Continuous electrochemical detection of hydrogen peroxide by Au-Ag bimetallic nanoparticles in microfluidic devices.

We developed electrochemical microfluidic devices containing Au-Ag bimetallic nanoparticles on single-walled carbon nanotube (SWCNT) electrodes for precise, rapid and non-enzymatic electrochemical detection of hydrogen peroxide (H 2 O 2 ). A homogeneous SWCNT layer on a glass substrate was patterned by a standard photolithography method and an O 2 -plasma technique. The patterned SWCNT layers were used as working electrode, counter electrode, and reference electrode in a 1 mm wide and 23 μm deep microchannel. To enhance the electrochemical catalytic properties of the working electrode, Au covered Ag nanoparticles (NPs) were electrochemically deposited on the SWCNT working electrode with current streaming solution into a microfluidic channel. The AgNPs had catalytic activity to improve the reduction of H 2 O 2 combined with AuNPs, which could support catalytic reaction of AgNPs. The reduction in H 2 O 2 in fabricated devices was monitored at an optimized condition and was linear with H 2 O 2 concentration, resulting in a sensitivity of 13.1 μA·cm − 2 ·mM − 1 , a correlation coefficient of r 2 = 0.985, and limit of detection 26.8 μM (S/N = 3). For the analysis of real samples, diluted antiseptic solutions containing 3 wt% H 2 O 2 were used to determine the concentration of H 2 O 2 in the pharmaceutical sample. The recovery values ranged from 97% to 107%, and relative standard deviations were below 5%. We expect that the developed microfluidic sensor is a prospective electrochemical platform for accurate, reproducible non-enzymatic detection of H 2 O 2 . [ABSTRACT FROM AUTHOR]