title: A doped polyaniline modified electrode amperometric biosensor for gluconic acid determination in grapes.
abstract: In winemaking gluconic acid is an important marker for quantitative evaluation of grape infection by Botrytis cinerea. A screen-printed amperometric bienzymatic sensor for the determination of gluconic acid based on gluconate kinase (GK) and 6-phospho-D-gluconate dehydrogenase (6PGDH) coimmobilized onto polyaniline/poly (2-acrylamido-2-methyl-1-propanesulfonic acid; PANI-PAAMPSA) is reported in this study. The conductive polymer electrodeposed on the working electrode surface allowed the detection of NADH at low potential (0.1 V) with a linear range from 4 × 10(-3) to 1 mM (R2 = 0.99) and a sensitivity of 419.44 nA∙mM(-1). The bienzymatic sensor has been optimized with regard to GK/6PGDH enzymatic unit ratio and ATP/NADP+ molar ratio which resulted equal to 0.33 and 1.2, respectively. Under these conditions a sensitivity of 255.2 nA∙mM(-1), a limit of detection of 5 μM and a Relative Standard Deviation (RSD) of 4.2% (n = 5) have been observed. Finally, the biosensor has been applied for gluconic acid measurements in must grape samples and the matrix effect has been taken into consideration. The results have been compared with those obtained on the same samples with a commercial kit based on a spectrophotometric enzyme assay and were in good agreement, showing the capability of the bienzymatic PANI-PAAMPSA biosensor for gluconic acid measurements and thus for the evaluation of Botrytis cinerea infection in grapes.
authors: Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. dalbanese@unisa.it.
authors: Donatella
authors: D
authors: Albanese
authors: Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. francesca.malvano@gmail.com.
authors: Francesca
authors: F
authors: Malvano
authors: Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. asannini@unisa.it.
authors: Adriana
authors: A
authors: Sannini
authors: Consiglio Nazionale delle Ricerche, Institute of Atmospheric Pollution Research, Via Salaria Montelibretti, Roma 00015, Italy. pilloton@iia.cnr.it.
authors: Roberto
authors: R
authors: Pilloton
authors: Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy. mdimatteo@unisa.it.
authors: Marisa
authors: M
authors: Di Matteo
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation; D020171:Botrytis / Q000302:isolation & purification / Q000378:metabolism*; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005504:Food Analysis / Q000295:instrumentation; D005506:Food Contamination / Q000032:analysis*; D005942:Gluconates / Q000032:analysis*; D027843:Vitis / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D000814:Aniline Compounds; D005942:Gluconates; C416807:polyaniline; C030691:gluconic acid