Plasma Polymer Surfaces Compatible with a CMOS Process for Direct Covalent Enzyme Immobilization

Abstract

Plasma polymerized surfaces, prepared using a CMOS compatible plasma enhanced chemical vapor polymerization technique, are found to covalently immobilize enzymes without the need for intermediate chemical linker groups. The polymerized surfaces are smooth, strongly adherent to substrates, and have a long shelf life for storage. After incubation with enzymes, a densely packed monolayer is attached. We report the effects of both oxygen etching and annealing post‐processing showing that they can be implemented so as not to affect the enzyme binding performance. The fully compatible polymerization method with CMOS device manufacture processes is a potential candidate for integration into nano‐CMOS biochemical sensors for direct immobilization of enzymes.

Plasma modified surfaces for covalent immobilization of functional biomolecules in the absence of chemical linkers: towards better biosensors and a new generation of medical implants

“…The plasma polymers and plasma-modified surfaces created using energetic ion bombardment reported more recently are even more hydrophilic (Yin et al 2009e;Kondyurin et al 2009b) than the most hydrophilic surface studied in the earlier works, but nevertheless show much higher levels of SDS-resistant protein attachment (see, for example, MacDonald et al 2008;Yin et al 2009d;Nosworthy et al 2007;Kondyurin et al 2008b, c;Bax et al 2009), rivalling those observed on the most hydrophobic of surfaces examined in the earlier studies. Figure 4 shows where the data obtained on the energetic ion-treated surfaces lie in relation to the adsorption curve of Kiaei et al (1992).…”

“…These properties are retained when nitrogen is added while the covalent binding capacity is reduced with oxygen or hydrogen additions, even though the ESR signal is strong in both cases (Yin et al 2009e). This loss of binding capacity could be explained by a reduction in the mobility of unpaired electrons when hydrogen or oxygen are present in the structure.…”

“…The contact angle for each surface is given in parentheses in the legend. The data are taken from (1) Chen et al (1993) (first four datasets reading from the top of the legend), (2) Yin et al (2009e) (next two datasets shown in the legend), and (3) Kondyurin et al (2008b) (last dataset shown in the legend). The best retention of enzyme activity is observed on two hydrophilic surfaces deposited with energetic ion bombardment, and the two surfaces with the worst activity retention are the most hydrophobic.…”

“…Where the surface is a plasma polymer, the nomenclature used in the legend shows the precursor chemical before the slash and the substrate after the slash. Where the surface is an untreated control the polymer alone is specified both prepared with energetic ion bombardment from nhexane and acetylene precursor gases with self bias on the excited electrode (Kondyurin et al 2008b) and pulsed bias of a few hundred volts (Yin et al 2009e), respectively. The worst performance in terms of enzyme activity retention is observed on the most hydrophobic surfaces (Chen et al 1993).…”

Immobilization of superoxide dismutase/catalase onto polysulfone membranes to suppress hemodialysis-induced oxidative stress: A comparison of two immobilization methods

“…Plasma-based approaches have gained considerable interest for immobilization of biomolecules, since they do not require complicated wet chemical steps to achieve binding allowing linker-free immobilization [13]. Moreover, in some conditions lowered stability of bioactive molecules due to usage of spacers can be prevented [14]. A key challenge for the plasma treatment process is aging as a result of post-plasma oxidation initiated by the reaction between remaining radicals and in-diffusing atmospheric oxygen as well as the movement of some of the polymer chains from the surface into the bulk [15].…”