Metal-organic frameworks in sample preparation for clinical applications - A review

The sample preparation step is one of the main challenges in clinical analysis considering the complexity of the biological samples. Exploring new materials as extraction phases is one of the main strategies to improve the efficiency and selectivity. Among them, metal-organic frameworks (MOFs) have attracted a lot of attention due to their high surface and structural and chemical versatility. Despite their diversity, most studies use the already well-known MOFs as extraction phases, and little is established about the desired features for specific analysis.

This overview shows the influence of metal center, ligand, surface post-functionalization and porosity for enhancing the selectivity for specific analytes via different interactions and size-exclusion mechanisms. Furthermore, oversights in sorbent design and method development are discussed considering the peculiarities and requirements of clinical analysis. This includes the impact of the sample matrix, the combination with other materials, the comparison with conventional phases and the selection of the (micro)extraction technique.

This article provides insights into the selection of the MOF-based extraction phase considering the physicochemical characteristics of the analytes, the properties of the MOFs and the possible interactions between them. The challenges in implementing these new extraction phases in clinical analysis are discussed with the aim of improving the design and the method development, while maximizing the efforts towards clinical translation.