This laboratory experiment is designed to introduce college students to paper microfluidics and the role of biomarkers in detecting various diseases. The procedure allows students to design paper microfluidic systems using inexpensive materials that are available in most college laboratories. In this experiment, taurine an organic acid which can also act as a cancer biomarker is prepared in a synthetic urine-phosphate buffer solution (pH = 10.3), and is allowed to react with sodium hypochlorite and phenol on rectangular filter paper. The reaction can be observed through the purple-colored indo-phenol dye formation on the filter paper. The intensity of this color change is measured with graphics software, such as Adobe Photoshop™. Over a three-hour laboratory period, students work in teams to prepare the necessary solutions and design paper microfluidic devices to quantify the intensity of the end product after the reaction. Calibration standards are prepared in a synthetic urine matrix in order to account for the matrix effect. Students can use the mean intensity versus taurine concentration calibration curve to quantify taurine in an unknown urine sample. The experiment can be done within two hours, which provides the students with the opportunity to use their additional time to redesign the systems and improve the precision of their work. This experiment is designed to help students explore the relationship between the concentration of taurine and the intensity of the indo-phenol dye through the construction of a calibration curve. They also learn the importance of the matrix effect in the quantitative analysis. Additionally, students are introduced to non-traditional methods of quantitative analysis. This shows them that although some things may seem unrelated to any field of scientific research, such as graphics editing software, they can still be combined with chemistry to make an ideal analytical tool. Finally, with simple modifications, this method can be used to quantify taurine in other types of samples, in addition to urine.

Paper microfluidic method to quantify taurine in urine samples: A college-level introductory chemistry experiment

249th National Meeting (2015)

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