Simple and Sensitive Detection of Bacterial Hydrogen Sulfide Production Using a Paper-Based Colorimetric Assay.

Hydrogen sulfide (H ₂ S) is known to participate in bacteria-induced inflammatory response in periodontal diseases. Therefore, it is necessary to quantify H ₂ S produced by oral bacteria for diagnosis and treatment of oral diseases including halitosis and periodontal disease. In this study, we introduce a paper-based colorimetric assay for detecting bacterial H ₂ S utilizing silver/Nafion/polyvinylpyrrolidone membrane and a 96-well microplate. This H ₂ S-sensing paper showed a good sensitivity (8.27 blue channel intensity/μM H ₂ S, R ² = 0.9996), which was higher than that of lead acetate paper (6.05 blue channel intensity/μM H ₂ S, R ² = 0.9959). We analyzed the difference in H ₂ S concentration released from four kinds of oral bacteria ( Eikenella corrodens , Streptococcus sobrinus , Streptococcus mutans , and Lactobacillus casei ). Finally, the H ₂ S level in Eikenella corrodens while varying the concentration of cysteine and treatment time was quantified. This paper-based colorimetric assay can be utilized as a simple and effective tool for in vitro screening of H ₂ S-producing ability of many bacteria as well as salivary H ₂ S analysis.