Enzymatic biosensor based on entrapment of d-amino acid oxidase on gold nanofilm/MWCNTs nanocomposite modified glassy carbon electrode by sol-gel network: analytical applications for d-Alanine in human serum

Publication date: Available online 2 February 2017 Source:Enzyme and Microbial Technology Author(s): Yalda Shoja, Amir Abbas Rafati, Javad Ghodsi Sensing and determination of D-Alanine is studied by using an enzymatic biosensor which was constructed on the basis of D-amino acid oxidase (DAAO) immobilization by sol-gel film onto glassy carbon electrode surface modified with nanocomposite of gold nanofilm (Au-NF) and multiwalled carbon nanotubes (MWCNTs). The Au-NF/MWCNT nanocomposite was prepared by applying the potentiostatic technique for electrodeposition of Au-NF on the MWCNT immobilized on glassy carbon electrode surface. The modified electrode is investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), linear sweep voltammetry (LSV) and cyclic voltammetry(CV) techniques. The linear sweep voltammetry was used for determination of D-Alanine and the results showed an excellent linear relationship between biosensor response and D-Alanine concentration ranging from 0.25μM to 4.5μM with correction coefficient of 0.999 (n=20). Detection limit for the fabricated sensor was calculated about 20nM (for S/N=3) and sensitivity was about 56.1μAμM−1cm−2. The developed biosensor exhibited rapid and accurate response to D-Alanine,a good stability (4 weeks) and an average recovery of 98.9% in human serum samples. Graphical abstract
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research