Fabrication of multiwalled carbon nanotubes/polyaniline modified Au electrode for ascorbic acid determination

Abstract

An ascorbate oxidase (AsOx) (E.C.1.10.3.3) purified from Lagenaria siceraria fruit was immobilized covalently onto a carboxylated multiwalled carbon nanotubes and polyaniline (c-MWCNT/PANI) layer electrochemically deposited on the surface of an Au electrode. The diffusion coefficient of ascorbic acid was determined as 3.05 × 10(-4) cm(2) s(-1). The behavior of different electrolytes on electro-deposition was also studied. An ascorbate biosensor was fabricated using a AsOx/c-MWCNT/PANI/Au electrode as a working electrode, Ag/AgCl (3 M/saturated KCl) as standard and Pt wire as an auxiliary electrode connected through a potentiostat. Linear range, response time and detection limit were 2-206 μM, 2 s and 0.9 μM respectively. The biosensor showed optimum response at pH 5.8 and in a broader temperature range (30-45 °C), when polarized at +0.6 V. The biosensor was employed for determination of ascorbic acid level in sera, fruit juices and vitamin C tablets. The sensor was evaluated with 91% recovery of added ascorbic acid in sera and 6.5% and 11.4% within and between batch coefficients of variation respectively for five serum samples. There was a good correlation (r = 0.98) between fruit juice ascorbic acid values by the standard 2,6-dichlorophenolindophenol (DCPIP) method and the present method. The enzyme electrode was used 200 times over a period of two months, when stored at 4 °C. The biosensor has advantages over earlier enzyme sensors in that it has no leakage of enzyme, due to the covalent coupling of enzyme with the support, lower response time, wider working range, higher storage stability and no interference by serum substances.

Silver nanoparticles/multiwalled carbon nanotube/polyaniline film for amperometric glutathione biosensor

“…The immobilization of enzyme within nanotubes may permit a mediated direct [39]. Polyaniline (PANI) is also an attractive conducting polymer, since it exhibits two redox couples facilitating efficient enzyme-polymer charge transfer [40,41]. Silver is the best conductor among metals and so silver nanoparticles (AgNPs) may facilitate more efficient electron transfer than gold nanoparticles in biosensors [42].…”

Fabrication of Gold Nanoparticles Modified Carbon Nanofibers/Polyaniline Electrode for H2O2Determination

“…16 Furthermore, AuNPs have been extensively used in electrochemical sensors due to their unique physicochemical properties. [17][18][19][20][21][22] With regards to small, welldispersed AuNPs grafted onto substrate materials, the fabrication of biosensors with low detection limits and a wide dynamic range for H 2 O 2 has become an intractable challenge for scientists. 23,24 In this work, CNFs were successfully obtained from the electrospun PAN nanofibers through a carbonization process.…”

Functionalization of poly-SNS-anchored carboxylic acid with Lys and PAMAM: surface modifications for biomolecule immobilization/stabilization and bio-sensing applications

“…[6][7][8][9] Also, electropolymerization enables easy control over several properties such as morphology and thickness. Furthermore, their chemical functionalizations offer a better microenvironment for biomolecules and electrochemical transduction of biological events.…”