Block ionomer complex micelle

Similar IPEC-based aqueous micelles can be obtained from the mixing of a double-hydrophilic copolymer AB with a homopolymer C or a diblock copolymer AC or a diblock copolymer DC, provided that IPECs can form between the B and C blocks. This kind of electrostatic complex has also been referred to as block ionomer complexes, or BIC. 

Figure 9.4 Core-shell polyplex structures (A) cationic particles with a core from neutralized DNA and polycation and a corona from polycation chains adsorbed on the core (B) electroneutral particles ( polyion complex micelles or block ionomer complex ) with a core from neutralized DNA and poly cation and a corona from nonionic water soluble polymer.

Figure 47.1. Types of naiiocaniers for dmg delivery. A liposomes B nanopaiticles C nanospheres D nanosuspensions E polymer micelles F- nanogel G block ionomer complexes H nanofibers and nanot ...

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. 

The most interesting situation is that where the complex formation occurs between two block copolymers A-B and A-C, respectively C-D, with specific interactions between the blocks B and C (see Figure 7.8, scheme (c)), such PIC, also called block ionomer complexes (BIC) have been studied quite extensively in aqueous medium by Harada and Kataoka [270] and by Kabanov and Alakhov [271] due to their practical interest in controlled delivery systems. Kataoka and co-workers have for instance shown that water-soluble PlCs for biomedical applications are formed by combination of PEO-poly(L-lysine) and PEO-poly (a, /3-aspartic acid). These authors have further demonstrated that the PIC micelles prepared under charge-neutralized conditions have an extremely narrow size distribution if matched pairs of copolymers with the same block lengths of polyanions and polycations are combined [272]. 

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]. 

Kim JO et al (2013) Cross-linked polymeric micelles based on block ionomer complexes. Mendeleev Commun 23 179-186. doi 10.1016/j.mencom.2013.07.001... 

Water-soluble interpolyelectrolyte complexes (IPECs) can be prepared by complexation of amphiphihc block copolymers, which comprise a hydrophobic block and an ionic or hydrophilic nonionic block [81,82]. Double hydrophilic block copolymers having an ionic block and a nonionic one can be prepared for IPECs even in 1 1 charge-to-charge ratio of the polymeric components in aqueous solution [81]. IPECs normally have a core/corona structure and are often referred to as polyion complex micelles, complex coacervate micelles, or block ionomer complexes [83,84]. 

Fig. 2.2 lypes of nanocarriers for drug delivery. (A) Liposomes (B) polymer and lipid NPs (C) nanospheres and nanocapsules (D) nanosuspensions (E) polymer micelles (F) nanogels (G) block ionomer complexes (H) nanofibers and (1) nanotubes. 

Lysenko EA et al (2004) Eormation of multilayer polyelectrolyte complexes by using block ionomer micelles as nucleating particles. J Phys Chem B 108 12352-12359... 

Harada A, Kataoka K (2003) Effect of charged segment length on physicochemical properties of core-shell type polyion complex micelles from block ionomers. Macromolecules 36 4995-5001. doi 10.102 l/ma025737i... 

Brzozowska et al. [18] reported on the stability of the polymer brushes formed by adsorption of ionomer complexes on hydrophilic and hydrophobic surfaces. The ionomer complexes or micelles consisted of oppositely charged polyelectrolyte blocks (poly(acrylic acid) and poly(N-methyl-2-vinyl pyri-dinium iodide)), and a neutral block (poly(vinyl alcohol)) or neutral grafts (poly(ethylene oxide)). The results showed that adsorbed micellar layers were relatively weakly attached to hydrophobic surfaces and much stronger... 

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