Simultaneous Imaging of Zn²⁺ and Cu²⁺ in Living Cells Based on DNAzyme Modified Gold Nanoparticle

Abstract

Trace Zn(2+) and Cu(2+) in living cells play important roles in the regulation of biological function. It is significant to simultaneously detect the cellular Zn(2+) and Cu(2+). Here, we present a novel two-color fluorescence nanoprobe based on the DNAzymes for simultaneous imaging of Zn(2+) and Cu(2+) in living cells. The probe consists of a 13 nm gold nanoparticle, DNAzymes that are specific for Zn(2+) and Cu(2+), and the substrate strands labeled with fluorophores at the 5' end and quenchers at the 3' end. The fluorescence of the fluoreophores is quenched both by the gold nanoparticle and the quencher. After the nanoprobes are transferred into the cells, the substrate strands would be cleaved in the presence of the Zn(2+) and Cu(2+) target, resulting in disassociation of the shorter DNA fragments containing fluorophores, which produce fluorescence signals correlated with the location and concentration of the Zn(2+) and Cu(2+). The nanoprobe exhibits high specificity, nuclease stability, and good biocompatibility. Moreover, the nanoprobe can simultaneously monitor the cellular Zn(2+) and Cu(2+) with an on-site manner, providing the information on localization and concentration of targets, which is significant to further research the Zn(2+)- and Cu(2+)-relative cellular events and biological process. The proposed method has shown great potential in the detection of multiple metal ions in living cells, which may help us to better understand the function of metal ions in the fields of biochemistry, molecular biology, and cellular toxicology.

Theranostic DNAzymes

“…The sensor can detect low micro molar UO 2 2+ in buffer and image 100 μM UO 2 2+ in living cell, while the inactive mutant DNAzyme showed much less intracellular fluorescence. Tang and coworkers similarly adsorbed two DNAzymes on the same nanoparticle for simultaneous imaging Zn 2+ and Cu 2+ in living cells, which can detect metal concentration lower than 2 μM 98.…”

Proximity hybridization triggered strand displacement and DNAzyme assisted strand recycling for ATP fluorescence detection in vitro and imaging in living cells

“…23,24 And it showed broad prospects for in situ detection of intracellular analytes because no additional tool enzyme is required. [25][26][27] Recently, a TAMRA-tagged substrate strands hybridized to DNAzyme strands functionalized gold nanoparticle probe was designed for in situ uorescence imaging and detection of cytoplasmic ATP activity. 25 Only the target molecule can activate the DNAzyme and then cleave and release the uorophore-labeled substrate strands from the AuNP, resulting in uorescence enhancement.…”

A rapid and visual turn-off sensor for detecting copper (II) ion based on DNAzyme coupled with HCR-based HRP concatemers

“…Cu 2+ -specific DNAzyme, which belongs to DNA-cleaving DNAzyme with the characteristics of easy synthesis, lower cost and better stability, leads to site-specific cleavage at the guanine position of the substrate in catalytic/substrate multiple strands, which makes it an ideal element for Cu 2+ ion detection due to inherent advantages of outstanding stability under harsh conditions and high selectivity comparable to antibodies143940. Over the past decade, different DNAzyme-based biosensors for Cu 2+ using various signal transduction methods have been developed, including fluorescence4142, colorimetry39424344 and lateral flow nucleic acid techniques45. Such DNAzyme-based sensing strategies require simpler apparatus and less professional personnel than traditional techniques.…”