The glucose oxidation cascade is fascinating; although
oxidation
products have high economic value, they can manipulate the biological
activity through posttranslational modification such as glycosylation
of proteins, lipids, and nucleic acids. The concept of this work is
based on the ability of reactive species induced by cold atmospheric
plasma (CAP) in aqueous liquids and the corresponding gas–liquid
interface to oxidize biomolecules under ambient conditions. Here,
we report the oxidation of glucose by an argon-based dielectric barrier
discharge plasma jet (kINPen) with a special emphasis on examining
the reaction pathway to pinpoint the most prominent reactive species
engaged in the observed oxidative transformation. Employing
d
-glucose and
d
-glucose-
13
C
6
solutions
and high-resolution mass spectrometry and ESI-tandem MS/MS spectrometry
techniques, the occurrence of glucose oxidation products, for example,
aldonic acids and aldaric acids, glucono- and glucaro-lactones, as
well as less abundant sugar acids including ribonic acid, arabinuronic
acid, oxoadipic acid, 3-deoxy-ribose, glutaconic acid, and glucic
acid were surveyed. The findings provide deep insights into CAP chemistry,
reflecting a switch of reactive species generation with the feed gas
modulation (Ar or Ar/O
2
with N
2
curtain gas).
Depending on the gas phase composition, a combination of oxygen-derived
short-lived hydroxyl (
•
OH)/atomic oxygen [O(
3
P)] radicals was found responsible for the glucose oxidation
cascade. The results further illustrate that the presence of carbohydrates
in cell culture media, gel formulations (agar), or other liquid targets
(juices) modulate the availability of CAP-generated species
in vitro
. In addition, a glycocalyx is attached to many
mammalian proteins, which is essential for the respective physiologic
role. It might be questioned if its oxidation plays a role in CAP
activity.