Polyelectrolyte complexes micelles

J. H. Jeong, S. H. Kim, S. W. Kim and T. G. Park, Polyelectrolyte complex micelles composed of c-raf antisense oligodeox)mu-cleotide-poly(ethylene glycol) conjugate and poly(ethylenimine) effect of systemic administration on tumor growth. Bioconjugate Chem., 16,1034-1037 (2005). 

Lindhoud S, Norde W, Cohen Stuart MA (2009) Reversibility and relaxation behavior of polyelectrolyte complex micelle formation. J Phys Chtan B 113 5431-5439... 

Fig. 7 Light scattering intensity (/) as a function of the composition (F ) for polyelectrolyte complex micelle formation. See text for a description of regions I-IV. Reprinted from [50] with permission. Copyright 2009, American Chemical Society...

These particles are called by several names in literature block ionomer complexes [57], polyion complex micelles [58], complex coacervate core micelles [59] and polyelectrolyte complex micelles. An extensive review of this type of micelle has been written by Voets et al. [60]. 

At a certain composition the slope (//C) becomes more pronounced. At this point, the polyelectrolyte complex micelles start to form (II). Their mass is considerably larger than that of the soluble complexes, with a more pronounced increase in scattering intensity as a result. A maximum in scattering intensity is found at F K. 0.5, where the system is electroneutral and the mass of the particles is maximal. This composition will be referred to as Addition of more... 

Polyelectrolyte Complex Micelles with Protein Molecules... 

In the previous section, the polyelectrolyte complex micelle formation of anionic diblock copolymers and cationic homopolymers was discussed. A simple way to obtain micelles tilled with protein molecules is to replace the cationic homopolymer with positively charged protein molecules. Harada and Kataoka were the first to apply this procedure [64], They formed protein-filled micelles by mixing lysozyme and polyfethylene glycol)-poly(aspartic acid) block copolymers. 

As has already been discussed, rheology is a powerful tool for studying the dynamical response of polyelectrolyte systems [43]. This experimental technique was also used to study transient networks of interconnected polyelectrolyte complex micelles [68, 79, 80]. These networks are formed by triblock copolymers having two like-charged end blocks, a neutral hydrophilic middle block and oppositely charged homopolymers. For low concentrations of these systems at = 0.5, flower-like micelles are formed the core of these micelles consists of the homopolymer and both charged end blocks of the triblock copolymer. Above a... 

Lindhoud S (2009) Polyelectrolyte complex micelles as wrapping for enzymes. PhD thesis. University of Wagtmingen, Wageningen... 

LemmCTs M, Voets IK, Cohen Stuart MA, van der Gucht J (2011) Transient network topology of interconnected polyelectrolyte complex micelles. Soft Matter 7 1378—1389... 

Lindhoud S, de Vries R, Schweins R, Cohen Stuart MA, Norde W (2009) Salt-induced release of lipase from polyelectrolyte complex micelles. Soft Matter 5 242-250. doi 10.1039/ b811640g... 

Fig. 4 Formation of polyelectrolyte complex micelles self-assembled from ODN-PEG conjugate and the peptide KALA [78] (figure reproduced with permission of American Chemical Society)...

Nanosized and stable chitosan-g-PEG/heparin polyelectrolyte complexes were developed by Bae et al. [133]. The nanocomplex was utilized to study apoptotic death of cancer cells. The prepared polyelectrolyte complex micelles had a spherical shape with an average diameter of 162.8 18.9 nm. They were highly stable and well dispersed even in the presence of serum due to the presence of a hydrophilic PEG shell layer surrounding the micelles. The polyelectrolyte complex micelles were internalized by cancer cells to a greater extent than free heparin alone, indicating that the dramatic cell death was attributed to the increased cellular uptake of heparin. The internalized heparin was shown to induce apoptotic death of the cancer cells via a caspase-dependent pathway. The proposed chitosan-g-PEG/ heparin polyelectrolyte complex micelles facilitated the intracellular delivery of heparin, triggered the caspase activation, and consequently promoted apoptotic death of cancer cells [133]. 

Interpolyelectrolyte complexes Micelles Nanostructures Polyelectrolytes Supramolecular chemistry... 

Spectacular increases in spontaneous and base-catalyzed or metal-assisted aquation rate constants of particularly pentaammineco-balt(III) complexes have been observed in the presence of polyelectrolytes and micelles. Polyelectrolytes are known to cause marked acceleration of reactions, though decelerations can be observed, and the effects are very large compared with those produced by equivalent amounts of corresponding low molecular weight substances similar effects are observed in solutions containing charged micelles. This area of research has been extensively reviewed (63,101,133,139,195, 206, 207), so discussion will be selective. 

Lability for at least one coordination site has been adequately demonstrated in the traditionally inert metal complexes in recent decades. Induction of lability by chemical reactions on a normally poor leaving group, by metal ions, protons, and base and by polyelectrolytes and micelles, offer opportunities in specific circumstances. Largely during the last decade, however, a number of ligands have appeared that are poor nucleophiles and inherently labile. Such molecules, of which tri-fluoromethanesulfonate is the most extensively studied, are univer-... 

The DDSs based on cationic polymers include polyelectrolyte complexes (PECs), micro- and nanoparticles, capsules, hybrid delivery systems, injectable hydrogels, liposomes, micelles, penetration enhancers, and release triggers. This distinction is, however, not a clear-cut one and some of the... 

Polyanions and polycations can co-react in aqueous solution to form polyelectrolyte complexes via a process closely linked to self-assembly processes [47]. Despite progresses in the field of (inter-) polyelectrolyte complexes [47] (IPEC from Gohy et al. [48], block ionomer complexes BIC from Kabanov et al. [49], polyion complex PIC from Kataoka and colleagues [50, 51], and complex coacervate core micelles C3M from Cohen Stuart and colleagues [52], understanding of more complex structures such as polyplexes (polyelectrolyte complexes of DNA and polycations) [53] is rather limited [54]. It has also to be considered that the behavior of cationic polymers in the presence of DNA and their complexes can be unpredictable, particularly in physiological environments due to the presence of other polyelectrolytes (i.e., proteins and enzymes) and variations in pH, etc. 

One way to study polyelectrolyte complex formation in solution is using dynamic light scattering (DLS) titrations on micelle-forming systems. Here, a solution of polyelectrolytes is titrated to a solution of oppositely charged polyelectrolytes, at least one of the polyelectrolytes should have a neutral hydrophilic block, and after every addition the intensity and hydrodynamic radius are measured. When a pH electrode is fitted into the measuring cell, the pH can be followed during the titration. In this titration, nanoparticles will be formed (instead of insoluble polyelectrolyte complexes) with a polyelectrolyte core and a neutral corona. 

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