Plasma immobilisation

Contrary to the monomer-based techniques described so far, low-pressure plasma immobilisation allows to permanently attach stimuli-responsive polymer films with a thickness of a few nanometers on polymeric substrates using an argon discharge. At appropriate treatment parameters, covalent fixation is achieved while important properties of the immobilised polymer like the thermo-responsive behaviour are preserved (Schmaljohann et al. 2004 Nitschke et al. 2004). 

The immobilisation by electrostatic interactions of longer, 26 bp ssDNA strands on hard, poly(lysine)-coated glass resulted in aggregates of 63 nm (Fig. 26) [163]. Finally, when DNA molecules of the same length (26 bp) were covalently immobilised on the surface of plasma-induced, NHS-... 

IgE in plasma Competitive or displacement immunoassay using surface-immobilised anti-IgE and ALP-labelled second antibody Amperometric detection of 4-aminophenol +300 mV 63-1000 ngml-1 (competitive) 100-1500 ngml 1 (displacement) 0.09 ngmr1 Kreuzere aZ. [77]... 

The immobilisation of unsaturated surfactant sodium 10-undecenoate [Cl 1( )] and the saturated surfactant sodium dodecanoate (C12) was carried out on PE surfaces [266] by means of an argon plasma treatment and characterised using XPS and SSIMS techniques. The typical SSIMS spectra for unmodified and modified PE films are shown in Fig. 21. The differences in the SSIMS spectra of PE and that of PE/C11( ) and PE/C11( )-Ar 5 are merely the spectra of the surfactant which can be attributed to the presence of a layer of Cll( ) on the PE sample. The SSIMS analysis showed that during... 

Elder, P.A., K.H.J. Yeo, J.G. Lewis, et al. 1987. An enzyme-linked immunosorbent assay (ELISA) for plasma progesterone Immobilised antigen approach. Clin. Chim. Acta 162 199-206. 

Many other applications for plasma polymers in the Life Sciences have been dted, often in relation to implantable medical devices or materials, with the goal of concealing the device from the bodies defence mechanisms, or improving cell colonisation of the material, e.g. endothelial cell growth into vascular grafts. A number of excellent studies from the group of Hans Griesser (CSIRO, Australia) describe the use of plasma polymers as substrates to which biomolecules can be immobilised. These immobilisations have been demonstrated to enhance the medium-term acceptability of contact lens materials and may prove relevant to implantable devices. 

Enzymes in their natural environment have been used as "solid reagents" and Saccharomyces cerevisae is a good example [118]. Enzyme cartridges have also been used, as demonstrated by the determination of glucose in plasma using flow injection manifolds with spectrophotometric and chemiluminometric detection and an in-line immobilised enzyme coil [119]. The coil consisted of glucose oxidase covalently bound to the inner surface of a nylon tube (25 cm long, 1.0 mm i.d.) which was coiled into a cylindrical acrylic exoskeleton. 

Reproducibility problems in the production of polymer layers as described above can sometimes occur. Since washing steps and drying procedures are often incorporated to remove loosely bound material, and changes in intensity or duration of these steps can result in different layers. Thus the amoimt of the immobilised protein will be different and reduce the reproducibility of the sensors response. The use of thick organic films produced by this method can also lead to frequency instabihty and loss of sensitivity. It is also difficult to control film thickness and homogeneity, which also effect the reproducibility of the surface produced. Weak adhesion between the polymer and the substrate can also be a problem. Methods, such as plasma polymerisation and electropolymerisation, have been developed to overcome these problems and to gain more control over the layer parameters. 

Fig. 2 Temperature-dependent swelling behaviour of PNIPAAm and poly(NiPAAm-co-DEG-MA) thin films immobilised by low-pressure argon plasma treatment (reproduced from (Nitschke et al. 2007a) with permission)...

Gianazza, E. and Arnaud, P. (1982b). Chromatography of Plasma Proteins on Immobilised Blue F3G-A. Biochem. J., 203, 637... 

Kojima K., Hiratsuka A., Susuki H., Yano K., Ikebukuro A., and Karube L, Electrochemical protein chip with arrayed immunosensors with antibodies immobilised in a plasma polymerized film, Anal. Chem., 75, 1116-1122, 2003. 

Lofthouse, S. D., Greenway, G. M., and Stephen, S. C. (1999). Miniaturisation of a matrix separation/preconcentration procedure for inductively coupled plasma mass spectrometry usir 8-hydroxyquinoUne immobilised on a microporous silica (tit. J. Anal. At. Spectrom. 14(12), 1839-1842. 

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