Nonanal Sensor Fabrication Using Aldol Condensation Reaction Inside Alkali-Resistant Porous Glass

Abstract

Monitoring the gases released during breathing or via the skin has gained significance towards diagnosing diseases. In this study, a sensor chip capable of detecting nonanal gas, which is known to be a marker of lung cancer, was developed. The gas detection agent used was vanillin, which underwent aldol condensation with nonanal in the presence of a basic catalyst, resulting in the formation of an unsaturated aldehyde. Porous glass was used as the reaction field to carry the detection agent. Alkali-resistant porous glass was chosen because conventional porous glasses show low durabilities under basic conditions, as they primarily consist of SiO2. Nonanal can be detected through changes in the absorption spectrum of the sensor. An accumulate-type sensor was used in this study, which exhibited a linear relationship between the degree of absorption changes at 470 nm and nonanal concentration in the 60 ppb-1.3 ppm range. Therefore, this biological marker gas sensor is effective for the early diagnosis of diseases. The alkali-resistant porous glass sensor chip exhibited a higher degree of absorption change than the conventional porous glass sensor chip.