Redox-sensitive polymers

Redox-sensitive polymers Drug formulated with azo polymer and disulfide polymers that selectively respond to the redox potential of the colon. 

Polyhydroquinone [60], which is soluble in organic media [61], was prepared with a defined architecture [62]. In this case, hydroquinone is part of the main chain [63] although side-chain polyhydroquinones also exist [64, 65]. Anthraquinone-based polymers, which can be connected in various ways, are known [66-71]. These are rather peculiar examples of redox-sensitive polymers because... 

A. Lewenstam, J. Bobacka, and A. Ivaska, Mechanism of ionic and redox sensitivity of p-type conducting polymers. 1. Theory. J. Electroanal. Chem. 368, 23—31 (1994). 

An interesting synthetic approach was introduced by Ito et al. [99], They covalently bound an azoinitiator, 4,4 -azobis(4-cyanovaleric acid) to trypsin. In the presence of the monomers, 3-carbamoyl-1 -(p-vinylbenzyl)pyridinium chloride, or a mixture of methacrylic acid and methyl methacrylate, trypsin-polymer conjugates were synthesized (Fig. 3) which were sensitive to external signals, i.e., redox sensitive and pH sensitive, respectively. 

In the near future, it is believed that a major part of macromolecular chemistry will receive a strong impact from homogeneous organometallic catalysis. Thus, poly-coupling reactions with redox-sensitive precursor compounds to give polymers like 38 were discovered [72]. 

Recently, we (82) and others (82-84) have shown that similar hetero-structures can be prepared by using two-dimensional inorganic sheets (made by exfoliation of various lamellar solids) in place of the organic polyanion. This technique offers a potentially powerful alternative to the construction of multi-component electron transfer systems, because it can, in principle, be used to stack up an arbitrary number of redox-active polymers without interpenetration (85). This chapter describes the preparation and photochemistry of simple multilayer composites on high-surface-area silica. Specifically, the synthesis and electron transfer kinetics of systems containing a polycationic sensitizer, poly-[Ru(bpy)2(vbpy)(Cl)2] (1), (abbreviated [Ru(bpy)3 ]n bpy = 2,2 -bipytidine and vbpy = 4-vinyl-4 -methyl-2,2 -bipyridine), and an electron-acceptor polycation poly[(styrene-co-]V-vinylbenzyl-N -methyl-4,4 -bipyridine)(Cl)2] (2), (PS-MV ) are presented. Using a solution-phase electron donor, 3, as the third electroactive component, it was possible to prepare and study the photoinduced electron transfer reactions of several different diad and triad combinations. 

Due to its high stability, the membrane of polymersomes has low fluidity, which leads to a very limited ttansport through the membrane. Thus, in order to allow for transmembrane transport, specific efforts are necessary. One option is the use of responsive polymer blocks, which allow a switching of the block from hydrophilic to hydrophobic, or vice versa. This can be achieved with thermo-responsive poly(Af-isopropylacrylamide) (PNIPAM), pH-sensitive amino-functionalized methacryl derivatives (e.g., poly(diethylaminoethyl methacrylate) (PDEAEM)), or the redox-sensitive poly(propylene sulfide) (PPS). 

A new type of (bio)chemical sensor, the redox-sensitive field-effect transistor is described It consists of a conventional ISFET with a noble metal added on top of the gate insulator The gate electrode is modified with a redox polymer containing osmium complexes The potentiostatic multi-puls method is introduced which allows the adjustment of the redox potential of the gate to a desired value in a stepwise way It is shown that the open circuit potential after switching off the potentiostat is a good measurement of the presence of the redox active species NADH... 

It was shown that bilayer composed of both polymers with anion exchanger properties, e.g., PMT(PF )/PPy(PF ) exhibited strong dependence of the open circuit potential on NaCl concentration with the slope 52 mV/p[NaCl]. Distinct redox sensitivity of such bilayers, with the slope -48 mV/p[Ox/Red], was observed as well. 

The deposition conditions, postdeposition treatment, ionic and redox sensitivity, and selected applications of the conducting polymer-based reference electrodes are summarized in Table 12.2. 

Nguyen, D.H., Choi, J.H., Joung, Y.K., Park, K.D. Disulfide-crossUnked heparin-plu-ronic nanogels as a redox-sensitive nanocarrier for intracellular protein delivery. J. Bioact. Compat. Polym. 26, 287-300 (2011)... 

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