Microfluidic paper-based analytical devices for the determination of salivary NOx

Salivary content of nitrite and nitrate (NOx) has been primarily believed to be correlated with oral cancer and other disfunctions and infections in the mouth. However, recently some studies reported newly found benefits to the presence of nitrite and nitrate in the oral cavity. In any case, it has become more and more relevant to carry out its assessment. In this context, the objective of this work was to develop a microfluidic paper-based analytical device (µPAD) for nitrite/nitrate determination in saliva samples. The choice of the µPAD approach intended to explore the advantages of these devices, which make them ideally suited to conduct on-hand analyte determinations. While many of the current monitoring techniques require specialized skills, laborious laboratory processes, or/and expensive equipment, µPADs provide a way to very quickly and cheaply attain an analytical result. The minimal use of reagent and sample, coupled to the portability has enabled the developed devices ideally suited for unskilled operators and regular monitoring. The determination was based upon the conversion of nitrate to nitrite using zinc powder followed by the colorimetric determination of nitrite with the Griess reaction.