ru +-cored dendrimer complexes are thought to be photo/redox-active, and photophysical properties, electrochemical behavior, and excited-state electron-transfer reactions are reported. 

This manuscript describes the dendritic macromolecules for optical and optoelectronic apph-cations, particularly stimulated emission, laser emission, and nonlinear optics. Dendrimers have been designed and synthesized for these applications based on simple concepts. A coreshell structure, through the encapsulation of active imits by dendritic branches, or a cone-shaped structure, through the step-by-step reactions of active imits, can provide particular benefits for the optical high-gain media and nonlinear optical materials. It also described experimental results that support the methods presented for designing and fabricating functionalized dendrimers for optoelectronic applications, and theoretical results that reveal the intermolecular electronic effect of the dendritic structure. 

Dendrimers, a relatively new class of macromolecules, differ from traditional Hnear, cross-Hnked, and branched polymers. The conventional way of introducing an active moiety into polymers is to Hnk it chemically into the polymeric backbone or a polymer branch. This synthetic approach results in a topologically complex material. Therefore, a significant effort has to be devoted to improve the structural complexities and functions of the polymers. 

The recent development of structurally controlled dendrimers has led to the development of a wide range of new functional macromolecules. These dendrimers were first applied in the fields of chemistry, including catalysis, pharmacology, and materials science [23-26]. More recently there have been several reports of dendrimers having electro active, photoactive, and recognition elements [27-34]. Important applications in photonics have recently been exploited, though the number of reports is still limited. 

We have found that dendrimers can be used to encapsulate active moieties, thereby preventing them from interacting. This passivation effect limits inter-molecular interactions such as self-aggregation and molecular clustering. We also found that dendrimers can be made dipolar. This asymmetry in molecular orientation enables dendrimers to be used in NLO. In this chapter we describe our application of dendrimers to lasers and NLO. 

An important goal of this study is to characterize the noncentrosymmetric arrangement of the azobenzene branches in dendrimers and the effect of these dendrimers on macroscopic second-order susceptibihty. The NLO activity of the dendrimers can be characterized by their molecular hyperpolarizabihty. The hyper-Rayleigh scattering (HRS) method is a reliable way of measuring the mol-... 

Gene Transfer in Eukaryotic Cells Using Activated Dendrimers... 

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