Covalent Immobilization of Urease on Poly(Pyrrole-3-carboxylic Acid): Electrochemical Impedance and Mott Schottky Study

Abstract

Pyrrole-3-carboxylic acid was electropolymerized on a glassy carbon electrode in 0.1 M NaClO4/ACN, Et4NBF4/ACN using cyclic voltammetry. Urease (Urs) was immobilized onto PPCA modified GCE via covalent binding, exploiting EDC/NHS chemistry. Electrochemical impedance spectroscopy was used to investigate the interfacial behavior of Urs immobilized PPCA surfaces at open circuit potential. The impedance spectra were fitted before and after immobilization of Urs using equivalent circuits of R(C(R(Q(RW)))). After immobilization of Urs onto the PPCA matrix, the charge transfer resistance (RCT) increased for electrodes, which RCT of urease immobilized PPCA-NaClO4 matrixes were lower than that of the Urs immobilized PPCA-Et4NBF4 matrixes indicating higher charge transfer ability. A decrease in double layer capacitance (Cdl) values when Urs was immobilized at the PPCA-NaClO4 electrode surface was observed, whereas an increase at the PPCA-Et4NBF4 electrode surface was observed. Urs immobilized electrodes resulted in a n-type semiconducting behavior revealing a positive slope. An increase in acceptor concentration of the electrodes, and a shift of the EFB to more positive values with increasing amount of urease was observed. The Urs based electrode (PPCA-NaClO4-Urs) was used for detection of urea, which was detected in range of 0.9 to 14 mM with a detection limit (LOD) of 8.28 μM.

Electropolymerization of 9-Carbazole Acetic Acid in Room Temperature Ionic Liquid-Acetonitrile Mixture: Morphology, Capacitance, and Mott–Schottky Analysis

“…The linear region generally appeared from Mott-Schottky behavior in the potential range between 0.2-0.6 V for a polymer prepared by electropolymerization. [45][46][47] In our case, this linear portion began at 0.3 V (100% BMIMBF 4 ) and reached 3.0 V (40% BMIMBF 4 ). Moreover, an additional linear region on the MS plot appeared which was reported in the literature when ionic liquid is used as an electrolyte due to RTIL enabling a deeper study of donor or acceptor level with a wider electrochemical window.…”

Peripherally and non-peripherally carboxylic acid substituted Cu(ii) phthalocyanine/reduced graphene oxide nanohybrids for hydrogen evolution reaction catalysts

“…The Randles–Sevcik equation at room temperature is given as: i p = 268600 n 3/2 AD 1/2 Cν 1/2 Here i p (A) is the maximum peak current, n (= 1) is the number of electrons transferred in the redox reaction, A is the effective surface area of the electrode (cm 2 ), D (cm 2 s −1 ) the diffusion coefficient of K 3 Fe(CN) 6 (7.6 × 10 −6 cm 2 s −1 ), 93 C is the concentration of the diffusing species (mol cm −3 ), and ν (V s −1 ) is the scan rate. The effective surface area is calculated as 6.27, 7.64 and 12.1 mm 2 for the rGO/CuPc( 1 ), rGO/CuPc( 2 ), and rGO/CuPc( 3 ), respectively.…”

Facile Preparation of Ionic Liquid‐coated Copper Nanowire‐modified Carbon Paste Electrode for Electrochemical Detection of Etilefrine Drug

“…Figure 5 illustrates the electro-polymerization of EMIMS on CPE/CuNWs, which was performed by dipping the CPE/CuNWs in PBS (pH 5.5) containing 0.1 M EMIMS by scanning range from 800 to 1200 mV for 30 cycles at the scan rate of 50 mV/s. [44][45][46] Electrochemical Behavior of ET-HCl. The oxidation peak current response increased drastically by the electropolymerization cycles were raised from the 5 to 30.…”

“…In this report, we have done 30 cycles as the ideal number for the construction of the polymeric film on the surface of CuNWs/CPE. It can be expected that the polymerization mechanism may be a radical polymerization …”