Cellulose nanocrystal/polyacrylic acid nanofiber composite aerogels characterized by 3D porous structure for colorimetric detection of breath acetone.

Breath acetone (BrAce) has been validated as a biomarker for diabetes, playing a crucial role in the non-invasive diagnosis of the diabetes. In this study, cellulose nanocrystal/polyacrylic acid nanofiber composite aerogels loaded with thymol blue (CNC/TB@PAA NFAs), featuring a 3D porous structure, were firstly synthesized and employed as a novel gas-sensitive sensor for BrAce detection. The characterization results reveal that cellulose nanocrystals as a reinforcing nanofiller successfully maintain the 3D hierarchical pore structure stability. The more achievable diffusion of target gas through the interconnected pore channels inside the nanofiber aerogels enables rapid contact and interaction between probe molecules immobilized on the interface of nanofiber and target gas. Consequently, this significantly shortens the response time (2-min acetone gas exposure) and enhances sensing sensitivity. The distinctive reaction mechanism between loaded hydroxylamine sulfate and acetone endows CNC/TB@PAA NFAs with heightened selectivity, effectively eliminating interferences of other components in exhaled breath during colorimetric analysis. Additionally, the sensing performance analysis demonstrates a limit of detection and limit of quantification for acetone at 0.0516 ppm and 0.172 ppm, respectively, and a linear range of 0.2-10 ppm with determination coefficient of 0.9946. It is expected that the proposed CNC/TB@PAA NFA-based colorimetric sensor can be applied as a new strategy for daily health management in healthy people as well as a means of ancillary monitoring for patients with diabetes.