“Light-on”
Sensing of Antioxidants Using
Gold Nanoclusters
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Abstract
Depletion
of intracellular antioxidants is linked to major cytotoxic
events and cellular disorders, such as oxidative stress and multiple
sclerosis. In addition to medical diagnosis, determining the concentration
of antioxidants in foodstuffs, food preservatives, and cosmetics has
proved to be very vital. Gold nanoclusters (Au-NCs) have a core size
below 2 nm and contain several metal atoms. They have interesting
photophysical properties, are readily functionalized, and are safe
to use in various biomedical applications. Herein, a simple and quantitative
spectroscopic method based on Au-NCs is developed to detect and image
antioxidants such as ascorbic acid. The sensing mechanism is based
on the fact that antioxidants can protect the fluorescence of Au-NCs
against quenching by highly reactive oxygen species. Our method shows
great accuracy when employed to detect the total antioxidant capacity
in commercial fruit juice. Moreover, confocal fluorescence microscopy
images of HeLa cells show that this approach can be successfully used
to image antioxidant levels in living cells. Finally, the potential
application of this “light-on” detection method in multiple
logic gate fabrication was discussed using the fluorescence intensity
of Au-NCs as output