Layer by Layer Immobilized Horseradish Peroxidase on Zinc Oxide Nanorods for Biosensing

Abstract

Using zinc powders as source material, ZnO nanorods (ZnONR) were fabricated on gold wire by a hydrothermal reaction without any other surfactant. The gold wire end was coated by a thin layer of Zn-Au alloy to improve the nucleation for growth of ZnO nanostructures and to further improve the performance of the biosensor, which was constructed by alternatively immobilizing poly(sodium 4-styrenesulfonate) (PSS) and horseradish peroxidase (HRP) on the ZnONR. Electrochemical measurement, ultraviolet-visible spectrum, zeta-potential, and scanning electron microscopic analysis demonstrated that PSS and HRP were stably adsorbed layer by layer on the ZnONR surface, and the HRP kept bioactivity for H(2)O(2) detection without an electron transfer mediator. The multilayered HRP sensors exhibited a wide linear range and low detection limit. The sensitivity of the biosensor increased with the immobilized HRP layers from the lowest value of 36.28 microA mM(-1) for a monolayer.

Direct electrochemistry of horseradish peroxidase immobilized on a monolayer modified nanowire array electrode

“…The surface concentration of electroactive HRP was larger than the saturated monolayer concentration of HRP (5.0 × 10 −11 mol cm −2 ) (Xiao et al, 2000) because HRP was coated over the entire surface topology of the nanowire electrode. Comparing to those reported for HRP surface concentration in a multilayer modified ZnO nanorod electrode (Gu et al, 2009), cysteine/AuNWs are more efficient for HRP immobilization.…”

“…The HRP/NAEs exhibited much higher k s values compared to the HRP/flat Au electrode, due to the high electrocatalytic reaction with elevated amounts of HRP on the NAEs and the excellent electron transfer accelerating property of the well-aligned gold nanowires. The electron transfer rate of HRP/NAEs was also much higher than the k s values of HRP immobilized on zinc oxide nanorods (1.15 s −1 ) ( Gu et al, 2009) and a Nafion-cysteine/Au electrode (1.13 s −1 ) (Hong et al, 2007), suggesting superior electron transfer kinetics of HRP on the NAEs. According to Faraday's law:…”

“…However, the distribution of enzyme in the gel or the polymer 3D matrix is usually not uniform, sometimes spatially hindered, resulting in relatively low electron transfer efficiency because only a very small percentage of the enzyme immobilized is electroactive. Thus, ordered 3D matrices, such as nanotube arrays (Cui et al, 2007;Lan et al, 2008), ordered porous materials and nanowire/nanorod/nanopillar electrode ensembles (Anandan et al, 2006;Gu et al, 2009;Yu et al, 2003), have been used for increasing the active surface area for enzyme immobilization. Nanowire electrode ensembles (NEEs) prepared from a polycarbonate (PC) membrane (Roberts and Kelley, 2007;Yang et al, 2007) and nanowire array electrodes (NAEs) prepared from an anodic alumina membrane (AAM) (Lee et al, 2008) have been reported for various enzyme immobilizations.…”

ZnO nanostructures in enzyme biosensors

“…ZnO nanorods were hydrothermally synthesized on Au wires, and used in the detection of H 2 O 2 [91]. Poly(sodium-4-styrenesulfonate) (PSS) and horseradish peroxidase (HRP) layers were alternately immobilized on the ZnO surface.…”

Development of a Biocompatible Layer-by-Layer Film System Using Aptamer Technology for Smart Material Applications

“…More recently, focus has shifted away from these synthetic systems and more towards natural polymer films which offer a promising new set of properties including biodegradability, biocompatibility, and lack of toxicity. Materials such as polysaccharides [18], polynucleotides [40], enzymes [41], polypeptides [21], and proteins [42] have been used to create novel films with different properties and functionalities. Thus, a new film model for use in aptamer-based materials, based on CHI and HA, was chosen to replace PSS and PAH.…”