Browsing by Author "Esen E."
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Scopus Bienzymatic fluorescence detection based on paraoxonase and laccase on anthracene-sequestered polyamic acid films: A novel approach for inhibition-based sensors(2020-12-01) Esen E.; Yazgan İ.; Odaci Demirkol D.A fluorescence assay based on paraoxonase (PO) and laccase (Lac) immobilized on anthracene-sequestered polyamic acid films is now being reported for the first time for ciprofloxacin (CFx) detection. In enzymatic reaction, PO converts phenyl acetate (PA) to acetic acid and phenol. The formed phenol is further oxidized by laccase using oxygen as a co-substrate. For indirectly fluorescence measurements of PA hydrolysis, increased fluorescence intensity was measured after oxygen consumption by laccase. This is because oxygen is quencher of anthracene (Ant) incorporated in the sequestered poly(amic) acid (PAA) film. The detection mechanism was based on inhibition of PO activity by CFx. Using PAA provided the advantage of controlling the film thickness. Firstly, morphology of PAA-Ant polymeric film was characterized by scanning electron microcopy (SEM) and the success of PO-Lac immobilization on PAA-Ant was proven by SEM plus Energy-dispersive X-ray spectroscopy (SEM-EDX) and fluorescence measurements. Then Ant-PAA/PO/Lac is calibrated for PA and CFx without any interfering of some potential interferences. All results make it a promising tool for monitoring CFx at minute levels in samples.Scopus Laccase assay based on electrochemistry and fluorescence detection via anthracene sequestered poly(amic acid) films(2018-10-01) Esen E.; Yazgan I.; Demirkol D.O.; Timur S.Phenols are among the most problematic organic compounds, which manipulates metabolism of living organisms and pose threat to environment. Detection of total phenol at the lowest allowable concentration is critical, so development of sensitive and easy to use methods have been heavily investigated. Hereby, for the first time, anthracene (Ant) was sequestered into poly(amic acid) (PAA) to form fluorescent and conductive film support for laccase (Lac) immobilization to quantify total phenol content at high specificity and selectivity. Ant-PAA/Lac films were applied to fluorescent and electrochemical quantification of phenol, which provided high sensitivity (LOD 46 μM) and reproducibility (RSD, 0.5%) for the tested 10 phenolic compounds including phenol, catechol, 3-acetominophenol, hydroquinone, L-DOPA, 2,6-dimethylphenyl, syringalzadine, 3,5-dimethoxy-4-hydroxycinnamic acid, 2,5-dimethoxyaniline and guaiacol. The sensor system showed strong rejection to common organic interferent while real sample application revealed the applicability of the sensor. Therefore, the results can call the sensor system, particularly fluorescence-based quantification in 96-well plate, is an alternative approach for high-throughput screening of total phenolic compounds in waste-water at cost-effective manner.