Light-Regulated Electrochemical Reaction Assisted Core-Shell Heterostructure for Detecting Specific Volatile Markers with Controllable Sensitivity and Selectivity.

Breath analysis has been considered a noninvasive, safe, and reliable way to diagnose cancer at very early stage. Rapid detection of cancer volatile markers in breath samples via a portable sensing device will lay the foundation of future early cancer diagnosis. Nevertheless, unsatisfactory sensitivity and specificity of these sensing devices restrain the clinical application of breath analysis. Herein, we proposed the strategy of designing the light-regulated electrochemical reaction assisted core-shell heterostructure to address the issue of concern; that is, the photoactive shell will be designed for trigging the light-regulated electrochemical reaction and enhancing the sensitivity while a catalytic active core will play the function of removing interference gases. After screening of various core candidates, Fe2O3 was found to exhibit relatively low conversion rate to 3-methylhexane, which is one of the representative volatile markers for breath analysis, suggesting that mutual interference would be eliminated by Fe2O3. Based on this assumption, an electrochemical sensor comprising core-shell Fe2O3@ZnO-SE (vs Mn-based RE) was fabricated and sensing properties to 6 kinds of volatile markers was evaluated. Interestingly, the thickness of ZnO shell significantly influenced the response behavior; typically, the Fe2O3@ZnO with shell thickness of 4.8 nm offers the sensor high selectivity to 3-methylhexane. In contrast, significantly mutual response interference is observed for the Fe2O3@ZnO with extremely thick/thin shell. Particularly, sensing properties are greatly enhanced upon illumination; a detection limit to 3-methylhexane can even be as low as 0.072 ppm which will be useful in clinic application. Besides, the high selectivity of the sensor to 3-methylhexane is further confirmed by the testing of simulated breath samples. In summary, we anticipate that the strategy proposed in this research will be a starting point for artificially tailoring the sensitivity and selectivity of future sensing devices.