Halogenated hydrocarbons are also of significant interest for environmental monitoring since they are the main components (sometimes even the only one) of agrochemicals, and their detection by MOF-based SERS platforms has also been explored. Although with lower volatility compared to other VOCs, they can be found in the atmosphere as aerosols or in particulate material, that can be later deposited on the soil, water courses, and even our skin, not to mention their inhalation. An example of this halogenated hydrocarbon is the hexachlorocyclohexane (HCH), a pesticide banned by EPA in 2006 but still found in water courses and soil. This is the case of the work of Zhou et al., where they have explored the development of a core-shell structure where ~100 nm urchin-like Au-Ag alloyed nanocrystals (UAANs) are wrapped by ZIF-8 with controllable thickness between 10 to 40 nm, as depicted in Figure -i. In their work, the authors have optimized the shell thickness at 20 nm, which presented an enhancement factor of 3.10 7 . Although the porous structure of ZIF-8 limits the diffusion of the HCH towards the surface of the UAANs, requiring almost 10 h to reach a stable intensity of the Raman signal (Figure -ii), they show the final intensity to be almost double than for the bare UAANs, reaching a detection limit of 5.10 -9 M (equivalent to 1.5 ppb).