1. TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS
GRUPO 19
Cristina Ruiz Martínez
Sara Ugarte Cerrato

2. INDEX Introduction Mechanisms Samples A new biosensor Red wine
Olive oil
Other vegetable extracts
A new biosensor

3. Introduction Mechanisms Samples A new biosensor Red wine Olive oil
Other vegetable extracts
A new biosensor

4. Introduction POLYPHENOL COMPOUNDS malvidin quercetin
Natural antioxidants widely distributed in the plant kingdom
Important determination
physiological effects
employment as markers in taxonomic studies
their properties to food quality control

5. Introduction Mechanisms Samples A new biosensor Red wine Olive oil
Other vegetable extracts
A new biosensor

6. Mechanism CLASSICAL METHODS RECENT METHODS rapid response
spectrophotometry
gas chromatography
liquid chromatography
capillary electrophoresis
Folin-Ciocalteau
RECENT METHODS
Biosensors: based on enzymes
Advantages:
rapid response
cost-effectiveness
simplicity of operation and manufacturing, minimal sample pretreatment and solvent requirements.

7. Biosensors for polyphenols determination

8. Introduction Mechanisms Samples A new biosensor Red wine Olive oil
Other vegetable extracts
A new biosensor

9. SAMPLES RED WINE Enzyme: laccase
Product of its oxidation: 1,2- benzoquinone reduced at the electrode.
Actual mechanism of reaction still unclear.
From spectroscopic and electron paramagnetic resonance (EPR) studies:
1º enzyme completely reduced
2º oxygen reduced to water

10. WINE SAMPLE Immobilization in polyethersulfone membranes:
1º Washings containing an excess of enzyme with acetate buffer.
2º A quantity deposited on polyethersulfone membrane cut in the form of discs.
3º Application to the electrode.
4º The biosensor is dipped in the buffer.
5º Injections of the sample or standard under magnetic stirring.

11. WINE SAMPLE
Conclusion: able to discriminate between catechin and caffeic acid but negligible responses when using with wine.
The complex matrix of the red wine samples interference in the response.
More research to overcome the deviations.

12. Introduction Mechanisms Samples A new biosensor Red wine Olive oil
Other vegetable extracts
A new biosensor

13. OLIVE OIL SAMPLE Two sensors:
Biosensor based on the catalytic activity of the tyrosinase.
Main advantages:
-prior extraction pre-treatment analysis time
not necessary eliminated decreased
- Flow injection analysis saving time
- Semiautomization of minimization of the
entire procedure exposure to solvent vapors

14. OLIVE OIL SAMPLE Tyrosinase Pre-actived membrane
Amperometric Gas Diffuse Electrode
Gas permeable membrane
Dialysis membrane
Sensor
Teflon O-ring

15. OLIVE OIL SAMPLE Voltammetric sensor Prior extraction
Using a disposable screen-printed sensor (SPE)
Reference compound: oleuropein
A calibration curve of oleuropein

16. OLIVE OIL SAMPLE
Electrode

17. Introduction Mechanisms Samples A new biosensor Red wine Olive oil
Other vegetable extracts
A new biosensor

18. VEGETABLE EXTRACTS Enzyme: horseradish peroxidase.
Inmmobilization: silica-titanium.
Material with high chemical stability.
Improvement of the amperometric detection.
No significant influence of the matrix was observed.

19. VEGETABLE EXTRACTS
Mechanism: double displacement or ping-pong.

20. Introduction Mechanisms Samples A new biosensor Red wine Olive oil
Other vegetable extracts
A new biosensor

21. New biosensor
Based on laccase immobilized onto silver nanoparticles/multiwalled carbon nanotube/polyaniline gold electrode.
Immobilization on AgNPs/PANI/MWCNT/Au (gold) electrode through covalent coupling to construct an enzyme electrode for determination of polyphenols.
Employed for amperometric determination of total phenolic content in beverages and pharmaceutical formulation.
Conclusion: good biosensor, likely to overcome the problem of leakage of enzyme.

22. THE END