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Determining the antioxidant power of biological fluids via palladium nanoparticles

analytical methodAntioxidantassay kitfoodNanoparticlesoilsPalladiumPoint-of-caresaliva


Numerous scientific studies and epidemiological investigations have linked oxidative stress to various diseases such as cancer, neurodegenerative diseases such as Alzheimer disease, and male infertility. Saliva and other biological fluids (blood, sweat and urine) thus have an important diagnostic potential, reflecting the physiological state of the individual. At present various methodologies exist to measure Total Antioxidant Capacity (TAC), however, the lack of consistency among the results obtained has led in using multiple tests to assess the overall real antioxidant power of a sample. Furthermore, there is a lack of tests available as portable, point-of-care devices, which could be used by patients at home and none of the currently available assays allows TAC to be assessed without the need of specific instrumentation.

Technical features

A 5-minute colorimetric test has been devised for determining the TAC power of a biological fluid or food; where the colour intensity of the solution obtained when contacting the sample with an aqueous solution of palladium nanoparticles and a chromogenic peroxidase substrate in the presence of hydrogen peroxide, is proportional to the antioxidant power of the sample. The assay does not require the sample to be pre-treated, and the colour change/intensity can be detected visually. The method can be used to determine the antioxidant power of various biological fluids such as saliva, blood, sweat, or urine. Its use can be extended to measure TAC in liquid foods such as fruit juices and edible oils. In the case of oils, the sample first needs to be mixed with a solution of methanol and isopropanol, to which assay kit reagents are added, without the need of a separation nor purification step.

Possible Applications

  • Invention can be fashioned into a portable kit;
  • Simple, low cost and stable in ambient conditions;
  • Does not require specific instrumentation;
  • Reproducible and reliable results, makes it suitable for analysing large pools of samples;
  • Can measure both lipophilic and hydrophilic antioxidants.


  • Point-of-care devices in hospitals, care homes and private habitations;
  • Quality control of foods and oils.