Micelles complex coacervate core

FIGURE 12.12 Aggregation of oppositely charged diblock copolymers to form a C3M. 

Various types of experiments (notably dynamic light scattering and neutron scattering) have revealed size, shape, and stability of C3Ms. The number of polymers in the micelle amounts to several tens. C3Ms are usually spherical, having radii of 

FIGURE 12.13 Schematic representation of polyelectrolyte complexation based on light scattering intensity. 

Similar to the polyelectrolyte multilayers, C3Ms may be used to preserve and stabilize (bio)functional compounds, such as enzymes and nucleic acids, and as nanobioreactors. C3Ms are, in principle, eminently suitable as carriers in drug and gene delivery because of their tunable stability and the possibility to incorporate site-recognizing functionality in the corona, and because they have the right sizes to pass biological membranes. 

Furthermore, C3Ms tend to adsorb at charged surfaces in a conformation where the complex coacervate forms a dense layer at the surface with the neutral soluble blocks extending in the solution. This allows preparation of bioactive surfaces, for instance, surfaces that resist aspecilic adsorption of proteins, cells, and microorganisms (cf. Section 20.4.3). When the coronal chains are modified with specific receptor molecules, surfaces may be prepared that selectively, and with high affinity, bind to target molecules. Applications may be found in biosensors, antimicrobial packaging, and so on. 

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Zhou H, Sun X, Zhang L, Zhang P, Li J, Liu Y-N. Fabrication of biopoly meric complex coacervation core micelles for efficient tea polyphenol delivery via a green process. Langmuir. 2012 28(41) 14553-14561. 

Characteristic Features of Complex Coacervate Core Micelles. 166... 

In this contribution, we describe our recent experimental and theoretical findings on complex coacervate core micelles. We have investigated the co-assembly of several types of oppositely charged ionic-hydrophilic block copolymers into mixed micelles. In particular, we have focused on chain mixing/segregation in the micellar corona as a function of monomer type and (the ratio between the) chain length of the polymer blocks in the corona. Our aim has been to employ co-assembly in such systems as a route towards formation of reversible Janus micelles. These are micelles with a corona that exhibits two distinguishable sides (hemispheres in the case... 

As we are interested in reversible Janus micelles, i.e. non-centrosymmetric nanoparticles with compartmentalised shells (Fig. 1), complex coacervate core micelles are a rather natural choice. As described in the previous section, electrostatic interaction is a rather weak driving force as compared to hydrophobic interaction. C3Ms may thus form under full thermodynamic control. Although ABC triblock copolymers in selective solvents (poor solvent for B good solvent for both A and C) may also yield Janus micelles, they most frequently aggregate into micelles with a quenched rather than a dynamic nature, such that the aggregation number is fixed and no reversible association/dissociation is observed (on experimental time scales). 

Voets, I.K., de Keizer, A., and Cohen Stuart, M.A. Complex coacervate core micelles. Adv. 

Voets IK, Keizer DA, Cohen Stuart MA (2009) Complex coacervate core micelles. Adv Colloid Interface Sci 147-148 300-318... 

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. 

Abstract In this review, novel hierarchical self-assembled structures based on reversible organo-metaUic supramolecular polymers are discussed. Firstly, we discuss recent advances in the field of coordination polymers, considering cases in which transition metal ions and bis- or multiligands are used to build up organo-metallic supramolecular polymers. Secondly, we review hierarchical self-assembled structures based on these coordination polymers, such as polyelectrolyte layer-by-layer films, capsules, complex coacervate core micelles and microemulsions, and nanoribbons. Finally, we give a short perspective on the formation of coordinationpolymeric hierarchical self-assembled structures. The implications of fundamental and applied research, as well as aspects of new technologies are also discussed. 

When the coordination polymer is mixed with an oppositely charged neutral diblock polymer, the electrostatic interaction will drive complex coacervate formation [40]. But, the growth of the complex coacervate will be constrained by the presence of the neutral blocks, and be stabilized at a finite size. In this way, so-called complex coacervate core micelles (C3Ms), or polyion coacervate (PIC) micelles are formed. This micelle formation is analogous to the formation of C3Ms in covalent polyelectrolyte/ block polymer systems [67, 68]. Obviously, the coordination polymer,... 

