Bioelectrocatalysis of Hemoglobin on Electrodeposited Ag Nanoflowers toward H2O2 Detection.

Hydrogen peroxide (H2O2) is a partially reduced metabolite of oxygen that exerts a diverse array of physiological and pathological activities in living organisms. Therefore, the accurate quantitative determination of H2O2 is crucial in clinical diagnostics, the food industry, and environmental monitoring. Herein we report the electrosynthesis of silver nanoflowers (AgNFs) on indium tin oxide (ITO) electrodes for direct electron transfer of hemoglobin (Hb) toward the selective quantification of H2O2. After well-ordered and fully-grown AgNFs were created on an ITO substrate by electrodeposition, their morphological and optical properties were analyzed with scanning electron microscopy and UV-Vis spectroscopy. Hb was immobilized on 3-mercaptopropionic acid-coated AgNFs through carbodiimide cross-linking to form an Hb/AgNF/ITO biosensor. Electrochemical measurement and analysis demonstrated that Hb retained its direct electron transfer and electrocatalytic properties and acted as a H2O2 sensor with a detection limit of 0.12 µM and a linear detection range of 0.2 to 3.4 mM in phosphate-buffered saline (PBS). The sensitivity, detection limit, and detection range of the Hb/AgNF/ITO biosensor toward detection H2O2 in human serum was also found to be 0.730 mA mM-1 cm-2, 90 µM, and 0.2 to 2.6 mM, indicating the clinical application for the H2O2 detection of the Hb/AgNF/ITO biosensor. Moreover, interference experiments revealed that the Hb/AgNF/ITO sensor displayed excellent selectivity for H2O2.

Sensitive electrochemical detection of amyloid beta peptide in human serum using an interdigitated chain-shaped electrode.

In this study, we developed a small size, low cost, highly sensitive electrochemical biosensor with a low limit of detection by immobilizing specific anti-amyloid-ß (aß) antibody onto a self-assembled monolayer functionalized interdigitated chain-shaped electrode (anti-aß/EDC-NHS/SAM/ICE). The anti-aß/EDC-NHS/SAM/ICE specifically detects aß 1-42 peptide (a peptide 1-42 amino acids long), which is one of main biomarkers of Alzheimer's disease in human serum (HS). Electrochemical impedance spectroscopy (EIS) was used to characterize the impedance change of the anti-aß/EDC-NHS/SAM/ICE biosensor for aß 1-42 detection, which provided a wide linear range of detection from 10-3-103 ng mL-1, and a low limit of detection of aß in HS (100 pg mL-1) much lower than the limit of detection of CSF aß 1-42 (∼500 pg mL-1), and other biosensors. Therefore, the developed biosensor is sensitive enough to be used for the diagnosis of early stage Alzheimer's disease.