Polycationic surfaces

Most of the methods of synthesis reported above present some limitations and constraints lack of solubility for polycationic phosphorus-containing dendrimers from generation 3 [2], dendrimers of weak molecular weight [4], difficulties to overcome cross Unking reactions [6], possibility only to incorporate phosphorus groups on the surface of dendrimers [3], etc. 

Indeed, up to 322 charges can be chemoselectively incorporated on the core, within the cascade structure (core and internal generations) or even within the cascade structure and on the surface. The polycationic species remain fairly soluble in several solvents. 

The wall of the silica column is lined with silanol groups that become de-pro tonated when the pH is above 2. Under these conditions, a fixed polyanionic layer is formed (Fig. 8.5). However, a polycationic layer due to the electrolyte acts as its counterpart. The H30+ ions and electrolyte cations are put in motion when the electrical field is applied. The net effect is to make all the species present migrate towards the cathode. This linear displacement of the electrolyte, which originates from the charge carried by the electrolyte ions and tangential applied electrical field, can be controlled or reversed by modifying the capillary inner surface, the pH, or by adding cationic surfactants. 

Polyamidoamine (PAMAM) dendrimers are non-linear polycationic cascade polymers that can bind plasmid DNA [43]. The interaction of activated PAMAM-dendrimers and plasmid DNA induces condensation of the nucleic acid. The compact transfection complexes can subsequently adhere to the cell surface and be taken up by endocytosis. 

The [Ru(NHs)5 pyridine]2+/3+ redox center exhibits well-defined, nearly ideal voltammetry across a wide range of electrolyte compositions, scan rates and temperatures. Despite the headgroups having comparable sizes, the saturation surface coverage is less than that found for ferrocene alkane thiol monolayers. This behavior is thought to reflect electrostatic repulsion between the polycationic redox centers and the need to incorporate counterions into the monolayer in both... 

Dendrimers with up to 96 redox-active TTF moieties on the periphery, which allow the generation of polycationic species bearing up to 192 positive charges on the surface, were incorporated into electrodes. These dendrimer-modified electrodes find application in electrochemical sensing of metal cations (i.e., Ba ), thanks to the grafting of crown ether/TTF units on the periphery of dendrimers < 2001AGE224>. 

Hyponatremia, hypokalemia, and hypocalcemia, with corresponding clinical manifestations, have occurred in patients treated for 3 weeks with doses of polymyxin B over 2 g/m body surface (18,19). These abnormalities were interpreted as consequences of polymyxin-induced nephrotoxicity. Hyperchloremia and a negative anion gap seem to result from the polycationic properties of polymyxin B (20). 

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