Dendrimers cationic

Ferrocenyl dendrimers also afford electroactive films on indium tin oxide (ITO) electrodes in the same manner as described above. UV-visible spectroelectro-chemical measurements of this modified electrodes on oxidation show changes characteristic for the formation of fenocenium cations. Thus, Figure 8 shows the UV-visible absorption spectrum of a film of 2 electrodeposited on a transparent ITO electrode, which exhibits a strong band at 260 nm and a weak absorption band centered at 600 nm, which agree with those observed for the cationic dendrimer [2 KPF j ]g in solution described above. 

Lim YB, Kim T, Lee JW et al (2002) Self-assembled ternary complex of cationic dendrimer, cucurbituril, and DNA noncovalent strategy in developing a gene delivery carrier. Bioconjug Chem 13 1181-1185... 

Chemoselective polyalkylation of phosphorus-based dendrimers offers an opportunity to produce cationic dendrimers from neutral ones [66]. 

These amidometallocenes do not significantly recognize halides, however, the redox potential shifts being very small [372]. Chloride and bromide were specifically recognized by 24-cationic dendrimers bearing iron sandwich units at the termini of the branches [376, 377]. The sandwich units was [FeCp ( / -A-alkylaniline)]+. 

Zhang GD, Harada A, Nishiyama N, Jiang DL, Koyama H, Aida T, Kataoka K (2003a) Polyion complex micelles entrapping cationic dendrimer porphyrin Effective photosensitizer for photodynamic therapy of cancer. J Control Release 93 141-150. 

A variety of secondary structures can be formed from dendrimer or dendron primary units (98). We have prepared dendrisomes (vesicles) from amphipathic dendrons (Fig. 16). Dendriplexes can be formed by interactions between anionic macromolecules and cationic dendrimers or dendrons, for example. Hydrophobic dendrimers whose surface groups are reacted to form an alkyl surface will aggregate and can be formulated as so-called dendrimer-derived nanoparticles some 200 nm in diameter (99). 

Pan, Z. et al.. Interactions of cationic dendrimers with hematite mineral. Colloids Surf. A, 238, 123, 2004. 

We studied the capacity of dendrimers 36-[G ] and 37-[G ] (n generation) (Scheme 26) to mediate the in vitro delivery of nucleic acids (pCMV-luc plasmid, luciferase gene) into mammalian cells (3T3 cells). The property expected in this case is the self-assembly of the cationic dendrimer with the gene bases, which would mediate the penetration of the gene within the cell. The results obtained strongly depend on the type of end groups, even if 36-[G ] and 37-[G J differ only by the type of agent used to induce the quaternarization of the terminal amines. Indeed, the methylated forms 37-[G ] were found to be rather tox-... 

Reaction of dendrimers 38-[G2] with L-hexadecylamino-l-deoxylactitol led to the formation of the cationic dendrimers 39-[G2] (Scheme 27). A spontaneous supramolecular self-assembly leading to the formation of vesicles was observed by transmission electron microscopy (TEM). It was shown that the size of these vesicles was around 100 nm, and that their shell was constituted by a bilayer (thickness 10 nm) made of two lipophilic layers (thickness 3 nm) separated by a hydrophilic layer. Furthermore, preliminary experiments show that these cationic dendrimers possess an anti-HIV activity in vitro [41]. 

Dendrimer-based drug delivery systems have been successful in both improving bioavailability as well as targeting drugs. The main advantages for the use of dendrimers as drug carriers reside in their multivalent design and their well-defined structure that results from the stepwise, iterative approach used in their preparation. The anionic and neutral dendrimers have been shown to be less toxic than the cationic dendrimers but at the same time they suffer from lower permeability compared to cationic dendrimers. Typically the smaller size of dendrimers... 

Cationic dendrimers have been reported to show antimicrobial [83-85], antiviral, and anti-inflammatory [86] properties. The dendrimer s antimicrobial activity is attributed to cationic charge of the dendrimers. Chen et al. [84] reported the synthesis of PPI dendrimers with quaternary... 

Figure 10.4 Monochlorotriazines used to generate libraries of cationic dendrimers for nucleic acid deliveiy.

Reactions of amines with other reagents can produce cationic dendrimers as well, or temper the degree of cationic character. Triazine dendrimers have been reacted to provide the charged species shown in Figure 10.5. 

The most important problem of cationic dendrimers is toxicity. However, they can be modified with fatty acids or PEG chains to overcome this problem. This kind of modification reduces the overall charge density and minimizes contact between the cell surface and dendrimer, thus reducing toxicity. 

Cationic dendrimers and hyperbranched polymers (HBPs), normally soluble in water solutions, have been shown to cross cell barriers at sufficient rates to act as potential carrier/delivery systems for small molecules, proteins and DNA, and have been studied as antibacterial agents. Some of the most studied cationic dendritic systems in the literature are discussed in the following sections. 

The presence of fluorescence groups in dendrimer scaffold is a main goal in dendrimer chemistry for biomedical applications. If we consider quaternization as the typical procedure to obtain cationic dendrimers, it is important to know whether protonation of amine groups, typically by HCl, or addition of iodoallq l derivatives (RI), maintain or not the properties of the dye units. 

The multivalency and uniformity of dendrimers make them very attractive for different biomedical applications. In the particular case of cationic dendrimers, one of their applications is gene therapy, due to the interaction between the positive surface of dendrimers and the anionic phosphate groups of nucleic acids. 

Applications of cationic dendrimers as transport vehicles have been described, with an emphasis on their use as transfection agents for nucleic acids. They can transfect them into a large number of cell lines and primary culture cells.Dendrimers with protonable amine groups can interact with all forms of nucleic acid by electrostatic interactions to form complexes that condense the nucleic acids. Whereas linear polymers often adopt random coil structures, the 3D structure of a dendrimer is characterized by radial symmetry. To solve many cellular obstacles of gene delivery, functionalization and variation of the dendrimer structure is an important tool that can be applied. These systems have shown stability and non-immunogenic properties for their potential use in a high variety of therapeutic applications and have been successfully used as carriers for nucleic acids and drug delivery. ... 

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