Poly(neutral red) based hydrogen peroxide biosensor for chromium determination by inhibition measurements

Amperometric hydrogen peroxide enzyme inhibition biosensors based on horseradish peroxidase (HRP) immobilised on electropolymerised neutral red (NR) or directly on the surface of carbon film electrodes (CFE) have been successfully applied to the determination of toxic Cr(III) and Cr(VI). Parameters influencing the performance of the biosensor including the enzyme immobilisation method, the amount of hydrogen peroxide, applied potential and electrolyte pH were optimised. The inhibition of horseradish peroxidase by the chromium species was studied under the optimised conditions. Results from the quantitative analysis of chromium ions are discussed in terms of detection limit, linear range and sensitivity. The HRP kinetic interactions reveal mixed binding of Cr(III) with I50 = 3.8 μM and inhibition binding constant Ki = 11.3 μM at HRP/PNR/CFE biosensors and uncompetitive binding of Cr(VI) with I50 = 3.9 μM and Ki = 0.78 μM at HRP/CFE biosensors in the presence of H2O2 substrate. Interferences from other heavy metal ions were studied and the inhibition show very good selectivity towards Cr(III) and Cr(VI)

Biosensors and the evaluation of food contaminant biosensors in terms of their performance criteria

Biosensor technology has been extensively investigated for determination of several analytes in clinical diagnosis, food analysis and environmental monitoring. A biosensor includes three parts; a transducer, a bioreceptor (biorecognition element) and a signal processing system. Biorecognition elements are important components of a biosensor because they recognise the target analytes of interest. To obtain a sensitive and a reproducible biosensor, nanomaterials are used as modification elements of transducer. They represent important promise as biorecognition element immobilisation platforms for the biosensor fabrication. This mini review summarises the biosensor’ features, the factors affect its performance and nanomaterials, which are used as modification elements in food analysis area. After a brief description of the biosensors and nanomaterials, the developed biosensors in literature were investigated by means of tables. Linear ranges, LODs, reproducibilities, stabilities of developed biosensors are compared. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group

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)