A Novel Biosensing System Using Biological Receptor for Analysis of Vascular Endothelial Growth Factor

An immunosensor with rapid and ultrasensitive response for vascular endothelial growth factor (VEGF) has been built up with 4-aminothiophenol (4-ATP) onto the gold surfaces. Quantitative analysis of VEGF was performed by recording the impedance changing of the gold electrode surface by binding of VEGF. The human vascular endothelial growth factor receptor 1 (VEGF-R1, Flt-1) was used as a biorecognition element for the first time in the literature. VEGF-R1 was covalently immobilized via 4-ATP self-assembled monolayer formed on gold thin film covered surface. Construction of the biosensor was carefully characterised by the techniques such as electrochemistry and electrochemical impedance spectroscopy. In order to characterize impedance data, Kramers-Kronig transform was performed on the experimental impedance data. The limit of detection of the immunosensor for qualitative detection was 100 pg/mL while the LOD for quantitative detection could down to 100 pg/mL by using the VEGF-R1 based biosensor. Finally, artificial serum samples spiked with VEGF was analyzed by the proposed immunosensor to investigate useful of the biosensor for early biomarker diagnosis.TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109 T 172]The authors greatly appreciate the support of the TUBITAK (The Scientific and Technological Research Council of Turkey, Project number: 109 T 172)

Improving the production of cofactor-containing proteins: production of human hemoglobin in yeast

Human hemoglobin is an essential protein, whose main function as an oxygen carrier is indispensable for life. Hemoglobin is a cofactor-containing protein with heme as prosthetic group. Same as in humans, heme is synthesized in many organisms in a complex pathway involving two cellular compartments (mitochondria and cytosol), which is tightly regulated. Red blood cells (erythrocytes) are specialized and adapted for production and transport of the hemoglobin molecules. In addition to oxygen binding, hemoglobin can participate in a variety of chemical reactions by\ua0its iron and heme and may become toxic when released from erythrocytes. Hemoglobin is a major target for the development of blood substitutes/oxygen carriers, and therefore its microbial production is attractive, as it may provide a cheap and reliable source of human hemoglobin. Significant efforts have been dedicated to this task for the last three decades. Moreover since the first generation of cell-free blood substitutes based on unmodified hemoglobin failed human trials, mutant forms became of great interest.In this chapter we summarize the existing knowledge about human hemoglobin, challenges of its microbial production, and its improvement, with a particular focus upon yeast as production host