Poly bilayers, functionalized

Poly(Lipid) Bilayers Functionalized with Labels and Biomolecules... 

Overall, these studies were the first to demonstrate that the activity of a TMP can be maintained in a highly cross-linked poly(PSLB). The location of the polymerizable moiety is clearly an important consideration. These findings should provide guidance for designing robust poly(lipid) bilayers functionalized with TMPs for use in membrane-based biochips and biosensors. 

Yang, Y., Fang, G., Wang, X., Pan, M., Qian, H., Liu, H., and Wang, S. [2014]. Sensitive and selective electrochemical determination of quinoxaline-2-carboxylic acid based on bilayer of novel poly(pyrrole] functional composite using one-step electropolymerization and molecularly imprinted poly(o-phenylenediamine]. Anal Chim. Acta, 806, pp. 136-143. 

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

The boundary between cases I-II has been explored by Flexer et al. [69] with LbL self-assembled GOx multilayers and poly(bipyridine-pyridine) redox polymer (PAH-Os). Figure 2.29 shows the catalytic response in excess glucose as a function of the number ofself-assembled polymer-enzyme bilayers. For the first bilayers (thin films)... 

Munro JC, Frank CW (2004) Adsorption of lipid-functionalized poly(ethylene glycol) to gold surfaces as a cushion for polymer-supported lipid bilayers. Langmuir 20 3339-3349... 

Poly(NIPAM-co-MAA) with MAA content above 5 mol% is soluble under both physiological pH (7.4) and temperature (37°C), when its carboxylic functions are ionized. However, when the pH is decreased to the pH of late endosomes and lysosomes ( pH = 5-5.5) (1), MAA protonation triggers dehydration of the polymer chains. If the polymer is anchored to a phospholipid membrane through randomly or terminally incorporated alkyl chains, transition, to a globule conformation induces reorganization of the bilayer that leads to massive content leakage (3). 

Figure 28 Schematic rendition of the cross-section of a unilamellar liposome made of a mixture of natural phospholipids and poly(ethylene glycol)-functionalized lipids (32). The polar polyether chains cover both surfaces of the bilayer, thus preventing interaction with macromolecules present in the biological fluids [95, 96]...

Fig. 12 Schematic representation of polymerized lipid patterning in a capillary, a SUVs prepared using bis-SorbPC are fused to the inner capillary surface to create a uniform supported bilayer, b The bilayer is polymerized via UV irradiation through a photomask placed over the capillary, c Unpolymerized lipid is removed from the capillary to yield a poly(lipid) pattern, d SUVs composed of other lipids are then fused into the bare silica regions between poly(bis-SorbPC) structures, generating chemically functionalized patterns. Reprinted with permission from [96]. Copyright 2007, American Chemical Society...

The polyelectrolyte multilayers employed in these studies consisted of alternating layers of poly(ethyleneimine) (PEI) and poly(4-styrenesulfonicacid) sodium salt (PSS) and were prepared via adsorption from solution as described by Decher et al. [26] on functionalized Au- or SiOx substrates. The lipids used for the preparation of the bilayers were dimyristoyl-L-a-phosphatidylglycerol (DMPG, negatively charged in aqueous solution) and DMPC. Uni-lamellar lipid vesicles were prepared via the extrusion technique. 

An interesting electrochemical method for the determination of bound sialic acid has been developed, making use of a potentiometric four-channel thick-film sensor [236]. The sialidase sensor consists of a bilayer of a membrane containing Clostridium perfringens sialidase immobilized in a poly(vinyl acetate)-polyethylene copolymer, which is placed on top of an fT -selective poly(vinyl chloride)-poly(vinyl acetate) indicator membrane. The enzyme-induced release of bound sialic acid leads to a concomitant decrease in pA a of the carboxyl function of sialic acid. This decrease affords a local pH change inside the sialidase-containing sensor membrane, which is monitored by the H -selective indicator membrane. The pH optimum of the sialidase sensor was pH 4 for sialyllactose, mucin and colominic acid. 

A bilayer structure usually consists of two different films deposited on a substrate, one overlying the other. A typical system consists of a Pt substrate with an electro-deposited film of poly-[Ru(vbpy)3 ] on which a film of poly-[Os(bpy)2(vbpy)2" ] is elec-trodeposited (25). Another type of sandwich structure involves a pair of closely spaced electrodes such as in an electrode array (26), bridged by a polymer film. Alternatively, a different polymer can be deposited on each electrode of an array pair to form a bilayerlike arrangement having a junction where the films meet. Three-electrode devices of this type can produce a structure functionally equivalent to a field effect transistor (FET) (27). 

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