Fabrication of Naphthalimide Chemosensor by Inkjet Printing on Paper for the Detection of Uric Acid in Solution

High uric acid (UA) concentrations are linked to many human health disorders. Currently, UA is detected in human samples through laboratory testing. However, laboratory testing is impractical in developing nations, which lack the diagnostic capability (trained professionals, complex laboratory equipment, and analytical instruments) necessary for this approach. The lack of resources leads to the spread of chronic illnesses in these countries. To combat this issue, a paper test strip is proposed that provides a measure of UA in a point-of-care setting without requiring the use of expensive instruments or qualified professionals. The rapid detection of UA in solution was achieved by a naphthalimide-based “turn-on” chemosensor. Divinyl sulfone was used to immobilize the chemosensor onto cellulose paper. A colorimetric detection technique was created that took advantage of photoinduced electron transfer (PET) technology, which allowed for the creation of a sensor whose fluorescence was directly proportional to the UA concentration. To interpret the results from the paper strips, a calibration curve was created that determined the concentration of UA in the solutions. The test strip was used to determine UA concentration in synthetic urine and grain samples. The results from the calibration curve show that UA concentration in the grain samples is within the range of the calibration curve, while it is slightly lower in the case of UA in synthetic urine due to possible quenching of the probe in urine.