Interfacial reactivity-modulated fluorescent metal–organic frameworks for sensitive detection of interferon-γ towards tuberculosis diagnosis

A new aptamer-based method has been developed for interferon-γ (IFN-γ) detection by utilizing interface reactivity-modulated fluorescent metal–organic frameworks (MOFs). Specifically, the binding of IFN-γ to its aptamer decreases the interface reactivity between the biotin-labeled aptamer and the streptavidin-functionalized magnetic beads by generating significant steric effects. As a result, several biotin-labeled aptamers escape from the enrichment of magnetic beads and remain in the supernatant, which subsequently undergo the terminal deoxynucleotidyl transferase-catalyzed polymerization elongation. Along with the elongation, pyrophosphate is continuously produced as the by-product, triggering the decomposition of fluorescent MOFs to generate a remarkable fluorescent response with the excitation/emission wavelength of 610 nm/685 nm. Experimental results show that the method enables the detection of IFN-γ in the range 0.06 fM to 6 pM with a detection limit of 0.057 fM. The method also displays high specificity and repeatability with an average relative standard deviation of 2.04%. Moreover, the method demonstrates satisfactory recoveries from 96.3 to 105.5% in serum samples and excellent utility in clinical blood samples. Therefore, this work may provide a valuable tool for IFN-γ detection and is expected to be of high potential in tuberculosis diagnosis in the future. Graphical Abstract