Unleashing the potential of UiO-66-NH2 nanozyme: A novel approach to exosomal biomarkers detection in body fluids

Exosomes, a subgroup of extracellular vesicles (EVs), are gaining their position as promising tools for diagnostic and treatment purposes. Their widespread application is however hindered by the lack of cost-effective and straightforward methods for detection and characterization. Addressing this challenge, our study introduces a colorimetric nanosensor utilizing a UiO-66-NH₂ nanozyme (UiO-66-NH₂ NZ) for the detection of exosomes. The nanozyme was synthesized successfully and characterized using various techniques including XRD, FTIR, EDS, TEM, DLS, and zeta potential. For this purpose, exosomes from human TERT-immortalized MSCs (hTERT-MSCs) were extracted and then characterized using FE-SEM imaging, AFM imaging, DLS analysis, zeta potential measurement, and flow cytometry for specific markers. The efficacy of UiO-66-NH₂ NZs was tested for conditioned cell culture medium and human blood plasma. In this way, the limits of detection (LOD) and the trend of response for different concentrations of exosomes were defined. Based on a colorimetric analysis, at lower exosome concentrations, the nanozyme induced a visible color shift from colorless to green-blue within two minutes. The selectivity of our method was validated by comparing exosome concentrations with those of exosome lysates and cell suspensions. Further assessment was conducted by confirming the suitability of the test for the samples from blood plasma, with potential applications at the clinical level. Compared with CD63 aptamer-modified nanozymes, the utility of bare UiO-66-NH₂ NZs in exosome detection was prominent. The rapid detection of exosomes from HT-29 colorectal adenocarcinoma cells and HFF fibroblastic cells confirmed the suitability of this assay as a promising approach for developing specific exosome-based clinical applications.