In the presence of oppositely charged block copolymers, the local concentration of coordination complexes is greatly enhanced, so that it is suitable to form polymeric structures (Fig. 15). These long coordination polymers simultaneously promote the formation of complex coacervate core micelles [40],... 

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]. 

Fig. 9 Light scattering titrations of complex coacervate core micelles made of dibiock copolymer and homopolymer (a) intensity versus composition, (b) hydrodynamic radius versus compositirai and (c) pH versus composition. Raw data were provided by Hofs et al. [48]. Reprinted from [62] with permission. Copyright 2007, American Chemical Society...

Micellar IPECs (also referred to as complex coacervate core micelles) [139,140] are formed from bis-hydrophilic diblock copolymers comprising a charged and... 

In a different context, complex coacervate core micelle can be obtained by the reaction of a polyion-neutral diblock copolymer with an oppositely charged polyelectrolyte. These micelle are formed upon hierarchical self-assembly in water of the two polymeric components and, more interestingly, upon self-assembly of metal ion coordination polymers [47],... 

Fig. 1 Schematic representation of co-assembly of two oppositely charged ionic-neutral diblock copolymers in water into complex coacervate core micelles, in short C3Ms, with a core comprising the oppositely charged monomers surrounded by a shell of neutral, water-soluble monomers. The two monomer types in the corona may mix left) or segregate radially (mid-left), laterally (mid-right) or both radially and laterally (right) depending on the chemical composition of the block copolymers and hence the miscibility and differential solvent quality of the neutral monomers. This may lead to the formation of onion-like micelles, also known as core-shell-corona structures (mid-left), Janus micelles (mid-right) or patchy micelles, also known as raspberry-like micelles (right). Figure from Ref. [188]...

Wang J et al (2010) Complex coacervate core micelles from iron-based coordination polymers. J Phys Chem B 114 8313-8319. doi 10.1021/jp1003209... 

Hofs B, Voets IK, de Keizer A, Cohen Stuart MA (2006) Comparison of complex coacervate core micelles from two diblock copolymers or a single diblock copolymer with a polyelectrolyte. Phys Chem Chem Phys 8 4242-4251. doi 10.1039/b605695d... 

Brzozowska AM, de Keizer A, Norde W, Detremblenr C, Cohen Stuart MA (2010) Grafted block complex coacervate core micelles and their effect on protein adsorption on silica and polystyrene. Colloid Polym Sci 288 1081-1095. doi 10.1007/s00396-010-2228-4... 

Lindhoud S, de Vries R, Norde W, Cohen Stuart MA (2007) Structure and stability of complex coacervate core micelles with lysozyme. Biomacromolecules 8 2219-2227. doi 10.1021/bm0700688... 

Bourouina N, Cohen Stuart MA, Kleijn JM (2014) Complex coacervate core micelles as diffusional nanoprobes. Soft Matter 10 320-331. doi 10.1039/c3sm52245h... 

Brzozowska AM et al (2009) Reduction of protein adsorption on silica and polystyrene surfaces due to coating with complex coacervate core micelles. Colloids Surf A 347 146-155. doi 10.1016/j.colsurfa.2009.03.036... 

Voets IK et al (2008) Temperature responsive complex coacervate core micelles with a PEO and PNIPAAm corona. J Phys Chem B 112 10833-10840. doi 10.1021/jp8014832... 

Another interesting system is based on the adsorption of so-called complex coacervate core micelles (also called polyion complex micelles) [28,29]. These micelles are formed in aqueous solution when two oppositely charged polyelectrolytes are mixed, with at least one of these polyelectrolytes being connected to an uncharged and water-soluble polymer. The complexed polyelectrolytes then form the complex coacervate core of the micelles, while the neutral chain forms the corona. These micelles have been shown to adsorb to surfaces with very different properties, such as silica and polystyrene. Although formed brushes are of low density, good antifouling properties have been observed [28,30]. 

Complex coacervate core micelles are spontaneously formed when one mixes aqueous solutions of two oppositely charged polyelectrolytes, if at least one of the polyelectrolytes is cormected to a neutral water-soluble polymer [51,52]. The formation of such micelles, and one possibility for their subsequent adsorption, is schematically shown in Figure 7.4 the polyelectrolytes form the complex coacervate core of the micelle while the neutral block forms the corona. 

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