Browsing by Author "Nemutlu, Emirhan"

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Analysis of 3-hydroxyisovaleric acid and 3-hydroxybutyric acid in plasma samples by LC-MS/MS
(2022) Recber, Tuba; Ozkan, Ece; Nemutlu, Emirhan; Beksac, Mehmet Sinan; Kir, Sedef
Down syndrome is a common genetic disorder that results from the presence of an extra chromosome in the 21st chromosome pair of humans. Metabolomics is an alternative method in discovery of new biomarkers for the screening and diagnosis of Down syndrome. In this study, quantitative analyzes of 3-hydroxybutyric acid and 3hydroxyisovaleric acid, selected as possible markers for prenatal diagnosis of Down syndrome were performed. LCMS/MS analyzes were performed on a Phenomenex Luna NH2(100 x 4.6 mm, 3 mu m) column using a mobile phase mixture of 0.1% formic acid and acetonitrile containing 0.1% formic acid at a flow rate of 0.35 mL/minute. The MRM transitions were 103.0 -> 59.0 for 3-hydroxybutyric acid and 117.1 -> 59.0 for 3-hydroxyisovaleric acid. Under these conditions, the retention times of 3-hydroxyisovaleric acid 3-hydroxybutyric acid were 2.7 and 3.1 minute, respectively. The method was found linear from 0.1 to 10.0 mu g/mL for both metabolites. The limit of detection (LOD) was 0.017 mu g/mL for 3-hydroxybutyric acid and 0.003 mu g/mL for 3-hydroxyisovaleric acid. The lower limit quantification (LLOQ) was 0.045 mu g/mL for 3-hydroxybutyric acid and 0.008 mu g/mL for 3-hydroxyisovaleric acid. The method has been proven to be selective, precise, accurate, sensitive, and robust based on the validation studies results. Finally, the method was applied to plasma samples of the pregnant women with healthy fetus (n = 30) and with Down syndrome fetus (n = 17). As a result of the analysis, a statistically significant increase (p <0.01) was observed in the 3-hydroxybutyric acid level of the group with Down syndrome compared to the healthy group. This result strengthens the use of 3-hydroxybutyric acid as an important biomarker in the prenatal screening/diagnosis of Down syndrome.
Development Of An Electrochemical Sensor Based On Porous Molecularly Imprinted Polymer Via Photopolymerization For Detection Of Somatostatin In Pharmaceuticals And Human Serum
(2022) Ozkan, Ece; Corman, Mehmet Emin; Nemutlu, Emirhan; Ozkan, Sibel A.; Kir, Sedef
This study applied a new methodology to create a porous molecularly imprinted material for the highly selective and sensitive recognition of somatostatin (SOM), a growth hormone inhibitor. N-methacryloyl-L-aspartic acid (MAAsp) was synthesized and used as a functional monomer to form a molecularly imprinted polymer (MIP) by photopolymerization method on a glassy carbon electrode (GCE). The MIP film was synthesized in the presence of 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) to form P(HEMA-MAAsp)@MIP/GCE sensor. The characterization of P(HEMA-MAAsp)@MIP/GCE was investigated by Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Electrochemical Impedance Spectroscopy (EIS) techniques. Afterward, the porous P(HEMA-MAAsp)@MIP/ GCE was optimized with removal agent, removal time, and incubation time to achieve a better response for SOM. Under optimum conditions, the calibration curve of SOM on the P(HEMA-MAAsp)@MIP/GCE sensor was linear in the range of 10 fM and 100 fM. The limit of detection (LOD) and lower limit of quantification (LLOQ) were found as 0.175 fM and 0.584 fM, respectively. The analytical performance of the P(HEMAMAAsp)@MIP/GCE sensor was investigated by comparing the electrochemical reaction of MIP with nonimprinted polymer (NIP). The analytical performance of the developed sensor was proved by applying it to the pharmaceutical preparation and serum. The selectivity of the sensor was shown by examining the binding of Octreotide and Lanreotide, which are the synthetic analogs of the SOM. The developed P(HEMA-MAAsp) @MIP/GCE sensor, which is green and sustainable, exhibited high sensitivity and selectivity for SOM and is the first method reported to be used in the electroanalysis of SOM.
Sensitive And Cost-Effective Boron Doped Diamond And Fe2O3/Chitosan Nanocomposite Modified Glassy Carbon Electrodes For The Trace Level Quantification Of Anti-Diabetic Dapagliflozin Drug
(2022) Ozkan, Ece; Cetinkaya, Ahmet; Ozcelikay, Goksu; Nemutlu, Emirhan; Kir, Sedef; Ozkan, Sibel A.; https://orcid.org/0000-0001-5014-0907; AAF-6076-2019
Dapagliflozin (DPG), used in the treatment of type 2 diabetes, is a drug widely used to treat type 1 diabetes with certain restrictions. Hypoglycemia, urinary tract, genital infections, and decreased body water are among the common side effects of DPG. The detailed electrochemical oxidation process of DPG at both electrodes was investigated using cyclic voltammetry. The bare boron-doped diamond electrode (BDDE) showed a diffusion-controlled process, while the glassy carbon electrode (GCE) was an adsorption-controlled process. Using iron (III) oxide/Chitosan nanocomposite showed (Fe2O3/Chitosan NCs) as the modification agent for the GCE, a highly sensitive and selective nanosensor was created for the DPG assay. Fe2O3/Chitosan NCs modified GC, and bare BDD electrodes were successfully applied for the electrochemical determination of DPG. The simple, eco-friendly, sensitive, and time-saving electroanalytical methods have been developed for the determination of DPG in urine, serum, and tablet samples using differential pulse (DPV) and adsorptive stripping differential pulse voltammetric (AdSDPV) methods with a BDDE and the proposed nanosensor (Fe2O3/Chitosan NCs modified GCE) in 0.1 M H2SO4 containing 20% methanol, respectively. Under optimized conditions, the developed methods gave detection limits of 2.0 nM and 15 nM and linear range of 0.1-8.0 mu M and 0.6-80.0 mu M for Fe2O3/Chitosan NCs modified GCE and BDDE, respectively. Both electrodes showed excellent recoveries (between 97.25 and 102.68 %) and repeatability with RSD lower than 2.4% (n = 5). The developed methods were successfully applied for the analysis of DPG in serum, urine, and pharmaceutical dosage forms.