The Application of Using 3-D Printed Colorimetric Paper Sensor for the Detection of Antioxidant Activity in Southern California Native Plants

Free radical is highly reactive and
is easy to react with molecules in biological system.  Previous research have shown that free
radical contributes to many chronic health problems. Provided that antioxidant
reduce oxidation reaction, the purpose of this research project is to develop a
low cost and fast bioassay method for detecting the presence of antioxidants in
various foods/Plants using 2, 2-diphenyl-1-picrylhydrazyl (DPPH).
 To verify the developed method, multiple
analyses were used in measuring the activity of antioxidants as it reacts with DPPH,
which include electrochemical analysis, UV Spectroscopy, and the proposed paper
bioassay.

Our research focused on measuring
the amount of antioxidant present in stinging nettle (Urtica dioica) since this plant
has a long history in medicine and food among native Indian tribes. Antioxidant
substance is extracted from by mixing grinded stinging nettle with methanol and
the resulted plant extract reacts with DPPH solution for detection. Ascorbic
acid was used as antioxidant standard in assay. The reduction of DPPH
absorbance from UV, oxidation current from electrochemical measurement, and HSB
values from paper sensor (paper bioassay) were compared to determine the
accuracy of paper sensor. Based on the growing interest in free radical
and preventive methods for many of the chronic diseases, the usefulness of
essential, safe nutrients in protecting against the adverse effects of
oxidative damage warrants further study.