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.