title: An ultrasensitive performance enhanced novel cytochrome c biosensor for the detection of rebaudioside A.
abstract: In this study a novel cyctochrome c modified nanocomposite electrochemical biosensor was developed for the electrochemical determination of rebaudioside A in different food samples. The electrode surface was fabricated with graphene oxide assimilated with gold nanoparticles decorated on multiwalled carbon nanotubes/cytochrome c. The developed biosensor exhibited a 10-fold enhancement in the differential pulse voltammetry signal carried out at pH 11.0 in a 0.1M borate buffer. Under the optimized conditions, Ip (µA) was proportional to the rebaudioside A concentration in the range of 0.001-0.05 mM (R(2)=0.8308) and 0.075-1.25 mM (R(2)=0.9920) with a detection limit (S/N=3) of 0.264 µM. Results of this study revealed that cyctochrome c was adsorbed tightly onto the surface of the modified electrode and showed an enzymatic catalytic activity towards the quasi-reversible reduction of rebaudioside A at -0.1 V (vs Ag/AgCl). The direct electron transfer by cytochrome c was further supported by HOMO-LUMO calculations performed at the density functional theory level. Additionally, the molecular docking simulations predicted a stronger binding affinity of rebaudioside A towards cytochrome c, thus supporting their host-guest relationship. The use of novel electrode materials in this study demonstrates the application of the electrochemical biosensor in the food industry.
authors.affiliation: Department of Chemistry, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa.
authors.forename: Ayyappa
authors.initials: A
authors.lastname: Bathinapatla
authors.affiliation: Department of Chemistry, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa. Electronic address: ksuvardhan@gmail.com.
authors.forename: Suvardhan
authors.initials: S
authors.lastname: Kanchi
authors.affiliation: School of Chemistry and Physics, University of KwaZulu Natal, Westville, Private Bag X54001, Durban 4000, South Africa.
authors.forename: Parvesh
authors.initials: P
authors.lastname: Singh
authors.affiliation: Department of Chemistry, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa.
authors.forename: Myalowenkosi I
authors.initials: MI
authors.lastname: Sabela
authors.affiliation: Department of Chemistry, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa. Electronic address: bisettyk@dut.ac.za.
authors.forename: Krishna
authors.initials: K
authors.lastname: Bisetty
mesh_terms: D015374:Biosensing Techniques; D003217:Conductometry / Q000295:instrumentation*; D045304:Cytochromes c / Q000737:chemistry*; D045786:Diterpenes, Kaurane / Q000032:analysis*; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005504:Food Analysis / Q000295:instrumentation*; D008832:Microchemistry / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D045786:Diterpenes, Kaurane; D004800:Enzymes, Immobilized; D045304:Cytochromes c; C025474:rebaudioside A
keywords: Biosensor; Cytochrome c; Differential pulse voltammetry; Food samples; HOMO-LUMO calculations; Rebaudioside A