Framework Nucleic Acid-Mediated DNAzyme Chaperoning for Sensitive Trace Metal Ion Mapping on Live Neuronal Cell Membranes.

The transient release of metal ions at neuronal cell membranes holds significant implications in neurophysiology and pathology. Consequently, there is a pressing need for sensitive methodologies capable of quantitatively mapping local metal ion concentrations in live cells, aiming to unravel potential mechanisms underlying neurological disorders. DNAzymes have emerged as versatile tools for metal ion detection in live cells, owing to their specificity and other inherent advantages. Efforts to broaden their utility have focused on enhancing the stability and sensitivity of DNAzymes. Inspired by the beneficial effects of molecular chaperones on the stability and functionality of proteins, we present in this study the development of tetrahedral DNA frameworks (TDF) as chaperones for DNAzymes, aiming at enhancing the stability and activity of DNAzymes. Integration of TDF with DNAzymes is shown to significantly enhance metal ion detection performance, resulting in elevated stability and a two-fold increase in sensitivity, attributed to alterations in the local net charge induced by TDF. In vitro investigations demonstrate that the nanodevice developed here faithfully maps Cu2+ concentrations within a range of 0-10 µM on the membrane of neuronal cells, meeting the requirements for Cu2+ sensing under both physiological and pathological conditions. This work presents an easily adaptable approach to enhance the performance of DNAzymes and lays the foundations for the development of other DNAzyme-based sensitive detection nanodevices.