Nanometric Surface-Selective Regulation of Au/In₂O₃ Nanofibers as an Exhaled H₂S Chemiresistor for Periodontitis Diagnosis

Abstract

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.

Target-Driven Z-Scheme Heterojunction Formation for ppb H2S Detection from Exhaled Breath at Room Temperature

“…Encouraged by the ultralow response concentration toward H 2 S and excellent anti-interference ability of the as-proposed TCN, we measured the oral H 2 S levels of healthy volunteers before and after brushing. As shown in Figure e, the average response of the as-proposed sensing device to morning exhalation (the tester did not brush the teeth) was recorded as 2.7 under UV-light irradiation, corresponding to 75 ppb H 2 S. This value is consistent with the previously reported physiological halitosis (morning halitosis) . Notably, the concentration of H 2 S in the oral cavity decreased substantially after brushing.…”

“…As shown in Figure 3e, the average response of the as-proposed sensing device to morning exhalation (the tester did not brush the teeth) was recorded as 2.7 under UV-light irradiation, corresponding to 75 ppb H 2 S. This value is consistent with the previously reported physiological halitosis (morning halitosis). 35 Notably, the concentration of H 2 S in the oral cavity decreased substantially after brushing. There was only a slight fluctuation of the H 2 S level in the oral cavity 12 h after brushing.…”

“…The unique functional group (−NH 2 ) on TiO 2 /Co-MOF is favorable for selective detection of H 2 S molecules. 35 Importantly, the formation of Zscheme heterojunctions between TiO 2 and Co-MOF facilitates the effective separation of electrons and holes, thus triggering the sensing reaction under UV irradiation. Such a sensing device can be fabricated on a flexible Ti base (Scheme 1c).…”

Review and Perspective: Gas Separation and Discrimination Technologies for Current Gas Sensors in Environmental Applications

“…CuO nanoparticle-coated TiO 2 nanochannels were reported by Song et al as a remarkably sensitive sensor for detecting H 2 S . In the same way, Xu et al applied Au modified In 2 O 3 nanofiber sensor for H 2 S detection . Gao et al reported a WO 3 nanoplate MOS sensor with significantly higher selectivity for cyclohexene than for other VOCs, such as benzene, ethanol, and acetone …”

“…68 CuO nanoparticle-coated TiO 2 nanochannels were reported by Song et al as a remarkably sensitive sensor for detecting H 2 S. 69 In the same way, Xu et al applied Au modified In 2 O 3 nanofiber sensor for H 2 S detection. 70 Gao et al reported a WO 3 nanoplate MOS sensor with significantly higher selectivity for cyclohexene than for other VOCs, such as benzene, ethanol, and acetone. 71 It is worth noting that polyoxometalates (POMs) and colloidal quantum dots (CQDs) have been investigated as sensing materials to improve the selectivity and sensitivity of MOSs.…”