Emerging biosensing platforms based on metal–organic frameworks (MOFs) for detection of exosomes as diagnostic cancer biomarkers: case study for the role of the MOFs

Exosomes, which are considered nanoscale extracellular vesicles (EVs), are secreted by various cell types and widely distributed in different biological fluids. They consist of multifarious bioactive molecules and use systematic circulation for their transfer to adjoining cells. This phenomenon enables exosomes to take part in intercellular and intracellular communications. They serve as novel and important cancer biomarkers due to their ability to be obtained from various biological fluids and the presence of nucleic acids, proteins, glycoconjugates, and lipids in their structure. The advancement of sensitive and selective exosome detection approaches continues to be a critical challenge that must be addressed. Metal–organic frameworks (MOFs) are a class of 2D and 3D synthetic organic and crystalline nanomaterials, forming through the self-assembly of organic linking molecules and metal ions. The exploration of MOF-based molecules in the recognition of exosomes is an essential aspect in the development of cutting-edge sensing platforms due to their tunable pore structures, excellent adsorption capabilities, and high surface area. Their advantages allow for the inclusion of a large number of electroactive molecules and biological elements, thereby enhancing their electrical conductivity and selectivity, respectively. The synergetic effect of nanomaterials and bioreceptors allows for efficient detection probes. In this review, the different roles of MOFs in the biosensing of exosomes are highlighted, providing a comprehensive understanding of biosensing approaches in this area. In addition, probes based on MOFs and different bioreceptors are investigated for detecting these important cancer biomarkers. The current gaps in this field and future perspectives are discussed.