Disulfide Compound-Impregnated Paper Substrate-Based Highly Efficient Colorimetric Gas Sensor for Detection of Volatile Sulfur Compounds in Noninvasive Breath Analysis

Volatile sulfur compounds (VSCs) are prevalent human biogases detectable in individuals with periodontal disease; therefore, measuring VSC gases in human breath can yield significant, noninvasive diagnostic information indicative of such diseases. In this study, we developed a gas sensor with selective and enhanced sensing capabilities for VSCs methyl mercaptan and hydrogen sulfide. This sensor comprises a cellulose paper substrate impregnated with 2,2'-dithiobis(5-nitropyridine) and sodium acetate. Upon exposure to VSC gases, the initially white sensor element was reversibly changed to yellow. A peak in the diffused reflectance spectrum was noted at 420 nm, establishing a linear relationship between the Kubelka-Munk (K-M) values at 420 nm and the VSC exposure concentration. The sensor demonstrated high sensitivity to methyl mercaptan and hydrogen sulfide with detection limits of 45 and 7.1 ppb in a 1 L volume, respectively. Furthermore, colorimetric analysis of the sensor element images indicated a negative correlation between the K-M value at 420 nm and the B/R value, enabling the calculation of VSC concentration based on the sensor's color change. The cost-effective paper-based sensor simplifies implementation in clinical applications and provides an assay ideally suited for point-of-care.