జర్నల్ ఆఫ్ మైక్రోబియల్ & బయోకెమికల్ టెక్నాలజీ

నైరూప్య

A Chromatic Sensor to Detect Free Radicals Using H2O2 as an Analyte with DTT and Au-NPs as Sensing Agents Microscopy

Wen-Xin Wu, Ying-Chan Hung, Kuei-Lin Chan, Tri-Rung Yew*

In this study, a simple chromatic biosensor for free radicals, which accumulate inside human bodies and can
be identified as an essential sign of various diseases, is presented. Hydrogen peroxide (H2O2) was selected as a
detection target as it is one of the main species of free radicals and owns longer life cycle than other species. Previous
studies also showed that the cancer and cardiovascular disease were strongly correlated with the concentration of
free radicals in urine greater than 10-4 M. Different concentrations of H2O2 were added into 1,4-dithiothreitol (DTT)
solution for detection. The DTT could not only act as a common reductant reacting with H2O2 through redox reaction,
but also cause the aggregation of gold-nanoparticles (Au-NPs), which resulted in color change of Au-NPs attributed
to the effect of surface plasmon resonance (SPR). The H2O2 concentration is therefore can be detected from its
correlation with the color change of H O /DTT/Au-NPs solutions, as more H 2O2 in solution will lead to more redox
reaction and consequently less DTT to cause Au-NPs aggregation. Results show that the H2O2 concentrations
ranged between 10-1 M to 10-6 M can be detected by naked eyes from color change. In additions, ultraviolet-visible
(UV-Vis) absorption spectra were measured to further verify the correlation. Furthermore, liquid transmission electron
microscopy (liquid-TEM) was also used to confirm the aggregation of Au-NPs in solutions. From above mentioned
methods, the feasibility of using a chromatic biosensing system for free radical detection was demonstrated, showing
the potential for future disease detection.