# In silico study of the sensing properties of C18, B9N9, and Al9N9 nanorings for diabetes monitoring via indole detection in exhaled breath

## TL;DR

This study explores nanoring structures for detecting indole in exhaled breath to monitor diabetes non-invasively.

## Contribution

The paper introduces a computational comparison of C18, B9N9, and Al9N9 nanorings for indole sensing in diabetes monitoring.

## Key findings

- B9N9 showed the highest adsorption energy and electrical conductivity for indole detection.
- Al9N9 exhibited a significant red shift in UV–Vis spectra, enabling colorimetric sensing.
- C18 had the weakest interaction with indole among the tested nanorings.

## Abstract

Detecting indole in exhaled breath has immense promise for non-invasive diabetes monitoring. Here, we pursued a computational evaluation of the performance of C18, B9N9, and Al9N9 nanoring structures as sensors for indole. The evaluated processes included Density Functional Theory calculations, Quantum Theory of Atoms in Molecules analysis, Non-Covalent Interaction studies, and UV–Vis spectral analysis, to interpret electronic interactions and adsorption between indole and sensors. The findings suggested that B9N9 showed the most significant interaction with indole, with the highest adsorption energy (− 20.71 kcal/mol) and longest recovery time (1.54 × 103 s), indicating its superior sensitivity. Al9N9 performed moderately, while C18 had the lowest interaction with indole. Furthermore, B9N9 showed a significant increase in electrical conductivity (2.81 × 109–2.88 × 109 S/m), making it an attractive candidate for electrochemical sensors. In the UV–Vis spectra, Al9N9@Indole showed a significant red shift of 87 nm, going from 376 to 463 nm. This change shifts it from the UV range into the visible spectrum, enabling a noticeable color change. Therefore, B9N9 is well-suited for electrochemical sensing due to its high sensitivity and fast response. Al9N9 is notable for its visible optical response, which makes it suitable for colorimetric sensing when indole is present.

The online version contains supplementary material available at 10.1038/s41598-025-33074-8.