| dc.description.abstract | In this contribution, a versatile, inexpensive and compact paper-based microfluidic
biosensor was developed to detect heavy metals in food products. The underlying
principle was based on sensing of ammonia (NH
) released during urease-
3
catalyzed hydrolysis of urea. At the presence of heavy metals, the amount of NH
3
produced diminished due to inhibition of urease enzyme. Therefore, the
concentration of target heavy metals could be indirectly determined from NH
,
3
qualitatively, semi-quantitatively or quantitatively. Hydrophobic barriers of
functional areas the sensor were fabricated by paraffin-dipping method. Urease
enzyme wa s physically immobilized onto the sensor and phenol red was used for
qualitative and semi-quantitative detection of heavy metal via image analysis. The
sensor was also integrated into an electrochemical system using simple screen-
printed electrodes. In the current study, Cu
was used as a model heavy metal
++
for testing performance of the sensor. Qualitative results showed that a strong
contrast between safe and unsafe sample, which was critical for the practical
applicability of the sensor. Relationship between color intensity and Cu
++
concentration was characterized by a R
of 0.98 and the linear range covered Cu
2
++
concentrations from 0.01 – 1 ppm. Detection limit was estimated to be 0.018 ppm
which was well below standard limit established by WHO and EC for Cu
.
+ +
Quantitative tests were still at beginning stage and were worth further
investigations. The findings from this study demonstrated that the proposed
paper-based biosensor could be a promising platform to develop low-cost test kits
for detection of heavy metals in foods.
Keywords:
Paper-based biosensor, wax-printing, screen-printing electrodes, SPEs,
colorimetric test, amperometric test. | en_US |
