A low-cost read-out photoresponsive colorimetric platform for nitrite detection based on smartphone APP

A sensitive strategy for nitrite detection (NO 2 − ) by read-out photoresponsive biosensing platform was developed based on smartphone APP. The biosensing platform was constructed based on the colorimetric reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by photooxidation. When nitrite was added, the diazotization reaction taken place with a color change from blue to green and finally to yellow. The reaction process between TMBox and NO 2 − was carried out on the low-cost filter paper modified with chitosan. And the color imaging is collected by smartphone APP. The APP is coded on the Android Studio and operated on android phone, which can realize multi-channel color analysis. Finally, nitrite was quantitatively analyzed by the developed smartphone APP. The biosensing platform not only exhibits a good specificity and sensitivity for detection of NO 2 − , but holds the advantage of low-cost and portable, which has broad application prospects in drug quality safety supervision.