Enzyme immobilization on Ag nanoparticles/polyaniline nanocomposites

Abstract

We show a simple strategy to obtain an efficient enzymatic bioelectrochemical device, in which urease was immobilized on electroactive nanostructured membranes (ENMs) made with polyaniline and silver nanoparticles (AgNP) stabilized in polyvinyl alcohol (PAni/PVA-AgNP). Fabrication of the modified electrodes comprised the chemical deposition of polyaniline followed by drop-coating of PVA-AgNP and urease, resulting in a final ITO/PAni/PVA-AgNP/urease electrode configuration. For comparison, the electrochemical performance of ITO/PAni/urease electrodes (without Ag nanoparticles) was also studied. The performance of the modified electrodes toward urea hydrolysis was investigated via amperometric measurements, revealing a fast increase in cathodic current with a well-defined peak upon addition of urea to the electrolytic solution. The cathodic currents for the ITO/PAni/PVA-AgNP/urease electrodes were significantly higher than for the ITO/PAni/urease electrodes. The friendly environment provided by the ITO/PAni/PVA-AgNP electrode to the immobilized enzyme promoted efficient catalytic conversion of urea into ammonium and bicarbonate ions. Using the Michaelis-Menten kinetics equation, a K(M)(app) of 2.7 mmol L(-1) was obtained, indicating that the electrode architecture employed may be advantageous for fabrication of enzymatic devices with improved biocatalytic properties.

Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite

“…[54][55][56] The low value of K M app may result from two facts: first, the electrode structure as seen in the SEM images exhibits densely distributed pores, which might favor the conformational rearrangements of the enzymes; second, the high surface area of the nanodimensional electrode material enables a more efficient attachment of Urs onto the electrode. 57 The electrode retains 81% of its initial activity after 15 days of storage at 4°C which is higher than the value reported in some of the earlier works. 58 As the amine nitrogen of conducting PANI has been observed to show good binding properties for biological molecules, 59,60 SG-PANI can bind Urs, restricting its overall movement, which may result in effective immobilization and stabilization of the enzyme without requiring additional entrapment.…”

Indium tin oxide synthesized by a low cost route as SEGFET pH sensor

“…Due to the latter properties, ITO has been used as optically transparent conducting electrode in a range of applications [2][3][4] . Recently, ITO films have been used as work electrode in the development of bioengineering devices such as ion sensors and biosensors [5][6][7] . The emerging sensor and biosensor technology based on ITO films has emerged as an advantageous alternative for applications in medicine 8,9 .…”

Metal-Polymer Nanocomposites: (Co-)Evaporation/(Co)Sputtering Approaches and Electrical Properties

“…The electrical signal is much related to the concentration of the analyte [135,136]. In this sense, for example, Crespilho et al [137], using PANI/PVA-Ag NP composites as electrodes, developed a simple, versatile and efficient enzymatic bioelectrochemical sensor. Figure 29 reports the plot of the time-dependent amperometric curves at different urea concentrations for ITO/PANI/urease and ITO/PANI/PVA-AgNP/urease electrodes.…”