Chronoamperometry as effective alternative technique for electro-synthesis ofortho-phenylendiamine permselective films for biosensor applications
JOURNAL OF APPLIED POLYMER SCIENCE
Authors: Monti, Patrizia; Bacciu, Andrea; Arrigo, Paola; Marceddu, Salvatore; Migheli, Quirico; Serra, Pier A.; Rocchitta, Gaia
Abstract
Analyte quantification in first generation electrochemical biosensors is threatened by electro-active molecules, such as ascorbic acid (AA). Electrochemical deposition ofortho-phenylendiamine (oPD) on transducer considerably reduces AA interfering. These properties of poly-oPD (PPD) are influenced by electro-polymerization conditions. Chronoamperometry (CA) is proposed as an alternative technique foroPD electro-deposition over Pt. Pt/PPD sensors are evaluated through functional parameters related to AA rejection and analytical performances. N-2, O-2, and air bubbled supporting electrolyte and several step duration times are used. Best performing CA-PPD sensor is obtained in N-2-purged phosphate solution containing 300 mMoPD by means of a 1 s step duration/120 steps CA. High performing PPD is achieved in shorter time compared to commonly used constant potential amperometry. Aging of polymeric features and scanning electron microscopy investigations are performed and optimized CA electro-polymerization conditions are used to build up an efficient interference blocking layer in a glucose oxidase biosensor.
Biosynthesis of adipic acid in metabolically engineered Saccharomyces cerevisiae
JOURNAL OF MICROBIOLOGY
Authors: Zhang, Xi; Liu, Yingli; Wang, Jing; Zhao, Yunying; Deng, Yu
Abstract
Adipic Acid (AA) is a valued platform chemical compound, which can be used as a precursor of nylon-6,6. Due to the generation of an enormous amount of nitric oxide metabolites and the growing depletion of oil resources as a result of AA production from a mixture of cyclohexanol and cyclohexanone, the microbial methods for synthesizing AA have attracted significant attention. Of the several AA-producing pathways, the reverse adipate degradation pathway in Thermobifida fusca (Tfu RADP) is reported to be the most efficient, which has been confirmed in Escherichia coli. In this study, the heterologous Tfu RADP was constructed for producing AA in S. cerevisiae by co-expressing genes of Tfu_0875, Tfu_2399, Tfu_0067, Tfu_1647, Tfu_2576, and Tfu_2576. The AA titer combined with biomass, cofactors and other by-products was all determined after fermentation. During batch fermentation in a shake flask, the maximum AA titer was 3.83 mg/L, while the titer increased to 10.09 mg/L during fed-batch fermentation in a 5-L bioreactor after fermentation modification.