Flower-like ZIF-L@Au NTs composite integrated with enrichment-enhancement ability for SERS detection of lung cancer VOC biomarker

Background: Volatile organic compounds (VOCs) in human exhaled breath serve as molecular fingerprints that reflect metabolic dysregulation and can indicate the onset and progression of diseases such as lung cancer. Surface-enhanced Raman scattering (SERS), characterized by its high sensitivity, molecular specificity, and tolerance to humidity, offers a promising approach for breath analysis. However, the intrinsically weak Raman activity of exhaled biomarkers and poor gas adsorption on solid substrates still hinder its practical implementation. Therefore, it is essential to develop a SERS-based breath sensor that simultaneously enables signal amplification, gas enrichment, rapid operation, and cost-effectiveness. Results: This study presents a novel ultrasensitive SERS sensing platform based on a core-shell ZIF-L@Au NTs composite, integrating high sensitivity, selectivity, and rapid detection capabilities. The anisotropic gold nanotriangles (Au NTs), serving as the plasmonic core, exhibit excellent structural stability and strong electromagnetic field enhancement. The outer ZIF-L metal-organic framework (MOF) shell facilitates the selective adsorption and pre-enrichment of target analytes, while its confinement effect synergistically amplifies the SERS signal, markedly improving detection sensitivity. As a result, the system enables reliable quantification of 4-ethylbenzaldehyde in the concentration range of 10⁻⁴-10⁻⁸ M, achieving a detection limit down to the sub-ppm level with high stability and repeatability. Simulated detection of the potential lung cancer biomarker 4-ethylbenzaldehyde demonstrated the platform's strong enrichment capability and outstanding sensing performance. Significance: This work establishes an ascorbic-acid-directed strategy to construct flower-like ZIF-L and, for the first time, integrates gold nanotriangles with a metal-organic framework into a core-shell ZIF-L@Au NTs SERS platform. The synergistic combination of MOF-based gas enrichment, sharp-tip plasmonic hot spots and 4-ATP/aldehyde chemistry enables sub-ppm level detection of exhaled 4-ethylbenzaldehyde, highlighting a promising route for non-invasive breath diagnostics.