As one of the most prevalent diseases in the world, timely early intervention for periodontitis is a great challenge because the indicator is imperceptible. The exhaled H2S is considered to be a promising biomarker for fast and invasive periodontitis screening; however, the high-performance H2S gas sensor with excellent selectivity and sensitivity which is applicable to the oral cavity remains technically challenging. Herein, a self-assembled monolayer (SAM)-functionalized Au/In2O3 nanofiber (NF) sensor for H2S exhalation analysis was developed to flexibly and effectively modulate the selectivity of the sensor. Through optimizing the specific binding capacity to H2S by systematic adjustment with terminal groups and alkyl chains of SAMs, the sensing performance of the SAM-functionalized Au/In2O3 NF sensor is greatly enhanced. In the optimal (Au/In2O3-MPTES) sensor, the functionalization of the MPTES molecule could achieve significant response enhancement because of the stronger interaction between the sulfhydryl group at the end of the MPTES and H2S. Density functional theory simulation supports the proposed selective sensing mechanism via the analysis of adsorption energy and charge density distribution. The sensor exhibited a high response to H2S (1505.3–10 ppm) at an operating temperature of 100 °C with a low practical detection limit of 10 ppb and 13–145 fold enhanced selectivity. Furthermore, the Au/In2O3-MPTES sensor was successfully applied to distinguish the breath of healthy individuals and patients with severe periodontitis. This study provides novel design insights for the development of highly selective gas sensors for clinical aids in the diagnosis and detection of oral diseases such as periodontitis.

Nowadays the multifunctional approaches to kill oral bacteria based on various nanocomposites have made great progress against periodontal infections, while the material structure and its functional integration are still insufficient. Herein, this work proposes a therapeutic strategy of chemodynamical therapy (CDT) and photothermal therapy (PTT) in monocrystals to effectively enhance the synergistic treatment. The CuS/MnS@MnO 2 consisting of hexagonal CuS/MnS nano-twin-crystal with a shell layer of MnO 2 is developed. In this nanosystem, the purpose of synergistic treatment of periodontitis by combining PTT/CDT is achieved within a CuS/MnS monocrystal, where CuS serves to achieve photothermal conversion, dissipate the biofilm and transfer the heat in situ to the integrated MnS, thus promoting the Mn 2+ -mediated CDT process. Meanwhile, the CDT process can generate the highly toxic hydroxyl radical to destroy extracellular DNA by utilization of endogenous H 2 O 2 produced by Streptococci in the oral biofilm, cooperating with PTT to dissipate the bacterial biofilm. With the design of the outer shell of MnO 2 , the selective bacteria-killing can be realized by producing oxygen which can protect the periodontal non-pathogenic aerobic bacteria and threaten the survival of anaerobic pathogens. Therefore, such design via multipattern strategies to combat microorganisms would provide a bright prospect for the clinical treatment of bacterial infections.