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Platinum group metal‐based (PGM) catalysts are widely applied in many electrochemical systems such as fuel cells or metal–air batteries because of their excellent catalytic performance. But the high raw material cost of PGM catalysts has become a significant issue. In recent years, huge efforts have been made to reduce the material cost of electrochemical systems by developing non‐PGM catalysts, and as one of the promising non‐PGM catalysts, nitrogen‐doped graphene (N‐G) has emerged. In this research, nanoscale high‐energy wet ball milling methodology was investigated as an effective synthesis method for N‐G catalysts by using graphene oxide and melamine as raw materials. The main purpose is to study reaction mechanism of the synthesis process and the physical, chemical, and electrochemical properties of N‐G catalysts generated by this mechanochemical approach. The elemental composition, chemical bonding composition, and electron transfer number of the synthesized products were characterized. The results show that the electron transfer number of the N‐G catalyst with 23.2 at% nitrogen doping content, synthesized by the high‐energy wet ball milling method, has attained a value of 3.87, which is close to the number (3.95) of Pt/C catalysts, and the grinding time was found to be a significant factor in the properties of N‐G catalysts in the experiments. The results also show that the high‐energy wet ball milling developed in this research is a promising method to synthesize high‐performance N‐G catalysts with a simple and easy controllable approach. Copyright © 2016 John Wiley & Sons, Ltd.

Integrating microfluidics with biosensors is of great research interest with the increasing trend of lab-on-the chip and point-of-care devices. Though there have been numerous studies performed relating microfluidics to the biosensing mechanisms, the study of the sensitivity variation due to microfluidic flow is very much limited. In this paper, the sensitivity of interdigitated electrodes was evaluated at the static drop condition and the microfluidic flow condition. In addition, this study demonstrates the use of gold nanoparticles to enhance the sensor signal response and provides experimental results of the capacitance difference during cancer antigen-125 (CA-125) antigen–antibody conjugation at multiple concentrations of CA-125 antigens. The experimental results also provide evidence of disease-specific detection of CA-125 antigen at multiple concentrations with the increase in capacitive signal response proportional to the concentration of the CA-125 antigens. The capacitive signal response of antigen–antibody conjugation on interdigitate electrodes has been enhanced by approximately 2.8 times (from 260.80 to 736.33 pF at 20 kHz frequency) in static drop condition and approximately 2.5 times (from 205.85 to 518.48 pF at 20 kHz frequency) in microfluidic flow condition with gold nanoparticle-coating. The capacitive signal response is observed to decrease at microfluidic flow condition at both plain interdigitated electrodes (from 260.80 to 205.85 pF at 20 kHz frequency) and gold nano particle coated interdigitated electrodes (from 736.33 to 518.48 pF at 20 kHz frequency), due to the strong shear effect compared to static drop condition. However, the microfluidic channel in the biosensor has the potential to increase the signal to noise ratio due to plasma separation from the whole blood and lead to the increase concentration of the biomarkers in the blood volume for sensing.